A device and method for preparing spiral auxetic fiber with stable initial structure

Abstract

The present invention discloses a device and method for preparing spiral auxetic fibers with a stable initial structure, belonging to the technical field of building fiber preparation. The device comprises a core fiber feeding control mechanism, a wrapping fiber feeding control mechanism, a spiral auxetic fiber forming and winding mechanism, and a fiber cutting mechanism, which are sequentially arranged. A glue dripping mechanism is provided above one end of the fiber cutting mechanism. The core fiber feeding control mechanism comprises a core fiber tube, a fiber feeding roller, a tension disk, and a fiber guide tube. The core fiber tube is placed on the fiber feeding roller, and the fiber guide tube is arranged above the tension disk. The end of the core fiber on the core fiber tube is wound around the tension disk and fed vertically from the bottom of the fiber guide tube into the wrapping fiber feeding control mechanism. This technical solution prepares spiral auxetic fibers with a uniform and stable initial structure and a significant negative Poisson's ratio effect through physical consolidation and chemical bonding. The fibers are then cut into short spiral auxetic fiber segments for convenient application in concrete.

Description

Technical Field

[0001] The present invention belongs to the technical field of preparation of building fibers, and in particular relates to a device and method for preparing spiral auxetic fibers with a stable initial structure. Background Art

[0002] The application of fibers in the field of civil engineering is mainly concentrated in the reinforcement of concrete. Usually, fibers play a role in the form of incorporation into concrete. When the concrete structure is subjected to external loads, the fibers connect the two sides of the crack through a bridging effect, effectively absorbing and dispersing stress, thereby reducing the width and number of cracks. In addition, the bonding force between the fibers and the matrix can disperse local high stress to a larger area, reduce stress concentration, and thus improve the overall strength and toughness of the concrete. At present, fiber-reinforced concrete mainly adopts the method of single fiber incorporation or mixed incorporation of multiple fibers. However, the incorporation of a single fiber has the disadvantage of a single and limited reinforcement effect, while the mixed incorporation of multiple fibers makes it difficult to fully exert the synergistic reinforcement effect of the mixed fibers. Spiral tensile fiber is a multi-component fiber, and its unique negative Poisson's ratio effect enables it to play a role in concrete.

[0003] Patent CN108558312A involves wrapping a layer of epoxy resin around the outer layer of a synthetic upper spiral expansion fiber and curing it. After air drying, the fiber is cut into 2.5±0.5mm long fiber segments and added to concrete. Although the resin curing can improve its performance and stabilize its structure, the cured fiber is relatively hard, which affects the effective negative Poisson's ratio effect and limits its application in concrete.

[0004] Therefore, the preparation method of the existing short-cut spiral expansion fibers is innovated to solve the problems of unclear negative Poisson's ratio effect and unstable initial structure after being cut into short fibers. A simple and universal preparation method is urgently needed to produce spiral expansion fibers with obvious negative Poisson's ratio effect and stable initial structure to promote their application in the field of concrete. Summary of the Invention

[0005] In view of this, the object of the present invention is to provide a device and method for preparing spiral auxetic fibers with a stable initial structure, wherein the wrapping fibers and core fibers are formed into spiral auxetic fibers with a uniform and stable initial structure and a significant negative Poisson's ratio effect by physical consolidation and chemical bonding, and then the fibers are cut into short spiral auxetic fibers by cutting to facilitate their application in concrete.

[0006] In order to achieve the above object, the present invention provides the following technical solutions:

[0007] The present invention provides a device for preparing spiral auxetic fibers with a stable initial structure, comprising a core fiber feeding control mechanism, a wrapping fiber feeding control mechanism, a spiral auxetic fiber forming and winding mechanism, and a fiber cutting mechanism, which are arranged in sequence. A glue dripping mechanism is provided above one end of the fiber cutting mechanism.

[0008] The core fiber feeding control mechanism includes a core fiber tube, a fiber feeding roller, a tension disk and a fiber guide tube. The core fiber tube is placed on the fiber feeding roller, and the fiber guide tube is arranged above the tension disk. The end of the core fiber on the core fiber tube is wound around the tension disk and is vertically fed into the wrapping fiber feeding control mechanism from the bottom of the fiber guide tube.

[0009] The wrapping fiber feeding control mechanism includes a base and a plurality of wrapping fiber tubes; the spiral auxetic fiber forming and winding mechanism includes a convergence hole, a first fiber guide roller, and a second fiber guide roller; the base is rotatably arranged, the fiber guide tube is arranged in the middle of the base, and a plurality of the wrapping fiber tubes are evenly distributed on the circumference of the base; the convergence hole is arranged above the wrapping fiber tube, and the wrapping fibers on the plurality of wrapping fiber tubes are spirally wrapped around the surface of the core fiber at the convergence hole to form spiral auxetic fibers, and the ends of the spiral auxetic fibers are sequentially wound around the first fiber guide roller and the second fiber guide roller, and the second fiber guide roller drives the ends of the spiral auxetic fibers to move toward the position of the cutting limit mechanism;

[0010] The fiber cutting mechanism includes a guide rail, a movable knife, and a fixed knife. The guide rail is used to transport the spiral auxetic fiber. The movable knife and the fixed knife are arranged behind one end of the guide rail away from the spiral auxetic fiber to cut the spiral auxetic fiber.

[0011] The glue dripping mechanism is arranged above one end of the guide bar close to the spiral auxetic fiber, and includes a glue dripping needle tube, which is used to drip the internal glue onto the designated position of the spiral auxetic fiber.

[0012] Furthermore, the fiber cutting mechanism also includes a driving device, the movable knife is connected to the driving device, a shield is provided on the outside of the fiber cutting mechanism, a discharge port is provided at the rear end of the shield, and a containing box is provided below the discharge port.

[0013] Furthermore, there are two first fiber guide rollers, the two first fiber guide rollers are arranged at the same height, and the rotation directions of the two first fiber guide rollers are opposite.

[0014] Furthermore, the number of the second fiber guiding rollers is two, the two second fiber guiding rollers are vertically arranged opposite to each other, and the rotation directions of the two second fiber guiding rollers are opposite.

[0015] Furthermore, the core fiber on the core fiber tube is made of one of polypropylene, polyvinyl alcohol and glass fiber filaments, the number of the wrapping fiber tubes is 2-3, and the material of the wrapping fibers on the wrapping fiber tubes is metal or flexible fiber.

[0016] Furthermore, a glue coating mechanism is provided between the glue dripping mechanism and the fiber cutting mechanism, and the glue coating mechanism includes an arc-shaped gear ring, and a plurality of cylindrical gears evenly distributed around the circumference are provided on the outer side of the arc-shaped gear ring, and the cylindrical gears are meshed with the arc-shaped gear ring. An arc-shaped plate is provided at one end of the arc-shaped gear ring, and a plurality of driving motors are provided on the arc-shaped plate, and the driving motor is connected to one end of the cylindrical gear. An arc-shaped airbag is provided on the inner side surface of the arc-shaped gear ring, and one side of the arc-shaped airbag is fixed on the arc-shaped gear ring, and a sponge layer is bonded to the other side of the arc-shaped gear ring. An air pump is provided on the arc plate, and the output end of the air pump is connected to the interior of the arc-shaped airbag through an air pipe.

[0017] Furthermore, a stopper is provided on the other end of some of the columnar gears, and the stopper limits the translation of the arc-shaped gear ring.

[0018] A method for preparing a spiral auxetic fiber with an initial stable structure, when the wrapped fiber is made of metal, comprises the following preparation steps:

[0019] Step 1: Place the core fiber tube on the fiber feeding roller. The core fiber on the core fiber tube passes through the tension disk under the rotation of the fiber feeding roller and is fed vertically from the center of the bottom of the fiber guide tube. Then, the wrapping fiber is unwound from the wrapping fiber tube. The wrapping fiber unwound from the wrapping fiber tube passes through the convergence hole and converges with the core fiber to form a spiral auxetic fiber. The spiral auxetic fiber is then wound on the first fiber guide roller, passes through the middle of the second fiber guide roller, and is placed on the guide rail. Finally, the formed spiral auxetic fiber is transported and passed over the fixed knife.

[0020] Step 2: By operating the control system, the rotation speed of the first fiber guide roller and the second fiber guide roller is set to 1-2 r / min, each rotation is three seconds and the stop is one second, and the base continues to rotate at a speed of 10-20 r / min to obtain spiral auxetic fibers;

[0021] Step 3: Align a section of the spiral auxetic fiber that has been wound on the guide rail with the fixed knife after being wrapped with a metal wire hoop, start the movable knife drive device, adjust its speed to 1-2r / min, and make its speed the same as that of the second fiber guide roller. The movable knife cuts off the tight section of the spiral auxetic fiber, and the cut short spiral auxetic fiber is discharged from the end of the guide rail.

[0022] Furthermore, when the wrapping fiber is a flexible fiber, the preparation method includes the following steps:

[0023] Step 1: Place the core fiber tube on the fiber feeding roller. The core fiber on the core fiber tube is fed vertically from the center of the bottom of the fiber guide tube through the tension disk under the rotation of the fiber feeding roller. Then, the wrapping fiber is unwound from the wrapping fiber tube. The wrapping fiber unwound from the wrapping fiber tube passes through the convergence hole and converges with the core fiber to form a spiral auxetic fiber. The spiral auxetic fiber is then wound on the first fiber guide roller, passes through the middle of the second fiber guide roller, and is placed on the guide bar. Finally, the spiral auxetic fiber is transported and passed over the fixed knife.

[0024] Step 2: By operating the control system, the rotation speed of the first fiber guide roller and the second fiber guide roller is set to 1-3 / min, and the rotation speed of the base is set to 10-20r / min, and they continue to rotate during the whole process to obtain the spiral auxetic fiber;

[0025] Step 3: Turn on the glue dripping device, place the spiral auxetic fiber on the guide rail under the needle of the glue dripping device, and control the glue dripping device so that the needle drips a drop of glue every 3-5 seconds, so that the glue adheres to the surface of the spiral auxetic fiber, and the spiral auxetic fiber formed by glue dripping can be obtained;

[0026] Step 4: Align a certain glue-dripped section of the spiral auxetic fiber that has been glue-dripped and wound on the guide rail with the fixed knife, start the movable knife drive device, adjust its speed to 1-3r / min, and make its speed the same as that of the second fiber guide roller. The movable knife cuts off the glue-dripped section of the spiral auxetic fiber, and the cut short spiral auxetic fiber is discharged from the end of the guide rail.

[0027] Furthermore, the step 3 further includes the following steps:

[0028] When the glue dripping device drips glue into the gap of the arc-shaped gear ring, the air pump inflates the arc-shaped airbag to make the sponge layer contact the surface of the spiral expansion fiber. Then, the driving motor drives the gear ring to rotate reciprocatingly to coat the glue evenly on the surface of the spiral expansion fiber. After coating, the driving motor drives the arc-shaped gear ring to return to its initial position, and then the arc-shaped airbag is deflated to separate the sponge layer from the surface of the spiral expansion fiber.

[0029] The beneficial effects of the present invention are:

[0030] (1) The spiral tensile fiber line adopts a new winding method, which effectively improves the slippage phenomenon caused by different types of wrapped fibers and effectively prevents the untwisting of multiple fibers due to residual torque, thereby improving the wrapping effect and fiber strength;

[0031] (2) The fiber spinning method of the preparation device is simple, easy to operate, low in cost, and suitable for continuous production and promotion and application. At the same time, the preparation device can also select different consolidation methods according to the materials of different wrapped fibers to ensure the preparation effect of the spiral expansion fiber segments.

[0032] (3) The short-cut tensile composite fiber wire of the present invention has good shape, stable structure, unique performance, obvious tensile effect, and can be widely used in concrete.

[0033] Other advantages, objectives and features of the present invention will be described in the following description and will be apparent to those skilled in the art to some extent, or those skilled in the art can be taught from the practice of the present invention. The objectives and other advantages of the present invention can be realized and obtained through the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] In order to make the purpose, technical solutions and beneficial effects of the present invention more clear, the present invention provides the following drawings for illustration:

[0035] Figure 1 A schematic plan view of a device for preparing a spiral auxetic fiber with a stable initial structure according to the present invention;

[0036] Figure 2 Schematic diagram of a top view of the spiral auxetic fiber forming mechanism of the present invention;

[0037] Figure 3 Schematic diagram of the glue dispensing device of the present invention;

[0038] Figure 4 This is a schematic diagram of the movable knife driving device of the present invention;

[0039] Figure 5 Schematic diagram of the cutting of the spiral auxetic fiber hoop segment of the present invention (left figure) and the schematic diagram of the short fiber after cutting (right figure);

[0040] Figure 6 Schematic diagram of cutting of spiral auxetic fibers at the glue-drip point of the present invention (left figure) and schematic diagram of short fibers after cutting (right figure);

[0041] Figure 7 A three-dimensional schematic diagram of the gluing mechanism of the present invention from one viewing angle;

[0042] Figure 8 A three-dimensional schematic diagram of the gluing mechanism of the present invention from another perspective;

[0043] Figure 9 It is a schematic diagram of the front view and cross-sectional view of the gluing mechanism of the present invention.

[0044] The following are marked in the accompanying drawings:

[0045] 1-fiber feeding roller, 2-core fiber tube, 3-core fiber, 4-tension disk, 5-fiber guide tube, 6-base, 7-wrapped fiber tube, 8-wrapped fiber, 9-converging hole, 10-spiral expanded fiber, 11-first fiber guide roller, 12-second fiber guide roller, 13-glue dispensing needle, 14-glue, 15-glue dispensing needle, 16-guide rail, 17-fixed knife, 18-movable knife, 19-shield, 20-discharge port, 21-packing box; 22-bracket, 23-compressed gas, 24-control device, 25-drive gear, 26-arc plate, 27-arc gear ring, 28-column gear, 29-drive motor, 30-stopper, 31-arc airbag, 32-sponge layer, 33-air pump, 34-trachea. DETAILED DESCRIPTION

[0046] like Figures 1 to 6 As shown, the present invention provides a preparation device for spiral expanded fibers with a stable initial structure, comprising a fiber component feeding control structure, a spiral expanded fiber forming and winding mechanism, a glue dripping mechanism and a fiber cutting mechanism, the fiber line component feeding control structure comprising a core fiber feeding control mechanism and a wrapping fiber feeding control mechanism; the core fiber feeding control mechanism comprises a core fiber tube 2, a fiber feeding roller 1, a fixed frame and a fiber guide tube 5, the core fiber tube 2 is placed on the fiber feeding roller 1, a fiber guide hole is provided on one side of the fixed frame close to the core fiber tube 2, and a tension disk 4 is provided on the other side, the fiber guide tube 5 is provided above the tension disk 4, the core fiber 3 on the core fiber tube 2 can be vertically fed from the bottom center position of the fiber guide tube 5 through the fiber guide hole and the tension disk 4 on the fixed frame in sequence under the rotation of the fiber feeding roller 1; the wrapping fiber feeding control mechanism comprises a base 6 and a wrapping fiber 8 provided on the base 6, the spiral expanded fiber forming and winding mechanism comprises a converging hole 9 provided with a converging hole A gathering device (converging plate), a first fiber guide roller 11, a second fiber guide roller 12, and at least one wrapping fiber 8 are arranged around the fiber guide tube 5, and a converging hole 9 is arranged above the fiber guide tube 5 and the wrapping fiber 8. The wrapping fiber 8 unwound from the wrapping fiber 8 can be spirally wrapped around the core fiber 3 at the converging hole 9 to form a spiral expansion fiber 10, and the spiral expansion fiber 10 can pass through the first fiber guide roller 11 and the second fiber guide roller 12 in sequence; the glue dripping mechanism includes a control device 24, compressed gas 23, a glue dripping needle tube 15, glue 14, and a glue dripping needle head 13; the fiber cutting mechanism includes a guide bar 16, a movable knife 18 and a fixed knife 17, the movable knife 18 is installed on the movable knife seat, the movable knife seat is connected to the driving device, the fixed knife 17 is installed on the fixed knife seat, and the fixed knife seat is fixed on the bracket 22, a protective cover 19 is provided on the outside of the fiber cutting mechanism, and a discharge port 20 is provided at the rear end of the protective cover 19, and a packaging box 21 is placed below the discharge port 20.

[0047] Preferably, the core fiber 3 is one of polypropylene, polyvinyl alcohol and glass fiber filaments; the number of wrapping fibers 8 is 2-3, which are a kind of metal or flexible fiber, and can be monofilament or multifilament, and the same or different types of filaments can be selected according to the purpose.

[0048] Preferably, the diameter ratio of the core fiber 3 to the wrapping fiber 8 is greater than 1 and the tensile modulus ratio of the wrapping fiber 8 to the core fiber 3 is greater than 10.

[0049] Preferably, when the wrapping fibers 8 are metal, they are wrapped by physical consolidation; when the wrapping fibers 8 are flexible fibers, they are wrapped by chemical bonding.

[0050] Preferably, the core fiber 3 is controlled by the fiber feeding roller 1 and the tension disk 4 to control its feeding state, stable feeding speed and uniform fiber line tension.

[0051] Preferably, the wrapping fibers 8 on each wrapping fiber 8 are fed simultaneously and at the same speed.

[0052] Preferably, the driving device adopts an electric element, which is provided with a driving gear 25. The rotation of the driving gear 25 drives the movable knife 18 to move up and down. The specific driving structure is the existing technology. Of course, it can also be driven by a telescopic rod, which will not be described in detail here.

[0053] Preferably, the control system adopts PLC. The control system is used to operate and control the working procedures of the machine.

[0054] Preferably, there are two first fiber guide rollers 11, which are arranged on a horizontal plane and rotate in opposite directions.

[0055] Preferably, there are two second fiber guide rollers 12, which are arranged on a vertical plane and rotate in opposite directions.

[0056] Preferably, the bracket 22 is further provided with a guide rail 16 arranged in the horizontal direction, and the guide rail 16 cooperates with the second fiber guide roller 12, the fixed knife 17 and the movable knife 18 respectively.

[0057] like Figure 7-9As shown, preferably, a gluing mechanism is provided between the gluing mechanism and the fiber cutting mechanism, and the gluing mechanism includes an arc-shaped gear ring 27, and a plurality of cylindrical gears 28 evenly distributed around the circumference are provided on the outer side of the arc-shaped gear ring 27, and the cylindrical gears 28 are meshed with the arc-shaped gear ring 27. An arc-shaped plate 26 is provided at one end of the arc-shaped gear ring 27, and a plurality of driving motors 29 are provided on the arc-shaped plate 26. The driving motor 29 is connected to one end of the cylindrical gear 28, and an arc-shaped airbag 31 is provided on the inner side surface of the arc-shaped gear ring 27. One side of the arc-shaped airbag 31 is fixed on the arc-shaped gear ring 27, and a sponge layer 32 is bonded to the other side of the arc-shaped gear ring 27. An air pump 33 is provided on the arc plate 26, and the output end of the air pump 33 is connected to the interior of the arc-shaped airbag 31 through an air pipe 34.

[0058] The working principle of the above technical solution is:

[0059] When the glue 14 drips into the arc-shaped gear ring 27, it first contacts the upper surface of the spiral auxetic fiber 10 and then falls onto the sponge layer 32. At this time, it is only necessary to inflate the airbag using the air pump 33 to bring the sponge layer 32 into contact with the spiral auxetic fiber 10. The motor 29 and the cylindrical gear 28 are then driven to rotate, thereby driving the sponge layer 32 to rotate. The glue 14 on the sponge layer 32 is then applied to the spiral auxetic fiber 10, and then the entire structure is restored. The advantage of this arrangement is that it can evenly apply the glue 14 to the parts of the spiral auxetic fiber 10 that need to be glued, while ensuring the glue coating effect at the lower part of the spiral auxetic fiber 10, thereby ensuring the subsequent consolidation effect. The arc-shaped airbag 31 also has the advantage that when the glue 14 is not applied, it will not affect the movement of the spiral auxetic fiber 10. The sponge layer 32 also has the advantage that it can absorb residual glue 14, facilitating subsequent application and use. The sponge layer 32 can also be replaced at any time to ensure the glue coating effect.

[0060] Preferably, a stopper 30 is provided on the other end of the partial cylindrical gear 28 , and the stopper 30 limits the translation of the arc-shaped gear ring 27 to prevent the arc-shaped gear ring 27 from falling out.

[0061] Preferably, the air pump 33 fills the arc-shaped airbag 31 with hot air, that is, the hot air heats the arc-shaped airbag 31 and transfers the heat to the sponge layer 32, thereby preventing the residual glue 14 on the sponge layer 32 from solidifying and affecting the gluing effect of the spiral expansion fiber 10.

[0062] A method for preparing a spiral auxetic fiber with an initial stable structure, when the wrapped fiber is made of metal, comprises the following preparation steps:

[0063] Step 1: Place the core fiber tube 2 on the fiber feeding roller 1. The core fiber 3 on the core fiber tube 2 is fed vertically from the bottom center of the fiber guide tube 5 through the pulley and the tension disk 4 in sequence under the rotation of the fiber feeding roller 1; then unwind the wrapping fiber 8 from the wrapping fiber tube 7, and the wrapping fiber 8 unwound from the wrapping fiber tube 7 passes through the converging hole 9 of the converging device and converges with the core fiber 3 to form a spiral expansion fiber 10, which is then wound on the first fiber guide roller 11, and then passes through the middle of the second fiber guide roller 12 and is placed on the guide bar 16. Finally, the formed spiral expansion fiber 10 is transported and passed over the fixed knife 17.

[0064] Step 2: By operating the control system, the rotation speed of the first fiber guide roller 11 and the second fiber guide roller 12 is 1-2 r / min, rotating for three seconds and stopping for one second, and the rotation speed of the base 6 is 10-20 r / min and does not stop during the process, so as to obtain spiral expansion fiber.

[0065] Step 3: Align a section of the spiral auxetic fiber 10 wound on the guide rail 16 with the portion wound with the wire tie wrapping it, with the fixed knife 17. The movable knife drive device is started and its rotational speed is adjusted to 1-2 rpm, making it the same as the rotational speed of the second fiber guide roller 12. The movable knife 18 cuts the tied section of the spiral auxetic fiber, and the cut short spiral auxetic fiber falls from the discharge port 20 into the storage box 21.

[0066] Example 1 Preparation of polypropylene / steel spiral auxetic fibers with a diameter ratio of 3:1 and a wrapping angle of 15°;

[0067] Using the above-mentioned preparation device, a 0.9mm diameter polypropylene fiber and a 0.3mm diameter steel wire were selected as the core fiber and the wrapping fiber respectively. The specific steps include:

[0068] Step 1: Place the polypropylene fiber tube on the fiber feeding roller 1. The polypropylene fibers on the polypropylene fiber tube are fed vertically from the bottom center of the fiber guide tube 5 through the pulley and tension disk 4 in sequence under the rotation of the fiber feeding roller 1; then unwind the single steel wire from the steel wire tube, and the steel wire unwound from the steel wire tube passes through the converging hole 9 of the converging device and converges with the polypropylene fibers to form a spiral expansion fiber 10, which is then wound on the first fiber guide roller 11, and then passes through the middle of the second fiber guide roller 12 and is placed on the guide rail 16. Finally, the formed spiral expansion fiber is transported and passed over the fixed knife 17.

[0069] Step 2: By operating the control system, the rotation speed of the first fiber guide roller 11 and the second fiber guide roller 12 is set to 2 r / min, and they stop for one second. The rotation speed of the base 6 is set to 15 r / min without stopping, and the spiral expansion fiber 10 with a spacing of 50 mm between the tight hoop sections can be obtained.

[0070] Step 3: Align a section of the spiral auxetic fiber 10 wound on the guide rail 16, where the section is wrapped with a tight steel wire, with the fixed blade 17. The movable blade drive is activated and its rotational speed is adjusted to 2 rpm, the same as that of the second fiber guide roller 12. The movable blade 18 severs the tight section of the spiral auxetic fiber. The severed spiral auxetic fibers 18 fall from the discharge port 20 into the container 21. Each fiber is 50 mm long.

[0071] To verify the innovative contribution of this invention, tensile tests were conducted on short chopped spiral auxetic fibers to observe changes in their diameter and calculate the Poisson's ratio. First, a universal tensile machine was used to stretch 50mm short fibers. During the stretching process, the fiber changes were recorded by a camera. Stretching was completed until the spiral auxetic fibers broke. Computer software was then used to analyze the experimental results and calculate the Poisson's ratio. The fibers optimized using the method of this invention achieved a negative Poisson's ratio, with the initial strain being optimized from 10% to 2%, and the maximum negative Poisson's ratio being optimized to -3.61. The fibers exhibited a significant negative Poisson's ratio effect and a greater expansion effect. The chopped fibers exhibited high strength and stability, meeting the requirements for concrete applications.

[0072] Example 2 Preparation of polypropylene / double-strand steel wire spiral auxetic fibers with a diameter ratio of 3:1 and a wrapping angle of 15°;

[0073] The preparation apparatus of Example 1 was used, and one polypropylene filament with a diameter of 0.9 mm and two steel wires with a diameter of 0.3 mm were selected as the core fiber and the wrapping fiber, respectively. The specific steps included:

[0074] Step 1: Place the polypropylene fiber tube on the fiber feeding roller 1. The polypropylene fibers on the polypropylene fiber tube are fed vertically from the bottom center of the fiber guide tube 5 through the pulley and tension disk 4 in sequence under the rotation of the fiber feeding roller 1; then unwind the double-strand steel wire from the steel wire tube, and the double-strand steel wire unwound from the steel wire tube passes through the converging hole 9 of the converging device and converges with the polypropylene fibers to form a spiral expansion fiber 10, which is then wound on the first fiber guide roller 11, and then passes through the middle of the second fiber guide roller 12 and is placed on the guide rail 16. Finally, the formed spiral expansion fiber is transported and passed over the fixed knife 17.

[0075] Step 2: By operating the control system, the rotation speed of the first fiber guide roller 11 and the second fiber guide roller 12 is 2 r / min, each rotation is three seconds and the stop is one second. The rotation speed of the base 6 is 15 r / min and does not stop during the process. The spiral expansion fiber can be obtained with a spacing of 50 mm between the tight hoop sections.

[0076] Step 3: Align a section of the spiral auxetic fiber already wound on the guide rail 16 with the portion wrapped with a tight wire band with the fixed knife 17. Start the movable knife drive and adjust its speed to 2 rpm, making it the same speed as the second fiber guide roller 12. The movable knife 18 cuts the tight band section of the spiral auxetic fiber. The cut spiral auxetic fibers fall from the discharge port 20 into the storage box 21. Each fiber is 50 mm long.

[0077] To verify the innovative contribution of this invention, tensile tests were conducted on short chopped spiral auxetic fibers to observe changes in their diameter and calculate the Poisson's ratio. First, a universal tensile machine was used to stretch 50mm short fibers. During the stretching process, the fiber changes were recorded by a camera. Stretching was completed until the spiral auxetic fibers broke. Computer software was then used to analyze the experimental results and calculate the Poisson's ratio. The fibers optimized using this method achieved a negative Poisson's ratio with an initial strain of 2% and a maximum negative Poisson's ratio of -11.59. The negative Poisson's ratio effect was significant, and the fibers exhibited a greater expansion effect. The chopped fibers exhibited high strength and stability, meeting the requirements for concrete applications.

[0078] Example 3 Preparation of polypropylene / three-strand steel spiral auxetic fibers with a diameter ratio of 3:1 and a wrapping angle of 15°;

[0079] The preparation apparatus of Example 1 was used, and one polypropylene filament with a diameter of 0.9 mm and three steel wires with a diameter of 0.3 mm were selected as the core fiber and the wrapping fiber, respectively. The specific steps included:

[0080] Step 1: Place the polypropylene fiber tube on the fiber feeding roller 1. The polypropylene fibers on the polypropylene fiber tube are fed vertically from the bottom center of the fiber guide tube 5 through the pulley and tension disk 4 in sequence under the rotation of the fiber feeding roller 1; then unwind the three steel wires from the steel wire tube, and the three steel wires unwound from the steel wire tube pass through the converging hole 9 of the converging device and converge with the polypropylene fibers to form a spiral expansion fiber 10, which is then wound on the first fiber guide roller 11, and then passes through the middle of the second fiber guide roller 12 and is placed on the guide bar 16. Finally, the formed spiral expansion fiber is transported and passed over the fixed knife 17.

[0081] Step 2: By operating the control system, the rotation speed of the first fiber guide roller 11 and the second fiber guide roller 12 is 2 r / min for three seconds and stops for one second. The rotation speed of the base 6 is 15 r / min and does not stop during the process. The spiral expansion fiber can be obtained with a spacing of 50 mm between the tight sections.

[0082] Step 3: Align a section of the spiral auxetic fiber already wound on the guide rail 16 with the portion wrapped with a tight wire band with the fixed knife 17. Start the movable knife drive and adjust its speed to 2 rpm, making it the same speed as the second fiber guide roller 12. The movable knife 18 cuts the tight band section of the spiral auxetic fiber. The cut spiral auxetic fibers fall from the discharge port 20 into the storage box 21. Each fiber is 50 mm long.

[0083] To verify the innovative contribution of this invention, tensile tests were conducted on short chopped spiral auxetic fibers to observe changes in their diameter and calculate the Poisson's ratio. First, a universal tensile machine was used to stretch 50mm short fibers. During the stretching process, the fiber changes were recorded by a camera. Stretching was completed until the spiral auxetic fibers broke. Computer software was then used to analyze the experimental results and calculate the Poisson's ratio. The fibers optimized using the method of this invention achieved a negative Poisson's ratio with an initial strain of 2% and a maximum negative Poisson's ratio of -8.65. The fibers exhibited a significant negative Poisson's ratio effect and a greater expansion effect. The chopped fibers exhibited high strength and stability, meeting the requirements for concrete application.

[0084] Example 4 Preparation of polypropylene / double-strand steel wire spiral auxetic fibers with a diameter ratio of 3:1 and a wrapping angle of 10°;

[0085] The preparation apparatus of Example 1 was used, and one polyvinyl alcohol filament with a diameter of 0.9 mm and two steel wires with a diameter of 0.3 mm were selected as the core fiber and the wrapping fiber, respectively. The specific steps included:

[0086] Step 1: Place the polypropylene fiber tube on the fiber feeding roller 1. The polypropylene fibers on the polypropylene fiber tube are fed vertically from the bottom center of the fiber guide tube 5 through the pulley and tension disk 4 in sequence under the rotation of the fiber feeding roller 1; then unwind the double-strand steel wire from the steel wire tube, and the double-strand steel wire unwound from the steel wire tube passes through the converging hole 9 of the converging device and converges with the polypropylene fibers to form a spiral expansion fiber 10, which is then wound on the first fiber guide roller 11, and then passes through the middle of the second fiber guide roller 12 and is placed on the guide rail 16. Finally, the formed spiral expansion fiber is transported and passed over the fixed knife 17.

[0087] Step 2: By operating the control system, the rotation speed of the first fiber guide roller 11 and the second fiber guide roller 12 is 2 r / min, each rotation is three seconds and the stop is one second. The rotation speed of the base 6 is 10 r / min and does not stop during the process. The spiral expansion fiber can be obtained with a spacing of 50 mm between the tight hoop sections.

[0088] Step 3: Align a section of the spiral auxetic fiber 10 wound on the guide rail 16 with the portion wrapped with a tight steel wire band. Align the fixed blade 17 with the fixed blade. The movable blade drive is activated and adjusted to a rotational speed of 2 rpm, the same as that of the second fiber guide roller 12. The movable blade 18 severs the tight band section of the spiral auxetic fiber. The severed spiral auxetic fibers fall from the discharge port 20 into the container 21. Each fiber is 50 mm long.

[0089] To verify the innovative contribution of this invention, tensile tests were conducted on short chopped spiral auxetic fibers to observe changes in their diameter and calculate the Poisson's ratio. First, a 50mm short fiber was stretched using a universal tensile machine. During the stretching process, the fiber's changes were recorded using a camera. Stretching was completed until the spiral auxetic fibers broke. Computer software then analyzed the experimental results and calculated the Poisson's ratio. The fibers optimized using this method produced a negative Poisson's ratio with an initial strain of 21% and a maximum negative Poisson's ratio of -7.58. The negative Poisson's ratio effect was significant, and the fibers exhibited a greater expansion effect. The chopped fibers exhibited high strength and stability, meeting the requirements for concrete applications.

[0090] Example 5 Preparation of polypropylene / double-strand steel wire spiral auxetic fibers with a diameter ratio of 3:1 and a wrapping angle of 20°;

[0091] The preparation apparatus of Example 1 was used, and one polypropylene filament with a diameter of 0.9 mm and two steel wires with a diameter of 0.3 mm were selected as the core fiber and the wrapping fiber, respectively. The specific steps included:

[0092] Step 1: Place the polypropylene fiber tube on the fiber feeding roller 1. The polypropylene fibers on the polypropylene fiber tube are fed vertically from the bottom center of the fiber guide tube 5 through the pulley and tension disk 4 in sequence under the rotation of the fiber feeding roller 1; then unwind the double-strand steel wire from the steel wire tube, and the double-strand steel wire unwound from the steel wire tube passes through the converging hole 9 of the converging device and converges with the polypropylene fibers to form a spiral expansion fiber 10, which is then wound on the first fiber guide roller 11, and then passes through the middle of the second fiber guide roller 12 and is placed on the guide rail 16. Finally, the formed spiral expansion fiber is transported and passed over the fixed knife 17.

[0093] Step 2: By operating the control system, the rotation speed of the first fiber guide roller 11 and the second fiber guide roller 12 is 1 r / min, each rotation for three seconds and a stop for one second, and the rotation speed of the base 6 is 15 r / min and does not stop during the process, so that the spiral expansion fiber 10 can be obtained with a spacing of 50 mm between the tight sections.

[0094] Step 3: Align a section of the spiral auxetic fiber wound on the guide rail 16 with the fixed blade 17 after being wrapped with a tight steel wire. Start the movable blade drive and adjust its speed to 1 r / min, making it the same speed as the second fiber guide roller 12. The movable blade 18 cuts the tight section of the spiral auxetic fiber. The cut spiral auxetic fibers fall from the discharge port 20 into the container 21. Each fiber is 50 mm long.

[0095] To verify the innovative contribution of this invention, tensile tests were conducted on short chopped spiral auxetic fibers to observe changes in their diameter and calculate the Poisson's ratio. First, a 50mm short fiber was stretched using a universal tensile machine. During the stretching process, the fiber changes were recorded by a camera. Stretching was completed until the spiral auxetic fibers broke. Computer software was then used to analyze the experimental results and calculate the Poisson's ratio. The fibers optimized using the present invention exhibited a significant negative Poisson's ratio effect and a greater expansion effect. The chopped fibers exhibited high strength and stability, meeting the requirements for concrete applications.

[0096] Example 6 Preparation of polypropylene / double-strand steel wire spiral auxetic fibers with a diameter ratio of 2:1 and a wrapping angle of 15°;

[0097] The preparation apparatus of Example 1 was used, and one polypropylene filament with a diameter of 0.6 mm and two steel wires with a diameter of 0.3 mm were selected as the core fiber and the wrapping fiber, respectively. The specific steps included:

[0098] Step 1: Place the polypropylene fiber tube on the fiber feeding roller 1. The polypropylene fibers on the polypropylene fiber tube are fed vertically from the bottom center of the fiber guide tube 5 through the pulley and tension disk 4 in sequence under the rotation of the fiber feeding roller 1; then unwind the double-strand steel wire from the steel wire tube, and the double-strand steel wire unwound from the steel wire tube passes through the converging hole 9 of the converging device and converges with the polypropylene fibers to form a spiral expansion fiber 10, which is then wound on the first fiber guide roller 11, and then passes through the middle of the second fiber guide roller 12 and is placed on the guide rail 16. Finally, the formed spiral expansion fiber is transported and passed over the fixed knife 17.

[0099] Step 2: By operating the control system, the rotation speed of the first fiber guide roller 11 and the second fiber guide roller 12 is 3 r / min, each rotation for three seconds, and then stops for one second. The rotation speed of the base 6 is 15 r / min and does not stop during the process. The spiral expansion fiber can be obtained with a spacing of 50 mm between the tight hoop sections.

[0100] Step 3: Align a section of the spiral auxetic fiber wound on the guide rail 16 with the fixed blade 17 after being wrapped with a tight steel wire. Start the movable blade drive and adjust its speed to 3 rpm to make it the same as the speed of the second fiber guide roller 12. The movable blade 18 cuts the tight section of the spiral auxetic fiber. The cut spiral auxetic fibers fall from the discharge port 20 into the container 21. Each fiber is 50 mm long.

[0101] In order to verify the innovative contribution of the present invention, a tensile test was conducted on the fiber to observe the change in its diameter, and thus the Poisson's ratio was calculated. First, a universal stretching machine was used to stretch a 50mm short fiber line. During the stretching process, the change process of the fiber was recorded by a camera. The stretching was completed until the fiber broke. Then, the experimental results were analyzed using computer software to calculate the Poisson's ratio. The fiber line optimized by the method of the present invention produces a negative Poisson's ratio. The initial strain of the fiber line is optimized to 2%, and the maximum negative Poisson's ratio is optimized to -8.27. The negative Poisson's ratio effect of the fiber line is obvious, and it has a greater expansion effect. The fiber line has high strength and stability, which meets the requirements of concrete application.

[0102] Example 7 Preparation of polypropylene / double-strand steel wire spiral auxetic fibers with a diameter ratio of 4:1 and a wrapping angle of 15°;

[0103] The preparation apparatus of Example 1 was used, and one polypropylene filament with a diameter of 1.2 mm and two steel wires with a diameter of 0.3 mm were selected as the core fiber and the wrapping fiber, respectively. The specific steps included:

[0104] Step 1: Place the polypropylene fiber tube on the fiber feeding roller 1. The polypropylene fibers on the polypropylene fiber tube are fed vertically from the bottom center of the fiber guide tube 5 through the pulley and tension disk 4 in sequence under the rotation of the fiber feeding roller 1; then unwind the double-strand steel wire from the steel wire tube, and the double-strand steel wire unwound from the steel wire tube passes through the converging hole 9 of the converging device and converges with the polypropylene fibers to form a spiral expansion fiber 10, which is then wound on the first fiber guide roller 11, and then passes through the middle of the second fiber guide roller 12 and is placed on the guide rail 16. Finally, the formed spiral expansion fiber is transported and passed over the fixed knife 17.

[0105] Step 2: By operating the control system, the rotation speed of the first fiber guide roller 11 and the second fiber guide roller 12 is 2 r / min, each rotation for three seconds and a stop for one second, and the rotation speed of the base 6 is 20 r / min without stopping, so that the spiral expansion fiber can be obtained with a spacing of 50 mm between the tight sections.

[0106] Step 3: Align a section of the spiral auxetic fiber already wound on the guide rail 16 with the fixed blade 17 after being wrapped with a tight steel wire. The movable blade drive device is started and its speed is adjusted to 2 rpm, making it the same speed as the second fiber guide roller 12. The movable blade 18 severs the tight section of the spiral auxetic fiber. The severed spiral auxetic fibers 10 fall from the discharge port 20 into the container 21. Each fiber is 50 mm long.

[0107] To verify the innovative contribution of this invention, tensile tests were conducted on spiral auxetic fibers to observe changes in their diameter and calculate the Poisson's ratio. First, a 50mm short fiber strand was stretched using a universal stretching machine. During the stretching process, the fiber's changes were recorded using a camera. Stretching was completed until the spiral auxetic fibers broke. Computer software was then used to analyze the experimental results and calculate the Poisson's ratio. The fiber strand optimized using the method of this invention exhibited a significant negative Poisson's ratio effect and a greater expansion effect, demonstrating high strength and stability, meeting the requirements for concrete applications.

[0108] Example 8 Preparation of polyvinyl alcohol / double-strand steel wire spiral auxetic fibers with a diameter ratio of 3:1 and a wrapping angle of 15°;

[0109] The preparation apparatus of Example 1 was used, and one polyvinyl alcohol fiber with a diameter of 0.9 mm and two steel wires with a diameter of 0.3 mm were selected as the core fiber and the wrapping fiber, respectively. The specific steps included:

[0110] Step 1: Place the polyvinyl alcohol fiber tube on the fiber feeding roller 1. The polyvinyl alcohol fibers on the polyvinyl alcohol fiber tube are fed vertically from the bottom center of the fiber guide tube 5 through the pulley and tension disk 4 in sequence under the rotation of the fiber feeding roller 1; then unwind the double-strand steel wire from the steel wire tube, and the double-strand steel wire unwound from the steel wire tube passes through the convergence hole 9 of the convergence device and converges with the polyvinyl alcohol fibers to form a spiral expansion fiber 10, which is then wound on the first fiber guide roller 11, and then passes through the middle of the second fiber guide roller 12 and is placed on the guide bar 16. Finally, the formed spiral expansion fiber is transported and passed over the fixed knife 17.

[0111] Step 2: By operating the control system, the rotation speed of the first fiber guide roller 11 and the second fiber guide roller 12 is 2 r / min, each rotation is three seconds and the stop is one second. The rotation speed of the base 6 is 15 r / min and does not stop during the process. The spiral expansion fiber can be obtained with a spacing of 50 mm between the tight hoop sections.

[0112] Step 3: Align a section of the spiral auxetic fiber already wound on the guide rail 16 with the portion wrapped with a tight wire band with the fixed knife 17. Start the movable knife drive and adjust its speed to 2 rpm, making it the same speed as the second fiber guide roller 12. The movable knife 18 cuts the tight band section of the spiral auxetic fiber. The cut spiral auxetic fibers fall from the discharge port 20 into the storage box 21. Each fiber is 50 mm long.

[0113] To verify the innovative contribution of this invention, tensile tests were conducted on spiral auxetic fibers to observe changes in their diameter and calculate the Poisson's ratio. First, a 50mm short fiber strand was stretched using a universal stretching machine. During the stretching process, the fiber's changes were recorded using a camera. Stretching was completed until the spiral auxetic fibers broke. Computer software was then used to analyze the experimental results and calculate the Poisson's ratio. The fiber strand optimized using the present invention exhibited a significant negative Poisson's ratio effect and a greater expansion effect, demonstrating high strength and stability, meeting the requirements for concrete applications.

[0114] In one practicable manner, when the wrapping fiber is a flexible fiber, the preparation method includes the following steps:

[0115] Step 1: Place the core fiber tube 2 on the fiber feeding roller 1, and the core fiber 3 on the core fiber tube 2 is fed vertically from the bottom center of the fiber guide tube 5 through the pulley and the tension disk 4 in sequence under the rotation of the fiber feeding roller 1; then unwind the wrapping fiber 8 from the wrapping fiber tube 7, and the wrapping fiber 8 unwound from the wrapping fiber tube 7 passes through the converging hole 9 of the converging device and converges with the core fiber to form a spiral expansion fiber 10, which is then wound on the first fiber guide roller 11, and then passes through the middle of the second fiber guide roller 12 and is placed on the guide bar 16. Finally, the spiral expansion fiber 10 is transported and passed over the fixed knife 17.

[0116] Step 2: By operating the control system, the rotation speed of the first fiber guide roller 11 and the second fiber guide roller 12 is 1-3 / min, and the rotation speed of the base 6 is 10-20r / min. The rotation does not stop during the whole process, and the spiral expansion fiber 10 can be obtained.

[0117] Step 3: Turn on the glue-dropping device and place the spiral auxetic fiber on the guide rail 16 under the needle 13 of the glue-dropping device. Control the glue-dropping device so that the needle 13 drips a drop of glue every 3-5 seconds. The glue adheres to the surface of the spiral auxetic fiber, and the spiral auxetic fiber is formed.

[0118] Step 4: Align a certain glue-dripped section of the spiral auxetic fiber that has been glue-dripped and wound on the guide rail 16 with the fixed knife 17, start the movable knife drive device, and adjust its speed to 1-3 r / min, so that its speed is the same as that of the second fiber guide roller. The movable knife 18 cuts the spiral auxetic fiber at the glue-dripped section, and the cut short spiral auxetic fiber falls from the discharge port 20 into the storage box 21.

[0119] Preferably, the step 3 further includes the following steps:

[0120] When the glue dripping device drips the glue 14 into the notch of the arc-shaped gear ring 27, the air pump 33 inflates the arc-shaped airbag 31, causing the sponge layer 32 to contact the surface of the spiral auxetic fiber 10. The drive motor 29 then drives the gear ring to rotate back and forth, coating the glue 14 evenly on the surface of the spiral auxetic fiber 10. After coating is completed, the drive motor 29 drives the arc-shaped gear ring 27 to return to its initial position, and then the arc-shaped airbag 31 is deflated, causing the sponge layer 32 to separate from the surface of the spiral auxetic fiber 10.

[0121] Example 9 Preparation of polypropylene / single-strand carbon fiber spiral auxetic fibers with a diameter ratio of 3:1 and a wrapping angle of 15°;

[0122] The preparation device of Example 1 was used, and one polypropylene fiber with a diameter of 0.9 mm and one carbon fiber with a diameter of 0.3 mm were selected as the core fiber and the wrapping fiber respectively:

[0123] Step 1: Place the carbon fiber tube on the fiber feeding roller 1. The carbon fibers on the carbon fiber tube are fed vertically from the bottom center of the fiber guide tube 5 through the pulley and the tension disk 4 in sequence under the rotation of the fiber feeding roller 1; then unwind the wrapping fiber 8 from the wrapping fiber tube 7, and the wrapping fiber 8 unwound from the wrapping fiber tube 7 passes through the converging hole 9 of the converging device and converges with the carbon fibers to form a spiral tensile fiber 10, which is then wound on the first fiber guide roller 11, and then passes through the middle of the second fiber guide roller 12 and is placed on the guide bar 16. Finally, the spiral tensile fiber 10 is transported and passed over the fixed knife 17.

[0124] Step 2: By operating the control system, the rotation speed of the first fiber guide roller 11 and the second fiber guide roller 12 is 2 r / min, and the rotation speed of the base 6 is 15 r / min. The rotation does not stop during the whole process, and the spiral expansion fiber can be obtained.

[0125] Step 3: Turn on the glue dripping device and place the spiral auxetic fiber on the guide rail 16 under the needle 13 of the glue dripping device. Control the glue dripping device so that the needle 13 drips a drop of glue every 3 seconds, with a drop spacing of 50 mm. This will produce a formed spiral auxetic fiber.

[0126] Step 4: Align a certain glue-sprayed section of the spiral auxetic fiber that has been glue-sprayed and wound on the guide rail 16 with the fixed knife 17, start the movable knife drive device, and adjust its speed to 2 r / min, making its speed the same as that of the second fiber guide roller 12. The movable knife 18 cuts the spiral auxetic fiber at the glue-sprayed section. The cut short spiral auxetic fibers fall from the discharge port 20 into the storage box 21. The length of each fiber is 50 mm.

[0127] To verify the innovative contribution of this invention, tensile tests were conducted on spiral auxetic fibers to observe changes in their diameter and calculate the Poisson's ratio. First, a 50mm short fiber was stretched using a universal tensile machine. During the stretching process, the fiber's changes were recorded with a camera. Stretching was completed until the spiral auxetic fibers broke. Computer software was then used to analyze the experimental results and calculate the Poisson's ratio. The fiber line optimized by the present invention achieved a negative Poisson's ratio with an initial strain of 2% and a maximum negative Poisson's ratio of -8.19. The negative Poisson's ratio effect was significant, and the fiber exhibited a greater expansion effect. The fiber line exhibited high strength and stability, meeting the requirements for concrete applications.

[0128] Example 10 Preparation of polypropylene / single-strand carbon fiber spiral auxetic fibers with a diameter ratio of 3:1 and a wrapping angle of 15°;

[0129] The preparation device of Example 1 was used, and one polypropylene fiber with a diameter of 0.9 mm and one carbon fiber with a diameter of 0.3 mm were selected as the core fiber and the wrapping fiber respectively:

[0130] Step 1: Place the carbon fiber tube on the fiber feeding roller 1. The carbon fibers on the carbon fiber tube are fed vertically from the bottom center of the fiber guide tube 5 through the pulley and the tension disk 4 in sequence under the rotation of the fiber feeding roller 1; then unwind the wrapping fiber 8 from the wrapping fiber tube 7, and the wrapping fiber 8 unwound from the wrapping fiber tube 7 passes through the converging hole 9 of the converging device and converges with the carbon fibers to form a spiral tensile fiber 10, which is then wound on the first fiber guide roller 11, and then passes through the middle of the second fiber guide roller 12 and is placed on the guide bar 16. Finally, the spiral tensile fiber 10 is transported and passed over the fixed knife 17.

[0131] Step 2: By operating the control system, the rotation speed of the first fiber guide roller 11 and the second fiber guide roller 12 is set to 2 r / min, and the rotation speed of the base 6 is set to 15 r / min and they rotate continuously during the whole process, so as to obtain the spiral expansion fiber 10.

[0132] Step 3: Turn on the glue dripping device and place the spiral auxetic fiber on the guide rail 16 under the glue dripping device's needle 13. Control the glue dripping device so that the needle 13 drips a drop of glue every 4 seconds, with a drop spacing of 60 mm. This will produce a formed spiral auxetic fiber 10.

[0133] Step 4: Align a certain glue-sprayed section of the spiral auxetic fiber formed by glue-spraying and winding on the guide rail 16 with the fixed knife 17, start the movable knife drive device, and adjust its speed to 2 r / min, making its speed the same as that of the second fiber guide roller. The movable knife 18 cuts the spiral auxetic fiber at the glue-sprayed section. The cut short spiral auxetic fibers fall from the discharge port 20 into the storage box 21. Each fiber is 60 mm long.

[0134] To verify the innovative contribution of this invention, tensile tests were conducted on spiral auxetic fibers to observe changes in their diameter and calculate their Poisson's ratio. First, a 60mm short fiber was stretched using a universal tensile machine. During the stretching process, the fiber's changes were recorded with a camera. Stretching was completed until the spiral auxetic fibers broke. Computer software was then used to analyze the experimental results and calculate the Poisson's ratio. The fibers optimized using this method exhibited a significant negative Poisson's ratio effect and exhibited a greater expansion effect. The fiber strands exhibited high strength and stability, meeting the requirements for concrete applications.

[0135] Table 1 Setting parameters of various embodiments

[0136]

[0137] The principle of the present invention is that the core fiber 3 and the wrapping fibers 8 that form the spiral auxetic fiber 10 have a certain diameter ratio and tensile modulus ratio, and the wrapping fibers 8 are wound around the surface of the core fiber 3. When subjected to an axial tensile force, the wrapping fibers 8 with less elasticity are gradually straightened and tightened. During this process, the core fiber 3 with greater elasticity gradually bends from a straight state, thereby increasing the apparent profile of the composite fiber line. At this time, the fiber has a negative Poisson's ratio effect. In addition, physical consolidation refers to the spiral winding of the wrapping fibers in a tightly wound manner at fixed intervals, which can effectively spatially consolidate the core fiber 3. Chemical bonding refers to the attachment of glue to the surface of the spiral auxetic fiber 10 at fixed intervals after it is formed, which can bond the core fiber 3 and the wrapping fibers together, making its structure stable and not easy to untwist (because the flexible wrapping fibers 8 are prone to untwist, resulting in the inability to achieve consolidation by winding, or poor consolidation effect).

[0138] In the present invention, the fiber guide roller, base 6, and fiber cutting mechanism each utilize a different servo motor and are equipped with a control system to control the use of the motors. The rotational speeds can be adjusted in real time according to individual needs. The different rotational speeds of the two motors can be used to create a relative speed difference. This relative speed difference can be used to form a tightly bound section of the wrapping fiber on the spiral auxetic fiber 10, ensuring that the structure of the spiral auxetic fiber 10 is stable and not easily untwisted. When the fiber guide roller rotates for three seconds, the base 6 operates normally, and the wrapping fiber is wrapped around the core fiber 3 according to the set wrapping angle. When the fiber guide roller stops for one second, the base 6 operates normally, and the wrapping fiber is tightly wrapped around the core fiber 3. These several turns of wrapping fiber tightly hold the core fiber 3, making it difficult to untwist and maintaining a stable structure. Furthermore, the relative speed difference can be used to control the wrapping angle of the spiral auxetic fiber 10. When the transmission rate of the core fiber 3 differs from that of the wrapping fiber, the wrapping angle of the spiral auxetic fiber 10 woven from the two will be different. The guide rail 16 in the fiber cutting mechanism transports the woven spiral auxetic fiber 10 to the mouth of the fixed knife 17. The gear connected to the movable knife 18 rotates at the same speed and frequency as the first fiber guide roller 11, ensuring that the movable knife 18 accurately cuts the spiral auxetic fiber 10 at the tight junction every time, ensuring that short spiral auxetic fibers 10 with stable structure and consistent length are produced. The glue dripping device controls the time and rate of glue dripping by controlling the compressed gas 23. The fiber feed roller 1, fiber guide roller, and guide rail 16 all transfer the fiber at the same rate and operate simultaneously.

[0139] Finally, it should be noted that the above preferred embodiments are only used to illustrate the technical solutions of the present invention and are not limiting. Although the present invention has been described in detail through the above preferred embodiments, those skilled in the art should understand that various changes can be made in form and details without departing from the scope defined by the claims of the present invention.

Claims

1. A device for preparing spiral auxetic fibers with a stable initial structure, characterized by: It includes a core fiber feeding control mechanism, a wrapping fiber feeding control mechanism, a spiral auxetic fiber forming and winding mechanism, and a fiber cutting mechanism, which are arranged in sequence. A glue dripping mechanism is provided above one end of the fiber cutting mechanism. The core fiber feeding control mechanism includes a core fiber tube, a fiber feeding roller, a tension disk and a fiber guide tube. The core fiber tube is placed on the fiber feeding roller, and the fiber guide tube is arranged above the tension disk. The end of the core fiber on the core fiber tube is wound around the tension disk and is vertically fed into the wrapping fiber feeding control mechanism from the bottom of the fiber guide tube. The wrapping fiber feeding control mechanism includes a base and a plurality of wrapping fiber tubes; the spiral auxetic fiber forming and winding mechanism includes a convergence hole, a first fiber guide roller, and a second fiber guide roller; the base is rotatably arranged, the fiber guide tube is arranged in the middle of the base, and the plurality of wrapping fiber tubes are evenly distributed on the circumference of the base; the convergence hole is arranged above the wrapping fiber tube, and the wrapping fibers on the plurality of wrapping fiber tubes are spirally wrapped around the surface of the core fiber at the convergence hole to form spiral auxetic fibers, and the ends of the spiral auxetic fibers are sequentially wound around the first fiber guide roller and the second fiber guide roller, and the second fiber guide roller drives the ends of the spiral auxetic fibers to move toward the position of the cutting limit mechanism; The fiber cutting mechanism includes a guide rail, a movable knife, and a fixed knife. The guide rail is used to transport the spiral auxetic fiber. The movable knife and the fixed knife are arranged behind one end of the guide rail away from the spiral auxetic fiber to cut the spiral auxetic fiber. The glue dripping mechanism is arranged above one end of the guide bar close to the spiral auxetic fiber, and includes a glue dripping needle tube, which is used to drip the internal glue onto the designated position of the spiral auxetic fiber.

2. The device for preparing a spiral auxetic fiber with a stable initial structure according to claim 1, characterized in that: The fiber cutting mechanism further comprises a driving device, the movable knife is connected to the driving device, a shield is provided on the outside of the fiber cutting mechanism, a discharge port is provided at the rear end of the shield, and a containing box is provided below the discharge port.

3. The device for preparing a spiral auxetic fiber with a stable initial structure according to claim 1, characterized in that: There are two first fiber guide rollers, the two first fiber guide rollers are arranged at the same height, and the rotation directions of the two first fiber guide rollers are opposite.

4. The device for preparing a spiral auxetic fiber with a stable initial structure according to claim 1, characterized in that: There are two second fiber guide rollers, which are arranged vertically opposite to each other and rotate in opposite directions.

5. The device for preparing a spiral auxetic fiber with a stable initial structure according to claim 1, characterized in that: The core fiber on the core fiber tube is made of one of polypropylene, polyvinyl alcohol and glass fiber filaments. The number of the wrapping fiber tubes is 2-3, and the wrapping fiber on the wrapping fiber tube is made of metal or flexible fiber.

6. The device for preparing a spiral auxetic fiber with a stable initial structure according to claim 1, characterized in that: A glue coating mechanism is provided between the glue dripping mechanism and the fiber cutting mechanism, and the glue coating mechanism includes an arc-shaped gear ring, and a plurality of cylindrical gears evenly distributed around the circumference are provided on the outer side of the arc-shaped gear ring, and the cylindrical gears are meshed with the arc-shaped gear ring. An arc-shaped plate is provided at one end of the arc-shaped gear ring, and a plurality of driving motors are provided on the arc-shaped plate, and the driving motor is connected to one end of the cylindrical gear. An arc-shaped airbag is provided on the inner side surface of the arc-shaped gear ring, and one side of the arc-shaped airbag is fixed on the arc-shaped gear ring, and a sponge layer is bonded to the other side of the arc-shaped gear ring. An air pump is provided on the arc plate, and the output end of the air pump is connected to the interior of the arc-shaped airbag through an air pipe.

7. The device for preparing a spiral auxetic fiber with a stable initial structure according to claim 6, characterized in that: A stopper is provided on the other end of some of the columnar gears, and the stopper limits the translation of the arc-shaped gear ring.

8. A method for preparing a spiral auxetic fiber with an initial stable structure, applied to the preparation device according to any one of claims 1 to 7, characterized in that: When the wrapping fiber is made of metal, the preparation steps include: Step 1: Place the core fiber tube on the fiber feeding roller. The core fiber on the core fiber tube passes through the tension disk under the rotation of the fiber feeding roller and is fed vertically from the center of the bottom of the fiber guide tube. Then, the wrapping fiber is unwound from the wrapping fiber tube. The wrapping fiber unwound from the wrapping fiber tube passes through the convergence hole and converges with the core fiber to form a spiral auxetic fiber. The spiral auxetic fiber is then wound on the first fiber guide roller, passes through the middle of the second fiber guide roller, and is placed on the guide rail. Finally, the formed spiral auxetic fiber is transported and passed over the fixed knife. Step 2: By operating the control system, the rotation speed of the first fiber guide roller and the second fiber guide roller is set to 1-2 r / min, each rotation is three seconds and the stop is one second, and the base continues to rotate at a speed of 10-20 r / min to obtain spiral auxetic fibers; Step 3: Align a section of the spiral auxetic fiber that has been wound on the guide rail with the fixed knife after being wrapped with a metal wire hoop, start the movable knife drive device, adjust its speed to 1-2r / min, and make its speed the same as that of the second fiber guide roller. The movable knife cuts off the tight section of the spiral auxetic fiber, and the cut short spiral auxetic fiber is discharged from the end of the guide rail.

9. A method for preparing a spiral auxetic fiber with an initial stable structure, applied to the preparation device according to any one of claims 1 to 7, characterized in that: When the wrapping fiber is a flexible fiber, the preparation method includes the following steps: Step 1: Place the core fiber tube on the fiber feeding roller. The core fiber on the core fiber tube is fed vertically from the center of the bottom of the fiber guide tube through the tension disk under the rotation of the fiber feeding roller. Then, the wrapping fiber is unwound from the wrapping fiber tube. The wrapping fiber unwound from the wrapping fiber tube passes through the convergence hole and converges with the core fiber to form a spiral auxetic fiber. The spiral auxetic fiber is then wound on the first fiber guide roller, passes through the middle of the second fiber guide roller, and is placed on the guide bar. Finally, the spiral auxetic fiber is transported and passed over the fixed knife. Step 2: By operating the control system, the rotation speed of the first fiber guide roller and the second fiber guide roller is set to 1-3 / min, and the rotation speed of the base is set to 10-20r / min, and they continue to rotate during the whole process to obtain the spiral auxetic fiber; Step 3: Turn on the glue dripping device, place the spiral auxetic fiber on the guide rail under the needle of the glue dripping device, and control the glue dripping device so that the needle drips a drop of glue every 3-5 seconds, so that the glue adheres to the surface of the spiral auxetic fiber, and the spiral auxetic fiber formed by glue dripping can be obtained; Step 4: Align a certain glue-dripped section of the spiral auxetic fiber that has been glue-dripped and wound on the guide rail with the fixed knife, start the movable knife drive device, adjust its speed to 1-3r / min, and make its speed the same as that of the second fiber guide roller. The movable knife cuts off the glue-dripped section of the spiral auxetic fiber, and the cut short spiral auxetic fiber is discharged from the end of the guide rail.

10. The method for preparing a spiral auxetic fiber with an initial stable structure according to claim 9, characterized in that: The step 3 further includes the following steps: When the glue dripping device drips glue into the gap of the arc-shaped gear ring, the air pump inflates the arc-shaped airbag to make the sponge layer contact the surface of the spiral expansion fiber. Then, the driving motor drives the gear ring to rotate reciprocatingly to coat the glue evenly on the surface of the spiral expansion fiber. After coating, the driving motor drives the arc-shaped gear ring to return to its initial position, and then the arc-shaped airbag is deflated to separate the sponge layer from the surface of the spiral expansion fiber.

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