Production equipment and method for a multi-U sandwich-type hollow special-shaped fiber

Abstract

The present invention belongs to the technical field of chemical fibers for polyester fabrics, and relates to a production device and method for multi-U sandwich-shaped hollow profiled fibers. The device includes a circular spinneret plate, a cooling filter element, and a pre-networker. The circular spinneret plate includes a spinning area and a non-spinning area. The spinning area is sequentially provided with multiple concentric arc layers from the center of the circular spinneret plate outward. A plurality of spinning holes are spacedly arranged on each concentric arc layer, and each spinning hole is composed of multiple U-shaped structures surrounding it; the cooling filter element is a double-cylinder structure, and the cooling filter element is used to cool the fiber filaments ejected from the spinneret plate; the pre-networker includes a first porcelain part, a second porcelain part, a third porcelain part, and an air supply channel. An air inlet hole is opened on the first porcelain part, and the pressurized gas passing through the air inlet hole is shunted in the air supply channel. An air outlet end with a first inclination direction is opened on the second porcelain part, and an air outlet end with a second inclination direction is opened on the second porcelain part. This application can optimize the fiber properties and improve the product quality.

Description

Technical Field

[0001] The present invention belongs to the technical field of chemical fibers for polyester fabrics, and particularly relates to a production device and method for multi-U sandwich-shaped hollow profiled fibers. Background Art

[0002] Since the mid-20th century, with the rapid development of the chemical fiber industry and the continuous progress of science and technology, people's performance requirements for fiber materials have become increasingly high. Especially in high-tech fields such as functional textiles, filtration materials, and biomedical materials, higher requirements have been put forward for the morphological structure and functionality of fiber materials.

[0003] The moisture permeability and air permeability of textile fabrics have become important indicators for excellent fabrics. Moisture-permeable and air-permeable fabrics can effectively transfer water vapor and moisture. When our body sweats, the fabric can quickly absorb the sweat and transfer the water vapor to the outside of the fabric through the micropores of the fabric or the profiled structure of the fibers, which can prevent sweat from accumulating on the skin and keep the skin dry and comfortable.

[0004] Multi-U sandwich-shaped hollow fibers are a special-shaped fiber with a multi-U cross-section and a hollow inner design. The outer contour of the fiber with a multi-micropore design structure is irregular, which can increase the fiber surface area and the storage space of the material, making the fabric have a fluffy feeling and good water molecule adsorption. Due to the continuous cavity inside, the internal space of the fiber is increased, the volume mass of the fiber is reduced, and an air layer is formed in the middle to improve the heat insulation and warmth retention performance of the fabric. Many grooves are generated longitudinally on the fiber, and the capillary phenomenon generated by the protrusions improves the capillary effect of the fiber in the fabric, so that the fabric has a dry and moisture-conducting performance due to the capillary action in the fiber or between the fibers. The greater the capillary action, the better the moisture-conducting performance.

[0005] The fabric is comfortable, warm, three-dimensional and symmetrical, moisture-permeable and dry, and is favored and widely used in high-grade wool-like fabrics, plush toys, carpets, and high-grade bedding filling materials, high-grade fabrics, etc., and the demand is large. Therefore, the development and application of multi-U sandwich-shaped hollow profiled fibers have broad development prospects and can generate very considerable economic benefits for enterprises.

[0006] During the spinning process, due to the complexity of the structure, problems such as fiber breakage, unqualified cross-sectional morphology, or deformation of the porous structure often occur. These defects result in a low finished product rate. Even in the post-treatment process, additional screening and trimming are required to ensure that the fibers meet the requirements. This not only increases the rework rate and scrap rate of production, but also causes waste of resources and costs. Therefore, how to improve the finished product rate and reduce the generation of defective fibers has become a major problem in the production of multi-U sandwich-shaped profiled fibers in the prior art. Summary of the Invention

[0007] To solve the above technical problems, the present application discloses a production device for multi-U sandwich-shaped hollow special-shaped fibers. The device includes: a circular spinneret, a cooling filter element, and a pre-networker. The circular spinneret includes two spinning areas arranged at a first relative angle and two non-spinning areas arranged relatively at a second relative angle. The first relative angle is greater than the second relative angle. The spinning areas are sequentially provided with multiple concentric arc layers outward from the center of the circular spinneret. Multiple spinneret holes are spaced on each concentric arc layer. Each spinneret hole is surrounded by multiple U-shaped structural plates;

[0008] The cooling filter element is of a double-cylinder structure and is used to cool the fiber filaments ejected from the spinneret. The pre-networker is used to process the fiber filaments after they form a tow to obtain network yarns. The pre-networker includes a first porcelain part, a second porcelain part, a third porcelain part, and an air supply channel. An air inlet hole is opened on the first porcelain part. The pressurized gas passing through the air inlet hole is branched in the air supply channel. One branch enters the second porcelain part and the other branch enters the third porcelain part. An air outlet end in a first inclined direction is opened on the second porcelain part, and an air outlet end in a second inclined direction is opened on the second porcelain part.

[0009] In some embodiments, the air supply channel includes a first air pipe and a second air pipe, and the first air pipe and the second air pipe are connected at the air inlet of the pre-networker.

[0010] In some embodiments, the bottom of the U-shaped structural plate is designed in a semi-circular shape. The inner distance between the left and right side plates of the U-shaped structural plate is 0.05 ± 0.002 mm, the distance between the inner and outer sides of the side plate is 0.06 ± 0.002 mm, the outer semi-circular radius of the bottom of the U-shaped structural plate is 0.025 ± 0.002 mm, and the inner semi-circular radius is 0.02 ± 0.002 mm.

[0011] In some embodiments, the cooling filter element includes a first hollow filter element and a second hollow filter element arranged inside and outside. A ventilation annular channel is formed between the first hollow filter element and the second hollow filter element. First ventilation holes are opened on the first side surface of the first hollow filter element, and second ventilation holes are opened on the second side surface of the second hollow filter element. Both ends of the first hollow filter element are connected to an external blower respectively.

[0012] In some embodiments, the second hollow filter element includes an air outlet area and a non-air outlet area, and the surface area of the air outlet area is greater than the surface area of the non-air outlet area.

[0013] In some embodiments, the tow channel formed by the second porcelain part and the third porcelain part is designed as a sloped triangle, and the angle β of the triangle is 36° to 40°.

[0014] According to another aspect of the present application, a method for producing a multi-U sandwich type hollow shaped fiber is also disclosed. The method is implemented based on the production equipment for the multi-U sandwich type hollow shaped fiber described in any one of the above items, and the method comprises:

[0015] S1) transporting the raw material high-quality semi-dull polyester melt to a booster pump for pressurization treatment to obtain a polyester melt;

[0016] S2) transporting the polyester melt to a spinning manifold through a melt pipe for spinning, wherein the spinning manifold includes a plurality of spinning assemblies, each of which includes the production equipment for multi-U sandwich hollow shaped fibers described in any one of the above items, and the flow rate of the polyester melt transported by the melt pipe is measured by a metering pump.

[0017] In some embodiments, the spinning box further includes an oil nozzle, a wire guide hook, a tunnel, a diamond-shaped wire guide, a wire pressing rod, a first comb-shaped wire guide, a stretching roller, a second comb-shaped wire guide, a shaping roller main network device and a winding machine. Step S2) includes the following process flow:

[0018] Circular spinneret → cooling filter → oiling nozzle → wire guide hook and bundle → tunnel → diamond wire guide → wire pressing rod → pre-intertwiner → first comb-shaped wire guide → stretching roller → second comb-shaped wire guide → shaping roller → main intertwiner → winding machine forming;

[0019] The oil nozzle is used to apply oil to the surface of the fiber filaments after cooling the cooling filter element, the wire guide hook is used to gather single or multiple fiber filaments together to form a tow, and guide the tow along the target path through the wire guide hook; the tunnel is used to further cool and air-condition the tow so that the temperature and humidity of the tow reach the target state; the diamond-shaped wire guide is used to guide and organize the tow so that the tow remains neat and stable and reduces the entanglement or deviation of the tow during movement; the wire pressing rod is used to compress and organize the tow by applying pressure; the first comb-shaped wire guide is used to comb and guide the tow passing through the pre-networking device; the stretching roller is used to stretch the fiber; the second comb-shaped wire guide is used to comb and guide the stretched tow; the shaping roller is used to perform heat-setting treatment on the stretched fiber; the main network device is used to form network points on the tow again to enhance the degree of entanglement between the fibers; the winding machine is used to wind the fibers that have undergone previous processing into packages of target shape and specifications.

[0020] In some embodiments, the spinning process parameters include: cooling air pressure of 60 - 80 Pa, height of the windless zone of 40 - 55 mm, temperature of the bottom heater of 300 - 310 °C; the winding process parameters include: speed of the drafting roller of 2450 - 2950 m / min, temperature of the drafting roller of 85 - 93 °C, speed of the setting roller of 4460 - 4870 m / min, temperature of the setting roller of 128 - 133 °C, winding speed of 4400 - 4800 m / min, pre-network pressure of 0.070 - 0.085 bar, main-network pressure of 0.36 - 0.40 bar, machine contact pressure of 240 - 270 cN.

[0021] In some embodiments, the linear density of the fibers formed based on the production method is 55.2 - 83.6, the unevenness rate of the linear density is ≤ 1.50%, the breaking strength is ≥ 3.55 cN / dtex, the unevenness rate of the breaking strength is ≤ 4.78%, the breaking elongation rate is 28.8 - 31.2%, the unevenness rate of the breaking elongation is ≤ 5.23%, the U half suppression value of the evenness is ≤ 0.64%, the boiling water shrinkage rate is 6.62 - 7.02%, the oiling rate is 0.75 - 0.96%, the number of network points is 16 - 23 per meter, the dyeing uniformity grade is > 4.5, the full bobbin rate is ≥ 97.5%, and the AA rate is ≥ 96.8%.

[0022] The present invention includes, but is not limited to, the following beneficial effects: (1) This solution has improved the spinneret holes, cooling filter elements, and pre-networkers. The advantages of the improvements are superimposed, optimizing the fiber properties, improving the product quality, and increasing the finished product rate; (2) The reasonable design of the multi-U-shaped spinneret holes in this solution increases the number and area of grooves and tentacles on the fiber surface compared with traditional profiled fibers, increasing the specific surface area of the fiber, reducing the density of the fiber, enhancing the thermal insulation performance, significantly increasing the fiber storage space, with a wider and more detailed coverage. Moisture is quickly absorbed, transmitted, and diffused to the fabric surface through wicking, diffusion, and transmission, significantly enhancing the fiber capillary wicking effect, which is beneficial for quickly absorbing and removing moisture. Due to the continuous cavity inside, an air layer is added inside the fiber, which helps to capture and retain air, forming an air layer in the middle to form a heat insulation layer, reducing the heat conductivity, thereby improving the thermal insulation and warmth retention performance of the fabric. Through the reasonable selection of production process parameters and the improvement of the tow cooling effect, the hollow profile degree of the fiber is increased, the warmth retention coefficient is improved, the water absorption performance is enhanced, and the air permeability is increased. The fiber not only has excellent moisture absorption, air permeability, and quick-drying properties, but also has excellent warmth retention and lightness and softness; (3) Under the suction of the external fan, the first hollow filter element with a double-cylinder structure in this solution sucks and cleans the excess cooling air reaching around the inner cylindrical filter element, achieving dynamic balance, avoiding the turbulent reverberation of the ring-blow cooling air in the filter element cavity after cooling the tow, and gathering and blowing downward out of the filter element, causing the tow to shake and interfere with each other, uneven cooling of the tow, and reducing the generation of defective fibers. The double-cylindrical ring-blow filter element of this design can suck and discharge the cooling air after cooling the tow out of the filter element cavity after it reaches the inner cylindrical filter element. They each perform their own functions without interference, with blowing and suction balance, achieving both the uniformity and stability of the ring-blow cooling and the function of stabilizing the tow by side blowing, reducing the interference of tow shaking, improving the physical properties of the tow, and improving the dyeing uniformity; (4) The pre-networker in this solution, the main networker that adds entanglement to the tow, is composed of three porcelain parts connected. The left porcelain part has a pressure hole inlet, and there are two upper and lower channels at its inlet leading to the upper and lower porcelain parts. The upper and lower porcelain bodies are respectively provided with air supply channels and turn to the compressed air outlet, and one compressed air outlet is inclined upward and the other is inclined downward, facilitating blowing towards the tow from two directions. The tow channels provided by the upper and lower magnets are designed in a gentle slope triangular shape. The compressed air is blown out from the outlet and deflects and extends in the tow channel, enabling the compressed air to blow the entire tow from front to back, increasing the tow entanglement power, evenly distributing the network nodes, and not requiring a very high network pressure, reducing tow defects and breaks, and increasing the finished product rate. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art.

[0024] Figure 1This is a schematic structural diagram of a production device for multi-U sandwich type hollow shaped fibers according to an embodiment of the present invention;

[0025] Figure 2 This is a schematic structural diagram of a circular spinneret according to an embodiment of the present invention;

[0026] Figure 3 Schematic diagram of a single U-shaped structure of a circular spinneret hole according to an embodiment of the present invention;

[0027] Figure 4 Schematic diagrams of the structures of the spinnerets of the circular spinnerets according to the embodiments of the present invention, wherein (a) is a 4U structure, (b) is a 5U structure, and (c) is a 6U structure;

[0028] Figure 5 This is a schematic diagram of a pre-network device tow channel according to an embodiment of the present invention;

[0029] Figure 6 Schematic diagram of a pre-network device according to an embodiment of the present invention, wherein (p) is a schematic diagram of the structure of the pre-network device from one angle, (q) is a schematic diagram of the structure of the pre-network device from another angle, and (m) is a schematic diagram of the structure of the pre-network device from yet another angle;

[0030] Figure 7 for Figure 6 A magnified view of point A;

[0031] Figure 8 Schematic diagram of the structure of the cooling filter element according to an embodiment of the present invention, wherein (e) is a schematic diagram of the structure of the second hollow filter element, and (f) is a perspective view of the first hollow filter element;

[0032] Figure 9 This is a structural schematic diagram of a cooling filter element according to another embodiment of the present invention from another angle;

[0033] In the figure, 1-circular spinneret, 11-spinneret hole, 12-U-shaped structural plate, 2-cooling filter element, 21-first hollow filter element, 22-second hollow filter element, 23-first ventilation hole, 24-second ventilation hole, 25-air outlet area, 26-non-air outlet area, 3-pre-network device, 31-first porcelain part, 32-second porcelain part, 33-third porcelain part, 34-first air pipe, 35-second air pipe, 36-sealing ring, 37-air inlet, 38-first air outlet end, 39-second air outlet end, 4-tow channel. DETAILED DESCRIPTION

[0034] The following will be combined with the accompanying drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0035] According to one aspect of the present application, as Figures 1-9 shown, a production device for multi-U sandwich-shaped hollow special-shaped fibers is disclosed. Specifically, referring to Figure 1 , the device includes a circular spinneret 1, a cooling filter element 2, and a pre-networker 3. The circular spinneret 1 is used to extrude fiber filaments through the spinneret holes 11 on the spinneret. The cooling filter element 2 is used to cool the fiber filaments. It can be understood that the extruded fiber filaments are in a high-temperature, liquid, or highly elastic state, and under the action of the cooling filter element 2, the fiber filaments can be cooled down, changing from a liquid or highly elastic state to a solid state, completing the preliminary curing and shaping. Further, the fiber filaments after cooling and curing, usually multiple, are bundled together and then enter the pre-networker 3. By applying compressed air or other means through the pre-networker 3, the fiber filaments are entangled and held together with each other to form network filaments. The network filaments have better holding force and processing performance, are not easily loosened during subsequent textile processing, and are beneficial to improving textile efficiency and product quality.

[0036] Specifically, the initial form of the fiber filaments is affected by the spinneret holes 11. In this example, as Figures 2 to 4 shown, the circular spinneret 1 includes two spinning regions arranged at a first relative angle and two non-spinning regions arranged opposite to each other at a second relative angle. The first relative angle is greater than the second relative angle. The spinning regions are sequentially provided with multiple concentric arc layers outward from the center of the circular spinneret 1. A plurality of spinneret holes 11 are arranged at intervals on each concentric arc layer. Each spinneret hole 11 is surrounded by a plurality of U-shaped structural plates 12. Specifically, the fact that each spinneret hole 11 is surrounded by a plurality of U-shaped structural plates 12 may mean that a circular array of a plurality of U-shaped structural plates 12 forms the spinneret hole 11. After the array, that is, after the spinneret hole 11 is formed, the middle of the spinneret hole 11 is constructed as a hollow region. The bottoms of the U-shaped structural plates 12 are sequentially attached to form the inner circle of the entire spinneret hole 11, and the openings of the U-shaped structural plates 12 form the outer circle of the entire spinneret hole 11. Specifically, a plurality of U-shaped structural plates 12 are arrayed to form a spinneret hole with a hollow region. This hollow structure can increase the specific surface area of the fiber. After the specific surface area increases, the adsorption performance of the fiber is improved, and it performs better when adsorbing substances such as dyes and moisture, and can endow the fiber with better dyeing uniformity and moisture absorption and breathability functions. And this array structure enables the U-shaped structural plates to be evenly distributed in the hollow region, allowing the fiber to disperse force more evenly when subjected to external forces, not easily breaking due to excessive local stress, enhancing the physical stability of the fiber, reducing the situation of fiber breakage during textile processing and subsequent use, and ensuring product quality and service life.

[0037] Preferably, the number of concentric arc layers can be 2 - 3 layers, and the spacing between adjacent spinneret holes 11 in each layer can be the same or different. The number of spinneret holes 11 arranged at intervals on each concentric arc layer can be set based on the actual spacing requirements and combined with the arc length of the arc layer. For example, the number of spinneret holes 11 can be set to Figure 2 36 holes as shown in Figure 2 , distributed in 2 layers, with 10 holes in the outer layer and 8 holes in the inner layer, and the number of U-shaped structure plates 12 can be Figure 4 6 as shown in (c) of Figure 4 , forming a 6U-shaped structure; or, in other feasible solutions, the bottom of the U-shaped structure plate 12 is designed as a semi-circle, the number of spinneret holes 11 can be set to 24 holes, distributed in 1 layer, the number of holes in the single layer within the semi-circle can be 12, and the number of U-shaped structure plates 12 can be Figure 4 5 as shown in (b) of Figure 4 , forming a 5U-shaped structure; or, in other feasible solutions; the number of spinneret holes 11 can also be 48 holes, distributed in 3 layers, among which, 10 holes are distributed in the outermost layer, 8 holes in the second layer, and 6 holes in the third layer, and the number of U-shaped structure plates 12 can be Figure 4 4 as shown in (a) of Figure 4 , forming a 4U-shaped structure.

[0038] It should be noted that the number of U-shaped structure plates 12 of the spinneret holes 11 can also be other numbers, such as a 7U-shaped structure formed by 7, or an 8U-shaped structure formed by 8, etc. The specific number can be set according to actual needs and will not be specifically limited here.

[0039] Furthermore, in one example, continue to refer to Figure 3 , the distance between the left and right sides of the U-shaped structure plate 12 is 0.05 ± 0.002 mm, the width of the left and right side edges is 0.01 ± 0.002 mm, the outer semi-circle radius of the bottom of the U-shaped structure plate 12 is 0.035 ± 0.001 mm, and the inner semi-circle radius is 0.025 ± 0.002 mm,

[0040] In some other embodiments, the bottom of the U-shaped structure plate 12 is designed as a semi-circle, the inner distance between the left and right side plates of the U-shaped structure plate 12 is 0.05 ± 0.002 mm, the distance between the inner and outer sides of the side plates is 0.06 ± 0.002 mm, the outer semi-circle radius of the bottom of the U-shaped structure plate 12 is 0.025 ± 0.002 mm, and the inner semi-circle radius is 0.02 ± 0.002 mm. The specific dimensions of the U-shaped structure plate 12 can be set according to requirements and will not be specifically limited here.

[0041] Specifically, by designing the spinneret with the above structure, the fiber filaments extruded from the spinneret holes 11 have a hollow special-shaped structure with a hollow part in the center surrounded by several U-shaped lines, enabling the fibers to have good moisture absorption and sweat wicking properties; the wavy edges formed by the peripheral U-shaped bends not only increase the fiber surface area and enhance the adsorption force, but also make the overall structure more stable and less prone to deformation, solving the problems of easy fiber breakage and difficult shape control in the production process. While ensuring the fiber properties, the production efficiency is also improved.

[0042] Further, as Figures 8 to 9 shown, the cooling filter element 2 has a double-cylinder structure. The cooling filter element 2 is arranged in the spinning box. The number of the cooling filter elements 2 can be one or more. When there are multiple cooling filter elements 2, the multiple cooling filter elements 2 are independently arranged in sequence, and the respective air extraction pipes of each cooling filter element 2 are communicated with the total integrated pipe.

[0043] Further, continue to refer to Figure 8 , the cooling filter element 2 includes a first hollow filter element 21 and a second hollow filter element 22 arranged inside and outside. A ventilation annular channel is formed between the first hollow filter element 21 and the second hollow filter element 22. First ventilation holes 23 are formed on the outer side surface of the first hollow filter element 21, and second ventilation holes 24 are formed on the outer side surface of the second hollow filter element 22. Both ends of the first hollow filter element 21 are communicated with an external fan. After the outside air enters the second hollow filter element 22 through the second ventilation holes 24, it continues to enter the first hollow filter element 21 through the ventilation annular channel and the first ventilation holes 23. The air passing through the first hollow filter element 21 cools the fiber filaments extruded from the circular spinneret 1, and the cooling air is sucked to the outside by the fan through the air extraction pipe. In one example, as Figure 1 shown, the circular spinneret 1 is arranged above the cooling filter element 2, and the fiber filaments extruded from the spinneret holes 11 of the circular spinneret 1 enter the hollow area of the first hollow filter element 21. It can be understood that by arranging the circular spinneret 1 above the cooling filter element 2, the fiber filaments extruded from the spinneret holes 11 naturally droop under the action of the gravity of the fiber filaments, which is consistent with the subsequent drawing and other operation directions, and can be more smoothly pulled and moved, reducing problems such as bending and winding caused by the inconsistent direction of external force traction and the natural direction of the fiber filaments, and ensuring the continuity and stability of the fiber filaments during the processing.

[0044] Further, in some embodiments, the second hollow filter element 22 includes an air outlet area 25 and a non-air outlet area 25, and the surface area of the air outlet area 25 is larger than that of the non-air outlet area 25. Exemplarily, as Figure 9As shown, the air outlet area 25 is set as two relatively arranged parts on the outer side of the second hollow filter element 22, and the non-air outlet area 25 is set as two relatively arranged parts on the outer side of the second hollow filter element 22. The air outlet area 25 and the non-air outlet area 25 are arranged at intervals. By setting the non-air outlet area 25, the non-air outlet area 25 can prevent the fiber filaments from cooling too rapidly. If the fiber filaments are cooled rapidly throughout the process, it may cause the internal structure to form too quickly, resulting in problems such as uneven internal stress and imperfect crystallization. Setting the non-air outlet area 25 can allow the fiber filaments to be appropriately buffered during the cooling process, achieve a more reasonable temperature gradient change, ensure the uniformity and stability of the internal structure of the fiber filaments, and the setting of the non-air outlet area 25 can assist in adjusting the overall cooling air flow field distribution, avoid the cooling air flow from being too concentrated or disordered in some areas, make the air flow in the air outlet area 25 more uniform and stable, enable the fiber filaments to obtain a more balanced cooling effect in the effective air outlet area 25, and improve the quality consistency of the fiber filaments.

[0045] In one example, the filter screen layer of the second hollow filter element 22 is 10u, and the filter screen layer of the first hollow filter element 21 is 20u. Two circular holes are opened in the upper and lower parts of the first hollow filter element 21 and are connected to the second hollow filter element 22 by a quick fork. The materials of both are metal pipes, which are convenient for disassembly and cleaning. As shown, the upper circular suction metal pipe in each filter element extends downward to communicate with the lower circular metal pipe and extends downward to the reserved hole at the bottom of the air box, and is connected by a quick fork. The lower part is connected with a flexible air pipe, which is connected to the first-floor suction air pipe for summarization.

[0046] Furthermore, the cooled fiber filaments are integrated together to form a filament bundle, and the filament bundle is further processed by a pre-networker 3 to form network filaments. In this example, as Figures 5 to 7As shown, the pre-networker 3 includes a first porcelain part 31, a second porcelain part 32, a third porcelain part 33, and an air supply channel. The second porcelain part 32 and the third porcelain part 33 are arranged vertically, and the first porcelain part 31 and the second porcelain part 32 are arranged horizontally. An air inlet hole 37 is formed on the first porcelain part 31, and a sealing ring 36 is installed on the inner wall of the air inlet hole 37 to improve the gas sealing effect through the sealing ring 36. Further, the air supply channel includes a first air pipe 34 and a second air pipe 35. The first air pipe 34 and the second air pipe 35 are connected at the air inlet of the pre-networker 3. One end of the air inlet of the first air pipe 34 is respectively connected to the air inlet hole 37 and the air inlet of the second air pipe 35, and the other end is respectively connected to the tow channel 4 of the pre-networker 3 and the air outlet of the second air pipe 35. One end of the air inlet of the second air pipe 35 is respectively connected to the air inlet hole 37 and the air inlet of the first air pipe 34, and the other end is respectively connected to the tow channel 4 of the pre-networker 3 and the air outlet of the first air pipe 34. Specifically, the air outlet of the first air pipe 34 is inclined, and the air outlet of the second air pipe 35 is inclined. Exemplarily, the air outlet of the first air pipe 34 is inclined downward to the right, and the air outlet of the second air pipe 35 is inclined upward to the right. When the gas entering through the air inlet hole 37 reaches the area where the fiber filaments are located by dividing into two strands through the first air pipe 34 and the second air pipe 35 respectively, a complex air flow field will be formed. By arranging the air outlets of the first air pipe 34 and the second air pipe 35 inclined in different directions, air flows in different directions can be generated, and the air flows in different directions exert forces on the tow in different directions. The upward-inclined and downward-inclined air flow components respectively cause the tow to have upward-inclined and downward-inclined movement trends, prompting the individual filaments in the tow to interweave and entangle with each other to form network nodes and improving the tow holding performance. Further, the air outlet of the first air pipe 34, the air outlet of the second air pipe 35, and the tow channel 4 form a three-dimensional space structure. This movement in different directions helps the individual filaments of the tow to interpenetrate and hold each other more fully in the three-dimensional space. The cooperation of the upward and downward movements can make the yarn form a more uniform and stable network structure, avoiding the individual filaments from aggregating or entangling only in a single direction, thereby improving the overall physical properties of the yarn, such as strength and abrasion resistance.

[0047] Further, the tow channel 4 between the second porcelain part 32 and the third porcelain part 33 is designed in a triangular shape. The triangular structure can change the interaction mode between the air flow and the tow. When the tow passes through, the sides and corners of the triangle can make the air flow act on each part of the tow more evenly, avoiding the situation of too dense or too sparse local nodes, thereby ensuring the uniformity and consistency of the overall network structure of the tow. In some examples, the triangular angle ( Figure 7The angle β in the triangle can range from 36° to 40°. A well-designed triangular shape optimizes the airflow path, reducing resistance and turbulence within the channel, thereby lowering network pressure. Lower network pressure reduces defects and breakage in the tow caused by excessive stress during processing, improving tow quality while also facilitating stable operation and extending the life of the equipment.

[0048] According to another aspect of the present application, a method for producing a multi-U sandwich type hollow shaped fiber is also disclosed. The method is implemented based on the above-mentioned multi-U sandwich type hollow shaped fiber production equipment, and the method includes:

[0049] S1) transporting the raw material of high-quality semi-dull polyester melt to a booster pump for pressurization treatment to obtain a polyester melt;

[0050] S2) transporting the polyester melt to a spinning manifold through a melt pipe for spinning, wherein the spinning manifold includes a plurality of spinning assemblies, each of which includes the production equipment for multi-U sandwich hollow shaped fibers described in any one of the above items; the flow rate of the polyester melt transported by the melt pipe is measured by a metering pump.

[0051] Furthermore, the spinning box also includes an oil nozzle, which is used to apply oil to the surface of the fiber filaments after cooling of the above-mentioned cooling filter element. The oil can reduce the friction coefficient of the fiber filament surface, prevent the fibers from sticking to each other, improve the processability and softness of the fiber filaments, and also play an anti-static role.

[0052] Furthermore, the spinning box also includes:

[0053] The wire guide hook is used to gather single or multiple fiber strands together to form a tow, and guide the tow along a certain path through the wire guide hook to prepare for subsequent processing steps;

[0054] The tunnel serves as a passage for the tow, where the tow can be further cooled and air-conditioned to achieve a more suitable temperature and humidity for subsequent processing.

[0055] Diamond-shaped yarn guides are used to guide and organize the yarn bundles, keeping them neat and stable, and preventing them from getting tangled or deviated during movement.

[0056] The wire pressing rod is used to compress and arrange the wire bundle properly by applying a certain pressure, making the wire bundle more compact, which helps to improve the strength and uniformity of the fiber;

[0057] The first comb-shaped yarn guide is used to comb and guide the yarn bundle passing through the pre-netting device, so that the fibers in the yarn bundle are arranged more neatly, further improving the uniformity and stability of the fibers;

[0058] A drawing roll is used to draw fibers. Through drawing, the macromolecular chains in the fibers are oriented along the fiber axis, thereby improving the physical properties of the fibers such as strength and modulus. At the same time, the diameter and morphology of the fibers are changed to meet the required specifications of the product.

[0059] A second comb-shaped wire guide is used to comb and guide the drawn tow again to ensure the neatness and stability of the tow and prepare for the subsequent shaping process.

[0060] A shaping roll is used to perform heat setting on the drawn fibers. Under certain temperature and tension conditions, the morphology and structure of the fibers are stabilized, the internal stress in the fibers is eliminated, and the dimensional stability and heat resistance of the fibers are improved.

[0061] A main texturing device is used to further form texturing points on the tow, enhance the entanglement degree between the fibers, improve the bundling property and bulkiness of the fibers, and improve the hand feeling and appearance quality of the fibers to make them more suitable for subsequent processing and use requirements.

[0062] A winding machine is used to wind the fibers after a series of processing into a package of a certain shape and specification, such as cheese yarn or wound bobbin, etc., for easy storage, transportation and subsequent textile processing. During the winding process, parameters such as winding speed and tension should be controlled to ensure good quality and appearance of the package.

[0063] Thus, the production method of the multi-U sandwich-shaped hollow profiled fiber in this application follows the following technological process:

[0064] Excellent semi-dull polyester melt → booster pump → melt pipeline → metering pump → circular spinneret → cooling filter element → oiling at the nozzle → guiding the tow with a guide hook → duct → diamond-shaped wire guide → press rod → pre-texturing device → first comb-shaped wire guide → drawing roll → second comb-shaped wire guide → shaping roll → main texturing device → winding machine for forming.

[0065] Among them, in this application, by replacing the traditional spinneret with the circular spinneret in this application and designing the spinneret holes of the circular spinneret as a multi-U structure, the reasonable design of the multi-U shaped spinneret holes increases the number and area of grooves and tentacles on the fiber surface compared with traditional profiled fibers, increases the specific surface area of the fiber, reduces the density of the fiber, and enhances the heat preservation performance. The fiber storage space is significantly increased, and the coverage is wider and more detailed. Moisture is absorbed, diffused, and transmitted through capillary action, quickly absorbing, transmitting, and diffusing the moisture and water on the surface layer to the fabric surface, significantly enhancing the capillary wicking effect of the fiber, which is beneficial to quickly absorb and remove moisture; due to the continuous cavity inside, the air layer inside the fiber is increased, which helps to capture and retain air, forming an air layer in the middle to form a heat insulation layer and reduce heat conductivity, thereby improving the heat insulation and heat preservation performance of the fabric. Through the reasonable selection of production process parameters and the improvement of the tow cooling effect, the hollow profile degree of the fiber is improved, the heat preservation coefficient is increased, the water absorption performance is improved, and the air permeability is increased. The fiber not only has excellent moisture absorption and air permeability and quick drying properties, but also has excellent heat preservation, lightness, and softness; further, through the cooling filter element, under the suction of the external fan, the first hollow filter element sucks and cleans the excess cooling air reaching around the inner cylindrical filter element to achieve dynamic balance, avoiding the turbulent backflow of the annular blowing cooling air in the filter element cavity after cooling the tow, gathering and blowing downward out of the filter element, causing the tow to shake and interfere with each other, uneven cooling of the tow, and unnecessary waste. The double-cylindrical annular blowing filter element of this design can suck and discharge the cooling air after cooling the tow out of the filter element cavity after reaching the inner cylindrical filter element, each performing its own functions without interference, with balanced blowing and suction, achieving both the uniformity and stability of the annular blowing cooling and playing the role of stabilizing the tow by side blowing, reducing the interference of tow shaking, improving the physical properties of the tow, and improving the dyeing uniformity; by improving the pre-networker, the pre-networker is composed of three porcelain parts connected. The left porcelain part (the first porcelain part) has a pressure hole inlet (air inlet hole), and there are two upper and lower channels at its inlet leading to the upper and lower porcelain parts (the second porcelain part and the third porcelain part). The upper and lower porcelain bodies are respectively provided with air supply channels and turn to the compressed air outlet, and one compressed air outlet is inclined upward and the other is inclined downward, facilitating blowing towards the tow from two directions; the tow channels provided by the upper and lower magnets are designed in a gentle slope triangular shape, and the compressed air is blown out from the outlet and deflects and extends in the tow channel, enabling the compressed air to blow the entire tow from front to back, improving the tow entanglement power, evenly distributing the network nodes, and not requiring a very high network pressure, saving costs.

[0066] It can be understood that the specifications of the hollow profiled fibers formed by the above method are 55.3~83.2D / 24~48F.

[0067] In some embodiments, the spinning process parameters include: cooling air pressure 60~80Pa, height of the windless area 40~55mm, and temperature of the bottom heater 300~310°C.

[0068] In some embodiments, the winding process parameters include: draw roll speed of 2450 - 2950 m / min, draw roll temperature of 85 - 93 °C, setting roll speed of 4460 - 4870 m / min, setting roll temperature of 128 - 133 °C, winding speed of 4400 - 4800 m / min, pre-network pressure of 0.070 - 0.085 bar, main-network pressure of 0.36 - 0.40 bar, and machine contact pressure of 240 - 270 cN.

[0069] Furthermore, after the spinning is completed, the obtained fibers can be tested for relevant performance indicators, such as the detection of breaking strength, breaking strength unevenness, breaking elongation, and breaking elongation unevenness. The methods are as follows:

[0070] For the tested samples that have been adjusted to balance, remove 5 m of the yarn at the beginning of the package. Clamp the yarn into the holder of a tensile strength tester (model YG023BⅡ), and then conduct a tensile test to measure the breaking strength and elongation values of the sample when it breaks. The computer automatically calculates the breaking strength, breaking strength unevenness, breaking elongation, and breaking elongation unevenness. Each sample is tested three times, and the average value is taken as the final result of the sample. Among them, the gauge length is 500 mm, the pre-tension is 0.05 ± 0.01 cN / dtex, and the test speed is 500 mm / min.

[0071] The detection method for the U half-suppression value of evenness is as follows:

[0072] Use a USTER-5 evenness tester to measure the U half-suppression value of the sample. The experimental data takes the average value of 6 groups of tested samples as the U half-suppression value of the test sample. Among them, the test speed is 100 m / min, the twist is 21000 r / min, and the test time is 2 min.

[0073] The detection method for boiling water shrinkage rate is as follows:

[0074] Wind 25 meters of the specimen on a length measuring instrument, tie the head and tail to form a specimen skein; under the atmospheric conditions in the physical inspection room (temperature 22 ± 3°C, humidity 60 ± 5%), hang the specimen skein on the hook at the upper end of the vertical scale, align the inner side of the skein with the 0 scale of the ruler, and then hang an appropriate pre-tension weight at the lower end of the skein (Calculation method of pre-tension: Pre-tension (g) = 2.55 × fineness (dtex)). After 30 seconds, accurately measure the length L0 before boiling, accurate to 0.5 mm; Twist the above specimen skein into a figure-eight shape, then fold it in half to form two layers of loops and put it into a yarn bag; Put the yarn bag into an electric heating constant temperature water bath (model HWS28) and boil it for 30 minutes (100°C boiling water); After boiling, take out the yarn bag from the electric heating constant temperature water bath and place it horizontally, press dry the water, remove the yarn bag, then unfold the specimen skein and hang it on the silk drying rack, and let it stand and balance to the temperature of the physical inspection room; Hang the balanced specimen skein on the hook at the upper end of the vertical scale, hang the original pre-tension weight at the lower end, after 30 seconds, accurately measure the length L1 after boiling, accurate to 0.5 mm; Calculate the boiling water shrinkage rate according to the following formula:

[0075]

[0076] The detection method of oil content rate is as follows:

[0077] Test principle: Use nuclear magnetic resonance method to test the oil content rate in the fiber; First, measure the nuclear magnetic resonance signal intensity corresponding to the standard sample with a known oil content rate, and draw a standard curve; Then test the nuclear magnetic resonance signal intensity of the sample with an unknown oil content rate and compare it with the standard curve to determine the oil content rate of the sample with an unknown oil content rate (sample to be tested);

[0078] Test process: First, wind about 1.5 g of the sample to be tested with a length measuring instrument and then take it off to form a skein, and then weigh it with a balance and record the accurate weight of the sample to be tested; Press the sample to be tested into a test tube with a wire pressing hook, pay attention to pressing the wire flat, and make the height of the wire in the test tube about 3 cm; Select the standard curve corresponding to the standard sample of the corresponding type of oil agent on the computer, input the weight of the sample to be tested, and then put the prepared sample to be tested on a nuclear magnetic resonance analyzer (model BRUKER MQ20) for testing. The computer calculates the oil content rate of the sample to be tested according to the curve of the sample to be tested.

[0079] The detection method of the dyeing uniformity grade is as follows:

[0080] First, socks are knitted using the sample to be tested and the standard yarn respectively (the sock knitting instrument is a dyeing test knitting machine, model KU483B). The length of the sock tape knitted on each bobbin is about 5 cm, and the length of the knitted sock tape is obtained by setting the yarn storage time. Then, a dyeing machine (model PR80CⅡ) is used to dye the knitted sock tape: first, weigh the mass (g) of the sock tape to be dyed in each cylinder, and weigh the corresponding mass of the dye (brand: Disperse Brilliant Blue 2BLN 100%) according to the formula (sock tape mass × 1.5%); then add an appropriate amount of 60°C hot water to fully dissolve the dye to obtain a dye solution, add 16 cm deep water to the dyeing machine, start the dyeing machine and gradually heat up to 60°C, add all the dye solutions and stir evenly, put in the sock tape, introduce the sock tape into the circulating nozzle of the dyeing machine, and arrange the sock tape flat and smooth, with the head and tail connected. Raise the temperature of the dye bath to 96°C and maintain it for 30 minutes, drain the dye solution, take out the sock tape after cooling, wash it with clean water, dehydrate it and dry it in a cool place; finally, perform color judgment. Put the dried sock tape on the judgment board, with the fabric surface at a 70-degree angle to the light, observe section by section, compare the darkest section and the lightest section in the sock tape with the gray scale (national standard 5.0 level) respectively, determine the color difference between the darkest section and the lightest section in the sock tape, and judge the dyeing uniformity grade of the fabric according to the color difference.

[0081] Test method for water absorption of polyester fiber:

[0082] Materials and tools: Polyester fiber sample, electronic balance (accuracy at least 0.01 g), water container, filter paper or absorbent paper;

[0083] Test steps:

[0084] 1. Prepare the fiber sample: Dry the polyester fiber sample to a constant weight. The fiber can be dried in an oven and then cooled in a desiccator to ensure that the sample does not absorb moisture;

[0085] 2. Initial weighing: Use an electronic balance to weigh the weight of the dried polyester fiber sample as W1;

[0086] 3. Immersion: Immerse the polyester fiber sample completely in water for 1 hour;

[0087] 4. Remove excess water: Take out the polyester fiber sample and gently blot the excess water on the surface with filter paper or absorbent paper, taking care not to squeeze hard to avoid affecting the test results;

[0088] 5. Final weighing: Immediately use an electronic balance to weigh the weight of the moistened polyester fiber sample as W2;

[0089] 6. Calculate the water absorption: Calculate the water absorption of the polyester fiber using the following formula:

[0090] Water absorption W = W2 - W1;

[0091] Water Absorption Rate: If the water absorption rate needs to be calculated, the following formula can be used:

[0092] .

[0093] Thermal Insulation Coefficient Test Method: Heat Flow Meter Method:

[0094] Principle: The heat flow meter method calculates the thermal resistance value (R value) and the thermal conductivity coefficient (λ value) by measuring the heat flow through the fiber sample. This method is widely used in laboratories because it provides highly accurate results and is relatively simple to operate.

[0095] Equipment: Heat Flow Meter: A device equipped with sensors that can measure the heat flow.

[0096] Hot Plate: Used to heat one side of the sample; Cold Plate: Used to keep the other side of the sample at a low temperature.

[0097] Steps:

[0098] 1. Prepare the sample: Cut the fiber sample into standard sizes to ensure uniform thickness;

[0099] 2. Install the device: Clamp the sample between the hot plate and the cold plate, ensuring no air gaps to avoid heat conduction loss;

[0100] 3. Control the temperature: Set the temperatures of the hot plate and the cold plate. Usually, the temperature of the hot plate is slightly higher than that of the cold plate to simulate actual usage conditions;

[0101] 4. Measure the heat flow: Use the heat flow meter to measure the heat flow through the sample;

[0102] 5. Calculate the thermal resistance: Calculate the thermal resistance value (R value) and the thermal conductivity coefficient (λ value) of the sample based on the measured heat flow and temperature difference.

[0103] Sample thickness d = 0.01m, sample area A = 0.01m 2 , temperature difference ΔT = 10K, heat flow Q = 0.05W;

[0104] Calculation of Thermal Resistance Value:

[0105]

[0106] Calculation of Thermal Conductivity Coefficient:

[0107]

[0108] Through the above calculations, it can be obtained that:

[0109] High thermal resistance value (R value = );

[0110] Low thermal conductivity coefficient (λ value = ).

[0111] Through combined analysis, the heat preservation performance of fibers is related to the R value and λ value of the fibers, and the R value and λ value are related to factors such as the cross-sectional shape, specific surface area, cavity structure, and processing technology of the fibers.

[0112] The method for testing the degree of profile is the test method for the degree of profile of chemical fibers, specifically the FZ-T5002-2013 standard: the relative radial profile degree Dr = (1 - r / R) × 100%.

[0113] The test results are as follows: the linear density is 55.2 - 83.6, the unevenness rate of linear density ≤ 1.50%, the breaking strength ≥ 3.55 cN / dtex, the unevenness rate of breaking strength ≤ 4.78%, the breaking elongation is 28.8 - 31.2%, the unevenness rate of breaking elongation ≤ 5.23%, the U half suppression value of evenness ≤ 0.64%, the boiling water shrinkage rate is 6.62 - 7.02%, the oiling rate is 0.75 - 0.96%, the number of network points is 16 - 23 per meter, the dyeing uniformity grade > 4.5, the full roll rate ≥ 97.5%, and the AA rate ≥ 96.8%.

[0114] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

[0115] The above shows and describes the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited by the above embodiments. What is described in the above embodiments and the specification only illustrates the principle of the present invention. Without departing from the spirit and scope of the present invention, the present invention will have various changes and improvements, and these changes and improvements all fall within the scope of the present invention claimed.

Claims

1. A production device for multi-U sandwich-shaped hollow special-shaped fibers, characterized in that, The device includes a circular spinneret, a cooling filter element, and a pre-network device, wherein the circular spinneret includes two spinning areas arranged at a first relative angle and two non-spinning areas arranged relative to each other at a second relative angle, wherein the first relative angle is greater than the second relative angle, and the spinning areas are sequentially provided with multiple concentric arc layers from the center of the circular spinneret outward, wherein each concentric arc layer is spaced apart and provided with multiple spinnerets, and each spinneret is composed of a plurality of U-shaped structural plates surrounding each other, wherein the bottom and the bottom of the U-shaped structural plates are sequentially attached to form the inner circle of the entire spinneret, and the opening of the U-shaped structural plate forms the outer circle of the entire spinneret; The cooling filter element is a double-cylindrical structure, and the cooling filter element is used to cool the fiber filaments ejected from the spinneret; the pre-network device is used to process the fiber filaments after they form a bundle to obtain a network filament, and the pre-network device includes a first porcelain part, a second porcelain part, a third porcelain part and an air supply channel, the first porcelain part is provided with an air inlet hole, and the pressurized gas passing through the air inlet hole is divided in the air supply channel, one stream enters the second porcelain part, and the other stream enters the third porcelain part, the second porcelain part is provided with an air outlet end in a first inclined direction, and the second porcelain part is provided with an air outlet end in a second inclined direction; the cooling filter element includes a first hollow filter element and a second hollow filter element arranged inside and outside, a ventilation loop is formed between the first hollow filter element and the second hollow filter element, a first ventilation hole is provided on the first side surface of the first hollow filter element, and a second ventilation hole is provided on the second side surface of the second hollow filter element, and the two ends of the first hollow filter element are respectively connected to an external fan.

2. The production equipment of a multi-U sandwich-shaped hollow special-shaped fiber according to claim 1, characterized in that, The air supply channel includes a first air pipe and a second air pipe, and the first air pipe and the second air pipe are connected to each other at the air inlet of the pre-network device.

3. The production equipment of a multi-U sandwich-shaped hollow special-shaped fiber according to claim 1, characterized in that, The bottom of the U-shaped structural plate is designed to be semicircular. The inner side spacing between the left and right side plates of the U-shaped structural plate is 0.05±0.002mm, the distance between the inner and outer sides of the side plates is 0.06±0.002mm, the outer semicircle radius of the bottom of the U-shaped structural plate is 0.025±0.002mm, and the inner semicircle radius is 0.02±0.002mm.

4. The production equipment of a multi-U sandwich-shaped hollow special-shaped fiber according to claim 1, characterized in that, The second hollow filter element includes an air outlet area and a non-air outlet area, and the surface area of the air outlet area is larger than the surface area of the non-air outlet area.

5. The production equipment of a multi-U sandwich-shaped hollow special-shaped fiber according to claim 1, characterized in that, The tow channel formed by the second porcelain piece and the third porcelain piece is designed as a triangle with a slope, and the angle β of the triangle is 36°~40°.

6. A production method of a multi-U sandwich-shaped hollow profiled fiber, characterized in that, The method is implemented based on the production equipment of the multi-U sandwich hollow shaped fiber according to any one of claims 1 to 5, and the method comprises: S1) transporting the raw material high-quality semi-dull polyester melt to a booster pump for pressurization treatment to obtain a polyester melt; S2) transporting the polyester melt to a spinning manifold through a melt pipe for spinning, wherein the spinning manifold includes a plurality of spinning assemblies, each of which includes the production equipment for multi-U sandwich hollow shaped fibers described in any one of the above items, and the flow rate of the polyester melt transported by the melt pipe is measured by a metering pump.

7. The production method of a multi-U sandwich type hollow profiled fiber according to claim 6, characterized in that, The spinning box further includes an oil nozzle, a godet hook for bunching filaments, a duct, a diamond-shaped godet, a press roll, a first comb-shaped godet, a drawing roll, a second comb-shaped godet, a setting roll, a main pre-networker, and a winding machine. Step S2) includes the following technological processes: Circular spinneret → Cooling filter element → Oiling by the oil nozzle → Godet hook for bunching filaments → Duct → Diamond-shaped godet → Press roll → Pre-networker → First comb-shaped godet → Drawing roll → Second comb-shaped godet → Setting roll → Main networker → Forming on the winding machine The oil nozzle is used to coat the surface of the fiber filaments cooled by the cooling filter element with an oil agent. The godet hook for bunching filaments is used to gather single or multiple fiber filaments together to form a filament bundle and guide the filament bundle to move along the target path through the godet hook. The duct is used to further cool and condition the air of the filament bundle so that the temperature and humidity of the filament bundle reach the target state. The diamond-shaped godet is used to guide and straighten the filament bundle so that the filament bundle remains neat and stable, reducing the entanglement or deviation of the filament bundle during movement. The press roll is used to compress and straighten the filament bundle by applying pressure. The first comb-shaped godet is used to comb and guide the filament bundle that has passed through the pre-networker. The drawing roll is used to draw the fibers. The second comb-shaped godet is used to comb and guide the drawn filament bundle. The setting roll is used to perform heat setting on the drawn fibers. The main networker is used to form network points on the filament bundle again to enhance the entanglement degree between the fibers. The winding machine is used to wind the fibers after the previous processing into a package with the target shape and specifications.

8. The production method of a multi-U sandwich-shaped hollow profiled fiber according to claim 6, characterized in that, The spinning process parameters include: cooling air pressure 60 - 80 Pa, height of the windless zone 40 - 55 mm, temperature of the bottom heater 300 - 310 °C; the winding process parameters include: speed of the drawing roll 2450 - 2950 m / min, temperature of the drawing roll 85 - 93 °C, speed of the setting roll 4460 - 4870 m / min, temperature of the setting roll 128 - 133 °C, winding speed 4400 - 4800 m / min, pre-network pressure 0.070 - 0.085 bar, main network pressure 0.36 - 0.40 bar, machine contact pressure 240 - 270 cN.

9. The production method of a multi-U sandwich-shaped hollow profiled fiber according to claim 7, characterized in that The linear density of the fibers formed based on the production method is 55.2 - 83.6, the unevenness rate of the linear density ≤ 1.50%, the breaking strength ≥ 3.55 cN / dtex, the unevenness rate of the breaking strength ≤ 4.78%, the breaking elongation rate is 28.8 - 31.2%, the unevenness rate of the breaking elongation ≤ 5.23%, the U half suppression value of the evenness ≤ 0.64%, the boiling water shrinkage rate is 6.62 - 7.02%, the oiling rate is 0.75 - 0.96%, the number of network points is 16 - 23 per meter, the dyeing uniformity grade > 4.5, the full bobbin rate ≥ 97.5%, the AA rate ≥ 96.8%.

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