Ultrahigh molecular weight polyethylene fiber stretching device and method

Abstract

The invention relates to an ultra-high molecular weight polyethylene fiber stretching device and method, and the device comprises a multi-tube type constant-temperature heat transfer assembly which comprises a closed jacket shell and a plurality of metal channel tubes which longitudinally penetrate through the jacket shell and are arranged in parallel in the transverse direction, and the two ends of each metal channel tube are provided with openings; a heating cavity for heating the metal channel pipe is formed in the jacket shell, and an independent stretching channel allowing a single fiber to penetrate through in a non-contact mode is formed in the metal channel pipe; the inlet end of the negative-pressure filament guiding mechanism can be tightly attached to the outlet end of the metal channel pipe, and the negative-pressure filament guiding mechanism is used for initial spinning-in and broken-end recovery of the fibers. Compared with the prior art, by means of the independent extremely-high uniform-temperature hot field without forced airflow interference, the wind shaking phenomenon is thoroughly eliminated, high-magnification and high-uniformity stretching of fibers is achieved, meanwhile, the problem of continuous yarn guiding in a long and thin limited space is solved in cooperation with the instantaneous negative pressure technology, and the production stability and the mechanical property limit of finished product fibers are greatly improved.

Description

Technical Field

[0001] This invention belongs to the field of high-performance special fiber manufacturing technology, and relates to a stretching device and method for ultra-high molecular weight polyethylene fiber. Background Technology

[0002] Ultra-high molecular weight polyethylene (UHMWPE) fiber, as one of the world's three major high-performance fibers, owes its extremely high tensile strength and modulus primarily to the high linearity of its macromolecular chains, its extremely high molecular weight, and the highly oriented crystalline structure formed during ultra-stretching. In gel spinning, the nascent fiber, extruded and solidified by a spinneret, is in a gel state. Its internal macromolecular chains exhibit a highly entangled and disordered state with extremely low orientation, essentially lacking the mechanical characteristics of high strength and high modulus. Therefore, a subsequent multi-stage ultra-stretching process is necessary to induce the macromolecular chains to fully de-entangle within a specific temperature range close to the polymer's melting point, resulting in high orientation and recrystallization along the fiber axis. This process places extremely stringent requirements on the uniformity and stability of the thermal environment; any minute temperature fluctuations or physical disturbances can directly lead to crystalline defects within the fiber, thereby limiting the overall performance of the finished fiber.

[0003] In current large-scale industrial production, the commonly used technical solution is a multi-stage horizontal flat-lay convection hot box stretching process. This process involves continuously passing hundreds of fiber bundles in a parallel, curtain-like arrangement through a sealed hot box typically 3 to 6 meters long. Heating units inside the hot box generate heat, which is then circulated within the box by a fan. The hot air, after being distributed through complex airflow ducts and perforated plates, blows across the high-speed moving fiber surface, achieving fiber heating and temperature control through convective heat transfer at the gas-solid interface.

[0004] However, in traditional hot-box stretching, it is difficult to precisely control the uniformity of the temperature field. The large volume of the hot box inevitably leads to dead zones, edge effects, and turbulent boundary layers, directly causing internal temperature gradients. Temperature differences often exceed ±2℃, resulting in a significant increase in the dispersion coefficient of the final fiber's mechanical properties, making it difficult to achieve highly uniform high-strength performance. Furthermore, the internal air circulation cannot achieve complete static pressure, with a large amount of hot air dissipating from both ends of the hot box, causing severe heat loss. These problems prevent further improvement in the stretching precision of polyethylene fibers, resulting in high production costs, limited product uniformity and performance, poor production stability, and a tendency for fiber breakage and drift. In the pursuit of higher breaking strength, lower linear density, and higher quality stability, its inherent physical and thermodynamic bottlenecks are becoming increasingly prominent. Summary of the Invention

[0005] The purpose of this invention is to provide a stretching device and method for ultra-high molecular weight polyethylene fibers. By creating an independent, highly uniform temperature thermal field without forced airflow interference, the wind tremor phenomenon is completely eliminated. Under extremely low energy consumption and inert gas protection, the fiber can be stretched with high ratio and high uniformity. At the same time, the instantaneous negative pressure technology solves the problem of continuous fiber drawing in slender and confined spaces, which greatly improves production stability and the mechanical property limit of the finished fiber.

[0006] The objective of this invention can be achieved through the following technical solutions: In a first aspect, the present invention provides a stretching device for ultra-high molecular weight polyethylene fibers, comprising: A multi-tube constant temperature heat transfer assembly includes a sealed jacket shell and a plurality of metal channel tubes with open ends that run longitudinally through the jacket shell and are arranged in parallel laterally. A heating chamber with a forced circulating flow of heat-conducting working fluid is formed inside the jacket shell, and an independent stretching channel for a single fiber to pass through without contact is formed inside the metal channel tube. And a negative pressure fiber-drawing mechanism, whose inlet end can be closely attached to the outlet end of the metal channel tube, and is used for the initial fiber generation and fiber breakage recovery.

[0007] Furthermore, the side wall at the inlet end of the metal channel tube is provided with an air inlet hole, and is connected to the inert gas distribution main pipe through parallel gas injection branches, so as to form a micro-positive pressure inert environment inside the independent stretching channel.

[0008] Furthermore, the jacket housing is sealed with metal end plates at both ends along the longitudinal direction, and the two ends of the metal channel tube pass through the two metal end plates respectively and are sealed and fixed with the metal end plates.

[0009] Furthermore, the inner diameter of the independent stretching channel is 3~15mm, the length is 2~8m, and its inner wall is mirror polished.

[0010] Furthermore, the heating chamber contains a forced-circulation heat transfer medium, or the heating chamber is equipped with heating elements covering the outer wall of the metal channel tube. Preferably, the heat source in the heating chamber is a forced-circulation heat transfer medium. Even further, the temperature of the heat transfer medium is 120~150℃, and preferably, the heat transfer medium is heat transfer oil.

[0011] Furthermore, an insulation layer is provided on the outside of the jacket shell.

[0012] Furthermore, the negative pressure fiber guiding mechanism includes a negative pressure fiber guiding shell and a Venturi nozzle structure placed inside the negative pressure fiber guiding shell. One end of the negative pressure fiber guiding shell is provided with an annular interface that communicates with the inlet end of the Venturi nozzle structure. When the annular interface of the negative pressure fiber guiding shell is tightly pressed against the outlet end of the metal channel tube, the high-speed jet generated by the Venturi nozzle structure can generate a local vacuum negative pressure at the outlet end of the metal channel tube being pressed, so as to guide the fiber through the corresponding metal channel tube.

[0013] In a second aspect, the present invention provides a method for stretching ultra-high molecular weight polyethylene fibers, comprising the following steps: S1. Construct the stretching device as described in the first aspect above to control the temperature of the heating chamber circulating within the multi-tube constant temperature heat transfer component to remain stable within a preset range. S2. Introduce gas to provide an inert atmosphere into the inlet end of the metal channel tube to create a slightly positive pressure inert environment within the independent stretching channel; S3. Place the negative pressure fiber-drawing mechanism close to the outlet end of the metal channel tube and connect compressed air to create a negative pressure environment in the corresponding metal channel tube. At the same time, send the fiber to be stretched into the inlet of the target metal channel tube and use the negative pressure to guide the fiber to be stretched out from the outlet end. Repeat this process until the fiber-drawing operation in all metal channel tubes is completed. S4. The protruding fibers are bundled together and introduced into the subsequent drawing equipment, so that the fibers are tensioned and kept from contacting the inner wall of the metal channel tube, and then thermally stretched.

[0014] Furthermore, in S2, the gas providing the inert atmosphere is nitrogen.

[0015] Furthermore, in S2, the pressure in the slightly positive pressure inert environment is 10~1000 Pa. Specifically, the flow rate of the gas providing the inert atmosphere is 0.1~10 L / min.

[0016] Compared with the prior art, the present invention has the following advantages: (1) Compared with the traditional large-space forced convection heat box process, it has an excellent temperature field and forms a quasi-static microenvironment in the tube that is not affected by external macro airflow crosstalk, which significantly improves the mechanical properties and uniformity of the fiber. The fiber is heated only by the close-range thermal radiation of the tube wall and the micro-thermal conduction of the static gas in the tube, which completely eliminates the wind shaking caused by the airflow impact of forced convection and greatly reduces the breakage rate and fuzz rate. Maintaining a high-purity nitrogen atmosphere in the traditional large-space heat box is extremely costly. However, this invention utilizes the volume advantage of the small tube diameter and only needs to introduce a small amount of low-pressure nitrogen into the inlet of each channel tube to form a micro-positive pressure in the tube, which effectively blocks the thermo-oxidative degradation of the fiber during stretching.

[0017] (2) This invention eliminates the need for a high-power hot air circulation fan, and because the total area of ​​the openings at both ends of the channel pipe is small, heat convection loss is minimized. The overall thermal efficiency of the device is greatly improved, and the comprehensive heating power consumption and heat loss are reduced by about 70% compared with the traditional hot box process with the same capacity.

[0018] (3) The special wire-starting method can avoid stopping the machine to start the wire, shortening the wire-starting operation time of a single channel tube to 3-5 seconds, and does not interfere with the adjacent normally operating pipelines, effectively reducing the labor intensity of operators and reducing the generation of waste wire. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the structure of a multi-tube constant temperature heat transfer assembly; Figure 2 This is a cross-sectional schematic diagram of a multi-tube constant temperature heat transfer assembly. Figure 3 This is a schematic diagram of the negative pressure wire-drawing mechanism; Explanation of markings in the diagram: 10-Multi-tube constant temperature heat transfer unit, 11-Heat medium outlet, 12-Fiber outlet, 13-Fiber inlet, 14-Metal channel tube, 15-Heat medium inlet, 16-Nitrogen inlet, 17-Insulation layer, 18-Fiber to be stretched, 19-Gas injection branch. 20-Negative pressure wire initiation mechanism, 21-Annular interface, 22-Air flow channel, 23-Compressed air inlet, 24-Negative pressure wire housing. Detailed Implementation

[0020] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments. These embodiments are based on the technical solution of the present invention and provide detailed implementation methods and specific operating procedures. However, the scope of protection of the present invention is not limited to the following embodiments.

[0021] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application.

[0022] As used herein, the terms "and / or," "or / and," and "and / or" encompass any one of two or more of the related listed items, as well as any and all combinations of the related listed items. These arbitrary and all combinations include any two related listed items, any more related listed items, or a combination of all related listed items. It should be noted that when at least three items are connected using at least two conjunctions selected from "and / or," "or / and," and "and / or," it should be understood that, in this application, the technical solution undoubtedly includes solutions connected by "logical AND," and also undoubtedly includes solutions connected by "logical OR."

[0023] In this application, the technical features described in an open-ended manner include both closed technical solutions consisting of the listed features and open technical solutions that include the listed features.

[0024] In this application, numerical ranges are referred to as continuous unless otherwise specified, and include the minimum and maximum values ​​of the range, as well as every value between the minimum and maximum values. Furthermore, when the range refers to integers, it includes every integer between the minimum and maximum values ​​of the range. Additionally, when multiple ranges are provided to describe a feature or characteristic, the ranges may be merged. In other words, unless otherwise specified, all ranges disclosed herein should be understood to include any and all subranges to which they are incorporated.

[0025] This document only specifically discloses some numerical ranges. However, any lower limit can be combined with any upper limit to form an unspecified range; and any lower limit can be combined with other lower limits to form an unspecified range, just as any upper limit can be combined with any other upper limit to form an unspecified range. Furthermore, each individually disclosed point or single value can itself serve as a lower or upper limit and be combined with any other point or single value or with other lower or upper limits to form an unspecified range.

[0026] Unless otherwise specified, the temperature parameters in this application may be either constant temperature processing or processing within a certain temperature range. The constant temperature processing allows temperature fluctuations within the precision range controlled by the instrument, such as ±5°C, ±4°C, ±3°C, ±2°C, or ±1°C.

[0027] In this document, the term "suitable" as used in phrases such as "suitable combination," "suitable method," and "any suitable method" refers to the ability to implement the technical solution of this application, solve the technical problem of this application, and achieve the expected technical effect of this application.

[0028] In this application, terms such as "further," "even more," and "particularly" are used for descriptive purposes and to indicate differences in content, but should not be construed as limiting the scope of protection of this application.

[0029] In this application, "optionally," "optionally," and "optional" mean that something is optional, that is, it means that it is selected from either "with" or "without." If there are multiple "optional" entries in a technical solution, unless otherwise specified, and there are no contradictions or mutual constraints, each "optional" entry shall be independent.

[0030] In the description of the application, "multiple" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0031] Unless otherwise specified, all preparations and tests described herein took place at 25°C.

[0032] The terms “comprising,” “including,” “containing,” “having,” “comprising,” or other variations thereof are intended to cover non-closed inclusion, and no distinction is made between these terms. The term “comprising” means that other steps and ingredients may be added without affecting the final result. The compositions and methods / processes of the present invention comprise, consist of, and substantially consist of the essential elements and limitations described herein, as well as any additional or optional ingredients, components, steps, or limitations described herein. No distinction is made between the terms “efficacy,” “performance,” “effect,” and “potency” herein.

[0033] Unless otherwise specified, all embodiments and optional embodiments of this application can be combined to form new technical solutions. Unless otherwise specified, all technical features and optional technical features of this application can be combined to form new technical solutions.

[0034] Unless otherwise specified, all steps in this application may be performed sequentially or randomly, but sequentially is preferred.

[0035] To achieve high-ratio, high-uniformity stretching of fibers and solve the problem of continuous fiber drawing in slender, confined spaces, this invention provides a stretching device for ultra-high molecular weight polyethylene fibers, the structure of which is described below. Figures 1 to 3 As shown, including: Ten multi-tube constant temperature heat transfer units, including a sealed jacket shell and several metal channel tubes 14 with open ends that run longitudinally through the jacket shell and are arranged in parallel laterally. A heating chamber with forced circulation of heat-conducting working fluid is formed inside the jacket shell, and an independent stretching channel for single fibers to pass through without contact is formed inside the metal channel tubes 14. And a negative pressure fiber-drawing mechanism 20, whose inlet end can be closely attached to the outlet end of the metal channel tube 14, and is used for the initial fiber-growth and fiber breakage recovery.

[0036] In this invention, a heat-conducting working fluid with high heat capacity (such as heat transfer oil) is forced to circulate inside the heating chamber in a sealed jacket shell. Its core function is to utilize the high thermal stability of liquid phase heat transfer to provide an abundant and consistent heat source for all parallel channel pipes on a macroscopic scale, thereby suppressing the temperature difference fluctuations in various corners of the macroscopic equipment from ±2℃ of traditional hot air to within ±0.2℃.

[0037] For some specific implementation methods, please refer to [link / reference]. Figure 1 As shown, the sidewall of the inlet end of the metal channel tube 14 is also provided with an air inlet hole, which is connected to the inert gas distribution main pipe through a parallel gas injection branch 19. This is used to create a micro-positive pressure inert environment inside the independent stretching channel, constructing an oxygen-free environment inside the tube and effectively blocking the thermo-oxidative degradation of the fiber during stretching. At the same time, by forming a quasi-static microenvironment inside the tube that is not disturbed by external macroscopic airflow, the mechanical properties and uniformity of the fiber are significantly improved. In addition, the fiber is heated only by the close-range thermal radiation of the tube wall and the microscopic thermal conduction of the static gas inside the tube, completely eliminating the wind shaking caused by the airflow impact of forced convection, and greatly reducing the breakage rate and fuzz rate.

[0038] In some specific embodiments, the jacket housing is sealed with metal end plates at both ends along the longitudinal direction, and the two ends of the metal channel tube 14 pass through the two metal end plates respectively and are sealed and fixed with the metal end plates.

[0039] In some specific embodiments, the inner diameter of the independent stretching channel is 3~15mm, the length is 2~8m, and its inner wall is mirror polished.

[0040] In some specific embodiments, the heat-conducting working fluid is heat-conducting oil.

[0041] In some specific embodiments, the temperature of the heat-conducting working fluid is 120~150°C.

[0042] In some specific embodiments, the negative pressure fiber guiding mechanism 20 includes a negative pressure fiber guiding housing 24 and a Venturi nozzle structure placed inside the negative pressure fiber guiding housing 24. One end of the negative pressure fiber guiding housing 24 is provided with an annular interface 21 that communicates with the inlet end of the Venturi nozzle structure. When the annular interface 21 of the negative pressure fiber guiding housing 24 is tightly pressed against the outlet end of the metal channel tube 14, the high-speed jet generated by the Venturi nozzle structure can generate a local vacuum negative pressure at the outlet end of the metal channel tube 14 to guide the fiber through the corresponding metal channel tube 14.

[0043] Each of the above implementation methods can be implemented individually, or in any combination of two or more.

[0044] Example 1: To achieve high-ratio, high-uniformity stretching of fibers and solve the problem of continuous fiber drawing in slender, confined spaces, this embodiment provides a stretching device for ultra-high molecular weight polyethylene fibers, the structure of which is described below. Figures 1 to 3 As shown, including: Ten multi-tube constant temperature heat transfer units, including a sealed jacket shell and a number of metal channel tubes 14 with openings at both ends (including fiber inlet 13 and fiber outlet 12) that run longitudinally through the jacket shell and are arranged in parallel laterally. A heating chamber with forced circulation of heat-conducting working fluid is formed inside the jacket shell, and an independent stretching channel for single fibers to pass through without contact is formed inside the metal channel tubes 14. And a negative pressure fiber-drawing mechanism 20, whose inlet end can be closely attached to the outlet end of the metal channel tube 14, and is used for the initial fiber-growth and fiber breakage recovery.

[0045] In this embodiment, a heat-conducting working fluid with high heat capacity (such as heat transfer oil, the temperature of which can be set to 120~150℃) is forced to circulate inside the heating chamber in the sealed jacket shell. Its core function is to utilize the high thermal stability of liquid phase heat transfer to provide a sufficient and uniform heat source for all parallel channel pipes on a macroscopic scale, thereby suppressing the temperature difference fluctuations in various corners of the macroscopic equipment from ±2℃ of traditional hot air to within ±0.2℃.

[0046] Please see again. Figure 1 As shown, the sidewall of the inlet end of the metal channel tube 14 is also provided with an air inlet hole, which is connected to the inert gas distribution main pipe (i.e., nitrogen inlet 16) through a parallel gas injection branch 19. The inert gas distribution main pipe is connected to an external gas supply device, such as a nitrogen supply device, to inject a small amount of nitrogen or other gas at a low flow rate into each metal channel tube 14. This is to create a micro-positive pressure inert environment inside the independent stretching channel, constructing an oxygen-free environment inside the tube and effectively blocking the thermo-oxidative degradation of the fiber during stretching. At the same time, by forming a quasi-static microenvironment inside the tube that is not disturbed by external macroscopic airflow, the mechanical properties and uniformity of the fiber are significantly improved. In addition, the fiber is heated only by the close-range thermal radiation of the tube wall and the microscopic thermal conduction of the static gas inside the tube, completely eliminating the wind shaking caused by the airflow impact of forced convection, and greatly reducing the breakage rate and fuzz rate.

[0047] Please see Figure 1 As shown, the jacket housing has metal end plates sealing both ends along its longitudinal direction. The two ends of the metal channel tube 14 pass through the two metal end plates respectively and are sealed and fixed to the metal end plates. The inner diameter of the independent stretching channel is 3~15mm, the length is 2~8m, and its inner wall is mirror polished.

[0048] Please see again. Figure 3As shown, the negative pressure fiber guiding mechanism 20 includes a negative pressure fiber guiding housing 24 and a Venturi nozzle structure placed inside the negative pressure fiber guiding housing 24. One end of the negative pressure fiber guiding housing 24 is provided with an annular interface 21 that communicates with the inlet end of the Venturi nozzle structure. When the annular interface 21 of the negative pressure fiber guiding housing 24 is tightly pressed against the outlet end of the metal channel tube 14, compressed air at a specific pressure is introduced by the compressed air inlet 23 on the Venturi nozzle structure, thereby generating a high-speed jet, which in turn generates an instantaneous local vacuum negative pressure at the outlet end of the metal channel tube 14 that is being pressed, so as to guide the fiber through the corresponding metal channel tube 14 and out through the air flow channel 22 in the Venturi nozzle structure.

[0049] Example 2 Based on Example 1, this example provides a tubular static microenvironment stretching method for high-ratio thermal stretching of ultra-high molecular weight polyethylene fibers. The specific steps are as follows: (1) Construct a horizontally arranged multi-tube constant temperature heat transfer unit consisting of 10 pieces, including a rectangular sealed metal jacket shell with a length of 4m and a width of 1m. 48 independent metal channel tubes 14 are horizontally parallel through the shell. The metal channel tubes 14 are made of seamless 304 stainless steel with mirror-polished inner walls, an inner diameter of 5mm, and a wall thickness of 1mm. Both ends of all metal channel tubes 14 are sealed and welded to the inlet and outlet end plates at the front and rear of the jacket shell, respectively, to achieve physical isolation between the tube space and the heating chamber inside the jacket. Each metal channel tube 14 has a corresponding independent number (01 to 48) on its end plate.

[0050] (2) A heat transfer oil inlet (i.e., heat medium inlet 15) is provided at the bottom of the jacket shell, and a heat transfer oil outlet (i.e., heat medium outlet 11) is provided at the top, which is connected to an external mold temperature control system. The outer wall of the heat transfer cavity is equipped with an insulation layer 17. The circulation system is turned on, and a flow rate of 20 m³ / s is pumped into the inner cavity of the jacket shell. 3 The system uses heat transfer oil at a rate of / h as the heat transfer medium and sets the circulating heating temperature to 125°C. The heat transfer oil fully washes the outer wall of the metal channel tubes 14 inside the jacket shell, so that the inner wall temperature of the 48 metal channel tubes 14 rises uniformly and stabilizes at 125°C. The system measures the temperature difference fluctuations in different positions and sections of the equipment.

[0051] (3) At the inlet end plate, each metal channel pipe 14 has a micro air inlet hole on its side wall, which is connected in parallel to the nitrogen supply main pipe through the gas injection branch 19. Open the valve and continuously introduce room temperature high-purity nitrogen (purity 99.99%) at a flow rate of 0.05 L / min into each metal channel pipe 14 to establish a slightly positive pressure inert environment in the narrow pipe.

[0052] (4) A portable negative pressure fiber-generating mechanism 20, independent of the main device, is used for fiber generation. The inside of this fiber-generating mechanism is equipped with a Venturi nozzle structure, and the compressed air inlet 23 at the tail end is connected to factory compressed air at a pressure of 0.6 MPa. Taking the metal channel tube 14 numbered 01 as an example, the operator places the negative pressure fiber-generating mechanism 20 at the outlet of tube 01 on the inlet end plate and fixes it; and pulls the trigger of the fiber generator to create a negative pressure environment. The fiber 18 to be stretched is fed into the inlet of tube 01, and the negative pressure instantly pulls the fiber in tube 01 out from the tail end of the fiber generator. This operation is repeated to complete the generation of the remaining 47 fiber bundles.

[0053] (5) The 48 fibers that pass through the metal channel tube 14 are bundled together and introduced into the subsequent drawing machine. The fibers are tensioned and do not come into contact with the high-temperature metal tube wall throughout the process, thus completing the thermal stretching.

[0054] The device operated continuously and stably for 72 hours according to the above embodiment. After completely eliminating the wind tremor phenomenon in traditional hot air stretching, the number of fiber breaks and fuzzing occurred throughout the stretching process was 0. The maximum tensile strength of the obtained UHMWPE finished fiber reached 10 times, the breaking strength reached 42.5 cN / dtex, and the CV value was as low as 1.1%. Compared with a traditional hot air box with the same capacity, the overall energy consumption of this tubular device decreased by 72%. The temperature difference at each temperature measuring point in the hot air box was <±0.2℃, and the ambient temperature at a distance of 2m from the hot air box was 5℃ lower than that of a traditional hot air box.

[0055] Example 3 This embodiment is similar to Embodiment 2 in basic structure and operation steps, but differs in the specific dimensions and process parameters of the core device, in order to verify the universality of this method under different specifications: (1) The length of the constructed jacket shell is shortened to 2m. The metal channel tube 14 is a stainless steel tube with an inner diameter of 10mm and a wall thickness of 1.5mm.

[0056] (2) The circulating heating temperature of the heat transfer oil is set to 135°C.

[0057] (3) The flow rate of room temperature high-purity nitrogen gas introduced into each metal channel tube 14 is adjusted to 0.1 L / min.

[0058] (4) The stretching ratio during the stretching stage is set to 5.5 times.

[0059] Continuous operation according to this embodiment also achieved zero wind shaking and zero fiber breakage for ultra-high linear density fibers. The temperature difference at each measuring point in the hot box was <±0.25℃. The resulting finished fiber had a breaking strength of 38.5 cN / dtex and a CV value of 1.5%, with overall energy consumption reduced by approximately 65% ​​compared to traditional large-capacity hot boxes with the same production capacity.

[0060] Example 4 This embodiment is similar to Embodiment 2 in terms of basic structure and operation steps.

[0061] (1) As attached Figure 2 As shown, the jacket shell is 5m long and 1.5m wide, with three layers containing a total of 180 staggered channel tubes. Each layer has 60 tubes. The channel tubes are made of stainless steel capillaries with an inner diameter of only 3mm, and the inner wall of the tubes is coated with a silicon carbide (SiC) high infrared emissivity ceramic coating using plasma spraying technology.

[0062] (2) The circulating temperature of the heat transfer medium is set to 142°C, which is close to the melting point limit of UHMWPE.

[0063] (3) The flow rate of room temperature high-purity nitrogen gas introduced into each metal channel tube 14 is adjusted to 0.05 L / min.

[0064] (4) In this microenvironment with extreme uniform temperature and enhanced thermal radiation, the fiber stretch ratio can exceed 11 times. No fuzz is generated after 48 hours of continuous operation, and the breaking strength of the finished fiber is as high as 43.0 cN / dtex with a CV value of 0.9%, which demonstrates the potential of static stretching in the microenvironment to explore the ultimate performance of the fiber.

[0065] Example 5 Except for the structure of the heating device and the medium, all other process steps in this embodiment are exactly the same as in Embodiment 2.

[0066] The outer walls of 48 independent metal channel tubes 14 are directly and tightly covered with flexible electric heating jackets (or electric heating wires), and a high-efficiency insulation layer 17 is wrapped around the heating layer. A centralized temperature sensor and temperature control module directly heat and stabilize the tube wall temperature at 125°C. Similarly, the fiber breaks zero times during the entire stretching process, and the breaking strength and CV value of the resulting finished fiber are basically the same as in Example 2. The mold temperature controller and heat transfer oil circulation pipeline are eliminated, simplifying the overall structure of the equipment. Under the same insulation conditions, the overall energy consumption is reduced by approximately 35% compared to a traditional large-capacity heat box with the same production capacity.

[0067] The above description of the embodiments is provided to enable those skilled in the art to understand and use the invention. It will be apparent to those skilled in the art that various modifications can be made to these embodiments, and the general principles described herein can be applied to other embodiments without inventive effort. Therefore, the present invention is not limited to the above embodiments, and any improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from the scope of the invention should be within the protection scope of the present invention.

Claims

1. A stretching device for ultra-high molecular weight polyethylene fibers, characterized in that, include: A multi-tube constant temperature heat transfer assembly includes a sealed jacket shell and a plurality of metal channel tubes with open ends that run longitudinally through the jacket shell and are arranged in parallel laterally. A heating chamber for heating the metal channel tubes is formed inside the jacket shell, and an independent stretching channel for a single fiber to pass through without contact is formed inside the metal channel tube. And a negative pressure fiber-drawing mechanism, whose inlet end can be closely attached to the outlet end of the metal channel tube, and is used for the initial fiber generation and fiber breakage recovery.

2. The stretching device for ultra-high molecular weight polyethylene fiber according to claim 1, characterized in that, The side wall at the inlet end of the metal channel tube is also provided with an air inlet hole, and is connected to the inert gas distribution main pipe through parallel gas injection branches, so as to form a micro-positive pressure inert environment inside the independent stretching channel.

3. The stretching device for ultra-high molecular weight polyethylene fiber according to claim 1, characterized in that, The jacket housing is sealed with metal end plates at both ends along the longitudinal direction. The two ends of the metal channel tube pass through the two metal end plates respectively and are sealed and fixed with the metal end plates.

4. The stretching device for ultra-high molecular weight polyethylene fiber according to claim 1, characterized in that, The inner diameter of the independent stretching channel is 3~15mm, the length is 2~8m, and its inner wall is mirror polished.

5. The stretching device for ultra-high molecular weight polyethylene fiber according to claim 1, characterized in that, The heating chamber is equipped with a forced circulation of heat-conducting working fluid, or the heating chamber is provided with heating elements covering the outer wall of the metal channel tube.

6. The stretching device for ultra-high molecular weight polyethylene fiber according to claim 5, characterized in that, The temperature of the heat-conducting working fluid is 120~150℃.

7. The stretching device for ultra-high molecular weight polyethylene fiber according to claim 1, characterized in that, The negative pressure fiber guiding mechanism includes a negative pressure fiber guiding shell and a Venturi nozzle structure placed inside the negative pressure fiber guiding shell. One end of the negative pressure fiber guiding shell is provided with an annular interface that communicates with the inlet end of the Venturi nozzle structure. When the annular interface of the negative pressure fiber guiding shell is tightly pressed against the outlet end of the metal channel tube, the high-speed jet generated by the Venturi nozzle structure can generate a local vacuum negative pressure at the outlet end of the metal channel tube being pressed, so as to guide the fiber through the corresponding metal channel tube.

8. A method for stretching ultra-high molecular weight polyethylene fibers, characterized in that, Includes the following steps: S1. Construct a stretching device as described in any one of claims 1-7, and control the temperature of the heating chamber circulating within the multi-tube constant temperature heat transfer component to remain stable within a preset range. S2. Introduce gas to provide an inert atmosphere into the inlet end of the metal channel tube to create a slightly positive pressure inert environment within the independent stretching channel; S3. Place the negative pressure fiber-drawing mechanism close to the outlet end of the metal channel tube and connect compressed air to create a negative pressure environment in the corresponding metal channel tube. At the same time, send the fiber to be stretched into the inlet of the target metal channel tube and use the negative pressure to guide the fiber to be stretched out from the outlet end. Repeat this process until the fiber-drawing operation in all metal channel tubes is completed. S4. The protruding fibers are bundled together and introduced into the subsequent drawing equipment, so that the fibers are tensioned and kept from contacting the inner wall of the metal channel tube, and then thermally stretched.

9. The method for stretching ultra-high molecular weight polyethylene fibers according to claim 8, characterized in that, In S2, the gas providing the inert atmosphere is nitrogen.

10. The method for stretching ultra-high molecular weight polyethylene fibers according to claim 8, characterized in that, In S2, the pressure in the slightly positive pressure inert environment is 10~1000Pa, and the gas flow rate is 0.1~10L / min.

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