Pre-oxidation furnace based on multi-specification tows and pre-oxidation method for preparing CNFs

Abstract

The invention relates to the technical field of carbon fiber production, in particular to a pre-oxidation furnace based on multi-specification tows and a pre-oxidation method for preparing CNFs, the pre-oxidation furnace comprises a furnace body, a tow feeding mechanism, an air duct and a filter screen, the tow feeding mechanism, the air duct and the filter screen are arranged in the furnace body, and the filter screen is provided with a cleaning mechanism for cleaning the tows accumulated on the filter screen. The cleaning mechanism comprises a cleaning box and a wind scooper, a roller shaft is arranged in the cleaning box, and a sawtooth-shaped scraping plate is arranged on the roller shaft; by means of synchronous movement of the cleaning box and the wind scooper and the design of the sawtooth-shaped scraper blade on the roller shaft, efficient cleaning of the surface of the filter screen is achieved, the roller shaft in the cleaning box can roll along the filter screen, the scraper blade effectively grabs and winds attached fiber filaments, and the wind scooper and the cleaning box are matched to shield part of the area of the filter screen during cleaning, so that the cleaning effect is improved, and the service life of the filter screen is prolonged. And the reverse blowing direction of airflow is optimized, the grabbing effect of the roller shaft on the cellosilk is enhanced, thorough cleaning is ensured, and therefore the follow-up maintenance requirement is reduced, and the normal operation time of equipment is prolonged.

Description

Technical Field

[0001] The present invention relates to the technical field of carbon fiber production, and specifically relates to a pre-oxidation furnace based on multi-specification tows and a pre-oxidation method for preparing CNFs. Background Art

[0002] Due to its light weight, high specific strength, high specific modulus, and excellent fatigue resistance and corrosion resistance, carbon fiber has been widely used in the fields of military and civilian materials. The preparation of CNFs (carbon nanofibers) is an important research direction in the field of carbon fiber. Carbon fibers can be divided into small tows and large tows according to the tow specifications. The two face different markets, and there are obvious differences in the production processes, especially in the pre-oxidation furnace in the production equipment.

[0003] In the prior art, the pre-oxidation furnace is usually designed for a specific specification of tow, with a single structure and unable to adapt to the production of carbon fibers of multiple specifications. Such a design limits the flexibility of process parameters, increases production costs and the floor area of the equipment. Chinese Patent CN114351292B discloses a multi-specification tow adaptable carbon fiber pre-oxidation furnace, including a pre-oxidation furnace wire passing channel, a common air duct, a central air damper, a fan, a circulating air duct, an upper inlet air damper, a lower return air chamber, and a lower air damper. Through the design of the common air duct, the central air damper, the upper inlet air damper, the lower air damper, and the circulating air duct, two circulating air modes (from the center to both ends, from top to bottom) are realized. This structure can save costs, adapt to the production of carbon fibers of multiple specifications, and reduce the number and floor area of the equipment. However, there are also some problems with this patent. During the operation of the circulating air, since the pre-oxidation furnace is applicable to tows of different specifications, the tows will break or tear due to the difference in tension when being transported inside the pre-oxidation furnace. As a result, the fiber filaments are likely to remain on the filter screen of the air duct driven by the circulating air. If not cleaned for a long time, the remaining fiber filaments may be coked due to high temperature and adhere to the filter screen, causing cleaning difficulties. The existing cleaning mechanism generally cleans the fiber filaments on the filter screen by setting bristles, but the cleaning effect of the bristles on the fiber filaments is not good. Since the fiber filaments are relatively soft, it is difficult to drive the fiber filaments to move and remove them through the bristles after being adsorbed on the filter screen, which affects the normal operation of the equipment and may lead to the equipment being shut down for a long time for thorough cleaning. Summary of the Invention

[0004] To solve the above problems, a pre-oxidation furnace based on multi-specification tow and a pre-oxidation method for preparing CNFs are provided. Through the synchronous movement of the cleaning box and the air guide hood, combined with the serrated scraper design on the roller shaft, efficient cleaning of the filter screen surface is achieved. The roller shaft in the cleaning box can roll along the filter screen, and the scraper effectively grabs and winds the attached fiber filaments. The cooperation between the air guide hood and the cleaning box shields part of the filter screen area during cleaning, optimizes the reverse blowing direction of the air flow, enhances the grabbing effect of the roller shaft on the fiber filaments, ensures thorough cleaning, thereby reducing subsequent maintenance requirements and extending the normal operation time of the equipment.

[0005] To solve the problems of the prior art, the present invention provides a pre-oxidation furnace based on multi-specification tow, which includes a furnace body and a wire feeding mechanism arranged in the furnace body for transporting multi-specification tows. At the top inside the furnace body, there is an air duct for exhausting air and a filter screen arranged on the air duct. A cleaning mechanism for cleaning the tows accumulated on the filter screen is arranged on the filter screen. The cleaning mechanism includes a cleaning box and an air guide hood. The cleaning box is located below the filter screen and can slide along the length direction of the filter screen. A roller shaft capable of grabbing the tows adsorbed on the filter screen is arranged inside the cleaning box, and a serrated scraper is arranged on the roller shaft; the air guide hood is located above the filter screen, and the air guide hood is used to absorb the air flow entering the air duct and direct it to the filter screen for reverse blowing on the filter screen, and the air guide hood can slide synchronously with the cleaning box along the length direction of the filter screen.

[0006] Preferably, there are multiple scrapers on the roller shaft, and the multiple scrapers are evenly arranged around the axis of the roller shaft at equal intervals. The scraper is made of an elastic material and extends spirally along the axis of the roller shaft.

[0007] Preferably, a cleaning channel connected to an external cleaning mechanism is arranged in the middle of the cleaning box. The scraper extends from one end of the roller shaft along a spiral line to the middle of the roller shaft, and reverses along the spiral direction of the scraper at the middle of the roller shaft, so that the scraper continues to extend along the spiral line to the other end of the roller shaft in the opposite direction.

[0008] Preferably, comb teeth for breaking the fiber filaments wound on the scraper are arranged on both sides of the cleaning box where the roller shaft is located. There are multiple comb teeth, and the multiple comb teeth extend at equal intervals along the length direction of the cleaning box.

[0009] Preferably, the air guide hood is a long strip-shaped cover body, which extends along the width direction of the filter screen. An air inlet and an air outlet are arranged at the bottom of the air guide hood, and the air outlet matches the cleaning box. A curved air flow channel is arranged inside the air guide hood, and the air flow rises from the bottom air inlet along the curved air flow channel and is directed to the air outlet.

[0010] Preferably, mounting grooves are provided on both sides of the bottom of the air duct. Sliders capable of sliding in the mounting grooves are provided at both ends of the roller shaft. A guide rod and a lead screw extending along the length direction of the filter screen are respectively provided in the two mounting grooves. The two sliders are respectively sleeved on the guide rod and the lead screw. The lead screw is in threaded cooperation with the slider, and the slider is in sliding cooperation with the guide rod.

[0011] Preferably, the roller shaft is rotatably arranged in the slider. Gears are provided at both ends of the roller shaft. A rack extending along the length direction of the filter screen is provided at the top in the mounting groove. The rack is located above the gear and is meshed with it.

[0012] Preferably, sliding grooves extending in the vertical direction are provided at both ends of the air guide cover. A connecting rod hinged to the slider is provided on the slider. The other end of the connecting rod is in sliding cooperation with the sliding groove. A limiting plate for limiting the connecting rod is provided on one side of the slider. When the slider moves horizontally to the side away from the limiting plate, the limiting plate limits the connecting rod, and the slider drives the air guide cover to move synchronously through the connecting rod; when the slider moves in the opposite direction, the connecting rod loses its limit, and the air guide cover is located obliquely above the slider.

[0013] Preferably, the wire feeding mechanism includes support frames respectively arranged at both ends of the furnace body and mirror-symmetric. A plurality of guide rollers arranged at equal intervals along the height direction are provided on both support frames. Multi-specification wire bundles are sleeved between the plurality of guide rollers on the two support frames.

[0014] A pre-oxidation method for the preparation of CNFs, applied to the above-mentioned pre-oxidation furnace based on multi-specification wire bundles, includes the following steps:

[0015] S1. Transmit the wire bundle into the furnace body through the wire feeding mechanism for heat treatment, control the heating temperature within the range of 150 - 250 °C, and adjust the duration according to the specification of the wire bundle.

[0016] S2. Filter the waste gas in the pre-oxidation furnace through the filter screen installed in the air duct of the furnace body.

[0017] S3a. Clean the wire bundle adsorbed on the filter screen through the cleaning mechanism. Slide the cleaning box along the length direction of the filter screen, and roll the roller shaft inside the cleaning box on the filter screen. The serrated scraper on the roller shaft effectively grabs and cleans the residual cellulose nanofibers on the filter screen.

[0018] S3b. The air guide cover synchronously slides along the length direction of the filter screen with the cleaning box, and guides the airflow entering the air duct into the machine box through the air guide cover, so that the airflow can backflush and clean the filter screen.

[0019] The beneficial effects of the present invention compared with the prior art are:

[0020] 1. Through the arrangement of the mobile cleaning box and the air guide cover in the present invention, the roller shaft in the cleaning box can roll along the surface of the filter screen, and the serrated scraper can effectively grab and wind the fiber filaments attached to the filter screen. This design avoids the problem that the traditional cleaning device cannot effectively remove the fiber filaments, and greatly reduces the dust accumulation and fiber accumulation on the filter screen, thereby reducing the number of times of equipment shutdown for maintenance. The arrangement of the spiral scraper on the roller shaft enables the fiber filaments to concentrate from both sides of the roller shaft to the middle during the cleaning process, maximizing the cleaning effect of the cleaning box, improving the cleaning efficiency, and reducing the maintenance frequency of the equipment.

[0021] 2. In the present invention, the air guide cover moves synchronously with the cleaning box. Through the cooperation of the two, it can block part of the filter screen area and guide the direction of the air flow, so that the air flow can flow to the surface of the filter screen to achieve reverse blowing cleaning in a local area. The arrangement of the air guide cover reduces the interference of the air flow on the fiber filaments during the cleaning process. At the same time, the reverse blowing of the air guide cover on the fiber filaments on the filter screen enhances the grabbing effect of the roller shaft on the fiber filaments, ensuring that the fiber filaments can be smoothly wound onto the roller shaft, thereby improving the cleaning effect of the cleaning mechanism on the filter screen and reducing the subsequent maintenance requirements.

[0022] 3. In the present invention, the slider drives the air guide cover to move synchronously, and through the arrangement of the connecting rod and the limiting plate, the position of the air guide cover can be flexibly adjusted after the cleaning operation is completed, reducing its interference with the disassembly of the filter screen. When the filter screen needs to be maintained, after the air guide cover is moved to the edge of the filter screen by the cleaning box, there is a positional difference between the air guide cover and the cleaning box, enabling the cleaning box to avoid the filter screen, providing enough space for the filter screen to be disassembled and replaced. The convenient structural design significantly improves the operation flexibility of the equipment and reduces the downtime during the maintenance process. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 is a three-dimensional structural schematic diagram of a pre-oxidation furnace based on multi-specification tow.

[0024] Figure 2 is a cross-sectional structural schematic diagram of a pre-oxidation furnace based on multi-specification tow.

[0025] Figure 3 is a three-dimensional structural schematic diagram of the air duct, filter screen and cleaning mechanism in a pre-oxidation furnace based on multi-specification tow.

[0026] Figure 4 is Figure 2 the enlarged view of part A in

[0027] Figure 5 is a three-dimensional cross-sectional structural schematic of the air duct, filter screen and cleaning mechanism in a pre-oxidation furnace based on multi-specification tow Figure 1 .

[0028] Figure 6 Schematic diagram of the three-dimensional sectional structure of the air duct, filter screen and cleaning mechanism in a pre-oxidation furnace based on multi-specification tow Figure 2 .

[0029] Figure 7 Schematic diagram of the three-dimensional structure of the cleaning mechanism and filter screen in a pre-oxidation furnace based on multi-specification tow.

[0030] Figure 8 Schematic diagram of the three-dimensional structure of the cleaning mechanism in a pre-oxidation furnace based on multi-specification tow.

[0031] Figure 9 Schematic diagram of the three-dimensional structure of the cleaning box in a pre-oxidation furnace based on multi-specification tow.

[0032] Figure 10 Schematic diagram of the three-dimensional structure of the roller shaft in a pre-oxidation furnace based on multi-specification tow.

[0033] Figure 11 Schematic diagram of the state where the air guide cover and cleaning box in a pre-oxidation furnace based on multi-specification tow are moved to the edge of the filter screen.

[0034] Figure 12 Schematic diagram of the three-dimensional structure of the air guide cover and cleaning box in a pre-oxidation furnace based on multi-specification tow.

[0035] Figure 13 Schematic diagram of the three-dimensional structure of the wire feeding mechanism in a pre-oxidation furnace based on multi-specification tow.

[0036] The reference numerals in the figure are:

[0037] 1, furnace body; 11, wire feeding mechanism; 111, support frame; 112, guide roller; 12, air duct; 121, filter screen; 122, installation groove; 1221, slider; 12211, limit plate; 12212, connecting rod; 1222, guide rod; 1223, lead screw; 1224, rack; 2, cleaning mechanism; 21, cleaning box; 211, roller shaft; 2111, scraper; 2112, gear; 22, cleaning channel; 23, comb teeth; 24, air guide cover; 241, air inlet; 242, air outlet; 243, air flow channel; 244, chute. Detailed implementation manners

[0038] In order to further understand the features, technical means, specific purposes and functions achieved by the present invention, the present invention will be further described in detail below in conjunction with the accompanying drawings and specific implementation manners.

[0039] Such as Figures 1 to 6 , Figure 9 , Figure 10 and Figure 13Shown: A pre-oxidation furnace based on multi-specification tow, including a furnace body 1 and a wire feeding mechanism 11 arranged in the furnace body 1 for transporting multi-specification tow. At the top inside the furnace body 1, there is an air duct 12 for exhausting air and a filter screen 121 arranged on the air duct 12. A cleaning mechanism 2 for cleaning the tow accumulated on the filter screen 121 is arranged on the filter screen 121. The cleaning mechanism 2 includes a cleaning box 21 and a wind guiding cover 24. The cleaning box 21 is located below the filter screen 121 and can slide along the length direction of the filter screen 121. A roller shaft 211 capable of grasping the tow adsorbed on the filter screen 121 is arranged inside the cleaning box 21, and a serrated scraping plate 2111 is arranged on the roller shaft 211. The wind guiding cover 24 is located above the filter screen 121. The wind guiding cover 24 is used to absorb the airflow entering the air duct 12 and direct it to the filter screen 121 for back blowing the filter screen 121, and the wind guiding cover 24 can slide synchronously with the cleaning box 21 along the length direction of the filter screen 121.

[0040] First, the tow is sent into the furnace body 1 of the pre-oxidation furnace through the wire feeding mechanism 11, and the tow is moved from one end of the furnace body 1 to the other end through the wire feeding mechanism 11. Since the pre-oxidation furnace can oxidize tows of different specifications, multiple tows may break due to different tensions during the pre-oxidation process. When the air duct 12 of the furnace body 1 is ventilated, fiber filaments are likely to remain on the filter screen 121 of the air duct 12. If not cleaned for a long time, the fiber filaments may adhere to the filter screen 121 due to coking at the temperature inside the furnace body 1, and the filter screen 121 needs to be thoroughly cleaned, resulting in the need to wait for the equipment. When the fiber filaments are cleaned by the existing bristles on the filter screen 121, there will be a problem that the bristles cannot scrape off the fiber filaments. At the same time, since the fiber filaments are relatively soft, it is difficult to clean them when they are on the filter screen 121 of the air duct 12.

[0041] When the air duct 12 is blocked, the cleaning box 21 is moved to slide along the length direction of the filter screen 121, so that the roller shaft 211 inside it can roll along the surface of the filter screen 121. The serrated scraper 2111 on the roller shaft 211 is used to clean the surface of the cleaning box 21. Since the scraper 2111 is serrated, the fiber filaments adsorbed on the filter screen 121 are easily wound around the serrated scraper 2111, thus realizing the grasping of the fiber filaments, improving the cleaning effect of the filter screen 121, reducing subsequent maintenance. With the setting of the air guide cover 24 that moves together with the cleaning box 21, part of the area on the filter screen 121 is blocked by the air guide cover 24 and the cleaning box 21, so that the flowing air flow in this area is reduced, which is convenient for the roller shaft 211 to grasp the fiber filaments. At the same time, the air guide cover 24 can direct the air flow to the filter screen 121, so as to blow back the filter screen 121 in this area, enabling the roller shaft 211 to better grasp the fiber filaments and facilitating the winding of the fiber filaments around the roller shaft 211. First, the wire bundle is introduced into the furnace body 1 of the pre-oxidation furnace through the wire feeding mechanism 11, and the wire bundle moves from one end of the furnace body 1 to the other end. The pre-oxidation furnace can be applied to oxidize wire bundles of different specifications. However, due to the different tensions of each wire bundle, especially when multiple wire bundles are pre-oxidized simultaneously, tension imbalance often occurs, resulting in the breakage of some wire bundles. The broken fiber filaments are easily retained in the air duct 12 of the furnace body 1. Especially during the ventilation process of the air duct 12, these fiber filaments will gradually accumulate on the filter screen 121 of the air duct 12. If not cleaned for a long time, with the high temperature in the pre-oxidation furnace, the fiber filaments may coke and adhere to the filter screen 121 of the air duct 12, affecting the ventilation effect of the air duct 12 and ultimately causing the equipment to stop for maintenance and cleaning. When the traditional bristle device cleans the filter screen 121, it is difficult to completely scrape off these coked fiber filaments. Especially the soft fiber filaments will increase the cleaning difficulty due to their adhesiveness and flexibility. Through the setting of the moving cleaning box 21, it can slide along the length direction of the filter screen 121. The roller shaft 211 in the cleaning box 21 will roll along the surface of the filter screen 121 during the sliding process. The surface of the roller shaft 211 is designed with a serrated scraper 2111, which is used to effectively clean the surface of the filter screen 121. The design of the serrations can not only enhance the grasping ability of the fiber filaments, but also enable the fiber filaments to be smoothly wound around the scraper 2111, thus significantly improving the cleaning efficiency and reducing the maintenance frequency caused by the blockage of the filter screen 121. The serrated scraper 2111 can strip the fiber filaments from the filter screen 121 through mechanical winding action to achieve thorough cleaning. In order to further optimize the cleaning effect, the cleaning box 21 and the air guide cover 24 will work together. The air guide cover 24 is arranged above the filter screen 121 and moves together with the cleaning box 21. When the cleaning box 21 slides on the filter screen 121, the cleaning box 21 and the air guide cover 24 can temporarily shield this part of the filter screen 121, reducing the air flow in this area and effectively reducing the air resistance.It is convenient for the squeegee 2111 to strip the fiber filaments from the filter screen 121. At the same time, the air guide hood 24 can redirect the air flow so that the air flow blows against the filter screen 121 in a directional manner, further cooperating with the grasping effect of the roller shaft 211, thereby ensuring that the fiber filaments can be fully grasped and wound by the roller shaft 211 during the cleaning process, avoiding the re-accumulation of fiber filaments on the filter screen 121, and there is no need to frequently stop the machine during the cleaning operation, greatly improving the continuity and stability of the equipment operation.

[0042] As Figures 1 to 6 , Figure 9 and Figure 10 shown: There are multiple squeegees 2111 on the roller shaft 211. The multiple squeegees 2111 are evenly arranged around the axis of the roller shaft 211 at equal intervals. The squeegee 2111 is made of an elastic material and extends spirally along the axis of the roller shaft 211.

[0043] By arranging multiple squeegees 2111 evenly around the axis of the roller shaft 211, the roller shaft 211 can clean the surface of the filter screen 121 in all directions when rotating, avoiding cleaning blind spots. The squeegee 2111 extends spirally, which can continuously and stably guide the fiber filaments to a specific area, effectively increasing the efficiency of winding and grasping the fibers. The squeegee 2111 made of an elastic material can reduce the wear on the filter screen 121 during the cleaning process and extend the service life of the filter screen 121. The spiral squeegee 2111 design can adapt to the irregular attachments on the surface of the filter screen 121, improve the grasping ability for irregular fiber filaments, increase the flexibility of the cleaning process, effectively clean the residual fiber filaments, and the setting of multiple squeegees 2111 can help improve the collection process of fiber filaments, reduce the cleaning time, and lower the equipment maintenance frequency.

[0044] As Figures 3 to 10 shown: A cleaning channel 22 connected to the external cleaning mechanism 2 is provided in the middle of the cleaning box 21. The squeegee 2111 extends along a spiral line from one end of the roller shaft 211 to the middle of the roller shaft 211, and reverses along the spiral direction of the squeegee 2111 at the middle of the roller shaft 211, so that the squeegee 2111 continues to extend along the spiral line to the other end of the roller shaft 211 in the opposite direction.

[0045] By setting the spiral direction of the scraper 2111 to reverse in the middle, the fiber filaments move from both sides to the middle after being wound around the roller 211, which can maximize the use of the cleaning area of the roller 211, ensure that the fibers will not be overly wound in the cleaning box 21 and affect the cleaning efficiency. By setting a cleaning channel 22 in the middle of the cleaning box 21, the fiber filament collection function of the spiral scraper 2111 is concentrated from both ends to the middle, which can effectively convey the fiber filaments attached to the filter screen 121 to the cleaning channel 22 for timely removal, reduce the accumulation of fibers in the cleaning box 21. Through the reverse of the spiral direction, the unbalanced torque caused by single-direction rotation can be reduced, making the roller 211 operate more smoothly during the operation process, thereby improving the stability and service life of the system. The reverse design of the spiral scraper 2111 helps to avoid the excessive accumulation of fiber filaments on one side, reduce the risk of blockage of the cleaning channel 22, improve the cleaning efficiency and reduce the subsequent maintenance requirements.

[0046] As Figures 3 to 10 shown: On both sides of the roller 211 on the cleaning box 21, there are comb teeth 23 for hooking and breaking the fiber filaments wound on the scraper 2111. There are multiple comb teeth 23, and the multiple comb teeth 23 extend equidistantly along the length direction of the cleaning box 21.

[0047] Through the setting of the comb teeth 23, the fiber filaments wound on the scraper 2111 can be timely hooked and removed, preventing the fibers from overly accumulating or winding on the scraper 2111, enabling the fiber filaments to be better cleaned, avoiding affecting the cleaning efficiency of the scraper 2111 and subsequent cleaning work, enabling the scraper 2111 to automatically remove the grabbed fibers during rotation, keeping the scraper 2111 in a clean state all the time, enabling it to continuously exert the best cleaning performance, improving the overall cleaning efficiency of the equipment, avoiding the decline in cleaning ability caused by fiber accumulation, thereby ensuring that the cleaning effect of the equipment on the filter screen 121 is more lasting and uniform. Since the comb teeth 23 can automatically hook and clean the fiber filaments wound on the scraper 2111, there is no need to frequently stop the machine to manually remove the deposits on the roller 211, improving the operating efficiency of the system. The comb teeth 23 can effectively prevent the fibers from overly winding on the scraper 2111, thereby reducing the friction and wear between the scraper 2111 and other mechanical components, extending the service life of the equipment and reducing the maintenance cost.

[0048] As Figures 3 to 8 and Figure 12 shown: The air guide hood 24 is a long strip-shaped hood body. The air guide hood 24 extends along the width direction of the filter screen 121. An air inlet 241 and an air outlet 242 are provided at the bottom of the air guide hood 24. The air outlet 242 is matched with the cleaning box 21. A curved air flow channel 243 is provided inside the air guide hood 24, and the air flow rises from the air inlet 241 at the bottom along the curved air flow channel 243 and is guided to the air outlet 242.

[0049] By setting the air guide cover 24 as a strip-shaped cover body and extending it along the width direction of the filter screen 121, the air flow can be evenly distributed within the entire width range of the filter screen 121, thus avoiding the air flow concentrating at a certain point, ensuring that the entire surface of the filter screen 121 can be blown back by the air flow, improving the cleaning effect. By setting a curved air flow channel 243 inside the air guide cover 24, the air flow is forced to change the flow direction after entering the air guide cover 24. Such a setting can increase the speed and pressure of the air flow. When the air flow reaches the air outlet 242, it has stronger kinetic energy, enhancing the cleaning ability of the fiber filaments or dust on the filter screen 121.

[0050] As Figures 3 to 8 , Figure 11 and Figure 12 shown: Installation grooves 122 are provided on both sides of the bottom of the air duct 12. Sliders 1221 capable of sliding in the installation grooves 122 are provided at both ends of the roller shaft 211. Guide rods 1222 and lead screws 1223 extending along the length direction of the filter screen 121 are respectively provided in the two installation grooves 122. The two sliders 1221 are respectively sleeved on the guide rod 1222 and the lead screw 1223. The lead screw 1223 is in threaded cooperation with the slider 1221, and the slider 1221 is in sliding cooperation with the guide rod 1222.

[0051] By setting the guide rod 1222, the slider 1221 can slide on the guide rod 1222, thereby keeping the movement direction of the roller shaft 211 stable, avoiding the roller shaft 211 from tilting or shifting during the cleaning process, ensuring the smooth movement of the cleaning box 21 on the surface of the filter screen 121. The additional support provided by the guide rod 1222 can improve the stability of the entire system and reduce the mechanical vibration of the equipment during operation. By the threaded cooperation between the slider 1221 and the lead screw 1223, the rotation of the lead screw 1223 drives the movement of the slider 1221 in threaded cooperation with it, enabling the roller shaft 211 to be accurately positioned in the length direction of the filter screen 121. Such precise control of the lead screw 1223 can ensure that the cleaning action can accurately reach each position on the filter screen 121, avoiding cleaning dead corners and improving the cleaning efficiency of the equipment. By the setting of the installation groove 122, the disassembly, installation and maintenance of the roller shaft 211 are more convenient. When the roller shaft 211 needs to be replaced or repaired, only simple operation of the slider 1221 can complete the disassembly and reinstallation. At the same time, the installation groove 122 can also play a role in protecting the components. The driving source of the lead screw 1223 is preferably a servo motor. The rotation of the output shaft of the servo motor drives the rotation of the lead screw 1223, and the rotation of the lead screw 1223 drives the movement of the slider 1221.

[0052] As Figures 3 to 8As shown in the figure: The roller shaft 211 is rotatably arranged in the slider 1221. Gears 2112 are arranged at both ends of the roller shaft 211. A rack 1224 extending along the length direction of the filter screen 121 is arranged at the top inside the installation groove 122. The rack 1224 is located above the gear 2112 and is meshed and connected with it.

[0053] By moving the roller shaft 211 along the length direction of the filter screen 121, the roller shaft 211 can rotate around its axis during sliding through the meshing connection between the gear 2112 and the rack 1224. Thereby, the scraper 2111 located on the roller shaft 211 can be driven to rotate. The rotating scraper 2111 grabs the fiber filaments on the filter screen 121, thus ensuring the cleaning effect of the filter screen 121. In the above way, there is no need to configure an independent drive source for the roller shaft 211. The movement of the slider 1221 driven by the lead screw 1223 can realize the drive of the roller shaft 211. Through the layout of the rack 1224 on the gear 2112, the equipment can still ensure efficient transmission function with less occupied space, improving the overall space utilization rate of the equipment.

[0054] As Figures 3 to 8 、 Figure 11 and Figure 12 shown in the figure: Chutes 244 extending along the vertical direction are arranged at both ends of the air guide cover 24. A connecting rod 12212 hinged to it is arranged on the slider 1221. The other end of the connecting rod 12212 is slidably matched with the chute 244. A limiting plate 12211 for limiting the connecting rod 12212 is arranged on one side of the slider 1221. When the slider 1221 moves horizontally to the side away from the limiting plate 12211, the limiting plate 12211 limits the connecting rod 12212, and the slider 1221 drives the air guide cover 24 to move synchronously through the connecting rod 12212; when the slider 1221 moves in the opposite direction, the connecting rod 12212 loses its limit, and the air guide cover 24 is located obliquely above the slider 1221.

[0055] Although the filter screen 121 is equipped with a cleaning mechanism 2, after the filter screen 121 has been used for a certain period of time, it still needs to be maintained. Since the air guide cover 24 and the cleaning box 21 are respectively located above and below the filter screen 121, the disassembly of the filter screen 121 is rather cumbersome. Through the limitation of the connecting rod 12212 by the limiting plate 12211, when the slider 1221 drives the air guide cover 24 to move synchronously in the horizontal direction, the connecting rod 12212 is in a vertical state under the action of the limiting plate 12211. The sliding end of the connecting rod 12212 on the chute 244 is located at the top of the chute 244. The air guide cover 24 is driven by the connecting rod 12212 to move synchronously with the slider 1221. When it is necessary to disassemble and maintain the filter screen 121, through the reverse movement of the slider 1221, at this time, since the connecting rod 12212 loses the limitation of the limiting plate 12211, the connecting rod 12212 rotates towards the side away from the limiting plate 12211, and the other end of the connecting rod 12212 slides to the bottom of the chute 244. At this time, the air guide cover 24 is located obliquely above the cleaning box, resulting in a position difference between the air guide cover 24 and the cleaning box. When the air guide cover 24 moves to the edge of the filter screen 121 in the length direction, the cleaning box has moved to the outside of the filter screen 121, thereby reducing the interference with the filter screen 121 and providing sufficient operating space for the later disassembly and maintenance of the filter screen 121, enhancing the flexibility of the cleaning system.

[0056] As Figure 1 , Figure 2 and Figure 13 shown: The wire feeding mechanism 11 includes support frames 111 that are respectively arranged at both ends of the furnace body 1 and are mirror-symmetrical. A plurality of guide rollers 112 arranged at equal intervals in the height direction are provided on both support frames 111. Multispecification wire bundles are sleeved between the plurality of guide rollers 112 of the two support frames 111.

[0057] By arranging a plurality of guide rollers 112, it is ensured that the wire bundles can pass through the guide rollers 112 smoothly regardless of their thickness, avoiding phenomena such as jamming, bending or knotting of the wire bundles during the conveying process, ensuring the smoothness of the conveying. The wire feeding mechanism 11 adopts a mirror-symmetrical structure, enabling the wire bundles to maintain a good balance state during the conveying process, reducing problems such as unstable conveying or deviation caused by the offset of the center of gravity of the wire bundles, improving the stability and operation safety of the equipment. The reasonable arrangement of the guide rollers 112 ensures uniform tension of the wire bundles during the conveying process, avoiding over-tight or over-loose phenomena, improving the processing efficiency of the wire bundles, and ensuring the quality consistency of the fiber bundles in the subsequent processing procedures.

[0058] As Figures 1 to 6 , Figure 9 , Figure 10 and Figure 13Shown: A pre-oxidation method for the preparation of CNFs, applied to the above-mentioned pre-oxidation furnace based on multi-specification tows, includes the following steps:

[0059] S1. Transfer the tow to the furnace body 1 through the wire feeding mechanism 11 for heat treatment, control the heating temperature within the range of 150 - 250 °C, and adjust the duration according to the specification of the tow.

[0060] S2. Filter the waste gas in the pre-oxidation furnace through the filter screen 121 installed in the air duct 12 of the furnace body 1.

[0061] S3a. Clean the tow adsorbed on the filter screen 121 through the cleaning mechanism 2. Slide the cleaning box 21 along the length direction of the filter screen 121, and roll the roller 211 inside the cleaning box 21 on the filter screen 121. The serrated scraper 2111 on the roller 211 effectively grabs and cleans the residual cellulose nanofibers on the filter screen 121.

[0062] S3b. The air guide hood 24 slides synchronously with the cleaning box 21 along the length direction of the filter screen 121, and guides the air flow entering the air duct 12 into the casing through the air guide hood 24, so that the air flow can backflush and clean the filter screen 121.

[0063] The above embodiments only represent one or several implementation manners of the present invention, and the description is relatively specific and detailed, but it should not be construed as a limitation on the scope of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present invention, several deformations and improvements can still be made, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the present invention should be subject to the appended claims.

Claims

1. A pre-oxidation furnace based on multi-specification wire bundles, comprising a furnace body (1) and a wire feeding mechanism (11) arranged in the furnace body (1) for transmitting wire bundles of multiple specifications, an air duct (12) for exhausting air and a filter (121) arranged on the air duct (12) are arranged on the top of the furnace body (1), characterized in that: The filter screen (121) is provided with a cleaning mechanism (2) for cleaning the filament bundles accumulated on the filter screen (121), and the cleaning mechanism (2) comprises a cleaning box (21) and an air guide cover (24); The cleaning box (21) is located below the filter screen (121), and the cleaning box (21) can slide along the length direction of the filter screen (121). A roller (211) capable of grabbing the silk bundle adsorbed on the filter screen (121) is arranged in the cleaning box (21), and a serrated scraper (2111) is arranged on the roller (211); The air guide cover (24) is located above the filter (121). The air guide cover (24) is used to absorb the airflow entering the air duct (12) and guide it to the filter (121) to back-blow the filter (121). The air guide cover (24) can slide along the length direction of the filter (121) synchronously with the cleaning box (21).

2. A pre-oxidation furnace based on multi-specification tows according to claim 1, characterized in that: There are multiple scrapers (2111) on the roller (211), and the multiple scrapers (2111) are arranged around the axis of the roller (211) at equal intervals. The scrapers (2111) are made of elastic material, and the scrapers (2111) extend in a spiral shape along the axis of the roller (211).

3. A pre-oxidation furnace based on multi-specification tows according to claim 2, characterized in that: A cleaning channel (22) connected to the external cleaning mechanism (2) is provided in the middle of the cleaning box (21); a scraper (2111) extends from one end of the roller (211) along a spiral line to the middle of the roller (211), and reverses along the spiral direction of the scraper (2111) at the middle of the roller (211), so that the scraper (2111) continues to extend along the spiral line in the opposite direction to the other end of the roller (211).

4. A pre-oxidation furnace based on multi-specification tows according to claim 1, characterized in that: Comb teeth (23) for hooking and breaking fiber filaments wound on the scraper (2111) are arranged on both sides of the cleaning box (21), and the plurality of comb teeth (23) are equidistantly extending along the length direction of the cleaning box (21).

5. A pre-oxidation furnace based on multi-specification tows according to claim 1, characterized in that: The air guide cover (24) is a long strip-shaped cover body. The air guide cover (24) extends along the width direction of the filter screen (121). An air inlet (241) and an air outlet (242) are arranged at the bottom of the air guide cover (24). The air outlet (242) matches the cleaning box (21). A curved air flow channel (243) is arranged inside the air guide cover (24). The air flow rises from the air inlet (241) at the bottom along the curved air flow channel (243) and is guided to the air outlet (242).

6. A pre-oxidation furnace based on multi-specification tows according to any one of claims 1 to 5, characterized in that: Both sides of the bottom of the air duct (12) are provided with mounting grooves (122), and both ends of the roller shaft (211) are provided with sliders (1221) that can slide in the mounting grooves (122). The two mounting grooves (122) are respectively provided with guide rods (1222) and screw rods (1223) extending along the length direction of the filter screen (121). The two sliders (1221) are respectively sleeved on the guide rods (1222) and the screw rods (1223). The screw rods (1223) and the sliders (1221) are threadedly matched, and the sliders (1221) and the guide rods (1222) are slidably matched.

7. A pre-oxidation furnace based on multi-specification tows according to claim 6, characterized in that: The roller shaft (211) is rotatably arranged in the slider (1221), and gears (2112) are arranged at both ends of the roller shaft (211). A rack (1224) extending along the length direction of the filter screen (121) is arranged at the top of the installation groove (122), and the rack (1224) is located above the gear (2112) and is meshed with it.

8. A pre-oxidation furnace based on multi-specification tows according to claim 6, characterized in that: Both ends of the air guide cover (24) are provided with a slide groove (244) extending in the vertical direction, a connecting rod (12212) hinged thereto is provided on the slider (1221), the other end of the connecting rod (12212) is slidably matched with the slide groove (244), and one side of the slider (1221) is provided with a limiting plate (12211) for limiting the connecting rod (12212); when the slider (1221) moves in the horizontal direction toward the side away from the limiting plate (12211), the limiting plate (12211) limits the connecting rod (12212), and the slider (1221) drives the air guide cover (24) to move synchronously through the connecting rod (12212); when the slider (1221) moves in the opposite direction, the connecting rod (12212) loses its limit, and the air guide cover (24) is located obliquely above the slider (1221).

9. A pre-oxidation furnace based on multi-specification tows according to claim 1, characterized in that: The wire feeding mechanism (11) comprises support frames (111) respectively arranged at two ends of the furnace body (1) and in a mirror-symmetrical manner, wherein the two support frames (111) are each provided with a plurality of guide rollers (112) arranged at equal intervals in a height direction, and wire bundles of various specifications are sleeved between the plurality of guide rollers (112) of the two support frames (111).

10. A pre-oxidation method for preparing CNFs, applied to a pre-oxidation furnace based on multi-specification tows as claimed in any one of claims 1 to 9, characterized in that: The following steps are involved: S1, transmitting the wire bundle to the furnace body (1) for heating treatment through the wire feeding mechanism (11), controlling the heating temperature within the range of 150-250° C., and adjusting the duration according to the specifications of the wire bundle; S2, filtering the exhaust gas in the pre-oxidation furnace through a filter (121) installed in the air duct (12) of the furnace body (1), S3a, cleaning the fiber bundles adsorbed on the filter screen (121) by means of a cleaning mechanism (2), sliding the cleaning box (21) along the length direction of the filter screen (121), rolling the roller (211) inside the cleaning box (21) on the filter screen (121), and cooperating with the serrated scraper (2111) on the roller (211) to effectively grab and clean the cellulose nanofibers remaining on the filter screen (121), S3b, the air guide cover (24) synchronously slides along the length direction of the filter screen (121) with the cleaning box (21), and the air guide cover (24) guides the air flow entering the air duct (12) into the box, so that the air flow can back-blow and clean the filter screen (121).

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