A carbon fiber pre-oxidation process simulation experiment device

Abstract

This invention provides a carbon fiber pre-oxidation process simulation experimental device, mainly comprising: a pre-oxidation furnace, a tension guiding device, and a transmission device. The carbon fiber tow can be driven by the transmission device, changing its running direction and adjusting its running tension at the tension guiding device, repeatedly entering the pre-oxidation furnace to achieve a continuous pre-oxidation reaction, more closely resembling the continuous running reaction state of the tow in actual production. This invention also improves upon the problem of poor temperature and flow field uniformity in the pre-oxidation simulation experimental device by adopting an internal circulation vertical air supply duct design, combined with an airflow distribution structure and furnace head gas sealing device, achieving good furnace uniformity. Experimental verification shows that the carbon fiber pre-oxidation process simulation experimental device proposed in this invention can accurately simulate the reaction effect of actual production, improve the simulation effect, reduce deviations from actual production, and plays an important role in guiding the adjustment of the pre-oxidation process in actual production.

Description

Technical Field

[0001] This invention relates to the field of carbon fiber pre-oxidation process technology, and specifically to a carbon fiber pre-oxidation process simulation experimental device. Background Technology

[0002] Pre-oxidation is a crucial step in the carbonization process of carbon fibers. During pre-oxidation, the polyacrylonitrile precursor fiber transforms from a linear molecular structure into a heat-resistant trapezoidal structure, ensuring the fiber morphology is maintained during subsequent high-temperature carbonization. The structural transformation that occurs during pre-oxidation directly affects the stability of subsequent processes and the performance of the final carbon fiber product. Therefore, pre-oxidation is a critical process in the carbonization of polyacrylonitrile carbon fibers.

[0003] The complete pre-oxidation process is lengthy, especially the long period required for the process to stabilize after each adjustment. This can lead to significant waste during process exploration and adjustment on large-scale production lines. Furthermore, production oxidation furnaces are often too large, resulting in inconsistencies and fluctuations in temperature and airflow uniformity. Smaller-scale experimental setups can mitigate these uniformity issues at a lower cost, making them more suitable for pre-oxidation experiments. The pre-oxidation process involves the combined effects of multiple factors, including temperature, residence time, and tension, making it a complex process. Existing pre-oxidation experimental setups often fail to accurately and comprehensively reflect actual production conditions, rendering the experimental results unreliable. In actual production, the pre-oxidation residence time often reaches nearly one hour, and the filament bundle is in motion during the process. Existing pre-oxidation experimental equipment cannot fully simulate this process. Some setups operate the filament bundle continuously but cannot guarantee the residence time while meeting actual operating speed requirements (due to the size limitations of the experimental equipment, the total filament bundle travel path is relatively short); others operate with the filament bundle stopped, resulting in even greater deviations from actual production conditions. Existing experimental equipment designs are often inadequate and fail to adequately meet the requirements for uniform airflow and temperature. Therefore, it is necessary to design a pre-oxidation process simulation experimental device that can fully simulate actual production and exhibit good uniformity to guide the process adjustment of the pre-oxidation process.

[0004] Because the experimental equipment in the existing technology has poor effect in simulating actual production of filament bundles and deviates significantly, which is reflected in the fact that the degree of filament bundle pre-oxidation is not as good as that in actual production, this invention studies and designs an experimental device for simulating carbon fiber pre-oxidation process. Summary of the Invention

[0005] Therefore, the technical problem to be solved by the present invention is to overcome the shortcomings of the existing experimental equipment in simulating actual production of filament bundles, which has poor effect and large deviation, and is reflected in the fact that the degree of filament bundle pre-oxidation is not as good as that in actual production. Thus, a carbon fiber pre-oxidation process simulation experimental device is provided.

[0006] To address the above problems, the present invention provides a carbon fiber pre-oxidation process simulation experimental apparatus, comprising:

[0007] The system consists of a pre-oxidation furnace, a tension guiding device, and a transmission device. The carbon fiber tow can be driven by the transmission device, and its running direction can be changed and the running tension can be adjusted at the tension guiding device, allowing it to repeatedly enter the pre-oxidation furnace to achieve a continuous pre-oxidation reaction.

[0008] In some embodiments, the tension guiding device includes a first guide roller, a second guide roller, and a tension adjusting roller. The carbon fiber bundle passes sequentially through the outer circumferential surfaces of the first guide roller, the tension adjusting roller, and the second guide roller. All three rollers—the first guide roller, the second guide roller, and the tension adjusting roller—are passive rollers driven by the movement of the bundle. The tension adjusting roller can adjust the tension of the carbon fiber bundle.

[0009] The carbon fiber tow is wound around the outer circumferential surface of the lower half of the tension regulating roller, and the tension regulating roller exerts a longitudinally downward force on the tow. The bearing of the tension regulating roller can slide longitudinally within the bearing sleeve. A first central shaft is inserted through the central shaft hole of the tension regulating roller, and a counterweight device is also sleeved on the first central shaft. The counterweight device includes a first tension regulating counterweight water tank and a second tension regulating counterweight water tank. The first tension regulating counterweight water tank is hung at one axial end of the first central shaft, and the second tension regulating counterweight water tank is hung at the other axial end of the first central shaft.

[0010] In some embodiments, the transmission device includes a transmission roller. The carbon fiber tow is wound around a portion of the outer circumferential surface of the transmission roller, and the transmission roller shaft is connected to a motor that drives its rotation, thereby moving the carbon fiber tow.

[0011] In some embodiments, the pre-oxidation furnace includes a shell, a heater, and a fan. The shell contains a heating chamber, a wire feeding chamber, a furnace top chamber, and a furnace bottom chamber. The heater is disposed in the heating chamber to heat the airflow flowing through it. The fan is disposed in the heating chamber and drives the airflow to flow sequentially through the heating chamber, the furnace top chamber, the wire feeding chamber, the furnace bottom chamber, and the heating chamber to form an internal airflow circulation. The carbon fiber bundle can move into the wire feeding chamber and undergo a pre-oxidation reaction with the heated airflow in the wire feeding chamber.

[0012] In some embodiments, the fiber feeding chamber includes an upper fiber feeding channel and a lower fiber feeding channel. The carbon fiber bundle can be driven by the transmission device and move along a first motion path to the upper fiber feeding channel in the pre-oxidation furnace for pre-oxidation reaction. Then, it moves out of the pre-oxidation furnace from the upper fiber feeding channel. After passing through the tension guiding device, it changes direction and moves along a second motion path to the lower fiber feeding channel in the pre-oxidation furnace for pre-oxidation reaction. Then, it moves out of the pre-oxidation furnace and onto the transmission device, forming a cyclic motion.

[0013] In some embodiments, the wire feeding chamber includes an upper wire feeding channel and a lower wire feeding channel. After the carbon fiber bundle changes direction through the tension guiding device and the transmission device, it can repeatedly pass through the upper and lower wire feeding channels of the pre-oxidation furnace wire feeding chamber to form a cyclic motion and continuously carry out the pre-oxidation reaction.

[0014] In some embodiments, a furnace head gas sealing device is provided above the upper wire feeding channel, between the upper wire feeding channel and the lower wire feeding channel, and below the lower wire feeding channel.

[0015] A thermocouple is installed above the wire feeding chamber. A first arc-shaped flow guide baffle is installed in the furnace top chamber above the heating chamber. A second arc-shaped flow guide baffle is installed in the furnace top chamber above the wire feeding chamber. A first filter and a second filter are also installed in the heating chamber. An insulation layer is also installed between the inner and outer walls of the shell.

[0016] In some embodiments, an airflow distribution structure is further provided above the wire-feeding chamber. The airflow distribution structure includes at least one perforated airflow distribution plate and at least one honeycomb-shaped flow equalization structure. The surface direction of the perforated airflow distribution plate is perpendicular to the airflow direction, and multiple through-holes are evenly distributed on the perforated airflow distribution plate. The surface direction of the honeycomb-shaped flow equalization structure is parallel to the airflow direction, and multiple through-holes are also provided on the honeycomb-shaped flow equalization structure. The honeycomb-shaped flow equalization structure is in contact with the surface of the perforated airflow distribution plate.

[0017] In some embodiments, the airflow distribution perforated plate includes a first airflow distribution perforated plate, a second airflow distribution perforated plate, and a third airflow distribution perforated plate, which are sequentially spaced apart along the direction of airflow. The opening ratio of the flow equalization holes on the first airflow distribution perforated plate is less than that on the second airflow distribution perforated plate, and the opening ratio of the flow equalization holes on the second airflow distribution perforated plate is less than or equal to that on the third airflow distribution perforated plate. The honeycomb flow equalization structure includes a first honeycomb flow equalization structure and a second honeycomb flow equalization structure. The first honeycomb flow equalization structure is disposed between the first airflow distribution perforated plate and the second airflow distribution perforated plate. The second honeycomb flow equalization structure is disposed between the second airflow distribution perforated plate and the third airflow distribution perforated plate.

[0018] The carbon fiber pre-oxidation process simulation experimental device provided by this invention has the following beneficial effects:

[0019] This invention changes the existing pre-oxidation simulation experimental device's fiber pre-oxidation operation mode, adopting a continuous pre-oxidation method with fiber bundle circulation. This allows for the simulation of the actual fiber bundle operating speed and total pre-oxidation time of large-scale pre-oxidation furnace production equipment using a lower-cost, smaller-scale pre-oxidation simulation experimental device. This invention incorporates a tension guiding device to precisely control the tension during the fiber bundle reaction process, a crucial process parameter in the pre-oxidation process. Furthermore, this invention improves the furnace structure of the simulated pre-oxidation furnace, designing an internal circulation air duct, a multi-layer airflow distribution structure, and a furnace head gas seal structure to improve the flow field and temperature uniformity within the furnace, achieving a uniform and stable pre-oxidation reaction. The pre-oxidation simulation experimental device designed using this invention can effectively simulate the pre-oxidation treatment effect of actual production equipment, thus enabling low-cost simulation experiments of the pre-oxidation process for reference in actual production process debugging. Attached Figure Description

[0020] Figure 1 This is a front structural view of the carbon fiber pre-oxidation process simulation experimental device of the present invention;

[0021] Figure 2 yes Figure 1 Right view of the pre-oxidation furnace in the carbon fiber pre-oxidation process simulation experimental device;

[0022] Figure 3 yes Figure 1 Left view of the tension guide device in the diagram;

[0023] Figure 4 This is a distribution diagram of test points for the uniformity of cold airflow and the uniformity of hot temperature field within the wire-feeding channel of the pre-oxidation experimental device of this invention.

[0024] Figure 5 This is a schematic diagram of the gas seal structure of the pre-oxidation furnace head in the pre-oxidation experimental device of the present invention;

[0025] Figure 6 This is a schematic diagram of the perforated plate 1 of the airflow distribution structure of the pre-oxidation furnace in the pre-oxidation experimental apparatus of the present invention;

[0026] Figure 7 This is a schematic diagram of the perforated plates 2 and 3 of the airflow distribution structure of the pre-oxidation furnace in the pre-oxidation experimental apparatus of the present invention;

[0027] Figure 8 This is a schematic diagram of the honeycomb-shaped flow equalization structure of the pre-oxidation furnace airflow distribution structure of the pre-oxidation experimental device of the present invention.

[0028] The reference numerals in the attached figures are as follows:

[0029] 100. Pre-oxidation furnace; 101. Shell; 1. Pre-oxidation furnace base; 2. Insulation layer; 3. First filter device; 4. Second filter device; 5. Heater; 6. Fan; 7. First arc-shaped guide baffle; 8. Second arc-shaped guide baffle;

[0030] 106. Airflow distribution structure; 9. First airflow distribution perforated plate; 91. Flow equalization hole; 10. First honeycomb flow equalization structure; 11. Second airflow distribution perforated plate; 12. Second honeycomb flow equalization structure; 121. Honeycomb hole; 13. Third airflow distribution perforated plate; 14. Thermocouple;

[0031] 102. Heating chamber; 103. Wire feeding chamber; 15. Upper wire feeding channel; 16. Lower wire feeding channel; 17. Furnace head gas seal device; 104. Furnace top chamber; 105. Furnace bottom chamber;

[0032] 200. Tension guiding device; 18. Tension guiding device base; 19. Tension adjusting roller; 191. First central shaft; 20. First guide roller; 21. Second guide roller; 24. First tension adjusting counterweight water tank; 25. Second tension adjusting counterweight water tank;

[0033] 300. Transmission device; 22. Transmission device base; 23. Transmission roller; 400. Carbon fiber bundle. Detailed Implementation

[0034] This invention designs an experimental device that can realistically and comprehensively simulate the actual pre-oxidation process in a production site. It is used to explore and guide the adjustment of the pre-oxidation process, and can also be used to verify the pre-oxidation reaction state of carbon fiber precursor.

[0035] like Figure 1-8As shown, the present invention provides a carbon fiber pre-oxidation process simulation experimental device, which includes:

[0036] The apparatus comprises a pre-oxidation furnace 100, a tension guiding device 200, and a transmission device 300. The tension guiding device 200 is located on one side of the pre-oxidation furnace 100, and the transmission device 300 is located on the other side. The carbon fiber tow 400 is driven and guided by the transmission device 300, and its operating tension is controlled by the tension guiding device 200, forming a cyclical motion that repeatedly enters and exits the fiber feeding channel of the pre-oxidation furnace for continuous pre-oxidation reaction. This allows the fiber tow in the experimental equipment to simulate actual production conditions (such as movement speed and reaction rate) to the greatest extent possible. The carbon fiber pre-oxidation process simulation experimental device of this invention can accurately or precisely simulate the reaction effects of actual production. The operating speed and total reaction time of the fiber tow pre-oxidation are closer to actual production conditions, improving the simulation effect, reducing deviation from actual production, and enabling more precise adjustment and guidance of the actual pre-oxidation process.

[0037] The pre-oxidation furnace 100 is structurally divided into a heating chamber, a wire feeding chamber, a furnace top chamber, and a furnace bottom chamber, and adopts an internal circulation vertical air supply duct design. The circulating fan 6 installed in the furnace draws air from the furnace bottom chamber and supplies air to the furnace top chamber to form an internal airflow circulation. The circulating hot air from the furnace bottom chamber passes through the first filter device 3 and the second filter device 4 (the two filter devices can be removed and cleaned separately) to filter out lint and other debris before being drawn into the heating chamber. In the heating chamber, it is heated to the specified temperature by the heater 5 (the temperature of the heater 5 is controlled by a temperature controller, and the control monitoring point is the temperature monitoring of the thermocouple 14), and then sent into the furnace top chamber by the circulating fan 6. The top chamber of the furnace is designed with a first arc-shaped guide baffle 7 and a second arc-shaped guide baffle 8 on both sides. After the circulating hot air enters the top chamber of the furnace, it forms a certain pressure in the top chamber of the furnace. Then, the airflow is distributed by the airflow distribution structure 106 (sequentially through the first airflow distribution perforated plate 9, the first honeycomb flow equalization structure 10, the second airflow distribution perforated plate 11, the second honeycomb flow equalization structure 12, and the third airflow distribution perforated plate 13) to form multiple vertical small air columns, forming hot air from top to bottom in the wire-feeding chamber, thereby forming the pre-oxidation reaction conditions.

[0038] This invention provides a novel experimental device for simulating carbon fiber pre-oxidation process, including a pre-oxidation furnace, a tension guiding device, and a transmission device.

[0039] This invention tested the uniformity of the pre-oxidation furnace in the experimental setup. Under conditions without wire bundles, experiments were conducted on the airflow uniformity in a cold state (circulating fan only, heater not activated) and the temperature field uniformity in a hot state (circulating fan activated, heater controlled at 260°C). Eighty-one test points were selected on each of the two wire feeding channels of the pre-oxidation furnace. An anemometer was used to measure the cold-state airflow velocity, and a Pt100 resistance thermometer was used to measure the hot-state temperature.

[0040] This invention tested the tension control capability of the experimental device and compared the theoretical calculations and actual tension test results of adjusting the counterweight weight under different filament bundle amounts.

[0041] This invention uses a pre-oxidation experimental apparatus to simulate a four-temperature zone pre-oxidation process, and compares the experimental pre-oxidized fiber with the test results of pre-oxidized fiber actually produced under the same conditions.

[0042] This invention uses a pre-oxidation experimental apparatus to simulate the matching relationship between different pre-oxidation temperatures and residence times, and experiments and summarizes the matching of pre-oxidation temperature and equivalent residence time at 220~230℃.

[0043] In some embodiments, the tension guiding device 200 includes a first guide roller 20, a second guide roller 21, and a tension adjusting roller 19. The carbon fiber bundle 400 is wound around a portion of the outer peripheral surface of the first guide roller 20, driving the first guide roller 20 to rotate and guiding the carbon fiber bundle 400. The carbon fiber bundle 400 is also wound around a portion of the outer peripheral surface of the second guide roller 21, driving the second guide roller 21 to rotate and guiding the carbon fiber bundle 400. Along the direction of movement of the carbon fiber bundle, the tension adjusting roller 19 is located between the first guide roller 20 and the second guide roller 21, and the tension adjusting roller 19 can adjust the tension of the carbon fiber bundle 400. This is a preferred structural form of the tension guiding device of the present invention. The tension guiding device includes a first guide roller and a second guide roller, and a tension adjusting roller located between the two guide rollers. It can guide the movement of the bundle at both ends of the tension adjusting roller through the two guide rollers, and the tension adjusting roller located between the two guide rollers can effectively adjust the tension of the bundle.

[0044] In some embodiments, the carbon fiber tow 400 is wound around the outer circumferential surface of the lower half of the tension adjusting roller 19, supporting the tension adjusting roller 19. A first central shaft 191 passes through the central shaft hole of the tension adjusting roller 19, and a counterweight device is also sleeved on the first central shaft 191. The tension adjusting roller of the present invention is gravity-fed onto the carbon fiber tow and is suspended on the first central shaft of the tension adjusting roller by the counterweight device. The tension of the tow can be adjusted by the combined gravity of the tension adjusting roller and the counterweight device. Furthermore, the counterweight of the present invention acts indirectly on the tow through the tension adjusting roller. Compared with existing schemes where the counterweight device acts directly on the tow, this results in a more uniform tension on the tow, prevents stress concentration, and does not change the tow path, thus improving the uniformity of tension on the tow and enhancing the pre-oxidation effect.

[0045] In some embodiments, the counterweight device includes a first tension-adjustable counterweight tank 24 and a second tension-adjustable counterweight tank 25. The first tension-adjustable counterweight tank 24 is suspended at one axial end of the first central shaft 191, and the second tension-adjustable counterweight tank 25 is suspended at the other axial end of the first central shaft 191. This is a further preferred structural form of the counterweight device of the present invention. By setting up two counterweight tanks, it is possible to adjust the tension of the counterweight device. Figure 1 The two sides act as a force balancer, thereby further improving the uniformity of tension (especially) Figure 1 (in the left and right width direction).

[0046] In some embodiments, the transmission device 300 includes a transmission roller 23 and a transmission device base 22. The carbon fiber bundle 400 is wound on a portion of the outer peripheral surface of the transmission roller 23. The carbon fiber bundle 400 can drive the transmission roller 23 to rotate by movement. The transmission device base 22 supports the transmission roller 23.

[0047] The transmission device of the present invention includes a transmission roller 23 (grooving roller), which is connected to a speed reducer and a frequency conversion motor, and can control the running speed of the filament bundle.

[0048] The tension guiding device includes two guide rollers (first guide roller 20 and second guide roller 21) and a tension adjusting roller 19. The bearing of the tension adjusting roller 19 can slide longitudinally within the bearing sleeve. The first tension adjusting counterweight water tank 24 and the second tension adjusting counterweight water tank 25 are suspended on both sides of the guide roller shaft. The tension applied to the running filament by the tension adjusting roller can be controlled by adjusting the weight of the water in the counterweight water tank, and the tension applied to each filament can be calculated by the weight of the water.

[0049] In some embodiments, the pre-oxidation furnace 100 includes a shell 101, a heater 5, and a blower 6. The shell 101 contains a heating chamber 102, a wire feeding chamber 103, a furnace top chamber 104, and a furnace bottom chamber 105. At least a portion of the heater 5 is disposed within the heating chamber 102 to heat the airflow flowing through the heating chamber 102. The blower 6 is disposed within the heating chamber 102 and can drive the airflow to flow sequentially through the heating chamber 102, the furnace top chamber 104, the wire feeding chamber 103, the furnace bottom chamber 105, and the heating chamber 102 to form an internal airflow circulation. The carbon fiber bundle 400 can move into the wire feeding chamber 103 and undergo a pre-oxidation reaction with the heated airflow in the wire feeding chamber 103.

[0050] This is a preferred structural form of the pre-oxidation furnace of the present invention. Through heaters and fans, and the heating chamber 102, wire feeding chamber 103, furnace top chamber 104 and furnace bottom chamber 105 arranged inside the shell, the fan runs to drive the airflow to circulate internally between the heating chamber 102, the furnace top chamber 104, the wire feeding chamber 103 and the furnace bottom chamber, thereby improving the uniformity of heating the airflow, improving the uniformity of airflow and temperature field distribution, and simulating the effect of actual production more accurately.

[0051] In some embodiments, the fiber feeding chamber 103 includes an upper feeding channel 15 and a lower feeding channel 16. The carbon fiber bundle 400 can be driven by the transmission device 300 and enter the upper feeding channel 15 in the pre-oxidation furnace 100 for pre-oxidation reaction. Then, it moves out of the pre-oxidation furnace 100 through the upper feeding channel 15 and, after being guided by the tension guide device 200, changes direction and enters the lower feeding channel 16 in the pre-oxidation furnace 100 for pre-oxidation reaction. Finally, it exits the pre-oxidation furnace 100 and moves to the transmission device 300, forming a cyclic motion. This is the preferred structural form of the fiber feeding chamber of the present invention, which includes an upper feeding channel and a lower feeding channel. This allows the fiber bundle to undergo pre-oxidation reaction in the upper feeding channel, and then, through the action of the transmission device, it can undergo pre-oxidation reaction in the lower feeding channel before entering the upper feeding channel again for reaction, forming continuous pre-oxidation of high-speed moving fibers, which better simulates the effect of actual production.

[0052] The pre-oxidation furnace of the present invention includes two upper and lower wire feeding channels. After the head and tail of the experimental raw filament are connected, the filament is guided by a tension guiding device and a transmission device to achieve continuous circulation in the two wire feeding channels. The maximum number of filament bundles that can be operated at the same time is 50.

[0053] In some embodiments, a furnace head gas sealing device 17 is provided above the upper wire feeding channel 15, between the upper wire feeding channel 15 and the lower wire feeding channel 16, and below the lower wire feeding channel 16.

[0054] A thermocouple 14 is also provided above the wire feeding chamber 103. A first arc-shaped flow guide baffle 7 is provided above the heating chamber 102 in the furnace top chamber 104. A second arc-shaped flow guide baffle 8 is provided above the wire feeding chamber 103 in the furnace top chamber 104. A first filter device 3 and a second filter device 4 are also provided in the heating chamber 102. A heat insulation layer 2 is also provided between the inner and outer walls of the shell 101.

[0055] This invention also features a furnace head gas sealing device that effectively seals the airflow inside the pre-oxidation furnace, further improving the uniformity of the pre-oxidation reaction between the gas and the yarn bundle, thus enhancing the pre-oxidation effect. Furthermore, a thermocouple detects the temperature of the gas entering the yarn-feeding chamber for effective control. Two arc-shaped baffles further guide the internal circulation, improving the uniformity of the internal circulation pre-oxidation reaction. Two filters filter the gas entering the shell from the yarn-feeding channel, and the insulation layer maintains the temperature inside the pre-oxidation furnace, improving the uniformity and stability of the pre-oxidation reaction and simulating better results in actual production.

[0056] The pre-oxidation furnace of the present invention includes a pre-oxidation furnace base 1, an insulation layer 2 (the furnace plate is made of 304 stainless steel and filled with aluminum silicate ceramic fiber), two filter screens (first filter device 3 and second filter device 4) (the filter screen is 200 mesh), a heater 5 (the maximum output power is 10KW, equipped with a power regulator and a temperature control instrument), a fan 6 (equipped with a frequency converter), a first arc-shaped flow guide baffle 7 and a second arc-shaped flow guide baffle 8, three airflow distribution perforated plates and two honeycomb flow equalization structures, a thermocouple 14, and a furnace head gas sealing device 17.

[0057] The pre-oxidation furnace adopts a vertical air circulation method. Circulating hot air is sent from the bottom chamber of the furnace into the heating chamber through two filters. The two filters are used to filter filaments and other impurities, and can be removed and cleaned one by one during operation. In the heating chamber, the circulating air is heated to a specified temperature by heater 5, and then drawn into the top chamber of the furnace by a circulating fan (fan 6). The frequency of the circulating fan (fan 6) can be adjusted to control the airflow. The top chamber of the furnace is designed with a first arc-shaped guide baffle 7 and a second arc-shaped guide baffle 8 on both sides to guide the airflow sent by the circulating fan. After the top chamber reaches a certain pressure, the airflow distribution structure (including three perforated airflow distribution plates and two honeycomb-shaped flow equalization structures) forms a uniformly distributed air column that is blown into the wire-carrying chamber. A thermocouple 14 is designed at the top of the wire-carrying chamber as a temperature monitoring point. The circulating hot air blows down through two layers of running filaments and then returns to the bottom chamber of the furnace.

[0058] The furnace head gas seal structure includes a furnace inlet gas seal structure and a furnace outlet gas seal structure, each comprising three layers of gas seal structures, with two layers of wire feeding channels sandwiched between them. The gas seal structure is designed with a narrow suction channel, and its interior is a cavity connected to the bottom chamber of the furnace. The suction gas seal function is achieved through a high negative pressure created by a circulating fan. Cold air from outside the furnace enters the furnace through the wire feeding channels, or hot air from inside the furnace escapes outwards through the wire feeding channels and is drawn into the gas seal structure, flowing towards the bottom chamber of the furnace. It is then heated to a specified temperature by a filter, heater, and circulating fan before being added to the circulation system.

[0059] The inventive point of this invention: a carbon fiber pre-oxidation process simulation experimental device, which has been rationally designed and improved based on the actual pre-oxidation treatment process in production, mainly including:

[0060] a. An internal furnace circulation system is adopted, with the circulating fan, heater, and filter located inside the furnace, eliminating the need for external air ducts. The circulating hot air circulates between four independent chambers: the wire feeding chamber, the bottom chamber, the heater chamber, and the top chamber. This reduces temperature loss caused by ducted air supply and minimizes temperature and flow field unevenness within the furnace. The top chamber is designed with an arc-shaped baffle to ensure that the circulating hot air from the heater chamber, after being delivered by the circulating fan, is evenly distributed within the top chamber and maintained at a certain pressure, which is then evenly forced into the wire feeding chamber through the airflow distribution structure.

[0061] b. An airflow distribution structure was designed, consisting of three layers of perforated plates and two layers of honeycomb-shaped flow equalization structures. The first layer of perforated plates has a low porosity, while the second and third layers have higher porosities. Circulating hot air first passes through the first layer of perforated plates with low porosity for initial airflow distribution. The low porosity reduces the airflow rate, thus improving the uniformity after initial distribution. After passing through the first layer of perforated plates, the air pressure increases, and the first layer of honeycomb-shaped flow equalization structures ensures flow equalization and prevents turbulence. The second layer of perforated plates with high porosity initially forms the desired airflow distribution. After redistribution, the airflow passes through another flow equalization structure and then through the third layer of perforated plates (with pores perfectly aligned with the second layer) to form a uniform air column. Since the air pressure increases after passing through the perforated plates, a honeycomb-shaped flow equalization structure is designed between the perforated plates to achieve flow equalization. After passing through the airflow distribution structure, the airflow forms multiple uniform small air columns, which is beneficial for the uniformity of pre-oxidation.

[0062] c. Unlike large-scale pre-oxidation equipment used in actual production, the furnace head gas seal of small experimental devices has a greater impact on the uniformity of the furnace. A large influx of cold air from outside the furnace can disrupt temperature differences and flow field uniformity, necessitating a well-designed furnace head gas seal structure to ensure effective sealing. This invention utilizes the negative pressure created by a circulating fan in the furnace bottom chamber, combined with the furnace head gas seal structure, for gas sealing. Each wire feeding channel is sandwiched between two layers of gas seals. Cold air from outside the furnace enters the furnace head through the wire feeding channel, is drawn into the furnace head gas seal structure, and then enters the furnace bottom chamber. After filtration and heating to the controlled temperature by a heater, it is then sent to the furnace top chamber by the circulating fan for circulation.

[0063] d. A tension guiding device was designed to precisely control the tension of the running filament bundle. The tension guiding device can be easily adjusted and controlled according to the amount of running filament bundle and the tension control value.

[0064] e. The entire pre-oxidation process is designed to better reflect actual production. As a small-scale pre-oxidation simulation device, it can simultaneously ensure the tow running speed and total residence time. Furthermore, a single unit can meet the needs of simulating multi-temperature zone pre-oxidation treatment.

[0065] The effects of this invention are as follows:

[0066] (1) The uniformity of the carbon fiber pre-oxidation process simulation experimental device provided by the present invention was tested. As can be seen from the test results of Example 1, the airflow uniformity of the simulation experimental device is within ±4%, and the temperature field uniformity is within ±0.5℃. Compared with the existing pre-oxidation experimental device, the airflow and temperature field uniformity are better, and the effect of the simulation experiment is better.

[0067] (2) The carbon fiber pre-oxidation process simulation experimental device provided by the present invention can effectively control the tension of the fiber bundle, and can adjust the weight of water added to the counterweight water tank according to the change of the amount of fiber bundle to control the tension stability. According to the test results of Example 2, 1g of water added ≈ total tension of the fiber bundle 1cN.

[0068] (3) The carbon fiber pre-oxidation process simulation experimental device provided by the present invention can truly simulate the actual production pre-oxidation continuous long-term operation process. According to the comparison between Example 3 and the actual production operation results, the simulation process is closer to the actual production situation, and the experimental results are more reliable.

[0069] (4) The matching relationship between different pre-oxidation temperatures and residence times was simulated using a carbon fiber pre-oxidation process simulation experimental device. Based on the results of Example 4, the matching relationship between pre-oxidation temperature and residence time of 220℃~230℃ can be obtained as shown in Table 1 below:

[0070] Table 1

[0071]

[0072] Using this device, more experiments can be conducted on matching and exploring carbon fiber pre-oxidation processes.

[0073] Example 1:

[0074] Uniformity tests were conducted on the pre-oxidation furnace simulation experimental setup, with 81 test points taken at each of the two wire feeding channels. Under cold conditions, the circulating fan frequency was adjusted to 45Hz; under hot conditions, the circulating fan frequency was adjusted to 45Hz, and the temperature was controlled at 260℃.

[0075] The test results of the cold airflow uniformity in the upper wire feeding channel are shown in Table 2 below:

[0076] Table 2

[0077]

[0078] Table 3

[0079]

[0080] Table 4

[0081]

[0082] Table 5

[0083]

[0084] The test results show that the airflow uniformity of the simulated oxidation furnace in this invention is within ±4%, and the temperature field uniformity is within ±0.5℃, which is a significant improvement over the airflow and temperature field uniformity of existing pre-oxidation experimental devices.

[0085] Example 2:

[0086] The tension control capability of the pre-oxidation furnace simulation experimental device was tested, and the theoretical calculations and actual tension test results for adjusting the counterweight weight under different filament bundle amounts were compared.

[0087] The tension test results obtained by changing the total weight of water added to the water tank when the pre-oxidation furnace temperature was controlled at 220℃, the operating speed was set to 8m / min, and the number of running filaments was 10 are shown in Table 6 below:

[0088] Table 6

[0089]

[0090] With the pre-oxidation furnace temperature controlled at 220℃, the operating speed set at 8m / min, and the number of running filaments at 20, the tension test results obtained by changing the total weight of water added to the water tank are shown in Table 7 below:

[0091] Table 7

[0092]

[0093] The tension test results obtained by changing the total weight of water added to the water tank when the pre-oxidation furnace temperature was controlled at 220℃, the operating speed was set to 8m / min, and the number of running filaments was 30 are shown in Table 8 below:

[0094] Table 8

[0095]

[0096] The tension test results obtained by changing the total weight of water added to the water tank when the pre-oxidation furnace temperature was controlled at 220℃, the operating speed was set to 8m / min, and the number of running filaments was 40 are shown in Table 9 below:

[0097] Table 9

[0098]

[0099] The tension test results obtained by changing the total weight of water added to the water tank when the pre-oxidation furnace temperature was controlled at 220℃, the operating speed was set to 8m / min, and the number of running filaments was 50 are shown in Table 10 below:

[0100] Table 10

[0101]

[0102] Based on the results of tension control and testing, it can be seen that the carbon fiber pre-oxidation process simulation experimental device provided by the present invention can effectively control the tension of the fiber bundle, and can adjust the weight of water added to the counterweight tank according to the change of fiber bundle amount to control the tension stability, and control the weight of water added to the tank to be approximately 1g ≈ 1cN of total fiber bundle tension.

[0103] Example 3:

[0104] The present invention uses the aforementioned pre-oxidation experimental apparatus to simulate a four-temperature zone pre-oxidation process.

[0105] First, the pre-oxidation furnace temperature was controlled at 228℃, the operating speed was set to 12.5 m / min, the circulating fan frequency was set to 45 Hz, the number of running filaments was 50, the total weight of water in the counterweight tank was 65 kg, the actual tested tension was 1521 cN, and the total operating time was 15.6 min. The pre-oxidation furnace temperature was then rapidly increased to 236℃ to simulate the second temperature zone, the total weight of water in the counterweight tank was 75 kg, the actual tested tension was 1769 cN, and the total operating time was 14.5 min. The pre-oxidation furnace temperature was then rapidly increased to 248℃ to simulate the third temperature zone, the total weight of water in the counterweight tank was 100 kg, the actual tested tension was 2242 cN, and the total operating time was 13.9 min. The pre-oxidation furnace temperature was then rapidly increased to 257℃ to simulate the fourth temperature zone, the total weight of water in the counterweight tank was 110 kg, the actual tested tension was 2453 cN, and the total operating time was 13.5 min.

[0106] The results of the simulated pre-oxidized fiber and the actual pre-oxidized fiber produced under the same process conditions are compared in Table 11 below:

[0107] Table 11

[0108]

[0109] According to the inspection results of the pre-oxidized wire obtained by the pre-oxidation simulation test device under the simulated actual production process conditions, it can be seen that the various test indicators of pre-oxidized wires 1 to 4 are similar to the results of actual large-scale pre-oxidation furnace production. The pre-oxidation simulation test device has a good effect on simulating actual production conditions.

[0110] Example 4:

[0111] This invention explores some applications of the pre-oxidation device for guiding process regulation. In this embodiment, a pre-oxidation experimental device is used to simulate the matching relationship between different pre-oxidation temperatures and residence times.

[0112] The pre-oxidation furnace temperature was controlled at 230℃, the operating speed was set to 12.5 m / min, the circulating fan frequency was set to 45 Hz, the number of filaments was 50, the total weight of water in the counterweight tank was 65 kg, the actual tested tension was 1521 cN, and the total operating time was 30 min. The density of the obtained pre-oxidized filaments was 1.287 g / cm³. 3 .

[0113] The pre-oxidation furnace temperature was controlled at 229℃, the operating speed was set to 12.5 m / min, the circulating fan frequency was set to 45 Hz, the number of running filaments was 50, and the total weight of water in the counterweight tank was 65 kg. The actual test tension was 1521 cN. Two filaments were removed at each time point for testing, and the water in the counterweight tank was reduced by 3 kg each time filaments were removed. The experimental results are shown in Table 12 below (the pre-oxidation filament density usually refers to the bulk density (degree of pre-oxidation reaction) after the pre-oxidation treatment is completed, and is the density of pre-oxidation filament #4 in Example 3 during the 4-stage pre-oxidation treatment process.)

[0114] Table 12

[0115]

[0116] The pre-oxidation furnace temperature was controlled at 228℃, the operating speed was set to 12.5 m / min, the circulating fan frequency was set to 45 Hz, the number of running wire bundles was 50, the total weight of water in the counterweight tank was 65 kg, and the actual test tension was 1521 cN. Two wires were removed at different time points for testing, and 3 kg of water was reduced from the water tank each time wires were removed. The experimental results are shown in Table 13 below:

[0117] Table 13

[0118]

[0119] The pre-oxidation furnace temperature was controlled at 227℃, the operating speed was set to 12.5 m / min, the circulating fan frequency was set to 45 Hz, the number of running wire bundles was 50, and the total weight of water in the counterweight tank was 65 kg. The actual test tension was 1521 cN. After the total operating time exceeded 15 minutes, two wires were removed at different time points for testing. Each time wires were removed, 3 kg of water was reduced from the water tank. The experimental results are shown in Table 14 below:

[0120] Table 14

[0121]

[0122] The pre-oxidation furnace temperature was controlled at 226℃, the operating speed was set to 12.5 m / min, the circulating fan frequency was set to 45 Hz, the number of running wire bundles was 50, and the total weight of water in the counterweight tank was 65 kg. The actual test tension was 1521 cN. After the total running time exceeded 15 minutes, two wires were removed at different time points for testing. Each time wires were removed, 3 kg of water was reduced from the water tank. The experimental results are shown in Table 15 below:

[0123] Table 15

[0124]

[0125] The pre-oxidation furnace temperature was controlled at 225℃, the operating speed was set to 12.5 m / min, the circulating fan frequency was set to 45 Hz, the number of running wire bundles was 50, and the total weight of water in the counterweight tank was 65 kg. The actual test tension was 1521 cN. After the total operating time exceeded 15 minutes, two wires were removed at different time points for testing. Each time wires were removed, 3 kg of water was reduced from the water tank. The experimental results are shown in Table 16 below:

[0126] Table 16

[0127]

[0128] The pre-oxidation furnace temperature was controlled at 224℃, the operating speed was set to 12.5 m / min, the circulating fan frequency was set to 45 Hz, the number of running wire bundles was 50, and the total weight of water in the counterweight tank was 65 kg. The actual test tension was 1521 cN. After the total running time exceeded 15 minutes, two wires were removed at different time points for testing. Each time wires were removed, 3 kg of water was reduced from the water tank. The experimental results are shown in Table 17 below:

[0129] Table 17

[0130]

[0131] The pre-oxidation furnace temperature was controlled at 223℃, the operating speed was set to 12.5 m / min, the circulating fan frequency was set to 45 Hz, the number of running wire bundles was 50, and the total weight of water in the counterweight tank was 65 kg. The actual test tension was 1521 cN. After the total running time exceeded 15 minutes, two wires were removed at different time points for testing. Each time wires were removed, 3 kg of water was reduced from the water tank. The experimental results are shown in Table 18 below:

[0132] Table 18

[0133]

[0134] The pre-oxidation furnace temperature was controlled at 222℃, the operating speed was set to 12.5 m / min, the circulating fan frequency was set to 45 Hz, the number of running wire bundles was 50, and the total weight of water in the counterweight tank was 65 kg. The actual test tension was 1521 cN. After the total running time exceeded 15 minutes, two wires were removed at different time points for testing. Each time wires were removed, 3 kg of water was reduced from the water tank. The experimental results are shown in Table 19 below:

[0135] Table 19

[0136]

[0137] The pre-oxidation furnace temperature was controlled at 221℃, the operating speed was set to 12.5m / min, the circulating fan frequency was set to 45Hz, the number of running wire bundles was 50, and the total weight of water in the counterweight tank was 65kg. The actual test tension was 1521cN. After the total running time exceeded 15 minutes, two wires were removed at different time points for testing. Each time a wire was removed, the water in the counterweight tank was reduced by 3kg. The experimental results are shown in Table 20 below:

[0138] Table 20

[0139]

[0140] The pre-oxidation furnace temperature was controlled at 220℃, the operating speed was set to 12.5 m / min, the circulating fan frequency was set to 45 Hz, the number of running wire bundles was 50, and the total weight of water in the counterweight tank was 65 kg. The actual test tension was 1521 cN. After the total running time exceeded 15 minutes, two wires were removed at different time points for testing. Each time wires were removed, 3 kg of water was reduced from the water tank. The experimental results are shown in Table 21 below:

[0141] Table 21

[0142]

[0143] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention. The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the technical principles of the present invention, and these improvements and modifications should also be considered within the protection scope of the present invention.

Claims

1. A carbon fiber pre-oxidation process simulation experiment device, characterized in that: include: The pre-oxidation furnace (100), tension guiding device (200), and transmission device (300) are provided. The tension guiding device (200) is located on one side of the pre-oxidation furnace (100), and the transmission device (300) is located on the other side of the pre-oxidation furnace (100). The carbon fiber bundle (400) can be driven by the transmission device (300) to enter the pre-oxidation furnace (100) and pass through it. After passing through the tension guiding device (200), the running direction is changed at the tension guiding device (200), and it enters the pre-oxidation furnace (100) again. Thus, the carbon fiber bundle (400) is driven to form a cyclic motion, forming a continuous pre-oxidation reaction. The pre-oxidation furnace (100) includes a shell (101) and a wire feeding chamber (103) is formed inside the shell (101). The wire feeding chamber (103) includes an upper wire feeding channel (15) and a lower wire feeding channel (16). The carbon fiber bundle (400) can be driven by the transmission device (300) and move along the first motion path to the upper wire feeding channel (15) in the pre-oxidation furnace (100) for pre-oxidation reaction. Then, it moves out of the pre-oxidation furnace (100) from the upper wire feeding channel (15). After passing through the tension guide device (200), it changes direction and moves along the second motion path to the lower wire feeding channel (16) in the pre-oxidation furnace (100) for pre-oxidation reaction. Then, it moves out of the pre-oxidation furnace (100) and onto the transmission device (300) to form a cyclic motion.

2. The carbon fiber pre-oxidation process simulation experimental apparatus according to claim 1, characterized in that: The tension guiding device (200) includes a first guide roller (20), a second guide roller (21), and a tension adjusting roller (19). The carbon fiber bundle (400) passes sequentially through the outer circumference of the first guide roller (20), the tension adjusting roller (19), and the second guide roller (21). The first guide roller (20), the second guide roller (21), and the tension adjusting roller (19) are all passive rollers driven by the movement of the bundle. The tension adjusting roller (19) can adjust the tension of the carbon fiber bundle (400).

3. The carbon fiber pre-oxidation process simulation experimental apparatus according to claim 2, characterized in that: The carbon fiber bundle (400) is wound on the outer circumferential surface of the lower half of the tension adjusting roller (19). The tension adjusting roller (19) exerts a longitudinal downward force on the bundle. The bearing of the tension adjusting roller (19) can slide longitudinally within the bearing sleeve. A first central shaft (191) is passed through the central shaft hole of the tension adjusting roller (19). A counterweight device is also sleeved on the first central shaft (191). The counterweight device includes a first tension adjusting counterweight water tank (24) and a second tension adjusting counterweight water tank (25). The first tension adjusting counterweight water tank (24) is hung on one axial end of the first central shaft (191), and the second tension adjusting counterweight water tank (25) is hung on the other axial end of the first central shaft (191).

4. The carbon fiber pre-oxidation process simulation experimental apparatus according to claim 1, characterized in that: The transmission device (300) includes a transmission roller (23), and the carbon fiber bundle (400) is wound around a portion of the outer circumferential surface of the transmission roller (23). The shaft of the transmission roller (23) is connected to a motor and driven to rotate by the motor, thereby driving the carbon fiber bundle (400) to move.

5. The carbon fiber pre-oxidation process simulation experimental apparatus according to claim 1, characterized in that: The pre-oxidation furnace (100) also includes a heater (5) and a fan (6). The housing (101) also forms a heating chamber (102), a furnace top chamber (104), and a furnace bottom chamber (105). At least part of the heater (5) is disposed in the heating chamber (102) to heat the airflow flowing through the heating chamber (102). The fan (6) is disposed in the heating chamber (102) and can drive the airflow to flow sequentially through the heating chamber (102), the furnace top chamber (104), the wire feeding chamber (103), the furnace bottom chamber (105), and the heating chamber (102) to form an internal airflow circulation. The carbon fiber bundle (400) can move into the wire feeding chamber (103) and undergo a pre-oxidation reaction with the heated airflow in the wire feeding chamber (103).

6. The carbon fiber pre-oxidation process simulation experimental apparatus according to claim 5, characterized in that: A furnace head gas sealing device (17) is provided on the upper side of the upper wire feeding channel (15), between the upper wire feeding channel (15) and the lower wire feeding channel (16), and on the lower side of the lower wire feeding channel (16). A thermocouple (14) is also provided above the wire feeding chamber (103). A first arc-shaped flow guide baffle (7) is provided in the furnace top chamber (104) above the heating chamber (102). A second arc-shaped flow guide baffle (8) is provided in the furnace top chamber (104) above the wire feeding chamber (103). A first filter device (3) and a second filter device (4) are also provided in the heating chamber (102). A heat insulation layer (2) is also provided between the inner and outer walls of the shell (101).

7. The carbon fiber pre-oxidation process simulation experimental apparatus according to claim 1, characterized in that: Above the wire-feeding chamber (103), an airflow distribution structure (106) is also provided. The airflow distribution structure (106) includes three layers of airflow distribution perforated plates and two layers of honeycomb flow equalization structures. The airflow distribution perforated plates include a first airflow distribution perforated plate (9), a second airflow distribution perforated plate (11), and a third airflow distribution perforated plate (13). Along the direction of airflow flow, the first airflow distribution perforated plate (9), the second airflow distribution perforated plate (11), and the third airflow distribution perforated plate (13) are arranged alternately. The opening ratio of the flow equalization holes on the first airflow distribution perforated plate (9) is smaller than that on the second airflow distribution perforated plate (13). The opening ratio of the flow equalization holes on the distribution perforated plate (11) is less than or equal to the opening ratio of the flow equalization holes on the third airflow distribution perforated plate (13); the honeycomb flow equalization structure includes a first honeycomb flow equalization structure (10) and a second honeycomb flow equalization structure (12), the first honeycomb flow equalization structure (10) is disposed between the first airflow distribution perforated plate (9) and the second airflow distribution perforated plate (11); the second honeycomb flow equalization structure (12) is disposed between the second airflow distribution perforated plate (11) and the third airflow distribution perforated plate (13).

8. The carbon fiber pre-oxidation process simulation experimental apparatus according to claim 7, characterized in that: The surface direction of the perforated airflow distribution plate is perpendicular to the airflow direction, and multiple through-holes (91) are evenly distributed on the perforated airflow distribution plate. The surface direction of the honeycomb flow equalization structure is parallel to the airflow direction, and multiple through-holes (121) are provided on the honeycomb flow equalization structure. The honeycomb flow equalization structure is connected to the surface of the perforated airflow distribution plate.

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