Polyacrylonitrile-based carbon fiber precursor filament electron beam online irradiation modification system

Abstract

The utility model discloses a kind of polyacrylonitrile-based carbon fiber protofilament's electron beam on-line irradiation modification system, including irradiation room, and the irradiation part of the electron beam accelerator is equipped in room. System is sequentially configured first tension control wheel, first beam lower godet, second beam lower godet and second tension control wheel along the direction of fiber bundle feeding. Beam lower godet is located in irradiation room, surface is equipped with several parallel interval distribution guide groove, each groove annularly is arranged around wheel axis line, groove width is compatible with fiber bundle width. Still including the tension sensor being respectively arranged at the entrance and exit of irradiation room, two sensors are electrically connected with control system;Control system is electrically connected with the drive part of first, second tension control wheel simultaneously, and closed loop tension control loop is formed. The utility model can effectively overcome the problems, such as low efficiency, great damage and product performance deterioration, in the irradiation treatment of polyacrylonitrile fiber, significantly improve the adaptability and application range of electron irradiation technology in actual production.

Description

Technical Field

[0001] This utility model relates to the field of polyacrylonitrile-based carbon fiber production technology, specifically to an electron beam online irradiation modification system for polyacrylonitrile-based carbon fiber precursor. Background Technology

[0002] Carbon fiber (CF) is a high-strength, high-modulus fiber with a carbon content exceeding 90%. It is made from organic precursors such as polyacrylonitrile (PAN), pitch, or viscose through pre-oxidation and high-temperature carbonization. As a key strategic material for both military and civilian use, carbon fiber is internationally recognized as a core new material in modern high-tech fields.

[0003] PAN is currently the mainstream precursor for carbon fiber, accounting for over 90% of the global market. Pre-oxidation, a crucial step in the production of PAN-based carbon fiber, directly affects the structure and properties of the final product. This process transforms linear molecular chains into heat-resistant trapezoidal structures, preventing the fibers from melting and breaking during the carbonization stage. However, pre-oxidation involves intense cyclization, dehydrogenation, and oxidation reactions, releasing a significant amount of heat. Improper temperature control can easily lead to localized overheating, fiber melting and adhesion, and even fire—a problem particularly prominent in large-tow production. Traditional processes use multi-stage gradient heating (200-300℃) to mitigate the exothermic reaction, but pre-oxidation still takes 50-120 minutes, accounting for over 70% of total energy consumption and 80-90% of total production time.

[0004] Electron beam irradiation is an innovative polymer material processing technology. After irradiation, PAN precursor fibers generate a large number of free radicals, which in turn trigger three key reactions: Intermolecular free radical recombination → cross-linking reaction; Free radical addition to cyano group → cyclization reaction; Free radicals combine with oxygen → oxidation reaction.

[0005] Existing technologies show that electron beam irradiation modification can significantly improve pre-oxidation efficiency and reduce the intensity of reaction exothermic reactions, thereby reducing energy consumption and production costs.

[0006] Patent CN 101798747 B proposes an offline electron beam irradiation modification method: PAN precursor fibers are laid flat in a tray and moved back and forth through the electron beam irradiation area along a track. However, this method has two major limitations: First, offline operation: it cannot be matched with the production line of a carbon fiber factory; second, imbalanced process parameters: excessively long irradiation time and excessively high dose (not matched with the production line speed), which restricts the industrialization of the technology.

[0007] Therefore, there is an urgent need to develop an online irradiation process that can seamlessly connect to the actual production line and meet the performance requirements of carbon fiber. Utility Model Content

[0008] The purpose of this invention is to provide an electron beam in-line irradiation modification system for polyacrylonitrile-based carbon fiber precursor.

[0009] To achieve the above objectives, the technical solution adopted by this utility model is as follows: An electron beam online irradiation modification system for polyacrylonitrile-based carbon fiber precursor is provided. The modification is achieved by an electron beam online irradiation modification system, which includes an irradiation chamber in which an irradiation section of an electron beam accelerator is installed. It also includes a first tension control wheel, a first lower guide wheel, a second lower guide wheel, and a second tension control wheel arranged sequentially according to the fiber bundle feeding direction during irradiation; The first and second lower guide wheels are both located in the irradiation chamber and have several parallel and spaced guide grooves on their surfaces. The guide grooves are arranged around the axis of the wheel and the width of the groove corresponds to the width of the fiber bundle. It also includes two tension sensors, which are respectively installed at the entrance and exit of the irradiation chamber; both tension sensors are electrically connected to a control system, which is electrically connected to the drive unit of the first tension control wheel and the second tension control wheel.

[0010] In a further technical solution, the irradiation section is positioned directly above the fiber bundle between the first lower guide roller and the second lower guide roller.

[0011] In a further technical solution, both the first tension control wheel and the second tension control wheel include three parallel rollers, with the horizontal position of the middle roller lower than that of the front and rear rollers. The fiber bundle travels from the upper surface of the front roller to the lower surface of the middle roller, and then to the upper surface of the rear roller. During tension adjustment, the online dynamic tension of the fiber bundle can be achieved by changing the relative height relationship of the three parallel rollers.

[0012] In a further technical solution, the width of each guide groove on the first and second lower guide rollers is 2-3 cm. The guide grooves are used to position the fiber bundles and ensure that the fiber bundle feeding direction does not deviate.

[0013] In a further technical solution, the electron beam online irradiation modification system also includes a pre-oxidation furnace, a low-temperature carbonization furnace, and a high-temperature carbonization furnace located behind the outlet of the irradiation chamber, arranged sequentially according to the fiber bundle feeding direction.

[0014] In a further technical solution, two tension sensors are respectively disposed between the first tension control wheel and the first lower guide wheel, and between the second lower guide wheel and the second tension control wheel.

[0015] The terms “include,” “including,” and “have” used in this article are all open-ended, meaning they include but are not limited to.

[0016] Unless otherwise specified, the terms used herein generally have their ordinary meaning in the context of the art, the subject matter, and the specific context. Certain terms used to describe this case will be discussed below or elsewhere in this specification to provide additional guidance to those skilled in the art in describing the case.

[0017] The working principle and advantages of this utility model are as follows: This invention relates to an online electron beam irradiation modification system for polyacrylonitrile-based carbon fiber precursor, which can be effectively integrated with carbon fiber production lines while ensuring that the properties of the prepared carbon fibers meet requirements. Addressing the problems of low irradiation efficiency, significant irradiation damage, and decreased mechanical properties after irradiation in existing technologies for PAN fibers, this invention significantly improves the compatibility of electron beam irradiation technology with industrial production through system optimization of irradiation parameters and integrated production line design, making it suitable for diverse practical production scenarios.

[0018] The technical features of this utility model include: 1. Wire guiding method of the bundle-down device: A "straight in, straight out" method is adopted to ensure that each bundle of polyacrylonitrile-based carbon fiber precursor receives only one irradiation. The specific implementation scheme is as follows: A bundle-down guide wheel with guide grooves is used, with each fiber bundle (precursor filament) running independently within a guide groove, thereby preventing overlap or crossing between bundles. Tension control wheels are installed before and after the bundle-down guide wheel to ensure the bundle passes smoothly under constant tension.

[0019] 2. Tension Control: A tension sensor is installed between the guide roller and the tension control roller to monitor the raw yarn tension in real time and transmit the data to the control system. The system controls the tension fluctuation of the raw yarn within ±1.0% of the rated value by adjusting the speed difference between the tension control rollers, ensuring stable operation.

[0020] The advantages of this utility model are mainly reflected in the following aspects: 1. Maximize irradiation capacity: By optimizing the layout of the under-beam device, this utility model can make full use of the effective irradiation width of the irradiation equipment, support the simultaneous processing of multiple bundles of polyacrylonitrile-based carbon fiber precursors, and significantly improve the processing capacity per unit time.

[0021] 2. Effective control of irradiation wear of precursor fibers: Through the coordinated action of the bundle guide wheel, tension sensor, tension control wheel and control system, a "straight in and straight out" bundle feeding method and precise tension control are achieved, which significantly reduces the wear of polyacrylonitrile-based carbon fiber precursor fibers during irradiation.

[0022] 3. Significantly shortened pre-oxidation time: The pre-oxidation time of polyacrylonitrile-based carbon fiber precursor treated by this invention can be shortened from 50 minutes in the traditional process to 30 minutes, thereby improving production efficiency.

[0023] 4. Improved mechanical properties of carbon fiber: The raw yarn treated with this invention exhibits superior mechanical properties after irradiation, pre-oxidation and carbonization processes.

[0024] 5. Achieve stable and controllable industrial production: Through online closed-loop control of tension and irradiation dose, the system ensures long-term stable operation and can meet the consistency requirements of efficiency and quality for industrial production of carbon fiber enterprises.

[0025] In summary, this invention effectively overcomes the problems of low processing efficiency, large process damage, and deterioration of finished product performance in the irradiation treatment of polyacrylonitrile fibers, and improves the adaptability and application scope of electron irradiation technology in actual production. Attached Figure Description

[0026] Appendix Figure 1 This is a schematic diagram of the modification system according to an embodiment of the present invention; Appendix Figure 2 This is a schematic diagram of the wire guide wheel in an embodiment of the present invention; Appendix Figure 3 This is a top view of the wire guide wheel in an embodiment of the present invention.

[0027] In the above figures: 1. Fiber bundle; 2. Irradiation chamber; 3. Irradiation section; 4. First tension control wheel; 5. First bundle lower guide wheel; 6. Second bundle lower guide wheel; 7. Second tension control wheel; 8. Tension sensor; 9. Guide groove; 10. Pre-oxidation furnace; 11. Low-temperature carbonization furnace; 12. High-temperature carbonization furnace; 13. Drawing machine; 14. Unwinding machine; 15. Winding machine; 16. Guide wheel; 17. Surface treatment tank; 18. Sizing tank; 19. Drying equipment. Detailed Implementation

[0028] The present invention will be further described below with reference to the accompanying drawings and embodiments: The present invention will be clearly described below with illustrations and detailed description. Any person skilled in the art who understands the embodiments of the present invention can make changes and modifications based on the technology taught in the present invention without departing from the spirit and scope of the present invention.

[0029] The terminology used herein is for the purpose of describing specific embodiments only and is not intended to limit the scope of this work. Singular forms such as “a,” “this,” “this,” “the,” and “the” as used herein also include plural forms.

[0030] See appendix Figure 1As shown, the present invention discloses an electron beam online irradiation modification system for polyacrylonitrile-based carbon fiber precursor, comprising an irradiation chamber 2, wherein an irradiation section 3 of an electron beam accelerator is provided in the irradiation chamber 2; the fiber bundle 1 (precursor fiber) to be modified enters the irradiation chamber 2 horizontally through the inlet of the irradiation chamber 2 and exits the irradiation chamber 2 horizontally through the outlet of the irradiation chamber 2.

[0031] It also includes a first tension control wheel 4, a first lower guide wheel 5, a second lower guide wheel 6, and a second tension control wheel 7 arranged sequentially from front to back according to the fiber bundle 1 feeding direction during irradiation. The axes of each wheel are parallel, and each wheel acts on the upper or lower surface of the fiber bundle 1 respectively.

[0032] The first tension control wheel 4 is located at the front end of the irradiation chamber 2 entrance side, and the second tension control wheel 7 is located at the rear end of the irradiation chamber 2 entrance side. The first lower guide wheel 5 and the second lower guide wheel 6 are both located inside the irradiation chamber 2, and each has several parallel and spaced guide grooves 9 on its surface. The guide grooves 9 are arranged around the axis of the wheel, and the width of the groove corresponds to the width of the fiber bundle 1.

[0033] Preferably, the irradiation section 3 is disposed above the fiber bundle 1 between the first lower guide roller 5 and the second lower guide roller 6.

[0034] Preferably, both the first tension control wheel 4 and the second tension control wheel 7 include three parallel rollers, with the horizontal position of the middle roller lower than that of the front and rear rollers; the fiber bundle 1 winds from the upper surface of the front roller to the lower surface of the middle roller, and then winds to the upper surface of the rear roller. During tension adjustment, the online dynamic tension of the fiber bundle can be achieved by changing the relative height relationship of the three parallel rollers.

[0035] It also includes two tension sensors 8, which are respectively installed at the entrance and exit of the irradiation chamber 2; both tension sensors 8 are electrically connected to a control system (such as a PLC), which is electrically connected to the drive unit of the first tension control wheel 4 and the second tension control wheel 7.

[0036] Preferably, the width of each guide groove 9 on the first lower guide wheel 5 and the second lower guide wheel 6 is 2~3cm.

[0037] Among them, such as Figure 1 As shown, the electron beam online irradiation modification system also includes a pre-oxidation furnace 10, a low-temperature carbonization furnace 11, and a high-temperature carbonization furnace 12 located behind the outlet of the irradiation chamber. The three are arranged in sequence from front to back according to the fiber bundle 1 feeding direction.

[0038] During the modification process, the fiber bundle 1 is provided with traction force by the drawing machine 13 in the production line, and the fiber is fed and wound by the feeding machine 14 and the winding machine 15 at both ends. The guide wheel 16 can be set to ensure the guidance of the fiber bundle 1.

[0039] After being irradiated in irradiation chamber 2, fiber bundle 1 sequentially enters pre-oxidation furnace 10, low-temperature carbonization furnace 11, high-temperature carbonization furnace 12, surface treatment tank 17, and sizing tank 18 for processing. Finally, it is dried in drying equipment 19 to complete the modification process and then filament winding. The post-irradiation processes can adopt the requirements of conventional carbon fiber processing technology, so they will not be described in detail in this case.

[0040] This invention utilizes a closed-loop control system to achieve precise dynamic adjustment of the raw yarn tension, effectively ensuring the stability and reliability of the production process.

[0041] The control process of this utility model system is as follows: When the fiber bundle 1 raw filament enters the irradiation chamber 2, the tension of the raw filament on the inlet side is first detected in real time by a tension sensor 8 installed at the inlet of the irradiation chamber 2; at the same time, a tension sensor 8 installed at the outlet of the irradiation chamber 2 synchronously detects the tension of the raw filament on the outlet side. The two detection signals are transmitted to the control system in real time.

[0042] After receiving the detection signal, the control system compares the real-time tension data with the preset tension threshold and calculates the tension deviation value through its internal calculation module. Based on the deviation calculation result, the system makes a judgment: when the inlet tension value exceeds the preset range, an inlet adjustment command is generated; when the outlet tension value is abnormal, an outlet adjustment command is generated.

[0043] The actuator adjusts the tension control wheels on the inlet or outlet side according to control commands: by changing the spatial position of the control wheels or adjusting their rotation speed, the tension of the precursor fiber is compensated and corrected in real time. This adjustment process is continuous and dynamic, ensuring that the precursor fiber in the irradiation zone always maintains a constant and ideal tension state.

[0044] This invention achieves precise online control of the raw yarn tension through a combination of dual-sensor monitoring and closed-loop control, effectively avoiding problems such as raw yarn wear and breakage caused by tension fluctuations in traditional production methods, and significantly improving product quality and production efficiency.

[0045] The technical features of this utility model embodiment include: 1. Wire feeding method of the bundle-down device: A "straight in, straight out" method is adopted to ensure that each bundle of polyacrylonitrile-based carbon fiber precursor receives only one irradiation. The specific implementation plan is as follows: a bundle-down guide wheel with a groove width of 2-3 cm is used as the bundle-down guide wheel (see...). Figure 2 , Figure 3Each bundle of raw filaments runs independently within a guide groove, thus preventing overlap or crossing between bundles. Tension control wheels are positioned before and after the guide rollers below the bundles, ensuring the bundles pass smoothly under constant tension.

[0046] 2. Tension Control: A tension sensor is installed between the guide roller and the tension control roller to monitor the raw yarn tension in real time and transmit the data to the control system. The system controls the tension fluctuation of the raw yarn within ±1.0% of the rated value by adjusting the speed difference between the tension control rollers, ensuring stable operation.

[0047] The above embodiments are only for illustrating the technical concept and features of this utility model, and are intended to enable those skilled in the art to understand the content of this utility model and implement it accordingly. They should not be construed as limiting the scope of protection of this utility model. All equivalent changes or modifications made in accordance with the spirit and essence of this utility model should be included within the scope of protection of this utility model.

Claims

1. An electron beam in-line irradiation modification system for polyacrylonitrile-based carbon fiber precursor, characterized in that: It includes an irradiation chamber (2) in which an irradiation section (3) of an electron beam accelerator is provided; It also includes a first tension control wheel (4), a first lower guide wheel (5), a second lower guide wheel (6), and a second tension control wheel (7) arranged sequentially in the direction of fiber bundle (1) feeding during irradiation. The first lower guide wheel (5) and the second lower guide wheel (6) are both located in the irradiation chamber (2), and their surfaces are provided with several parallel and spaced guide grooves (9). The guide grooves (9) are arranged around the axis of the wheel, and the width of the groove corresponds to the width of the fiber bundle (1). It also includes two tension sensors (8), which are respectively set at the entrance and exit of the irradiation chamber (2); both tension sensors (8) are electrically connected to a control system, which is electrically connected to the drive unit of the first tension control wheel (4) and the second tension control wheel (7).

2. The electron beam in-line irradiation modification system for polyacrylonitrile-based carbon fiber precursor according to claim 1, characterized in that: The irradiation section (3) is positioned above the fiber bundle (1) between the first lower guide roller (5) and the second lower guide roller (6).

3. The electron beam in-line irradiation modification system for polyacrylonitrile-based carbon fiber precursor according to claim 1, characterized in that: The first tension control wheel (4) and the second tension control wheel (7) each include three parallel rollers, and the horizontal position of the middle roller is lower than that of the front and rear rollers; the fiber bundle (1) is wound around the upper surface of the front roller to the lower surface of the middle roller, and then around to the upper surface of the rear roller.

4. The electron beam in-line irradiation modification system for polyacrylonitrile-based carbon fiber precursor according to claim 1, characterized in that: The width of each guide groove (9) on the first lower guide wheel (5) and the second lower guide wheel (6) is 2~3cm.

5. The electron beam in-line irradiation modification system for polyacrylonitrile-based carbon fiber precursor according to claim 1, characterized in that: The electron beam online irradiation modification system also includes a pre-oxidation furnace (10), a low-temperature carbonization furnace (11), and a high-temperature carbonization furnace (12) located behind the outlet of the irradiation chamber, which are arranged in sequence according to the feeding direction of the fiber bundle (1).

6. The electron beam in-line irradiation modification system for polyacrylonitrile-based carbon fiber precursor according to claim 1, characterized in that: Two tension sensors (8) are respectively disposed between the first tension control wheel (4) and the first lower guide wheel (5), and between the second lower guide wheel (6) and the second tension control wheel (7).

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