Carbon fiber uniaxial precursor and carbon fiber uniaxial precursor constant weight control method

Abstract

The invention discloses a carbon fiber uniaxial precursor and a carbon fiber uniaxial precursor constant weight control method, and belongs to the field of carbon fibers. The carbon fiber uniaxial precursor meets the formula:; wherein Y is the fixed weight of the carbon fiber single-axis precursor, N is the number of axes of carbon filaments produced by the carbon fiber single-axis precursor, X is the fixed weight of the carbon fiber single-axis carbon filaments, A1 is the real-time carbon yield, K is a multi-parameter correction factor, and the multi-parameter correction factor K is the product of a filament withdrawing tension fluctuation coefficient KT and a precursor filament density variation coefficient K sigma; wherein when the yarn retreating tension fluctuation T is smaller than or equal to 3 cN, the yarn retreating tension fluctuation coefficient KT is 1.0, and on the basis that the yarn retreating tension fluctuation T is 3 cN, the KT is reduced by 0.05 every time the yarn retreating tension fluctuation T exceeds 1 cN; when the density variation coefficient sigma of the original silk yarn is smaller than or equal to 1.5%, K sigma is equal to 1.0, and on the basis that sigma is 1.5%, K sigma is reduced by 0.02 when the sigma exceeds 0.1%. The method can effectively improve the whole-axis rate of the carbon fiber carbon filaments in the batch preparation process.

Description

Technical Field

[0001] This application relates to the field of carbon fiber, and more specifically, to a carbon fiber uniaxial precursor and a method for controlling the weight of the carbon fiber uniaxial precursor. Background Technology

[0002] As a strategic high-performance fiber with a carbon content of over 90%, the accuracy of carbon fiber precursor weight directly affects the quality of products in high-end fields such as aerospace.

[0003] Existing technologies mainly rely on manual experience to determine the weight of carbon fiber precursors. This results in fragmented process parameters, a lack of dynamic response, and an inability to adjust the weight in real time to accommodate changes in carbonization yield. Consequently, there is a discrepancy between the quality of precursor input and the quality of carbon fiber output, leading to a low overall axial ratio of carbon fiber filaments in the mass production process. Summary of the Invention

[0004] This application provides a carbon fiber uniaxial precursor and a method for controlling the weight of carbon fiber uniaxial precursor, which can effectively improve the axial ratio of carbon fiber filaments during mass production.

[0005] The embodiments of this application are implemented as follows: In a first aspect, this application provides an example of a carbon fiber uniaxial precursor fiber, comprising: Carbon fiber uniaxial precursor satisfies the following formula: Where Y is the weight of the carbon fiber uniaxial precursor, N is the number of carbon filaments produced from the carbon fiber uniaxial precursor, X is the weight of the carbon fiber uniaxial filament, A1 is the real-time carbon yield, K is a multi-parameter correction factor, and the multi-parameter correction factor K is the unwinding tension fluctuation coefficient K. T and the coefficient of variation of the linear density of the raw silk K σ The product of; where K is the unwinding tension fluctuation coefficient when the unwinding tension fluctuation T≤3cN. T The value is 1.0. When the unwinding tension fluctuation T is above 3 cN, K increases by 1 cN for every additional 1 cN. T Reduce by 0.05; when the coefficient of variation of the linear density of the original yarn σ ≤ 1.5%, K σ =1.0, and for every 0.1% exceeding σ from 1.5%, K... σ Decrease by 0.02.

[0006] The carbon fiber uniaxial precursor provided in this application, by controlling the carbon fiber uniaxial precursor to satisfy the above formula, can not only obtain the fixed weight of the carbon fiber uniaxial precursor and improve the axial ratio of carbon fiber filaments in the mass production process, but also adjust the fixed weight of the carbon fiber uniaxial precursor in real time according to the real-time changes in carbon yield, realize dynamic response, further improve the axial ratio of carbon fiber filaments in the mass production process, thereby improving the carbon fiber preparation efficiency and reducing the production cost, and improving the economic efficiency of carbon fiber filaments.

[0007] In some alternative implementations, the unwinding tension fluctuation T is controlled within 0.1 cN - 10 cN.

[0008] In some alternative implementations, the value of K ranges from 0.9 to 1.1.

[0009] In some alternative implementations, A1 is obtained in the following ways: A1 = Where Vz is the final carbon fiber filament driving linear velocity, Dz is the final carbon fiber filament linear density, Vc is the initial carbon fiber precursor feeding speed, and Dc is the initial carbon fiber precursor linear density.

[0010] In some alternative embodiments, A1 is obtained by: collecting carbon yields corresponding to different precursor specifications and preparation parameters during the preparation of carbon fiber filaments, forming a carbon yield database; obtaining the precursor specifications and preparation parameters used in the preparation of carbon fiber uniaxial filaments, and obtaining carbon yield A2 in the carbon yield database; if A1≠A2, adjusting the Dc data to make A1=A2.

[0011] In a second aspect, this application provides a method for controlling the weight of carbon fiber uniaxial precursor fibers, comprising: According to the formula: The target weight of the carbon fiber uniaxial precursor was measured.

[0012] Wherein, Y is the weight of the carbon fiber uniaxial precursor, N is the number of carbon filaments produced from the carbon fiber uniaxial precursor, X is the weight of the carbon fiber uniaxial filament, A1 is the real-time carbon yield, and K is a multi-parameter correction factor, wherein the multi-parameter correction factor K is the unwinding tension fluctuation coefficient K. T and the coefficient of variation of the linear density of the raw silk K σ The product of; the unwinding tension fluctuation coefficient K when the unwinding tension fluctuation T≤3cN. T The value is 1.0. When the unwinding tension fluctuation T is above 3 cN, K increases by 1 cN for every additional 1 cN. T Reduce by 0.05; when the coefficient of variation of the linear density of the original yarn σ ≤ 1.5%, K σ =1.0, and for every 0.1% exceeding σ from 1.5%, K... σ Decrease by 0.02.

[0013] Adjust the actual weight of the carbon fiber uniaxial precursor to the target weight.

[0014] The carbon fiber uniaxial precursor fiber weight control method provided in this application controls and adjusts the carbon fiber uniaxial precursor fiber to meet the above formula. This not only obtains the weight of the carbon fiber uniaxial precursor fiber and improves the axial ratio of carbon fiber filaments in the mass production process, but also adjusts the weight of the carbon fiber uniaxial precursor fiber in real time according to the real-time changes in carbon yield, achieving dynamic response. This further improves the axial ratio of carbon fiber filaments in the mass production process, thereby improving the carbon fiber production efficiency and reducing the production cost, thus improving the economic efficiency of carbon fiber filaments.

[0015] In some alternative implementations, the unwinding tension fluctuation T is controlled within 0.1 cN - 10 cN.

[0016] In some alternative implementations, the value of K ranges from 0.9 to 1.1.

[0017] In some alternative implementations, A= Where Vz is the final carbon fiber filament driving linear velocity, Dz is the final carbon fiber filament linear density, Vc is the initial carbon fiber precursor feeding speed, and Dc is the initial carbon fiber precursor linear density.

[0018] In some optional embodiments, the carbon fiber uniaxial precursor yarn weight control method further includes: collecting carbon yield corresponding to different precursor yarn specifications and preparation parameters during the preparation of carbon fiber filaments, forming a carbon yield database; obtaining the precursor yarn specifications and preparation parameters used in the preparation of carbon fiber uniaxial filaments, and obtaining the carbon yield A2 in the carbon yield database; if A1≠A2, adjusting the Dc data to make A1=A2. Detailed Implementation

[0019] The embodiments of this application will be described in detail below with reference to examples. However, those skilled in the art will understand that the following examples are for illustrative purposes only and should not be considered as limiting the scope of this application. Unless otherwise specified in the examples, conventional conditions or conditions recommended by the manufacturer shall apply. Reagents or instruments whose manufacturers are not specified are all commercially available conventional products.

[0020] The preparation process of carbon fiber is divided into two steps: carbon fiber precursor preparation and carbon fiber filament preparation. The specific preparation process usually includes: PAN-based nascent fiber, which becomes PAN-based carbon fiber precursor after water washing, water drawing, oiling, drying and steam drawing processes, and is then wound on a winding machine to obtain carbon fiber uniaxial precursor. After unwinding, the carbon fiber uniaxial precursor undergoes pre-oxidation treatment and carbonization treatment before being wound to obtain carbon fiber uniaxial filament.

[0021] Existing technologies mainly rely on manual experience to determine the weight of carbon fiber precursors. This results in fragmented process parameters, a lack of dynamic response, and an inability to adjust the weight in real time to accommodate changes in carbonization yield. Consequently, there is a discrepancy between the quality of precursor input and carbon fiber output, leading to increased splicing and breakage rates, reduced carbon fiber skein ratio, and decreased production efficiency.

[0022] The inventor invented a method to control the uniaxial precursor fiber to satisfy the following formula: This is beneficial for improving the axial ratio of carbon fiber filaments, increasing the efficiency of carbon fiber preparation, reducing manufacturing costs, and improving the economic efficiency of carbon fiber filaments.

[0023] In view of the above, this application is hereby submitted.

[0024] The following provides a detailed description of the carbon fiber uniaxial precursor and the carbon fiber uniaxial precursor weight control method according to embodiments of this application: The first aspect of this application provides a carbon fiber uniaxial precursor fiber, comprising: Carbon fiber uniaxial precursor satisfies the following formula: .

[0025] Where Y is the weight of the carbon fiber uniaxial precursor, N is the number of carbon filaments produced from the carbon fiber uniaxial precursor, X is the weight of the carbon fiber uniaxial filament, A1 is the real-time carbon yield, K is a multi-parameter correction factor, and the multi-parameter correction factor K is the unwinding tension fluctuation coefficient K. T and the coefficient of variation of the linear density of the raw silk K σ The product of; where K is the unwinding tension fluctuation coefficient when the unwinding tension fluctuation T≤3cN. T The value is 1.0. When the unwinding tension fluctuation T is above 3 cN, K increases by 1 cN for every additional 1 cN. T Reduce by 0.05; when the coefficient of variation of the linear density of the original yarn σ ≤ 1.5%, K σ =1.0, and for every 0.1% exceeding σ from 1.5%, K... σ Decrease by 0.02.

[0026] It should be noted that the fixed weight of carbon fiber uniaxial precursor yarn refers to the weight of the carbon fiber uniaxial precursor yarn, while the fixed weight of carbon fiber uniaxial carbon filament refers to the weight of the carbon fiber uniaxial carbon filament.

[0027] When the unwinding tension fluctuation T ≤ 3cN, the unwinding tension fluctuation coefficient K T The value is 1.0. When the unwinding tension fluctuation T is above 3 cN, K increases by 1 cN for every additional 1 cN. T Decrease by 0.05, that is, K T=1-0.05×max(0,T-3), where max(0,T-3) represents a maximum value function, meaning it takes the larger value between 0 and (T-3). In other words, if T-3 is greater than 0, then T-3 is taken; otherwise, 0 is taken. For example, when T=4, K... T = 0.95.

[0028] When the coefficient of variation of the linear density of the raw yarn σ ≤ 1.5%, K σ =1.0, and for every 0.1% exceeding σ from 1.5%, K... σ Decrease by 0.02. That is, K σ =1-0.02×max(0,(σ-1.5%)×1000), where max(0,(σ-1.5%)×1000) represents a maximum value function, meaning it takes the larger of 0 and (σ-1.5%)×1000; that is, if (σ-1.5%)×1000 is greater than 0, then (σ-1.5%)×1000 is taken; otherwise, 0 is taken. For example, when σ=1.6%, K... σ = 0.98.

[0029] The multi-parameter correction factor K is the unwinding tension fluctuation coefficient K. T and the coefficient of variation of the linear density of the raw silk K σ The product of, that is, K = K T × K σ .

[0030] It is understandable that, since carbon fiber is produced in large quantities, the axial ratio of carbon filaments produced in large quantities can be controlled by the above formula.

[0031] To control stability, mass production typically requires keeping the carbon fiber uniaxial filament weight X, the number of carbon filaments N produced from the carbon fiber uniaxial precursor fiber, and the multi-parameter correction factor K essentially constant. However, the carbon yield may change instantaneously by ±1.2% due to fluctuations in the heating rate during pre-oxidation and carbonization. Since A1 is the real-time carbon yield, the weight of the carbon fiber uniaxial precursor fiber can be adjusted in real time according to the changes in the real-time carbon yield, achieving dynamic response and effectively improving the axial ratio of carbon fiber filaments during mass production.

[0032] In other words, the carbon fiber uniaxial precursor provided in this application, by controlling the carbon fiber uniaxial precursor to satisfy the above formula, can not only obtain the fixed weight of the carbon fiber uniaxial precursor and improve the axial ratio of carbon fiber filaments in the mass production process, but also adjust the fixed weight of the carbon fiber uniaxial precursor in real time according to the real-time changes in carbon yield, realize dynamic response, further improve the axial ratio of carbon fiber filaments in the mass production process, thereby improving the carbon fiber preparation efficiency and reducing the production cost, and improving the economic efficiency of carbon fiber filaments.

[0033] Optionally, a real-time monitoring system can be introduced during the unwinding process of the raw yarn. The real-time monitoring system includes a tension sensor and a breakage detection device, thereby connecting the unwinding stability parameters (such as the average number of breaks and the tension fluctuation range) with the aforementioned constant weight model Y=N. K-coupling establishes a "stability-weight correction factor" to dynamically adjust the weight value. For example, when the unwinding stability is poor, the weight of the raw yarn is automatically reduced to decrease the length of the uniaxial raw yarn and reduce the risk of breakage.

[0034] In some implementations, the unwinding tension fluctuation T is controlled within 0.1 cN - 10 cN.

[0035] Yes, the tension fluctuation T of the unwinding process should be controlled within 0.1 cN - 10 cN. If it is not within this range, it should be adjusted to avoid excessive tension fluctuation that could lead to yarn breakage.

[0036] For example, the unwinding tension fluctuation T is any value among 0.1 cN, 0.5 cN, 1.0 cN, 1.5 cN, 2.0 cN, 2.5 cN, 3.0 cN, 3.5 cN, 4.0 cN, 4.5 cN, 5.0 cN, 5.5 cN, 6.0 cN, 6.5 cN, 7.0 cN, 7.5 cN, 8.0 cN, 8.5 cN, 9.0 cN, 9.5 cN, and 10.0 cN, or between any two values.

[0037] In some implementations, the value of K ranges from 0.9 to 1.1.

[0038] When the value of K is controlled within the above range, the deviation of the multi-parameter correction factor from 1 is small, which is beneficial to improving the axial ratio of carbon fiber filaments. It is understood that if the value of K is not controlled within the above range, the multi-parameter correction factor can be adjusted by regulating the tension fluctuation during the fabrication process.

[0039] For example, the value of K is any one of 0.90, 0.92, 0.95, 0.97, 0.10, 0.12, 0.15, 0.17 and 0.20 or between any two values.

[0040] In some implementations, A1 is obtained in the following ways: A1 = Where Vz is the final carbon fiber filament driving linear velocity, Dz is the final carbon fiber filament linear density, Vc is the initial carbon fiber precursor feeding speed, and Dc is the initial carbon fiber precursor linear density.

[0041] It is understandable that the final carbon fiber filament driving linear speed refers to the speed at which the fiber travels during carbonization, affecting the residence time of the fiber in the reaction zone. The final carbon fiber filament linear density refers to the linear density of the carbonized carbon fiber filament. The initial carbon fiber precursor feeding speed refers to the speed at which the precursor filament enters the pre-oxidation furnace from the yarn rack. The initial carbon fiber precursor linear density refers to the linear density of the precursor filament.

[0042] It should be noted that the linear density can be obtained by setting up an online weighing sensor. The online weighing sensor includes a detection box, a gravity weigher and a sensor set up in the detection box. The gravity weigher automatically detects the weight of the raw filament and carbon fiber, and the sensor detects the length of the raw filament and carbon fiber. Based on the weight and length, the linear density Dz and Dc are automatically calculated. The linear velocity Vz and Vc can be obtained in real time by setting up a velocity sensor. Then, the online weighing sensor and the velocity sensor are connected to the controller. The controller calculates the real-time carbon yield A1 according to the formula above based on the linear density Dz and Dc obtained by the online weighing sensor and the linear velocity Vz and Vc obtained by the velocity sensor.

[0043] The real-time carbon yield can be calculated using the above formula.

[0044] In some embodiments, A1 is obtained by collecting carbon yields corresponding to different precursor specifications and preparation parameters during the preparation of carbon fiber filaments, and forming a carbon yield database. Obtain the specifications and preparation parameters of the precursor fiber used in the preparation of carbon uniaxial carbon filament, and obtain the carbon yield A2 from the carbon yield database; If A1≠A2, then adjust the Dc data to make A1=A2.

[0045] It should be noted that the preparation parameters include those that affect the carbon yield, including but not limited to the pre-oxidation oxygen concentration, pre-oxidation temperature, carbonization temperature, heating rate, and draw ratio.

[0046] It should be noted that errors may occur during the actual preparation process, resulting in A1 ≠ A2. A1 is the actual carbon yield corresponding to the equipment and preparation parameters used in this application. Vz, Dz, and Vc are usually fixed in the same batch production. Therefore, A1 can be made to equalize A2 by adjusting the Dc data, so as to obtain a more accurate carbon yield that conforms to the actual operation of the production line, which is more conducive to improving the carbon fiber filament axial ratio during the batch preparation process.

[0047] A second aspect of this application provides a method for controlling the weight of carbon fiber uniaxial precursor fibers, comprising: According to the formula: The target weight of the carbon fiber uniaxial precursor was measured.

[0048] Where Y is the target weight of the carbon fiber uniaxial precursor, N is the number of carbon filaments produced from the carbon fiber uniaxial precursor, X is the weight of the carbon fiber uniaxial filament, A1 is the real-time carbon yield, K is a multi-parameter correction factor, and the multi-parameter correction factor K is the unwinding tension fluctuation coefficient K. T and the coefficient of variation of the linear density of the raw silk K σ The product of the two, with the unwinding tension fluctuation coefficient K when the unwinding tension fluctuation T≤3cN. T The value is 1.0. When the unwinding tension fluctuation T is above 3 cN, K increases by 1 cN for every additional 1 cN. T Reduce by 0.05, so that the coefficient of variation of the linear density of the original yarn σ ≤ 1.5% when K σ =1.0, and for every 0.1% exceeding σ from 1.5%, K... σ Decrease by 0.02.

[0049] Adjust the actual weight of the carbon fiber uniaxial precursor to the target weight.

[0050] It should be noted that the fixed weight of carbon fiber uniaxial precursor yarn refers to the weight of the carbon fiber uniaxial precursor yarn, while the fixed weight of carbon fiber uniaxial carbon filament refers to the weight of the carbon fiber uniaxial carbon filament.

[0051] When the unwinding tension fluctuation T ≤ 3cN, the unwinding tension fluctuation coefficient K T The value is 1.0. When the unwinding tension fluctuation T is above 3 cN, K increases by 1 cN for every additional 1 cN. T Decrease by 0.05, that is, K T =1-0.05×max(0,T-3), where max(0,T-3) represents a maximum value function, meaning it takes the larger value between 0 and (T-3). In other words, if T-3 is greater than 0, then T-3 is taken; otherwise, 0 is taken. For example, when T=4, K... T = 0.95.

[0052] When the coefficient of variation of the linear density of the raw yarn σ ≤ 1.5%, K σ =1.0, and for every 0.1% exceeding σ from 1.5%, K... σ Decrease by 0.02. That is, K σ =1-0.02×max(0,(σ-1.5%)×1000), where max(0,(σ-1.5%)×1000) represents a maximum value function, meaning it takes the larger of 0 and (σ-1.5%)×1000; that is, if (σ-1.5%)×1000 is greater than 0, then (σ-1.5%)×1000 is taken; otherwise, 0 is taken. For example, when σ=1.6%, K... σ = 0.98.

[0053] The multi-parameter correction factor K is the unwinding tension fluctuation coefficient K. Tand the coefficient of variation of the linear density of the raw silk K σ The product of, that is, K = K T × K σ .

[0054] It is understandable that, since carbon fiber is produced in large quantities, the axial ratio of carbon filaments produced in large quantities can be controlled by the above formula.

[0055] To control stability, mass production typically requires keeping the carbon fiber uniaxial filament weight X, the number of carbon filaments N produced from the carbon fiber uniaxial precursor fiber, and the multi-parameter correction factor K essentially constant. However, the carbon yield may change instantaneously by ±1.2% due to fluctuations in the heating rate during pre-oxidation and carbonization. Since A1 is the real-time carbon yield, the weight of the carbon fiber uniaxial precursor fiber can be adjusted in real time according to the changes in the real-time carbon yield, achieving dynamic response and effectively improving the axial ratio of carbon fiber filaments during mass production.

[0056] In other words, the carbon fiber uniaxial precursor weight control method provided in this application, by controlling and adjusting the carbon fiber uniaxial precursor to meet the above formula, can not only obtain the carbon fiber uniaxial precursor weight and improve the carbon fiber filament axiality during the batch production process, but also adjust the carbon fiber uniaxial precursor weight in real time according to the real-time carbon yield change, realize dynamic response, further improve the carbon fiber filament axiality during the batch production process, thereby improving the carbon fiber preparation efficiency and reducing the production cost, and improving the economic efficiency of carbon fiber filament.

[0057] In some implementations, the unwinding tension fluctuation T is controlled within 0.1 cN - 10 cN.

[0058] Yes, the tension fluctuation T of the unwinding process should be controlled within 0.1 cN - 10 cN. If it is not within this range, it should be adjusted to avoid excessive tension fluctuation that could lead to yarn breakage.

[0059] For example, the unwinding tension fluctuation T is any value among 0.1 cN, 0.5 cN, 1.0 cN, 1.5 cN, 2.0 cN, 2.5 cN, 3.0 cN, 3.5 cN, 4.0 cN, 4.5 cN, 5.0 cN, 5.5 cN, 6.0 cN, 6.5 cN, 7.0 cN, 7.5 cN, 8.0 cN, 8.5 cN, 9.0 cN, 9.5 cN, and 10.0 cN, or between any two values.

[0060] In some implementations, the value of K ranges from 0.9 to 1.1.

[0061] When the value of K is controlled within the above range, the deviation of the multi-parameter correction factor from 1 is small, which is beneficial to improving the axial ratio of carbon fiber filaments. It is understood that if the value of K is not controlled within the above range, the multi-parameter correction factor can be adjusted by regulating the tension fluctuation during the fabrication process.

[0062] For example, the value of K is any one of 0.90, 0.92, 0.95, 0.97, 0.10, 0.12, 0.15, 0.17 and 0.20 or between any two values.

[0063] In some implementations, A1 is obtained in the following ways: A1 = Where Vz is the final carbon fiber filament driving linear velocity, Dz is the final carbon fiber filament linear density, Vc is the initial carbon fiber precursor feeding speed, and Dc is the initial carbon fiber precursor linear density.

[0064] It is understandable that the final carbon fiber filament driving linear speed refers to the speed at which the fiber travels during carbonization, affecting the residence time of the fiber in the reaction zone. The final carbon fiber filament linear density refers to the linear density of the carbonized carbon fiber filament. The initial carbon fiber precursor feeding speed refers to the speed at which the precursor filament enters the pre-oxidation furnace from the yarn rack. The initial carbon fiber precursor linear density refers to the linear density of the precursor filament.

[0065] The real-time carbon yield can be calculated using the above formula.

[0066] In some embodiments, the carbon fiber uniaxial precursor yarn weight control method further includes: collecting the carbon yield corresponding to different precursor yarn specifications and preparation parameters during the carbon fiber precursor yarn preparation process to form a carbon yield database. Obtain the specifications and preparation parameters of the precursor fiber used in the preparation of carbon uniaxial carbon filament, and obtain the carbon yield A2 from the carbon yield database; If A1≠A2, then adjust the Dc data to make A1=A2.

[0067] It should be noted that the preparation parameters include those that affect the carbon yield, including but not limited to the pre-oxidation oxygen concentration, pre-oxidation temperature, carbonization temperature, heating rate, and draw ratio.

[0068] It should be noted that errors may occur during the actual preparation process, resulting in A1 ≠ A2. A1 is the actual carbon yield corresponding to the equipment and preparation parameters used in this application. Vz, Dz, and Vc are usually fixed in the same batch production. Therefore, A1 can be made to equalize A2 by adjusting the Dc data, so as to obtain a more accurate carbon yield that conforms to the actual operation of the production line. This is more conducive to accurately adjusting the weight of the carbon fiber uniaxial precursor and improving the carbon fiber filament axial ratio during the batch preparation process.

[0069] In some embodiments, the carbon fiber uniaxial precursor yarn weight control method further includes: integrating a real-time carbon yield monitoring module into the carbonization production line. The real-time carbon yield monitoring module includes a controller, an online weighing sensor, and a speed sensor. The online weighing sensor includes a detection box, and a gravity weigher and sensor installed in the detection box. The gravity weigher automatically detects the weight of the precursor yarn and carbon fiber, and the sensor detects the length of the precursor yarn and carbon fiber. Based on the weight and length, the linear density Dz and Dc are automatically calculated. The linear velocity Vz and Vc can be obtained in real time by setting a speed sensor. Then, the online weighing sensor and the speed sensor are respectively connected to the controller. The controller calculates the real-time carbon yield A1 according to the above formula based on the linear density Dz and Dc obtained by the online weighing sensor and the linear velocity Vz and Vc obtained by the speed sensor.

[0070] Optionally, the carbon fiber uniaxial precursor fiber weight control method further includes: a controller connected to a carbon yield database, the controller being configured to obtain the carbon yield A2 from the carbon yield database based on the precursor fiber specifications and preparation parameters used in the preparation of the carbon fiber uniaxial filament, compare it with A1=A2, and if A1≠A2, adjust the Dc data to make A1=A2. This forms a "monitoring-calculation-adjustment" closed-loop control.

[0071] The following describes in further detail the carbon fiber uniaxial precursor and the carbon fiber uniaxial precursor weight control method of this application with reference to embodiments.

[0072] Example 1 When T800 grade -12K precursor yarn is carbonized, the calculated carbon yield A1 = 0.49 (theoretical value 0.50), and the unwinding tension fluctuation is 2.8 cN (standard ≤ 3 cN). The fixed weight of a single-axis carbon yarn is X = 2 kg, and the number of carbon yarns produced from a single-axis precursor yarn is N = 30. The unwinding stability parameter, tension fluctuation T = 2.8 cN (≤ 3 cN, therefore K...). T =1), the coefficient of variation of the linear density of the raw yarn σ=1.2% (≤1.5%, therefore K σ =1), multi-parameter correction factor K=1 1 = 1. Therefore: Y = 30 1.0 = 122.44 kg.

[0073] The carbon fiber uniaxial precursor was weighed at 122kg for carbon fiber filament production, and the uniaxial yield of this batch was 89%.

[0074] Comparative Example 1 The only difference between this and Example 1 is that, based on the theoretical carbon yield of 0.50 for T800 grade -12K precursor carbonization, if the total weight of the target carbon fiber is 2kg × 30 spools = 60kg, the fixed weight of the carbon fiber monoaxial precursor should be 60kg ÷ 0.50 = 120kg according to the theoretical value. Therefore, the original preparation process set the fixed weight of the carbon fiber monoaxial precursor to 120kg, and the whole spool rate of this batch is 75%.

[0075] As can be seen from Example 1 and Comparative Example 1, Example 1 of this application can effectively improve the axial ratio in the mass production process by adjusting the weight of the carbon fiber uniaxial precursor yarn compared to Comparative Example 1.

[0076] The reason why Comparative Example 1 has the above-mentioned problems is that it does not take into account the slight fluctuations that may occur in the carbon yield in actual production, such as the actual carbon yield of 0.49 in Example 1, which is slightly lower than the theoretical value.

[0077] Example 2 When T700 grade -24K precursor yarn is carbonized, the calculated carbon yield A1 = 0.52 (theoretical value 0.50), and the unwinding tension fluctuation is 3.8 cN (standard ≤ 3 cN). The fixed weight of a single-axis carbon yarn is X = 6 kg, and the number of carbon yarns produced from a single-axis precursor yarn is N = 15. The unwinding stability parameter, tension fluctuation T = 3.8 cN (> 3 cN, therefore K...). T =0.96), the coefficient of variation of the linear density of the raw yarn σ=1.2% (≤1.5%, therefore K σ =1), multi-parameter correction factor K=0.96 1 = 0.96. Therefore: Y = 15 0.96 = 176.32 kg.

[0078] The raw yarn weight was adjusted to 176kg for carbon fiber production, and the spooling rate of this batch was 73%.

[0079] Comparative Example 2 The only difference between this and Example 2 is that the original preparation process set the raw yarn weight to 180 kg, and the skein rate of this batch was 65%.

[0080] The reason for setting the raw fiber weight to 180kg in the original preparation process is as follows: 1. Historical equipment operation data: carbon yield compensation: For T700 grade -24K raw fiber, historical data shows that the actual carbon yield sometimes exceeds the theoretical value (0.50) (such as the actual carbon yield reaching 0.52 in Example 2). In order to avoid the carbon fiber being overweight due to the high carbon yield (the upper limit of the single-axis carbon fiber weight is usually set at 6.2kg, and if it exceeds this, it is judged as an unqualified axis), the process personnel calculated based on the logic of "theoretical value back-calculation + upward compensation": the total weight of the target carbon fiber is 6kg × 15 axes = 90kg. Based on the theoretical carbon yield of 0.50, the raw fiber weight is calculated to be 90kg ÷ 0.50 = 180kg, thus reserving a buffer space for the carbon yield to rise. 2. Risk Mitigation in Large Tow Production: T700-24K raw yarns have a high K-number, and early processes had limited control over tension fluctuations during unwinding (historical data shows tension fluctuations often exceeded 4 cN). Process engineers empirically believed that "high-weight raw yarns can reduce peak tension during unwinding," thus favoring higher weight settings. Simultaneously, because the impact of the linear density variation coefficient (e.g., 1.2%) on the overall skein ratio of large tows was not quantified, the risk of "short skein due to insufficient weight" was reduced solely by increasing the raw yarn weight. 3. Empirical Threshold for Equipment Load: Traditional production equipment has empirical load thresholds for the raw yarn frame load-bearing and unwinding drive systems. Based on historical fault data (e.g., equipment jamming easily occurs when the weight exceeds 185 kg), process engineers set the upper limit for raw yarn weight at 180 kg to balance the needs of "sufficient yarn supply" and "stable equipment operation."

[0081] As can be seen from Example 2 and Comparative Example 2, Example 2 of this application can effectively improve the axial ratio in the mass production process by adjusting the weight of the carbon fiber uniaxial precursor yarn compared to Comparative Example 2.

[0082] In summary, the carbon fiber uniaxial precursor and the method for controlling the weight of carbon fiber uniaxial precursor provided in this application can effectively improve the axial ratio of carbon fiber filaments during mass production.

[0083] The above are merely specific embodiments of this application and are not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A carbon fiber uniaxial precursor, characterized in that, include: The carbon fiber uniaxial precursor satisfies the following formula: ; Wherein, Y is the weight of the carbon fiber uniaxial precursor, N is the number of carbon filaments produced from the carbon fiber uniaxial precursor, X is the weight of the carbon fiber uniaxial filament, A1 is the real-time carbon yield, and K is a multi-parameter correction factor, wherein the multi-parameter correction factor K is the unwinding tension fluctuation coefficient K. T and the coefficient of variation of the linear density of the raw silk K σ The product; Among them, the unwinding tension fluctuation coefficient K is used when the unwinding tension fluctuation T ≤ 3cN. T The value is 1.

0. When the unwinding tension fluctuation T is above 3 cN, K increases by 1 cN for every additional 1 cN. T Decrease by 0.05; When the coefficient of variation of the linear density of the raw yarn σ ≤ 1.5%, K σ =1.0, and for every 0.1% exceeding σ from 1.5%, K... σ Decrease by 0.

02.

2. The carbon fiber uniaxial precursor fiber according to claim 1, characterized in that, The unwinding tension fluctuation T is controlled within 0.1 cN - 10 cN.

3. The carbon fiber uniaxial precursor fiber according to claim 1, characterized in that, The value of K ranges from 0.9 to 1.

1.

4. The carbon fiber uniaxial precursor fiber according to claim 1, characterized in that, The methods for obtaining A1 include: A1 = Where Vz is the final carbon fiber filament driving linear velocity, Dz is the final carbon fiber filament linear density, Vc is the initial carbon fiber precursor feeding speed, and Dc is the initial carbon fiber precursor linear density.

5. The carbon fiber uniaxial precursor fiber according to claim 4, characterized in that, The method of obtaining A1 also includes: collecting the carbon yield corresponding to different precursor specifications and preparation parameters during the process of preparing carbon fiber filaments from carbon fiber precursors, and forming a carbon yield database. Obtain the specifications and preparation parameters of the precursor fiber used in the preparation of the carbon fiber uniaxial carbon filament, and obtain the carbon yield A2 from the carbon yield database; If A1≠A2, then adjust the Dc data to make A1=A2.

6. A method for controlling the weight of carbon fiber uniaxial precursor, characterized in that, include: According to the formula: The target weight of the carbon fiber uniaxial precursor was measured. Wherein, Y is the weight of the carbon fiber uniaxial precursor, N is the number of carbon filaments produced from the carbon fiber uniaxial precursor, X is the weight of the carbon fiber uniaxial filament, A1 is the real-time carbon yield, and K is a multi-parameter correction factor, wherein the multi-parameter correction factor K is the unwinding tension fluctuation coefficient K. T and the coefficient of variation of the linear density of the raw silk K σ The product of the two, with the unwinding tension fluctuation coefficient K when the unwinding tension fluctuation T≤3cN. T The value is 1.

0. When the unwinding tension fluctuation T is above 3 cN, K increases by 1 cN for every additional 1 cN. T Reduce by 0.05, so that the coefficient of variation of the linear density of the original yarn σ ≤ 1.5% when K σ =1.0, and for every 0.1% exceeding σ from 1.5%, K... σ Decrease by 0.02; Adjust the actual weight of the carbon fiber uniaxial precursor to the target weight.

7. The method for controlling the constant weight of carbon fiber uniaxial precursor fiber according to claim 6, characterized in that, The unwinding tension fluctuation T is controlled within 0.1 cN - 10 cN.

8. The method for controlling the constant weight of carbon fiber uniaxial precursor fiber according to claim 6, characterized in that, The value of K ranges from 0.9 to 1.

1.

9. The method for controlling the weight of carbon fiber uniaxial precursor fibers according to claim 6, characterized in that, A= Where Vz is the final carbon fiber filament driving linear velocity, Dz is the final carbon fiber filament linear density, Vc is the initial carbon fiber precursor feeding speed, and Dc is the initial carbon fiber precursor linear density.

10. The method for controlling the constant weight of carbon fiber uniaxial precursor fiber according to claim 6, characterized in that, The method for controlling the weight of carbon fiber uniaxial precursor yarn also includes: collecting the carbon yield corresponding to different precursor yarn specifications and preparation parameters during the process of preparing carbon fiber filaments from carbon fiber precursor yarns, and forming a carbon yield database. Obtain the specifications and preparation parameters of the precursor fiber used in the preparation of the carbon fiber uniaxial carbon filament, and obtain the carbon yield A2 from the carbon yield database; If A1≠A2, then adjust the Dc data to make A1=A2.

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