Wet measurement device and test method for broadening property of carbon fiber tow

Abstract

The invention discloses a wet measurement device and a test method for the broadening property of a carbon fiber tow, and relates to the technical field of carbon fibers. The system comprises a front image acquisition device, an ultrasonic device, a broadening device and a rear image acquisition device which are arranged in sequence, the ultrasonic device is arranged between the front image acquisition device and the broadening device, the ultrasonic device comprises an ultrasonic solution pool for accommodating an organic solvent, an ultrasonic generating device is arranged in the ultrasonic solution pool, and the ultrasonic generating device is used for enabling the organic solvent to oscillate; the conveying path of the carbon fiber tows passes through the area, containing the organic solvent, of the ultrasonic solution pool; the front image acquisition device acquires a picture of the carbon fiber tow before widening; and the rear image acquisition device acquires a picture after the carbon fiber tow is broadened. The sizing agent on the surface of the carbon fiber tow is dissolved through the organic solvent and the ultrasonic effect, and the broadening quality is improved; the front image acquisition device and the rear image acquisition device are used for shooting, so that the test efficiency and accuracy are improved.

Description

Technical Field

[0001] This invention relates to the field of carbon fiber technology, and in particular to a wet method for measuring and testing the stretchability of carbon fiber tows. Background Technology

[0002] Carbon fiber, with its superior properties such as high specific strength, high specific modulus, high temperature resistance, corrosion resistance, and fatigue resistance, has become an indispensable high-performance fiber reinforcement in modern aerospace, pressure vessels, and new energy fields. With the rapid growth of market demand, the refinement of its production process and the stability of subsequent processing have increasingly become the focus of industry attention.

[0003] In the secondary processing of carbon fibers (such as composite winding and layup), spreadability is one of the core process parameters that determines the quality of the final product. Spreadability refers to the width of the fiber bundle after the carbon fiber is spread under specific conditions. It reflects the distribution of fibers during use. If the spreadability is too small, poor wettability, low fiber strength conversion rate, and reduced structural efficiency may occur. If the spreadability is too large or the width is uneven, overlaps or gaps are easily formed in the prepreg, which seriously affects the areal density uniformity and appearance quality of the composite material.

[0004] However, the dry mechanical stretching techniques widely used in the industry today (such as stretching rollers based on low-frequency vibration) have significant limitations. These methods rely on macroscopic mechanical friction, which has a large force scale and is difficult to control precisely. This not only exacerbates fiber wear and fuzzing but also makes it difficult to overcome the adhesion effect caused by sizing agents on the carbon fiber surface, resulting in poor stretching uniformity and insufficient process stability. Furthermore, existing quality control methods mostly remain at the offline manual measurement stage, only sampling the static fiber bundle width. This is not only time-consuming and labor-intensive but also produces limited data, and the fact that only the stretched fiber bundle width is measured results in low reliability.

[0005] Therefore, how to provide a wet measurement device and testing method for carbon fiber tow spreadability, reduce the problems of fiber damage, high fuzz rate and poor spreadability caused by friction during the existing dry mechanical spreadability process, improve measurement efficiency and data measurement accuracy, and improve the reliability of test results are technical problems that urgently need to be solved by those skilled in the art. Summary of the Invention

[0006] The purpose of this invention is to address the deficiencies and shortcomings of existing technologies by providing a wet-method measurement device and method for carbon fiber tow broadening. This method dissolves the sizing agent on the surface of the carbon fiber tow through organic solvents and ultrasonic treatment, reducing the viscosity of the carbon fiber tow and accelerating its dispersion and broadening, thereby improving the broadening quality and efficiency. During the test, a large number of images of the carbon fiber tow before and after broadening are continuously captured by a pre-image acquisition device and a post-image acquisition device. After analysis and processing by the control module, the average width and broadening ratio of the carbon fiber tow before and after broadening are obtained, effectively improving testing efficiency and the accuracy of experimental results.

[0007] To achieve the above objectives, the technical solution adopted by the present invention is as follows: This invention provides a wet measurement device for the stretchability of carbon fiber tow, comprising a front image acquisition device, an ultrasonic device, a stretching device, and a rear image acquisition device arranged sequentially. The ultrasonic device is positioned between the front-end image acquisition device and the widening device. The ultrasonic device includes an ultrasonic solution pool for containing organic solvent. An ultrasonic generator is installed in the ultrasonic solution pool to cause the organic solvent to vibrate. The transport path of the carbon fiber bundle passes through the area of ​​the ultrasonic solution pool containing the organic solvent. The front image acquisition device acquires images of the carbon fiber bundle before it is stretched; the rear image acquisition device acquires images of the carbon fiber bundle after it is stretched.

[0008] In one embodiment, the ultrasonic generator includes at least two ultrasonic rollers, an ultrasonic support is provided in the ultrasonic solution pool, and the spacing between the ultrasonic rollers on the ultrasonic support is adjustable; the carbon fiber bundle enters the ultrasonic solution pool and is output towards the widening device around the ultrasonic rollers.

[0009] In one embodiment, the stretching device includes a plurality of first stretching rollers arranged in a row, a second stretching roller arranged in the direction in which the carbon fiber bundle is output from the first stretching rollers, and the rear image acquisition device is arranged at at least one of the second stretching rollers.

[0010] In one embodiment, the widening device further includes a perforated plate with a plurality of mounting holes, the number of mounting holes being greater than the number of the first widening rollers, and the first widening rollers being detachably connected to the mounting holes.

[0011] In one embodiment, a spraying device is provided at the first spreading roller.

[0012] In one embodiment, both the first stretching roller and the second stretching roller are provided with stretching grooves of different widths at intervals.

[0013] In one embodiment, the device further includes an unwinding device and a winding device; a tension controller is provided at the unwinding device.

[0014] In one embodiment, a guiding assembly is also included, the guiding assembly comprising a plurality of guide rollers for conveying carbon fiber bundles, and the front image acquisition device is disposed at at least one of the guide rollers.

[0015] In one embodiment, both the front image acquisition device and the rear image acquisition device include a second column, a camera, and a ring light. The camera is connected to the second column via a second adjustable connection device; the ring light is connected to the second column via a third adjustable connection device; the light-emitting end of the ring light and the camera-receiving end of the camera both face the carbon fiber bundle, and the ring light is located between the camera and the carbon fiber bundle.

[0016] This invention also provides a wet method for testing the stretchability of carbon fiber tow, applied to the aforementioned wet method for measuring the stretchability of carbon fiber tow, comprising the following: S1. Test of fiber bundle width before stretching: The carbon fiber bundle is conveyed through the ultrasonic generator and the stretching device in sequence; no organic solvent is added to the ultrasonic liquid pool, the ultrasonic generator is not started, and the carbon fiber bundle is wound at a constant speed at a preset winding speed; after the carbon fiber bundle runs stably, the front image acquisition device records the width of the carbon fiber bundle before stretching at a preset frequency. S2. Fiber bundle width test after stretching: After the fiber bundle width test before stretching, add organic solvent to the ultrasonic liquid pool, start the ultrasonic generator, and after the carbon fiber bundle runs stably, wind the carbon fiber bundle at a constant speed at a preset winding speed; after the carbon fiber bundle runs stably, the rear image acquisition device records the width of the carbon fiber bundle after stretching at a preset frequency. S3. Image Processing and Data Analysis: The control module analyzes and processes the images acquired by the front image acquisition device and the rear image acquisition device to obtain the average width of the carbon fiber bundle before and after widening, and calculates the carbon fiber bundle widening ratio.

[0017] The present invention achieves the following technical effects compared to the prior art: The organic solvent of this invention can dissolve or soften the sizing agent on the surface of carbon fiber tows, reducing the adhesion between carbon fiber tows. The ultrasonic generator installed in the ultrasonic solution tank can produce high-frequency vibrations, forming an ultrasonic field in the solvent, generating cavitation effects and mechanical vibrations, weakening the adhesion between carbon fiber tows, and promoting the dissolution of the sizing agent and the dispersion of the carbon fiber tows. By dissolving the sizing agent with the organic solvent combined with ultrasonic vibration, fiber dispersion and broadening can be accelerated, improving broadening efficiency and quality. The organic solvent and ultrasonic action dissolve the sizing agent on the surface of the carbon fiber tows, reducing the viscosity of the carbon fiber tows, accelerating the dispersion and broadening of the carbon fiber tows, and improving broadening quality and efficiency.

[0018] During the test, a large number of images of the carbon fiber bundles before and after widening are continuously captured by the front-end image acquisition device and the rear-end image acquisition device. The control module analyzes and processes the images acquired by the front-end image acquisition device and the rear-end image acquisition device to obtain the average width of the carbon fiber bundles before and after widening, and calculates the carbon fiber bundle widening ratio, which effectively improves the testing efficiency and the accuracy of the experimental results. Attached Figure Description

[0019] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0020] Figure 1 This is a schematic diagram of the structure of a wet method for measuring the spreadability of carbon fiber tow disclosed in a specific embodiment of the present invention; Figure 2 This is a schematic diagram of the structure of the guide roller disclosed in a specific embodiment of the present invention; Figure 3 This is a schematic diagram of the structure of the first widening roller (second widening roller) disclosed in a specific embodiment of the present invention; Figure 4 This is a schematic diagram of the structure of a front-view image acquisition device (rear-view image acquisition device) disclosed in a specific embodiment of the present invention; Figure 5 This is a schematic diagram of the structure of a spraying device disclosed in a specific embodiment of the present invention; Figure 6 This is a comparison image of carbon fiber tow before and after image processing, as disclosed in a specific embodiment of the present invention. Figure 7 This is a scatter plot (ad) of the width of a certain carbon fiber bundle before and after widening under different tensions in a specific embodiment of the present invention. Figure 8This is a scatter plot (eh) of the width of a certain carbon fiber bundle before and after widening under different tensions, as disclosed in a specific embodiment of the present invention. Figure 9 This is a graph showing the stretching results of a certain carbon fiber tow under different stretching rates at a stretching tension of 0.06 cN / dtex, as disclosed in a specific embodiment of the present invention. The components include: 1. Unwinding device; 2. Guide roller; 3. Front image acquisition device; 4. First widening roller; 5. Second widening roller; 6. Rear image acquisition device; 7. Rewinding device; 8. Widening groove; 9. Perforated plate; 10. Mounting hole; 11. Spraying device; 12. First column; 13. Spray head; 14. First adjustable connection device; 15. Ultrasonic solution tank; 16. Liquid inlet; 17. Liquid outlet; 18. Ultrasonic support; 19. Ultrasonic roller; 20. Tension controller; 21. Second column; 22. Camera; 23. Second adjustable connection device; 24. Ring light; 25. Third adjustable connection device; 26. Control module. Detailed Implementation

[0021] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0022] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0023] like Figure 1-9 As shown, this invention provides a wet method for measuring the stretchability of carbon fiber tow, comprising a pre-image acquisition device 3, an ultrasonic device, a stretching device, and a post-image acquisition device 6 arranged sequentially. The ultrasonic device is positioned between the pre-image acquisition device 3 and the stretching device, and includes an ultrasonic solution pool 15 for containing organic solvent. An ultrasonic generator is installed within the ultrasonic solution pool 15 to cause the organic solvent to vibrate. The transport path of the carbon fiber tow passes through the area of ​​the ultrasonic solution pool 15 containing the organic solvent. The pre-image acquisition device 3 acquires an image of the carbon fiber tow before stretching, and the post-image acquisition device 6 acquires an image of the carbon fiber tow after stretching.

[0024] Understandably, while the sizing agent coating the surface of carbon fiber tows is beneficial for fiber protection and subsequent processing, it significantly increases the adhesion between fibers during the broadening process, hindering the uniform unfolding of the tows. Organic solvents can dissolve or soften the sizing agent on the surface of the carbon fiber tows, reducing the adhesion between the carbon fiber tows. Organic solvents include, but are not limited to, acetone, ethanol, and dimethylformamide. The ultrasonic generator installed in the ultrasonic solution tank 15 can produce high-frequency vibrations, forming an ultrasonic field in the solvent, generating cavitation effects and mechanical vibrations, weakening the adhesion between the carbon fiber tows, and promoting the dissolution of the sizing agent and the dispersion of the carbon fiber tows. By dissolving the sizing agent with organic solvents combined with ultrasonic vibration, fiber dispersion and broadening can be accelerated, improving broadening efficiency and quality.

[0025] The front image acquisition device 3 acquires images of the carbon fiber bundle before it is broadened; the rear image acquisition device 6 acquires images of the carbon fiber bundle after it is broadened; the control module 26 analyzes and processes the images acquired by the front image acquisition device 3 and the rear image acquisition device 6 to obtain the average width of the carbon fiber bundle before and after it is broadened, and calculates the carbon fiber bundle broadening ratio.

[0026] The ultrasonic solution tank 15 may be provided with an inlet 16 and an outlet 17. Organic solution is injected from the inlet 16 or from the opening of the ultrasonic solution tank 15, and organic solution flows out from the outlet 17 or is extracted from the opening of the ultrasonic solution tank 15.

[0027] The ultrasonic solution tank 15 can also be equipped with an inlet 16 and an outlet 17, which are connected by a solution circulation device. The solution circulation device connects the inlet 16 and the outlet 17 to form a closed solution circulation loop, achieving the filtration of impurities such as fibers and lint. Specifically, the solution circulation device includes a circulation pump, a filtration system, and a piping system. The circulation pump provides the power for the organic solvent circulation, driving the organic solvent to flow out of the outlet 17, pass through the filtration system, and return to the inlet 17. The filtration system includes a cartridge filter, a gravity-flow filter array, or a membrane filter, etc., to filter impurities such as fibers and lint from the organic solvent. The piping system connects the various components, forming a closed loop. The solution circulation device can also be equipped with a heating / cooling device and a solvent recovery and renewal unit as needed to achieve temperature regulation and online renewal of the organic solvent. The heating / cooling device maintains a constant temperature within the tank by heating or cooling the organic solvent; the solvent recovery and renewal unit achieves online renewal of the organic solvent by recovering or adding / replenishing it with new organic solvent.

[0028] In one embodiment, the ultrasonic generator includes at least two ultrasonic rollers 19. A carbon fiber bundle travels around the surface of the ultrasonic rollers 19, and the ultrasonic rollers 19 apply ultrasonic vibrations to the bundle while transporting it, thus broadening and dispersing the carbon fiber bundle. An ultrasonic support 18 is provided within the ultrasonic solution pool 15, and the spacing between the ultrasonic rollers 19 on the ultrasonic support 18 is adjustable. The carbon fiber bundle enters the ultrasonic solution pool 15 and is output towards the broadening device after passing around the ultrasonic rollers 19.

[0029] Understandably, taking the ultrasonic solution tank 15 with two ultrasonic rollers 19 as an example, one ultrasonic roller 19 guides the carbon fiber bundle below the surface of the organic solvent, while the other ultrasonic roller 19 guides the carbon fiber bundle away from the surface of the organic solvent, allowing the sizing agent on the carbon fiber bundle to be dissolved in the organic solvent. The distance between the two ultrasonic rollers 19 can be adjusted as needed to change the immersion length and immersion time of the carbon fiber bundle in the ultrasonic solution tank 15, so as to perform different degrees of desizing treatment on carbon fiber bundles of different specifications and with different sizing agents. For example, when the sizing agent content is low and easily dissolved, the distance between the two ultrasonic rollers 19 can be widened to reduce the mechanical effect of the ultrasonic rollers 19 vibration and reduce the risk of fiber damage; when the carbon fiber bundle is thicker, the distance between the two ultrasonic rollers 19 can be widened to reduce bending stress and avoid excessive bending that could lead to breakage of the carbon fiber bundle.

[0030] The spacing adjustment methods for the ultrasonic rollers 19 include, but are not limited to, manual adjustment and electric adjustment. In manual adjustment, the ultrasonic support 18 has multiple spaced adjustment holes, and the ultrasonic rollers 19 are detachably connected to these holes. The ultrasonic support 18 also has a guide rail mechanism and a slider that slides on the guide rail mechanism. The ultrasonic rollers 19 are fixed to the slider. The drive mechanism includes a nut seat and a screw. The nut seat is fixed to the slider and moves with it. The screw is fixed to the guide rail mechanism, forming a threaded transmission pair with the nut seat. Rotating the screw converts its rotational motion into linear movement of the slider. Adjusting the distance between the two sliders by rotating the screw adjusts the distance between the two ultrasonic rollers 19. In electric adjustment, the ultrasonic support 18 has a guide rail mechanism and a slider that slides on the guide rail mechanism. The ultrasonic rollers 19 are fixed to the slider. The drive mechanism includes a servo motor or a stepper motor. The rotational motion of the motor converts its rotational motion into linear movement of the slider. Adjusting the distance between the two sliders by controlling the servo motor or stepper motor adjusts the distance between the two ultrasonic rollers 19.

[0031] It should be noted that the ultrasonic roller 19 is a deformable structure of an ultrasonic generator and has the function of an ultrasonic generator. The roller body material of the ultrasonic roller 19 can be stainless steel, titanium alloy, or ceramic, etc., which has corrosion resistance and good ultrasonic wave conduction performance. The device structure used for adjusting the spacing of the ultrasonic roller 19 is waterproof.

[0032] In one embodiment, the stretching device includes a plurality of first stretching rollers 4 arranged in a row, a second stretching roller 5 arranged in the direction in which the carbon fiber bundle is output from the first stretching rollers 4, and a rear image acquisition device 6 arranged at at least one second stretching roller 5.

[0033] Understandably, the multiple first widening rollers 4 are positioned differently, and the carbon fiber bundles repeatedly pass around these different roller positions, with repeated bending stress promoting thorough fiber dispersion. Simultaneously, the multiple first widening rollers 4 widen the carbon fiber bundles multiple times, improving widening performance. The second widening roller 4 is fixed in position, facilitating the fixation of the rear image acquisition device 6.

[0034] In one embodiment, the widening device further includes a perforated plate 9, which has a plurality of mounting holes 10. The number of mounting holes 10 is greater than the number of the first widening rollers 4. The first widening rollers 4 are detachably connected to the mounting holes 10.

[0035] Understandably, the first spreading roller 4 can be adjusted on the perforated plate 9 as needed to change the wrap angle between the carbon fiber tow and the first spreading roller 4 (here referring to the central angle corresponding to the contact arc between the carbon fiber tow and the spreading roller), thereby adjusting the degree of bending and bending stress of the carbon fiber tow. By adjusting the wrap angle, the mechanical spreading strength of the first spreading roller 4 can be controlled to meet the spreading requirements of carbon fiber tows of different specifications. Different wrap angles can be set for different roller positions to adapt to different spreading stages and improve spreading uniformity.

[0036] In one embodiment, a spraying device 11 is provided at the first widening roller 4.

[0037] It is understandable that the spraying device 11 is used to spray organic solvents (including but not limited to acetone, ethanol, dimethylformamide, etc., the specific types of organic solvents are consistent with the types of organic solvents contained in the ultrasonic solution pool 15) onto the carbon fiber bundle, so that the carbon fiber bundle remains wet in the entire spreading roller area, avoiding the generation of static electricity or fuzz that may affect the test results, and preventing the sizing agent from redepositing due to drying, thus affecting the spreading effect.

[0038] Specifically, the spray device 11 includes a first column 12, a spray head 13, and a solvent supply device communicating with the spray head 13. The solvent supply device is used to provide the spray head 13 with a continuous, stable, clean, and pressure-controllable organic solvent. The spray head 13 is connected to the first column 12 via a first adjustable connection device 14, which can adjust the height of the spray head 13 on the first column 12.

[0039] In one embodiment, the first widening roller 4 and the second widening roller 5 are each provided with widening grooves 8 of different widths at intervals.

[0040] It is understandable that the widening grooves 8 of different widths are used to widen carbon fiber bundles of different specifications, and the widening grooves 8 can stabilize the carbon fiber bundles, making it easier for the rear image acquisition device 6 to take pictures.

[0041] In one embodiment, it further includes an unwinding device 1 and a winding device 7; a tension controller 20 is provided at the unwinding device 1.

[0042] Understandably, the tension controller 20 precisely controls the tension of the carbon fiber tow throughout the entire process, preventing tension instability from affecting the widening of the carbon fiber tow. Tension detectors for detecting tension can be installed at the guide roller 2, the first widening roller 4, the second widening roller 5, and the winding device 7.

[0043] In one embodiment, a guiding assembly is also included, comprising a plurality of guide rollers 2 for conveying carbon fiber bundles, and a front image acquisition device 3 is provided at at least one guide roller 2.

[0044] Understandably, tension fluctuations occur during the unwinding process of the unwinding module. Multiple guide rollers 2 allow the tension of the carbon fiber tow to gradually stabilize and become controllable during transport, providing a foundation for subsequent widening. In addition, the guide rollers 2 can also assist in the initial dispersion of the carbon fiber tow.

[0045] In one embodiment, both the front image acquisition device 3 and the rear image acquisition device 6 include a second column 21, a camera 22, and a ring light 24. The camera 22 is connected to the second column 21 via a second adjustable connection device 23; the ring light 24 is connected to the second column 21 via a third adjustable connection device 25; the light-emitting end of the ring light 24 and the imaging end of the camera 22 both face the carbon fiber bundle, and the ring light 24 is located between the camera 22 and the carbon fiber bundle.

[0046] Understandably, the second adjustable connecting device 23 can adjust the height of the camera 22 on the second column 21; the third adjustable connecting device 25 can adjust the height of the ring light 24 on the second column 21. The distance between the ring light 24 and the camera 22 can be adjusted through the second adjustable connecting device 23 and the third adjustable connecting device 25. The ring light 24 is located between the camera 22 and the carbon fiber bundle, and the camera end of the camera 22 can pass through the hollow area in the middle of the ring light 24 to collect images of the carbon fiber bundle.

[0047] Specifically, camera 22 can be a 50mm focal length area array camera 22, which can reduce the error caused by lens shake and lens distortion, capture the instantaneous image of the object more accurately, reduce image distortion, and make the measurement of the filament width more accurate and stable.

[0048] This invention also provides a wet method for testing the stretchability of carbon fiber tow, applied to a wet method measuring device for carbon fiber tow stretchability, comprising the following: S1. Test of fiber bundle width before stretching: The carbon fiber bundle is conveyed through the ultrasonic generator and the stretching device in sequence; no organic solvent is added to the ultrasonic solution pool 15, the ultrasonic generator is not started, and the carbon fiber bundle is wound at a constant speed at a preset winding speed; after the carbon fiber bundle runs stably, the front image acquisition device 3 records the width of the carbon fiber bundle before stretching at a preset frequency. S2. Fiber bundle width test after stretching: After the fiber bundle width test before stretching, add organic solvent to the ultrasonic solution pool 15, start the ultrasonic generator, and after the carbon fiber bundle runs stably, wind the carbon fiber bundle at a constant speed at a preset winding speed; after the carbon fiber bundle runs stably, the rear image acquisition device 6 records the width of the carbon fiber bundle after stretching at a preset frequency. S3. Image Processing and Data Analysis: The control module 26 analyzes and processes the images acquired by the front image acquisition device 3 and the rear image acquisition device 6 to obtain the average width of the carbon fiber bundle before and after widening, and calculates the carbon fiber bundle widening ratio.

[0049] Detailed steps of a wet method for testing the stretchability of carbon fiber tow: S1. Test the width of the tow before stretching: The carbon fiber tow is sequentially conveyed through the unwinding device 1, the guiding component, the ultrasonic generator, and the stretching device, and fixed on the winding device 7; no organic solvent is added to the ultrasonic solution pool 15, the ultrasonic generator is not activated, and the carbon fiber tow is wound at a constant speed at a preset winding speed; after the carbon fiber tow runs stably, the front-end image acquisition device 3 records the width of the carbon fiber tow before stretching at a preset frequency; the preset winding speed is 1.8 m / min, and the preset frequency is to record once every 10 cm of carbon fiber tow travels, for a total of 150 records.

[0050] It should be noted that before the carbon fiber tow is transported, no tension should be applied and the carbon fiber tow should not come into contact with any rollers to avoid damaging the carbon fiber tow. Also, care should be taken to avoid the carbon fiber tow from turning over or twisting.

[0051] S2. Fiber bundle width test after stretching: After the fiber bundle width test before stretching, organic solvent is added to the ultrasonic solution pool 15, and the ultrasonic generator and spray device 11 are started. After the carbon fiber bundle runs stably, the carbon fiber bundle is wound at a constant speed at a preset winding speed. After the carbon fiber bundle runs stably, the rear image acquisition device 6 records the width of the stretched carbon fiber bundle at a preset frequency. The preset winding speed is 1.8 m / min, and the preset frequency is to record once every 10 cm of carbon fiber bundle movement, for a total of 150 records.

[0052] It should be noted that before the carbon fiber tow is transported, the distance between the ultrasonic rollers 19 is adjusted according to the carbon fiber tows of different specifications and different sizing agents, and a suitable organic solvent solution, acetone solution, is added to the ultrasonic solution pool 15; a suitable tension is applied at the unwinding device 1, and a suitable spreading rate is set.

[0053] S3. Image Processing and Data Analysis: The control module 26 analyzes and processes the images acquired by the front image acquisition device 3 and the rear image acquisition device 6 to obtain the average width of the carbon fiber bundle before and after widening, and calculates the carbon fiber bundle widening ratio.

[0054] The control module 26 analyzes and processes the image using an automated image processing workflow, including image reading, preprocessing, binarization, noise filtering, and width calculation. The specific processing methods are as follows: a. Image reading: The control module 26 reads the images acquired by the front image acquisition device 3 and the rear image acquisition device 6.

[0055] b. Preprocessing: The control module 26 crops and rotates the read image according to the preset parameters, removes most of the invalid information other than the carbon fiber bundles, and ensures that the movement direction of the fiber bundles is as parallel as possible to the edge of the image width direction. On this basis, the brightness and contrast of the image are adjusted so that the fiber bundles and the background area in the image can be clearly distinguished.

[0056] c. Image binarization: The preprocessed image is converted into a binary image, i.e., an 8-bit monochrome image with a brightness value of 0 in the fiber bundle region and a brightness value of 255 in the background region.

[0057] d. Noise Filtering: A custom function is used to filter noise in the image, removing noise points with a width or area smaller than a set threshold, while retaining fiber regions. Then, connected component analysis is performed to extract regions that may represent fibers.

[0058] e. Width Calculation: In the image, calculate the area of ​​the region that may represent the fiber, and simultaneously extract the image width. The width of the fiber bundle is the ratio of the number of pixels representing the area to the number of pixels representing the image width, expressed in pixels. Then, based on the device calibration results, i.e., the actual length corresponding to each pixel in the image, the actual width of the fiber bundle can be obtained.

[0059] Image reference for image analysis and processing Figure 6 , Figure 6 In the image, (a) shows the carbon fiber bundle before image processing, and (b) shows the carbon fiber bundle after image processing.

[0060] Obtain the average width of the carbon fiber bundle before and after widening, and calculate the widening ratio of the carbon fiber bundle, including: the bundle width before widening, denoted as Mi (i=1, 2, ..., 150), accurate to 0.01mm. The bundle width after widening, denoted as Ni (i=1, 2, ..., 150), accurate to 0.01mm.

[0061] The carbon fiber tow width ratio w is calculated using the following formula: In the formula: w—the aspect ratio of carbon fiber tow; Mi – Initial width of carbon fiber bundle, in millimeters (mm); Ni – the width of the carbon fiber bundle, measured in millimeters (mm).

[0062] It should be noted that this specific embodiment only sets up one front image acquisition device 3 and one rear image acquisition device 6 for image acquisition. To improve the accuracy of the acquired data, two or more front image acquisition devices 3 and rear image acquisition devices 6 can be set up.

[0063] It should be noted that the average width of the obtained carbon fiber tow before and after broadening, and the carbon fiber tow broadening ratio are referenced. Figure 7-9 , Figure 7 (a) Initial width at a stretching rate of 0.9 m / min under different tension conditions, (b) Stretch width at a stretching rate of 0.9 m / min under different tension conditions, (c) Initial width at a stretching rate of 1.8 m / min under different tension conditions, (d) Stretch width at a stretching rate of 1.8 m / min under different tension conditions. Figure 8 (e) Initial width at a stretching rate of 2.7 m / min under different tension conditions; (f) Stretch width at a stretching rate of 2.7 m / min under different tension conditions; (g) Initial width at a stretching rate of 3.6 m / min under different tension conditions; (h) Stretch width at a stretching rate of 3.6 m / min under different tension conditions; The discrete line segments from top to bottom in Figure ah represent stretching tensions of 0.04 cN / dtex, 0.06 cN / dtex, and 0.08 cN / dtex, respectively. Figure 9 (a) is a scatter plot of the expanded width, and (b) is a plot of the width and the expanded width ratio.

[0064] The unwinding device 1, guide roller 2, front image acquisition device 3, first widening roller 4, second widening roller 5, rear image acquisition device 6, winding device 7, spraying device 11, ultrasonic solution pool 15, ultrasonic generator, ultrasonic roller 19, tension controller 20, solution circulation device, tension detector, etc. involved in the above embodiments are products and electrical components using existing technology. The electrical connection and control methods between them and the control module 26 are all existing technologies and will not be described in detail.

[0065] It should be noted that, for those skilled in the art, it is obvious that the present invention is not limited to the details of the above exemplary embodiments, and that the present invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments should be considered exemplary and non-limiting in all respects, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the present invention, and no reference numerals in the claims should be construed as limiting the scope of the claims.

Claims

1. A wet method for measuring the stretchability of carbon fiber tow, characterized in that, It includes a front image acquisition device, an ultrasonic device, a widening device, and a rear image acquisition device arranged in sequence. The ultrasonic device is positioned between the front-end image acquisition device and the widening device. The ultrasonic device includes an ultrasonic solution pool for containing organic solvent. An ultrasonic generator is installed in the ultrasonic solution pool to cause the organic solvent to vibrate. The transport path of the carbon fiber bundle passes through the area of ​​the ultrasonic solution pool containing the organic solvent. The front image acquisition device acquires images of the carbon fiber bundle before it is stretched; the rear image acquisition device acquires images of the carbon fiber bundle after it is stretched.

2. The wet method measuring device for carbon fiber tow stretching according to claim 1, characterized in that, The ultrasonic generator includes at least two ultrasonic rollers, and an ultrasonic support is provided in the ultrasonic solution pool. The spacing between the ultrasonic rollers on the ultrasonic support is adjustable. The carbon fiber bundle enters the ultrasonic solution pool and is output towards the widening device around the ultrasonic rollers.

3. The wet method measuring device for carbon fiber tow stretching according to claim 1, characterized in that, The stretching device includes a plurality of first stretching rollers arranged in a row, a second stretching roller arranged in the direction in which the carbon fiber bundle is output from the first stretching rollers, and the rear image acquisition device is arranged at at least one of the second stretching rollers.

4. The wet method measuring device for carbon fiber tow stretching according to claim 3, characterized in that, The widening device also includes a perforated plate with a plurality of mounting holes, the number of which is greater than the number of the first widening rollers, and the first widening rollers are detachably connected to the mounting holes.

5. The wet method measuring device for carbon fiber tow stretching according to claim 3, characterized in that, A spraying device is installed at the first widening roller.

6. The wet method for measuring the stretchability of carbon fiber tow according to claim 3, characterized in that, Both the first and second widening rollers are provided with widening grooves of different widths at intervals.

7. The wet method measuring device for carbon fiber tow stretching according to claim 1, characterized in that, It also includes an unwinding device and a winding device; a tension controller is provided at the unwinding device.

8. The wet method measuring device for carbon fiber tow stretching according to claim 1, characterized in that, It also includes a guiding assembly comprising a plurality of guide rollers for conveying carbon fiber bundles, and the front image acquisition device is disposed at at least one of the guide rollers.

9. The wet method measuring device for carbon fiber tow stretching according to claim 1, characterized in that, Both the front-view image acquisition device and the rear-view image acquisition device include a second column, a camera, and a ring light. The camera is connected to the second column via a second adjustable connection device. The ring light is connected to the second column via a third adjustable connection device. The light-emitting end of the ring light and the camera-emitting end of the camera both face the carbon fiber bundle. The ring light is located between the camera and the carbon fiber bundle.

10. A wet method for testing the stretchability of carbon fiber tow, characterized in that, The wet-method measuring device for the stretchability of carbon fiber tows as described in claims 1-9 includes the following: S1. Test of fiber bundle width before stretching: The carbon fiber bundle is conveyed through the ultrasonic generator and the stretching device in sequence; no organic solvent is added to the ultrasonic liquid pool, the ultrasonic generator is not started, and the carbon fiber bundle is wound at a constant speed at a preset winding speed; after the carbon fiber bundle runs stably, the front image acquisition device records the width of the carbon fiber bundle before stretching at a preset frequency. S2. Fiber bundle width test after stretching: After the fiber bundle width test before stretching, add organic solvent to the ultrasonic liquid pool, start the ultrasonic generator, and after the carbon fiber bundle runs stably, wind the carbon fiber bundle at a constant speed at a preset winding speed; after the carbon fiber bundle runs stably, the rear image acquisition device records the width of the carbon fiber bundle after stretching at a preset frequency. S3. Image Processing and Data Analysis: The control module analyzes and processes the images acquired by the front image acquisition device and the rear image acquisition device to obtain the average width of the carbon fiber bundle before and after widening, and calculates the carbon fiber bundle widening ratio.

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