Carbon fiber joint detection device and method suitable for warp knitting

Abstract

The invention belongs to the technical field of carbon fiber joint detection, and relates to a carbon fiber joint detection device and method suitable for warp knitting, a carbon fiber yarn production line comprises a plurality of second fixed wheels used for conveying carbon fiber yarns, and the carbon fiber joint detection device comprises a fixed seat, a connecting rod, a reset mechanism, a first fixed wheel and an angle sensor; the detection method comprises the steps that firstly, the detection device is installed on a rack on a carbon fiber yarn production line, the first fixed wheel is set at the initial position of one side of the second fixed wheel through the reset mechanism, and the initial reading theta 0 of the angle sensor is recorded; then the carbon fiber yarn is controlled to start advancing, and the real-time reading theta1 of the angle sensor is recorded; and finally, calculating a real-time change angle delta theta = theta 1-theta 0 of the angle sensor, and when delta theta is greater than or equal to theta c, detecting the carbon fiber joint. According to the detection device, yarn replacement or maintenance is facilitated, and the operation convenience and production efficiency of the detection device are improved; the detection method has high detection accuracy.

Description

Technical Field

[0001] The invention belongs to the technical field of carbon fiber joint detection, and relates to a device and method for detecting warp-woven carbon fiber joints. Background Art

[0002] Carbon fiber composites, due to their high strength and lightweight properties, are widely used in aerospace, automotive, and other fields. During the carbon fiber yarn production process, yarn splices—the connection points between two yarn segments formed by gluing or hot pressing—can affect the quality of subsequent warp knitting and the performance of the finished product. Therefore, yarn splices must be accurately detected and eliminated.

[0003] In the existing technology, common detection methods include optical detection, mechanical detection and manual observation; mechanical detection relies only on a single mechanical displacement, which makes it difficult to detect tiny joints or high-speed yarns. It has a simple structure but low accuracy; optical detection uses a camera or infrared sensor to capture images of the yarn surface and analyze the color, thickness or transmittance differences at the joints. Although it has high accuracy, it is costly and environmentally sensitive.

[0004] For example, patent CN119090856A uses images of carbon fiber tows to analyze connected areas in the images to determine joint defects. However, this detection method is costly and sensitive to the environment, and fluctuations during operation will interfere with inaccurate test results.

[0005] Therefore, it is of great significance to study a device and method for detecting carbon fiber joints suitable for warp knitting to solve the problems existing in the prior art. Summary of the Invention

[0006] The purpose of the present invention is to solve the problems existing in the prior art and to provide a device and method for detecting warp-woven carbon fiber joints.

[0007] In order to achieve the above object, the technical solution adopted by the present invention is as follows:

[0008] A carbon fiber joint detection device suitable for warp knitting, wherein the carbon fiber yarn production line includes a plurality of second fixed wheels for conveying carbon fiber yarns, and the carbon fiber joint detection device suitable for warp knitting includes a fixing seat, a connecting rod, a reset mechanism, a first fixed wheel and an angle sensor;

[0009] The fixing seat is arranged on a frame of a carbon fiber yarn production line, and one end of the connecting rod is rotatably connected to the fixing seat, with a rotation range from one side close to the second fixed wheel to the other side close to the second fixed wheel (the second fixed wheel close to one end of the connecting rod and the other end of the connecting rod are the same); the other end of the connecting rod is fixedly connected to the first fixed wheel;

[0010] One end of the reset mechanism is fixedly connected to the fixing seat, and the other end is fixedly connected to the connecting rod; the reset mechanism can adopt a pneumatic or hydraulic system to achieve a timely reset function, or can adopt a spring or electric drive system to control the reset of the first fixed wheel;

[0011] The angle sensor is coaxially arranged on the first fixed wheel.

[0012] As the preferred technical solution:

[0013] In the above-mentioned device for detecting warp-woven carbon fiber joints, a positioning block is provided on the fixing seat, and the positioning block is located between the rotating end of the connecting rod and the second fixed wheel;

[0014] The first fixed wheel has a rotation range from one side of the connecting rod contacting the positioning block to the other side of the connecting rod contacting the positioning block.

[0015] Preferably, the positioning block is designed not to contact the connecting rod during the rotation of the connecting rod, so as to avoid the connecting rod being unable to rotate due to the abutment of the positioning block; the positioning block can limit the rotation range of the connecting rod, and prevent the connecting rod from rotating too much and causing damage to the detection device when the first fixed wheel needs to be moved away from the second fixed wheel and the connecting rod needs to be rotated; and when the first fixed wheel needs to be close to the second fixed wheel, the reset mechanism can keep the distance between the first fixed wheel and the second fixed wheel stable, preventing the yarn joint from being missed due to the large spacing, and effectively improving the detection accuracy; it also avoids the first fixed wheel directly hitting the second fixed wheel, affecting the progress of the carbon fiber yarn on the production line.

[0016] As described above, a carbon fiber joint detection device suitable for warp knitting is provided with a plurality of positioning holes on the fixing seat, and the positioning block is fixed to the fixing seat through one of the positioning holes; such a design can fine-tune the positioning block, change the relative position between the positioning block and the connecting rod, and allow the operator to flexibly adjust the position of the positioning block according to the thickness of the carbon fiber yarn or the detection requirements; because the position of the positioning block is different, the position of the connecting rod when it is against the positioning block is also different, which will change the spacing between the first fixed wheel at one end of the connecting rod and the second fixed wheel, thereby improving the versatility and adaptability of the detection device, and being suitable for carbon fiber yarns of different specifications.

[0017] As described above, a detection device for warp-woven carbon fiber joints is suitable for use with a buffer pad, wherein the surface of the positioning block is provided with a buffer pad, which is used to reduce the impact force generated by the connecting rod colliding with the positioning block during repeated resetting, thereby reducing noise and mechanical wear, extending the service life of the device, and improving stability during the detection process.

[0018] As described above, a carbon fiber joint detection device suitable for warp weaving, the reset mechanism includes a spring, one end of the spring is fixedly connected to the fixing seat, and the other end is fixedly connected to the connecting rod; the spring is used to control the distance between the first fixed wheel and the second fixed wheel; the spring is designed to be in a stretched state, and the spring will provide an elastic reset force, pulling the connecting rod so that the first fixed wheel moves toward the direction close to the second fixed wheel, cooperating with the restriction of the positioning block, thereby controlling the distance between the first fixed wheel and the second fixed wheel.

[0019] The above-described device is applicable to a warp-woven carbon fiber joint detection device, wherein the reset mechanism further includes a guide rod fixed to the interior of the spring along the length of the spring. When the spring is compressed or stretched due to the rotation of the connecting rod, lateral bending may occur, causing the spring to become unstable or even stuck or damaged. The guide rod can limit the lateral movement of the spring, ensuring that the spring always moves axially, preventing the spring from frequently bending laterally and affecting the detection results, thereby improving the stability of the spring and ensuring the reliability of the detection results. It also reduces the lateral stress of the spring, making the force more even and extending the service life.

[0020] The present invention also provides a method for detecting warp-woven carbon fiber joints, using a device for detecting warp-woven carbon fiber joints as described above, such as Figure 4 As shown, the detection method includes the following steps:

[0021] S1: Install the detection device on a frame of a carbon fiber yarn production line, set the first fixed wheel to an initial position on one side of the second fixed wheel through the reset mechanism, control the minimum distance between the first fixed wheel and the second fixed wheel to be between 0.5 and 1 mm, and record the initial reading θ0 of the angle sensor coaxial with the first fixed wheel;

[0022] S2: Control the carbon fiber yarn to start moving and record the real-time reading θ1 of the angle sensor;

[0023] S3: Calculating the real-time change angle Δθ of the angle sensor = |θ1-θ0|. When Δθ≥θc, it is detected as a carbon fiber joint and a detection result is generated.

[0024] Among them, θc is an artificially set angle threshold and is a constant.

[0025] By calculating the angle change of the angle sensor, the impact of abnormalities on the carbon fiber yarn on the first fixed wheel can be identified. Since the thickness of the joint is thicker than the thickness of the yarn when the filaments are not completely wrapped, or when the yarn is twisted (yarn twisting means that during the spinning process, one end is fixed and the other end rotates, so that the yarn formed will be thicker than the normal yarn thickness), the extra thickness brought by the joint is converted into a change in the angle sensor, the physical quantity detected is converted, and then compared with the set angle threshold, so as to achieve the effect of quickly judging the joint in the yarn production line; the test results are then generated and output to the operator, and the joint can be cut in time according to the test results to prepare for subsequent production.

[0026] As described above, a method for detecting carbon fiber joints suitable for warp knitting, step S2 also includes: installing a pressure sensor at a preset position on the first fixed wheel, for real-time detection of the pressure P1 when the yarn travels; effectively improving the comprehensiveness and multidimensionality of the detection data, and can better distinguish between joints and other interference items such as hair entanglement; the preset position is directly below the first fixed wheel when the spring is not deformed.

[0027] As the preferred technical solution:

[0028] The above-mentioned method for detecting warp-woven carbon fiber joints further includes step S4: calculating the real-time pressure change Pc=|P1-P0| monitored by the pressure sensor. This formula calculates the instantaneous pressure change. If there is a joint on the yarn or the yarn undergoes an abnormal change, it will cause a local pressure change, which is used to assist in determining whether there is a joint, and then calculate C=Pc / Δθ;

[0029] When C0≤C≤2C0, it is detected as a carbon fiber joint, and the detection result in step S3 is updated and output (that is, the carbon fiber joint detected in this step is output together with the carbon fiber joint detected in step S3 as the final detection result);

[0030] Among them, P0 is the initial reading of the pressure sensor; C is the real-time correlation coefficient between pressure and angle; C0 is the manually set initial correlation coefficient between pressure and angle, which is a constant.

[0031] If the ratio of the changing pressure Pc to the changing angle Δθ is large, this means that the pressure at the detected location has increased suddenly. This may be due to hair entanglement on the yarn surface, uneven twisting, etc., or it may be due to equipment vibration or yarn shaking, which causes increased pressure fluctuations but no obvious angle change. Therefore, it can be judged that the larger the real-time correlation coefficient C is, the more likely it is that interference or anomaly is detected, rather than a joint.

[0032] When the ratio is smaller, it means that at the same change angle Δθ, the change pressure Pc is smaller. This may be because the yarn moves smoothly, the pressure and angle changes are small, and the change trends are consistent. It may also be that the thickness of the hair winding at this time changes little and has not yet been superimposed to a very thick degree, resulting in smaller angle changes Δθ and pressure changes Pc, and the ratio C is still close to the normal range. Therefore, it can be judged that the smaller the real-time correlation coefficient C is, the more likely it is that normal yarn or tiny hair is detected.

[0033] When connecting two carbon fiber strands (such as PAN-based precursors), the two ends usually need to be overlapped to ensure strength. This overlap will increase the fiber density in local areas, forming a significant thickness mutation. If adhesives or hot-melt materials are used to assist in the connection, the extra material will accumulate at the joint. It can be seen that the essence of the joint is the change in thickness, and the change in thickness will cause changes in angle and pressure at the same time, and the two are linearly related. Therefore, regardless of the size of the joint, the ratio C will tend to be balanced; so we compare the real-time correlation coefficient C with the set range to determine whether there is a real joint on the yarn, effectively improving the detection accuracy and reliability.

[0034] The above-mentioned method for detecting carbon fiber joints suitable for warp knitting also includes step S5: after a section of carbon fiber yarn is detected, the connecting rod is rotated to drive the first fixed wheel to rotate to a side away from the second fixed wheel; preventing the first fixed wheel and the production line from interfering with each other during subsequent yarn replacement, production line maintenance or detection device maintenance, thereby achieving the purpose of protecting the yarn and the detection device, and improving the convenience and maintenance efficiency of the detection device.

[0035] The specific working principle of the present invention is as follows:

[0036] There will be many second fixed wheels on the carbon fiber yarn production line frame for conveying carbon fiber yarn. A detection device is installed near one or more of the second fixed wheels to detect the carbon fiber yarn. Since the thickness of the yarn with joints is thicker than that of the yarn without joints, the joints can be detected based on the thickness, and then the joints can be cut in subsequent work.

[0037] The detection device is installed on a frame close to the second fixed wheel, and the reset mechanism is adjusted according to the type of carbon fiber yarn, thereby adjusting the distance between the first fixed wheel and the second fixed wheel to meet the needs of carbon fiber yarn types of different thicknesses, so that the first fixed wheel will not contact the yarn transmitted on the second fixed wheel; a connecting rod is used to drive the first fixed wheel to rotate around the rotating end of the connecting rod, so that one side of the first fixed wheel is close to the second fixed wheel, and the angle sensor is coaxially arranged with the first fixed wheel, and the two are fixedly connected.

[0038] The hair on the carbon fiber yarn will sometimes be entangled on the second fixed wheel during the process of moving; if the hair is entangled too much and the thickness is added up, it will also touch the first fixed wheel, causing the angle sensor reading to change; at this time, we can distinguish whether it is a joint or hair entanglement based on the fact that the hair exists for a long time and the touching of the first fixed wheel is regular, which touches the first fixed wheel at periodic intervals, while the joint is irregular; if it is hair entanglement, it can be cleaned up in time to reduce the downtime of the carbon fiber production line.

[0039] When the carbon fiber yarn starts to move, due to the thickness brought by the joint, the joint will touch the first fixed wheel when passing through it, pushing the first fixed wheel away from the second fixed wheel. At this time, the reading of the angle sensor will change, thereby intuitively observing and recording the abnormality of the yarn thickness; after the first fixed wheel is pushed away, the reset mechanism will promptly pull the first fixed wheel toward the direction close to the second fixed wheel, so that the angle sensor and the first fixed wheel can be quickly reset, and continuously detect whether there is a joint on the carbon fiber yarn, thereby reducing the missed detection rate.

[0040] Beneficial effects:

[0041] (1) The present invention is a device for detecting warp-woven carbon fiber joints, which rotates the first fixed wheel away from the second fixed wheel through a connecting rod, thereby facilitating the replacement or maintenance of the yarn and improving the operational convenience and production efficiency of the detection device.

[0042] (2) The present invention provides a method for detecting carbon fiber joints suitable for warp knitting. The method detects in real time whether there are joints in the carbon fiber yarn by using an angle sensor and a first fixed wheel that rotate when touched by the joint. The accuracy of joint detection is high. The angle sensor is quickly reset by a reset mechanism, and accurately reset in conjunction with a positioning block, thereby improving detection efficiency and reducing the missed detection rate during the yarn travel process. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] Figure 1 Schematic diagram of the cross-sectional structure of the carbon fiber joint detection device of the present invention;

[0044] Figure 2 This is a schematic structural diagram of the carbon fiber joint detection device of the present invention when the first fixed wheel approaches the second fixed wheel;

[0045] Figure 3 This is a schematic structural diagram of the carbon fiber joint detection device of the present invention when the first fixed wheel is away from the second fixed wheel;

[0046] Figure 4 These are the steps of the carbon fiber joint detection method of the present invention.

[0047] Among them, 1-fixed seat; 11-positioning block; 12-positioning hole; 13-buffer pad; 2-connecting rod; 3-first fixed wheel; 4-angle sensor; 5-reset mechanism; 51-spring; 52-guide rod; 6-second fixed wheel. DETAILED DESCRIPTION

[0048] Below in conjunction with specific embodiment, further set forth the present invention.Should be understood that these embodiments are only used to illustrate the present invention and are not used in limiting the scope of the present invention.In addition, should be understood that after reading the content taught by the present invention, those skilled in the art can make various changes or modifications to the present invention, and these equivalent forms fall equally within the scope limited by the appended claims of the application.

[0049] A carbon fiber joint detection device suitable for warp knitting, such as Figure 1 As shown, the carbon fiber yarn production line includes a plurality of second fixed wheels 6 for conveying carbon fiber yarns, and the carbon fiber joint detection device suitable for warp knitting includes a fixing seat 1, a connecting rod 2, a reset mechanism 5, a first fixed wheel 3, an angle sensor 4 and a pressure sensor;

[0050] The fixed seat 1 is set on the frame of the carbon fiber yarn production line. One end of the connecting rod 2 is rotatably connected to the fixed seat 1, and the rotation range is from one side close to the second fixed wheel 6 to the other side close to the second fixed wheel 6; the other end of the connecting rod 2 is fixedly connected to the first fixed wheel 3;

[0051] like Figure 2 As shown, a positioning block 11 and a plurality of positioning holes 12 are provided on the fixing base 1. The positioning block 11 is located between the rotating end of the connecting rod 2 and the second fixed wheel 6. The positioning block 11 is fixed to the fixing base 1 through one of the positioning holes 12. A buffer pad 13 is provided on the surface of the positioning block 11.

[0052] The rotation range of the first fixed wheel 3 is from one side of the connecting rod 2 contacting the positioning block 11 to the other side of the connecting rod 2 contacting the positioning block 11;

[0053] like Figure 3 As shown, the reset mechanism 5 includes a spring 51 and a guide rod 52. One end of the spring 51 is fixedly connected to the fixing seat 1, and the other end is fixedly connected to the connecting rod 2. The guide rod 52 is fixed inside the spring 51 along the length direction of the spring 51.

[0054] The angle sensor 4 is coaxially arranged on the first stator wheel 3 ; the pressure sensor is installed at a preset position on the first stator wheel 3 , ie, directly below the first stator wheel 3 when the spring 51 is not deformed.

[0055] A method for detecting warp-woven carbon fiber joints, using the above-mentioned device for detecting warp-woven carbon fiber joints, comprises the following steps:

[0056] S1: The detection device is installed on the frame of the carbon fiber yarn production line. The first fixed wheel 3 is set to the initial position on one side of the second fixed wheel 6 through the reset mechanism 5. The minimum distance between the first fixed wheel and the second fixed wheel is controlled to be between 0.5 and 1 mm. The initial reading θ0 of the angle sensor 4 coaxial with the first fixed wheel 3 is recorded.

[0057] S2: Control the carbon fiber yarn to start moving, record the real-time reading θ1 of the angle sensor 4, and detect the pressure P1 of the yarn in real time when it moves;

[0058] S3: Calculate the real-time change angle Δθ=|θ1-θ0| of the angle sensor 4. When Δθ≥θc, detect it as a carbon fiber joint and generate a detection result.

[0059] Among them, θc is the angle threshold set manually;

[0060] S4: Calculate the real-time pressure change Pc = |P1-P0| monitored by the pressure sensor, and then calculate C = Pc / Δθ;

[0061] When C0≤C≤2C0, it is detected as a carbon fiber joint, and the detection result in step S3 is updated and output;

[0062] Wherein, P0 is the initial reading of the pressure sensor; C is the real-time correlation coefficient between pressure and angle; C0 is the manually set initial correlation coefficient between pressure and angle;

[0063] S5: After a section of carbon fiber yarn is tested, the connecting rod 2 is rotated to drive the first fixed wheel 3 to rotate to a side away from the second fixed wheel 6.

[0064] Example 1

[0065] A method for detecting warp-woven carbon fiber joints, the specific process is as follows:

[0066] S1: The detection device is installed on the frame of the carbon fiber yarn production line, and the first fixed wheel is set to the initial position on one side of the second fixed wheel through the reset mechanism. The minimum distance between the first fixed wheel and the second fixed wheel is controlled to be 0.8 mm;

[0067] S2: Record the initial reading of the angle sensor coaxial with the first fixed wheel θ0 = 0°, the initial reading of the pressure sensor P0 = 0, and control the carbon fiber yarn to start moving. When the real-time reading of the angle sensor θ1 = 50° is recorded, the pressure of the yarn detected in real time by the pressure sensor P1 = 0.01 MPa;

[0068] S3: Calculate the real-time change angle of the angle sensor Δθ=|θ1-θ0|=50°; the manually set angle threshold θc=0°. Since Δθ>θc, it is detected as a carbon fiber joint and a detection result is generated;

[0069] S4: Calculate the real-time pressure change monitored by the pressure sensor Pc = |P1-P0| = 0.01MPa, and then calculate C = Pc / Δθ = 2×10 -4 The initial correlation coefficient between pressure and angle is set to C0 = 1 × 10 -4 , since when C0≤C≤2C0, it is detected as a carbon fiber joint, and the detection result in step S3 is updated and output;

[0070] S5: The carbon fiber joints in the carbon fiber yarn are detected in real time according to the above steps. After the detection is completed, the connecting rod is rotated to drive the first fixed wheel to rotate to a side away from the second fixed wheel.

Claims

1. A carbon fiber joint detection device suitable for warp knitting, wherein the carbon fiber yarn production line includes a plurality of second fixed wheels (6) for conveying carbon fiber yarns, characterized in that: A device for detecting warp-woven carbon fiber joints comprises a fixing seat (1), a connecting rod (2), a reset mechanism (5), a first fixed wheel (3), and an angle sensor (4); The fixed seat (1) is arranged on a frame of a carbon fiber yarn production line; one end of the connecting rod (2) is rotatably connected to the fixed seat (1), and the rotation range is from one side close to the second fixed wheel (6) to the other side close to the second fixed wheel (6); the other end of the connecting rod (2) is fixedly connected to the first fixed wheel (3); One end of the reset mechanism (5) is fixedly connected to the fixed seat (1), and the other end is fixedly connected to the connecting rod (2); The angle sensor (4) is coaxially arranged on the first fixed wheel (3).

2. A carbon fiber joint detection device suitable for warp knitting according to claim 1, characterized in that: A positioning block (11) is provided on the fixing seat (1), and the positioning block (11) is located between the rotating end of the connecting rod (2) and the second fixed wheel (6); The rotation range of the first fixed wheel (3) is from one side of the connecting rod (2) contacting the positioning block (11) to the other side of the connecting rod (2) contacting the positioning block (11).

3. A carbon fiber joint detection device suitable for warp knitting according to claim 2, characterized in that: A plurality of positioning holes (12) are provided on the fixing seat (1), and the positioning block (11) is fixed on the fixing seat (1) through one of the positioning holes (12).

4. A carbon fiber joint detection device suitable for warp knitting according to claim 3, characterized in that: A buffer pad (13) is sleeved on the surface of the positioning block (11).

5. A carbon fiber joint detection device suitable for warp knitting according to claim 4, characterized in that: The reset mechanism (5) comprises a spring (51), one end of the spring (51) is fixedly connected to the fixing seat (1), and the other end is fixedly connected to the connecting rod (2).

6. A carbon fiber joint detection device suitable for warp knitting according to claim 5, characterized in that: The reset mechanism (5) further comprises a guide rod (52), wherein the guide rod (52) is fixed inside the spring (51) along the length direction of the spring (51).

7. A method for detecting warp-woven carbon fiber joints, comprising: The detection method includes the following steps: S1: The detection device is mounted on a frame of a carbon fiber yarn production line, and the first fixed wheel (3) is set to an initial position on one side of the second fixed wheel (6) by the reset mechanism (5), and the minimum distance between the first fixed wheel and the second fixed wheel is controlled to be between 0.5 and 1 mm, and the initial reading θ0 of the angle sensor (4) is recorded; S2: Control the carbon fiber yarn to start moving and record the real-time reading θ1 of the angle sensor (4); S3: Calculating the real-time change angle Δθ=|θ1-θ0| of the angle sensor (4); when Δθ≥θc, detecting it as a carbon fiber joint; Among them, θc is the angle threshold set manually.

8. A method for detecting warp-woven carbon fiber joints according to claim 7, characterized in that: step S2 also includes: installing a pressure sensor at a preset position on the first fixed wheel (3) for real-time detection of the pressure P1 when the yarn travels; the preset position is directly below the first fixed wheel (3) when the spring (51) is not deformed.

9. A method for detecting warp-woven carbon fiber joints according to claim 8, characterized in that: The method further includes step S4: calculating the real-time pressure change Pc=|P1-P0| monitored by the pressure sensor, and then calculating C=Pc / Δθ; When C0≤C≤2C0, it is detected as a carbon fiber joint, and the detection result in step S3 is updated and output; Among them, P0 is the initial reading of the pressure sensor; C is the real-time correlation coefficient between pressure and angle; C0 is the initial correlation coefficient between pressure and angle set manually.

10. A method for detecting warp-woven carbon fiber joints according to claim 9, characterized in that: The method further comprises step S5: after a section of carbon fiber yarn is inspected, the connecting rod (2) is rotated to drive the first fixed wheel (3) to rotate to a side away from the second fixed wheel (6).

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