Large-tow carbon fiber parallel multi-stage yarn spreading device and method based on ultrasonic array

Abstract

The present invention provides a large-tow carbon fiber parallel multi-stage yarn spreading device and method based on an ultrasonic array, belonging to the technical field of composite material preparation processes, comprising an ultrasonic water tank and an ultrasonic array, wherein a trapezoidal boss is provided at the bottom of the ultrasonic water tank, and the ultrasonic array comprises several rows of ultrasonic vibrators, which are respectively installed at the bottom and valley positions on both sides of the trapezoidal boss, and a vibration rod is provided directly above each row of ultrasonic vibrators. The present invention also comprises a multi-channel ultrasonic transducer power control unit, which comprises a connected ultrasonic generator and a power amplifier, and the power amplifier is provided with several ultrasonic power amplification channels. The present invention adopts a centrally symmetrical method to control the actual power of different ultrasonic vibrators in the ultrasonic array; by combining the mechanical impedance matrix formed by the node impedance of each ultrasonic vibrator, the purpose of optimizing the drag force distribution applied to the yarn spreading surface by adjusting the ultrasonic transducer power is achieved.

Description

Technical Field

[0001] The present invention belongs to the technical field of composite material preparation technology, and in particular relates to a large-tow carbon fiber parallel multi-stage yarn spreading device and method based on an ultrasonic array. Background Art

[0002] Carbon fiber composites are a new generation of reinforcing materials, boasting exceptional properties such as lightweight, high strength, and high modulus. Large-tow carbon fiber is the most promising and promising type of carbon fiber. In practical applications, a fiber spreading process is required to widen and thin the carbon fiber tows to produce composite materials with minimal deviation in physical properties and enhanced mechanical properties.

[0003] The existing yarn spreading method has the following problems:

[0004] (1) Problems with existing robot control technology based on vision technology:

[0005] In the mechanical unwinding method, the carbon fiber tow passes through multiple sets of mechanical rollers that can swing left and right (swing rods) and vibrate up and down (vibration rods). The lateral separation provided by the swing rods and the vertical tension applied by the vibration rods drive the fiber filaments in the fiber bundle to disperse. Because the fiber tow is in direct contact with the mechanical rollers, and some of the mechanical rollers are usually heated to high temperatures to improve dispersion efficiency, high friction exists at the contact interface, causing wear on the fiber surface and even filament breakage.

[0006] Airflow yarn spreading is the world's leading non-contact yarn spreading technology. This method creates an internal airflow field by creating a pressure difference between the airflow inlet and outlet of the spreading device, thereby dispersing the carbon fiber tows. However, due to the difficulty in controlling the uniformity of the airflow medium distribution, the yarn surface is prone to uneven thickness during the spreading process, and alignment issues are difficult when multiple tows are spread in parallel.

[0007] (2) Problems with existing ultrasonic yarn spreading solutions:

[0008] Ultrasonic plates or rods are typically placed on the side walls or bottom of the cavity. Ultrasonic waves cause the solvent in the cavity to vibrate regularly, thereby unfolding the carbon fibers. In this approach, ultrasound cannot directly act on the carbon fiber surface, resulting in reduced ultrasonic unfolding efficiency. Currently, ultrasonic yarn spreading can stretch 12K carbon fibers to 2-4 times the original tow. Furthermore, the ultrasonic propagation characteristics of the plates and rods hinder alignment between tows, hindering the parallel unfolding of multiple tows and limiting their practical engineering applications.

[0009] Therefore, the present invention proposes a parallel multi-stage spreading method for large-tow carbon fibers based on an ultrasonic array, which can achieve full spreading of a single large-tow carbon fiber and control of the positioning, alignment and overall width of the yarn surface after spreading. Summary of the Invention

[0010] The problem to be solved by the present invention is to provide a large-tow carbon fiber parallel multi-stage yarn spreading device and method based on an ultrasonic array.

[0011] To solve the above technical problems, the technical solution adopted by the present invention is: a large-tow carbon fiber parallel multi-stage yarn spreading device based on an ultrasonic array, comprising an ultrasonic water tank and an ultrasonic array, the ultrasonic array being installed at the bottom of the ultrasonic water tank, and at least one trapezoidal boss being provided at the bottom of the ultrasonic water tank, the ultrasonic array comprising several columns of ultrasonic vibrators, the several columns of ultrasonic vibrators being respectively installed at the bottom of the trapezoidal boss and the valley positions on both sides of the bottom of the trapezoidal boss, the columns of ultrasonic vibrators being arranged correspondingly, and a vibration rod being horizontally provided along the direction of arrangement of the ultrasonic vibrators directly above each column of ultrasonic vibrators, the input end of the ultrasonic water tank being provided with a multi-tow carbon fiber parallel transmission device, pulling the tow from the carbon fiber reel and pulling it into the ultrasonic water tank, the output end of the ultrasonic water tank being provided with a yarn spreading output pressure roller group, a drying workbench and a width winding device in sequence, and the unfolded width is transmitted to the drying workbench by the yarn spreading output pressure roller group on the output side of the ultrasonic water tank through the multi-stage vibration rod.

[0012] The multi-tow carbon fiber parallel transmission device includes a yarn splitting rod and a yarn spreading input pressure roller group. The yarn splitting rod positions and divides the multi-tow carbon fiber to avoid mutual interference between the bundles; the drying workbench is equipped with an ultrasonic vibration plate drying device and a width quality detection device.

[0013] The ultrasonic vibrator includes an ultrasonic transducer and a horn.

[0014] The width quality detection device is a CMOS laser displacement sensor, which is connected to a computer. The CMOS laser displacement sensor returns the change in the distance from the laser light source at different points on the stretched yarn width through laser ranging, and scans the stretched carbon fiber width to determine the width quality.

[0015] The present invention also includes a multi-channel ultrasonic transducer power control unit, which includes a connected ultrasonic generator and a power amplifier, wherein the power amplifier is provided with a plurality of ultrasonic power amplification channels. The multi-channel ultrasonic transducer power control unit uses a centrosymmetric method to control the actual power of different ultrasonic transducers in the ultrasonic array. During use, the mechanical impedance matrix formed by the node impedance of each ultrasonic transducer is combined to achieve the purpose of optimizing the drag force distribution applied to the yarn spreading surface by adjusting the ultrasonic transducer power.

[0016] The present invention also provides a large-tow carbon fiber parallel multi-stage yarn spreading method based on an ultrasonic array, comprising the following steps:

[0017] S1. Arrangement of ultrasonic vibrators: ultrasonic vibrators are installed at the bottom of the ultrasonic water tank in a centrosymmetrical array arrangement to form an ultrasonic array. Ultrasonic vibrators are installed in even-numbered rows at the bottom of the trapezoidal bosses, and in odd-numbered rows at the bottom of the valleys.

[0018] S2. Driving the ultrasonic vibrator: Winding multiple carbon fibers that need to be spread around the surface of the vibration rod, connecting the ultrasonic vibrator to the ultrasonic power amplification channel of the multi-channel ultrasonic transducer power control unit to achieve driving of the ultrasonic vibrator;

[0019] Specifically, the ultrasonic vibrators are controlled by an ultrasonic generator and a power amplifier. The first channel of the ultrasonic generator and the power amplifier controls the two groups of ultrasonic vibrators on the outermost sides of the web, the second channel controls the two groups of ultrasonic vibrators slightly off the center of the web, and so on. The N-1th channel controls the two groups of ultrasonic vibrators on both sides of the center of the web, and the Nth channel controls a group of ultrasonic vibrators in the center of the web.

[0020] S3. Determine the problems existing on the surface of the yarn spread: Use an industrial computer to control the width detection device to scan along the width direction of the yarn spread to obtain a series of distance values ​​S between the yarn spread and the laser light source. At the same time, the industrial computer obtains the distance and displays it on the computer. S is the change value, which reflects the high and low change trend of the yarn spread surface;

[0021] Specifically, if there is a yarn bundle gap on the surface of the yarn spread, the distance measurement value returned by the CMOS laser displacement sensor at this location will increase sharply, and may even exceed the detection range of the CMOS laser displacement sensor, and this part will be judged as a yarn bundle gap; if there is a yarn bundle overlap on the surface of the yarn spread, the distance measurement value returned by the CMOS laser displacement sensor at this location will decrease, and this part will be judged as a yarn bundle overlap.

[0022] S4. Based on the actual parallelism between the yarn bundles and the distribution of the yarn bundle gaps on the yarn spreading surface obtained by the width quality detection device, determine the location where the yarn spreading drag force needs to be adjusted, and symmetrically adjust the power of the ultrasonic vibrator under each vibration rod through the multi-channel ultrasonic transducer power control unit to achieve adjustment and control of the drag force at different positions on the yarn spreading surface.

[0023] In step S4, the specific method for adjusting and controlling the drag force at different positions on the yarn spreading surface is as follows:

[0024] S41, calculate the mechanical impedance at each ultrasonic vibrator node, the vibration system composed of a single vibrating rod includes the excitation force f Z , elastic force f K , damping force f R , inertial force f M Four forces satisfy the equation:

[0025] f Z =f M +f R +f K (1)

[0026] Assuming K is the inverse of the elastic coefficient s of the vibration system, that is, K = 1 / s, x is the deviation of the vibration rod from the equilibrium position, and v is the linear velocity of the sound wave, then formula (1) can be written as:

[0027]

[0028] Where M is the mass of the vibrating rod; R is the mechanical damping coefficient of the vibrating rod; t is the time variable; τ is the differential time variable;

[0029] The exciting force of the vibration system can be expressed by the sine function:

[0030] f Z =F Z sin(ωt) (3)

[0031] Where, F Z is the amplitude, ω is the vibration frequency;

[0032] Substituting equation (3) into equation (2), the exciting force can be rewritten in complex form as:

[0033]

[0034] Where, F Z is the complex form of the exciting force; V is the complex number of the vibration rod velocity response; j is the symbol representing the imaginary part of the complex number;

[0035] Therefore, the mechanical impedance of the ultrasonic transducer (here the ratio of the complex form of the simple harmonic excitation force to the complex form of the simple harmonic motion velocity response) is:

[0036]

[0037] Where, Z mech is the mechanical impedance; Z mech is the amplitude of mechanical impedance; is the phase of mechanical impedance;

[0038] Z mech and The specific expression is as follows:

[0039]

[0040]

[0041] Since the vibration velocity V of the vibrating rod is the first-order derivative of the vibration amplitude X, according to formula (5):

[0042]

[0043] From formula (8), we can see that the amplitude of mechanical impedance Z mech Taking the minimum value, the vibration amplitude X is the largest; according to formula (6), at this time ωM=1 / (ωK), the elastic force f K and inertial force f M Balance, that is:

[0044] f M +f K =0 (9)

[0045] In order to make the exciting force f Z and the damping force f R To cancel each other out, it is necessary to make the vibration frequency ω of the external exciting force and the natural frequency ω of the vibration system m Equal, that is:

[0046]

[0047] S42. Establish a nodal mechanical impedance matrix for the entire ultrasonic field, establish a quantitative relationship between the driving power of the ultrasonic transducer of each ultrasonic vibrator and the excitation force at different points in the ultrasonic field, and construct an n×n nodal mechanical impedance matrix Z, where n is the number of all ultrasonic vibrators in the entire ultrasonic field. The nodal mechanical impedance matrix Z is shown as follows:

[0048]

[0049] Each element Z on the diagonal of the node mechanical impedance matrix ii Refers to the self-impedance of the i-th ultrasonic transducer. Its physical meaning is: when only the ultrasonic transducer on the i-th node is working and the ultrasonic transducers on the other nodes are in the disconnected state, the impedance at the i-th node, Z ij ,(i≠j) refers to the mechanical impedance at node i when all ultrasonic transducers except the jth ultrasonic transducer are disconnected, also known as mutual impedance.

[0050] According to the relationship between the node excitation force and the node excitation response (speed) shown in formula (5), the ultrasonic array power adjustment scheme is determined to optimize the distribution of the drag force in the ultrasonic field, which can effectively improve the generation of gaps between bundles in the width, thereby realizing the parallel ultra-thin uniform yarn spreading of multiple bundles of large-tow carbon fibers.

[0051] It can be seen that compared with the traditional carbon fiber mechanical spreading method, the present invention is suitable for mass production, is more environmentally friendly and efficient, and can quickly realize the parallel widening of multiple carbon fiber tows and overall width control; especially for large tow carbon fiber tows, such as 24K~48K carbon fiber tows, it can simultaneously complete the uniform widening of a single carbon fiber tow and the alignment of multiple tows and overall width control.

[0052] After the yarn is spread, ultrasonic vibration can be used to turn water into water mist to evaporate the moisture attached to the surface of the carbon fiber during the yarn spreading process.

[0053] The present invention focuses on solving the problem of adjusting the spread and positioning of large-tow carbon fibers by adjusting the lattice arrangement and power distribution of the ultrasonic transducer.

[0054] Due to the adoption of the above technical solution, the present invention has the following beneficial effects:

[0055] 1) Compared with the existing ultrasonic plate and ultrasonic rod carbon fiber yarn spreading method, the ultrasonic array yarn spreading method of the present invention can act on the yarn spreading surface at a close distance, thereby greatly improving the yarn spreading efficiency of large-tow carbon fiber.

[0056] 2) By adjusting the x- and z-positions of the vibrating rod, the tension of the web along the yarn direction can be planned.

[0057] 3) By grouping and regulating the power of different ultrasonic transducers in the ultrasonic array, the intensity distribution of the entire ultrasonic field is designed, and then the thickness uniformity of the entire yarn surface is controlled to eliminate the gaps between the yarn bundles as much as possible.

[0058] 4) The present invention is based on a mechanical impedance matrix. By changing the working power of the ultrasonic transducer, the distribution of ultrasonic intensity in the entire ultrasonic field is achieved, thereby changing the magnitude of the lateral drag force applied to the large-tow carbon fiber yarn surface at different positions. This facilitates the establishment of a quantitative relationship between the ultrasonic transducer power and the lateral drag force distribution on the yarn surface, facilitating direct regulation. BRIEF DESCRIPTION OF THE DRAWINGS

[0059] The present invention will be described in detail below with reference to the accompanying drawings and in combination with examples, and the advantages and implementation modes of the present invention will become more apparent. The contents shown in the accompanying drawings are only used to illustrate the present invention and do not constitute any limitation to the present invention. In the accompanying drawings:

[0060] Figure 1 It is a structural schematic diagram of the present invention.

[0061] Figure 2 This is a diagram showing the arrangement position relationship of each ultrasonic vibrator in the ultrasonic array of the present invention.

[0062] Figure 3It is a connection diagram of the multi-channel ultrasonic transducer power control unit of the present invention.

[0063] Figure 4 It is a schematic diagram of a model of a vibration system composed of a single vibration rod of the present invention.

[0064] Figure 5 It is a schematic diagram of the physical meaning of the node mechanical impedance matrix of the present invention.

[0065] In the picture:

[0066] 1. Ultrasonic water tank; 2. Ultrasonic array; 3. Ultrasonic vibrator; 4. Vibrating rod; 5. Yarn splitting rod; 6. Ultrasonic vibration plate drying device; 7. Width quality detection device; 8. Ultrasonic transducer; 9. Amplitude transformer; 10. Yarn spreading input pressure roller group; 11. Multi-tow carbon fiber; 12. Drying output pressure roller group; 13. Yarn spreading output pressure roller group; 14. Drying workbench. DETAILED DESCRIPTION

[0067] like Figures 1 to 5 As shown, the present invention is a large-tow carbon fiber parallel multi-stage yarn spreading device based on an ultrasonic array, comprising an ultrasonic water tank 1 and an ultrasonic array 2, wherein the ultrasonic array 2 is mounted at the bottom of the ultrasonic water tank 1, and at least one trapezoidal boss is provided at the bottom of the ultrasonic water tank 1, and the ultrasonic array 2 comprises a plurality of columns of ultrasonic vibrators 3, wherein the plurality of columns of ultrasonic vibrators 3 are respectively mounted at the bottom of the trapezoidal boss and at the valley positions on both sides of the bottom of the trapezoidal boss, and the columns of ultrasonic vibrators 3 are arranged correspondingly, and a vibration rod 4 supported by a stainless steel sheet is horizontally provided directly above each column of ultrasonic vibrators 3 along the direction in which the ultrasonic vibrators 3 are arranged, and the ultrasonic water tank 1 transmits A multi-tow carbon fiber parallel transmission device is provided at the input end, and the multi-tow carbon fiber parallel transmission device includes a yarn dividing rod 5 and a yarn spreading input pressure roller group 10. The yarn dividing rod 5 positions and divides the multi-tow carbon fiber 11 to avoid mutual interference between the yarn bundles, and then pulls the yarn bundles from the carbon fiber reel through the yarn spreading input pressure roller group 10 and pulls them into the ultrasonic water tank 1, and realizes ultrasonic yarn spreading through the multi-stage vibrating rod 4; then the yarn spreading output pressure roller group 13 on the output side of the ultrasonic water tank 1 transmits the unfolded width to the drying workbench 14, and finally the drying output pressure roller group 12 on the output side of the drying workbench 14 transmits it to the width winding device.

[0068] The drying workbench 14 is equipped with an ultrasonic vibration plate drying device 6 and a width quality detection device 7 .

[0069] The ultrasonic vibrator 3 includes an ultrasonic transducer 8 and a horn 9 .

[0070] An appropriate amount of deionized water is poured into the ultrasonic water tank 1 .

[0071] The width quality detection device 7 is a CMOS laser displacement sensor, which is connected to a computer. The CMOS laser displacement sensor returns the change in the distance from the laser light source at different points on the stretched yarn width through laser ranging, and scans the stretched carbon fiber width to determine the width quality, such as the size and distribution characteristics of the yarn bundle overlap area and the yarn bundle gap area.

[0072] The ultrasonic water tank 1 is made of stainless steel thin plate.

[0073] The position where the ultrasonic vibrator 3 is pre-placed at the bottom of the ultrasonic water tank 1 is welded with screws, and then the area around the screws is cleaned and made to be flat to avoid affecting the installation of the ultrasonic vibrator 3. The end face of the horn 9 is connected to the ultrasonic water tank 1 by welded screws, and the end face of the horn 9 is ensured to be in close contact with the bottom of the ultrasonic water tank 1 by gluing. Specifically, the glue matching the ultrasonic vibrator 3 is stirred evenly in proportion, and then the glue is evenly applied to the bottom of the ultrasonic vibrator 3. The bottom of the ultrasonic transducer 8 is gently twisted to squeeze out the air and excess glue on the contact surface between the end face of the horn 9 and the bottom of the ultrasonic water tank 1, so that the ultrasonic vibrator 3 is more tightly combined with the stainless steel ultrasonic water tank 1 as a whole.

[0074] The present invention also includes a multi-channel ultrasonic transducer power control unit, which controls the actual power of different ultrasonic vibrators 3 in the ultrasonic array 2 in a centrally symmetrical manner; during use, the mechanical impedance matrix formed by the node impedance of each ultrasonic vibrator 3 is combined to achieve the purpose of optimizing the drag force distribution applied to the yarn surface by adjusting the power of the ultrasonic transducer 8.

[0075] The multi-channel ultrasonic transducer power control unit includes a connected ultrasonic generator and a power amplifier, and the power amplifier is provided with a plurality of ultrasonic power amplification channels.

[0076] A parallel multi-stage spreading method for large-tow carbon fiber yarns based on an ultrasonic array comprises the following steps:

[0077] S1. Arrangement of ultrasonic vibrators: Ultrasonic vibrators are installed at the bottom of the ultrasonic water tank 1 in a centrally symmetrical array arrangement to form an ultrasonic array 2. The number of rows and columns of ultrasonic vibrators 3 in the ultrasonic array 2 needs to be calculated based on the actual number of carbon fiber tows to be spread in parallel and the target width of the spread. The number of rows and columns is preferably an odd number to facilitate symmetrical arrangement and control.

[0078] An even-numbered array of ultrasonic vibrators 3 is installed at the bottom of the trapezoidal boss, and an odd-numbered array of ultrasonic vibrators 3 is installed at the bottom of the valley, wherein the height of the trapezoidal boss is H.

[0079] like Figure 2As shown, taking a 3×5 ultrasonic array as an example, there are 5 ultrasonic vibrators in each column. The ultrasonic vibrators in the first column are placed in the valley near the input side of the ultrasonic water tank 1, and the ultrasonic vibrators in the second column are placed under the trapezoidal boss in the middle of the bottom of the ultrasonic water tank 1; the ultrasonic vibrators in the third column are placed under the valley near the output side of the ultrasonic water tank 1. The y coordinates of the ultrasonic vibrators in each row of the three columns are consistent. The third ultrasonic vibrator is located at the center of the ultrasonic water tank in the y direction, and the remaining ultrasonic vibrators are symmetrically distributed with equal spacing about the y-direction center position. The spacing between the second and fourth rows of ultrasonic vibrators and the third row of ultrasonic vibrators is d1, and the spacing between the first and second rows of ultrasonic vibrators and the spacing between the fifth and fourth rows of ultrasonic vibrators are both d2; the spacing between the first and second columns of ultrasonic vibrators is L1, and the spacing between the second and third columns of ultrasonic vibrators is L2;

[0080] S2. Driving the ultrasonic vibrator: Wind the multiple carbon fibers that need to be spread around the surface of the vibrating rod 4, where the distance between the vibrating rod 4 and the bottom of the ultrasonic water tank 1 is H1. Connect the ultrasonic vibrator 3 to the ultrasonic power amplification channel of the multi-channel ultrasonic transducer power control unit to achieve driving of the ultrasonic vibrator.

[0081] like Figure 3 As shown, the 1st and 5th rows of the ultrasonic array are driven by the same ultrasonic power amplification channel (first channel), the 2nd and 4th rows are driven by the same ultrasonic power amplification channel (second channel), and the 3rd row located at the y-center position of the ultrasonic water tank is driven by a separate ultrasonic power amplification channel (third channel).

[0082] Specifically, based on Figure 2 and Figure 3 It can be seen that the ultrasonic vibrators are controlled by the ultrasonic generator and the power amplifier. The first channel of the ultrasonic generator and the power amplifier controls the two groups of ultrasonic vibrators on the outermost side of the width (numbered ①⑥ and ⑤ ), the second channel controls two sets of ultrasonic vibrators (numbered ②⑦) with the amplitude slightly off-center. and ④⑨ ) The third channel controls a set of ultrasonic vibrators (numbered ③⑧) in the center of the format. ).

[0083] S3. Determine the problems existing on the surface of the yarn spread: The industrial computer controls the surface quality detection device 7 to scan along the width direction of the yarn spread to obtain a series of distance values ​​S between the yarn spread and the laser light source. At the same time, the industrial computer obtains the distance and displays it on the computer. S is the change value, which reflects the high and low change trend of the yarn spread surface.

[0084] If there is a tow gap on the surface of the yarn spread, the distance measurement value returned by the CMOS laser displacement sensor at this location will increase sharply, and may even exceed the detection range of the CMOS laser displacement sensor, and the portion will be judged as a tow gap.

[0085] If there is yarn bundle overlap on the surface of the yarn spread, the distance measurement value returned by the CMOS laser displacement sensor at that location will be slightly reduced, and this part will be judged as yarn bundle overlap.

[0086] S4. According to the parallelism between the yarn bundles and the distribution of the gaps between the yarn bundles on the actual yarn spreading surface obtained by the width quality detection device 7, the position where the yarn spreading drag force needs to be adjusted is determined, and the power of the ultrasonic vibrator under each vibration rod 4 is symmetrically adjusted by the multi-channel ultrasonic transducer power control unit, so that the drag force at different positions on the yarn spreading surface can be adjusted and controlled.

[0087] In step S4, the specific method for adjusting and controlling the drag force at different positions on the yarn spreading surface is as follows:

[0088] S41. Calculate the mechanical impedance at each ultrasonic vibrator node, that is, the diagonal elements in the impedance matrix represent the ratio of the force and response at the same point, which is called self-impedance.

[0089] like Figure 4 As shown, the vibration system composed of a single vibration rod includes the exciting force f Z , elastic force f K , damping force f R , inertial force f M Four forces satisfy the equation:

[0090] f Z =f M +f R +f K (1)

[0091] Assuming K is the inverse of the elastic coefficient s of the vibration system, that is, K = 1 / s, x is the deviation of the vibration rod from the equilibrium position, and v is the linear velocity of the sound wave, then formula (1) can be written as:

[0092]

[0093] Where M is the mass of the vibrating rod; R is the mechanical damping coefficient of the vibrating rod; t is the time variable; τ is the differential time variable;

[0094] The exciting force of the vibration system can be expressed by the sine function:

[0095] f Z =F Z sin(ωt) (3)

[0096] Where, FZ is the amplitude, ω is the vibration frequency;

[0097] Substituting equation (3) into equation (2), the exciting force can be rewritten in complex form as:

[0098]

[0099] Where, F Z is the complex form of the exciting force; V is the complex number of the vibration rod velocity response; j is the symbol representing the imaginary part of the complex number;

[0100] Therefore, the mechanical impedance of the ultrasonic transducer (here the ratio of the complex form of the simple harmonic excitation force to the complex form of the simple harmonic motion velocity response) is:

[0101]

[0102] Where, Z mech is the mechanical impedance; Z mech is the amplitude of mechanical impedance; is the phase of mechanical impedance;

[0103] Z mech and The specific expression is as follows:

[0104]

[0105]

[0106] Since the vibration velocity V of the vibrating rod is the first-order derivative of the vibration amplitude X, according to formula (5):

[0107]

[0108] From formula (8), we can see that the amplitude of mechanical impedance Z mech Taking the minimum value, the vibration amplitude X is the largest; according to formula (6), at this time ωM=1 / (ωK), the elastic force f K and inertial force f M Balance, that is:

[0109] f M +f K =0 (9)

[0110] In order to make the exciting force f Z and the damping force f R To cancel each other out, it is necessary to make the vibration frequency ω of the external exciting force and the natural frequency ω of the vibration system m Equal, that is:

[0111]

[0112] S42. Establish a node mechanical impedance matrix for the entire ultrasonic field, establish a quantitative relationship between the driving power of the ultrasonic transducer 8 of each ultrasonic vibrator 3 and the excitation force at different points in the ultrasonic field, and construct an n×n node mechanical impedance matrix Z, where n is the number of all ultrasonic vibrators in the entire ultrasonic field. The node mechanical impedance matrix Z is shown as follows:

[0113]

[0114] Each element Z on the diagonal of the node mechanical impedance matrix ii It refers to the self-impedance of the i-th ultrasonic transducer 8. Its physical meaning is: when only the ultrasonic transducer 8 on the i-th node is working and the ultrasonic transducers 8 on the other nodes are in the disconnected state, it is the impedance on the i-th node.

[0115] Z ij ,(i≠j) refers to the mechanical impedance at node i when all ultrasonic transducers except the jth ultrasonic transducer are disconnected, also known as mutual impedance.

[0116] The node mechanical impedance matrix has the following two characteristics:

[0117] (1) The node mechanical impedance matrix is ​​a symmetrical square matrix, and the off-diagonal elements Z ij =Z ji ;

[0118] (2) The nodal mechanical impedance matrix is ​​a full-rank matrix with no zero elements.

[0119] However, in practical applications, it is difficult to directly measure the elements of the nodal mechanical impedance matrix because it requires only one point in the system to respond. The elements of the mechanical admittance matrix, which is the inverse of the nodal mechanical impedance matrix, are easier to measure (requiring only one point of force application).

[0120] Therefore, in practical applications, the mechanical admittance matrix of the ultrasonic field can be obtained through measurement, and then the nodal mechanical impedance matrix can be calculated using the inverse elimination method or the LU triangular decomposition method. The off-diagonal elements represent the ratio of the force and response at different points, which is called the cross-point impedance.

[0121] like Figure 5 As shown in Figure 5, according to the relationship between the node excitation force and the node excitation response (speed) shown in formula (5), the ultrasonic array power adjustment scheme is determined to optimize the distribution of the drag force in the ultrasonic field, which can effectively improve the generation of the gap between the bundles in the width, thereby realizing the parallel ultra-thin uniform yarn spreading of multiple large-tow carbon fibers.

[0122] Specifically, the ultrasonic array power adjustment scheme of the present invention is as follows:

[0123] When the distribution of the gaps between the strands is mostly concentrated in the center area of ​​the width and the strand overlaps mostly occur in the areas on both sides of the width center, the output power of the third channel is reduced; when the distribution of the gaps between the strands is mostly concentrated in the areas on both sides of the width center and the strand overlaps mostly occur in the edge areas on both sides of the width, the output power of the first channel is increased; when the distribution of the strand overlaps is mostly concentrated in the area near the center of the width and the gaps between the strands mostly occur in the edge areas on both sides of the width, the output power of the third channel is increased and the output power of the first channel is reduced.

[0124] The increase and decrease of the output power of the ultrasonic power amplification channel can be obtained by quantitative calculation:

[0125] The self-impedance of each ultrasonic transducer 8 in the ultrasonic power amplification channel group is calculated according to formula (11). For example, the self-impedance of the i-th ultrasonic transducer 8 corresponds to the element Z in the impedance matrix: ii , then according to formula (5) the incremental exciting force ΔF can be calculated z Required self-impedance Z ii The increment △Z ii .

[0126] The lateral drag force of the vibration rod 4 on the yarn spreading width is expressed as the resultant moment of the exciting force of the connected ultrasonic transducer 8 relative to the center.

[0127] Taking the vibration rod 4 located at the input side of the ultrasonic water tank 1 as an example, the adjustment scheme for the drag force distribution in the ultrasonic field is as follows:

[0128] The vibration rod on the input side of the ultrasonic water tank is connected to the ultrasonic transducers numbered ① to ⑤. The excitation force of each ultrasonic transducer will generate a torque relative to the center of the yarn spread, and when the excitation force is the same, the magnitude of the torque is proportional to the distance between the ultrasonic transducer and the center of the spread. Assuming that the torque on the inside of the center of the spread is positive and the torque on the outside of the center of the spread is negative, the resultant torque of the excitation forces of the five ultrasonic transducers is recorded as the lateral drag force acting on the yarn spread by the vibration rod.

[0129] The embodiments of the present invention are described in detail above, but the contents described are only preferred embodiments of the present invention and should not be considered to limit the scope of the present invention. All equivalent changes and improvements made within the scope of the present invention should still fall within the scope of this patent.

Claims

1. A parallel multi-stage spreading method for large-tow carbon fiber yarns based on an ultrasonic array, characterized by: The ultrasonic array is mounted on the bottom of the ultrasonic water tank. The bottom of the ultrasonic water tank is provided with at least one trapezoidal boss. The ultrasonic array includes a plurality of rows of ultrasonic vibrators. The plurality of rows of ultrasonic vibrators are respectively mounted on the bottom of the trapezoidal boss and the valley positions on both sides of the bottom of the trapezoidal boss. The rows of ultrasonic vibrators are arranged correspondingly. A vibration rod is horizontally arranged directly above each row of ultrasonic vibrators along the direction of arrangement of the ultrasonic vibrators. The specific steps include: S1. Arrangement of ultrasonic vibrators: ultrasonic vibrators are installed at the bottom of the ultrasonic water tank in a centrosymmetrical array arrangement to form an ultrasonic array. Ultrasonic vibrators are installed in even-numbered rows at the bottom of the trapezoidal bosses, and in odd-numbered rows at the bottom of the valleys. S2. Driving the ultrasonic vibrator: Winding multiple carbon fibers that need to be spread around the surface of the vibration rod, connecting the ultrasonic vibrator to the ultrasonic power amplification channel of the multi-channel ultrasonic transducer power control unit to achieve driving of the ultrasonic vibrator; S3. Determine the problems existing on the surface of the yarn spread: Use an industrial computer to control the width detection device to scan along the width direction of the yarn spread to obtain a series of distance values ​​S between the yarn spread and the laser light source. At the same time, the industrial computer obtains the distance and displays it on the computer. S is the change value, which reflects the high and low change trend of the yarn spread surface; S4. Based on the actual parallelism between the yarn bundles and the distribution of the yarn bundle gaps on the yarn spreading surface obtained by the width quality detection device, determine the location where the yarn spreading drag force needs to be adjusted, and symmetrically adjust the power of the ultrasonic vibrator under each vibration rod through the multi-channel ultrasonic transducer power control unit to achieve adjustment and control of the drag force at different positions on the yarn spreading surface.

2. The method for parallel multi-stage large-tow carbon fiber yarn spreading based on ultrasonic array according to claim 1, characterized in that: The input end of the ultrasonic water tank is provided with a multi-tow carbon fiber parallel transmission device, and the output end of the ultrasonic water tank is provided with a yarn output pressure roller group, a drying workbench and a width winding device in sequence.

3. The method for parallel multi-stage large-tow carbon fiber yarn spreading based on ultrasonic array according to claim 2, characterized in that: The multi-tow carbon fiber parallel transmission device includes a yarn splitting rod and a yarn spreading input pressure roller group, and the drying workbench is equipped with an ultrasonic vibration plate drying device and a width quality detection device.

4. The method for parallel multi-stage large-tow carbon fiber yarn spreading based on ultrasonic array according to claim 3, characterized in that: The format quality detection device is a CMOS laser displacement sensor, and the CMOS laser displacement sensor is connected to a computer.

5. The method for parallel multi-stage spreading of large-tow carbon fibers based on an ultrasonic array according to claim 1, characterized in that: The ultrasonic vibrator includes an ultrasonic transducer and a horn.

6. The method for parallel multi-stage spreading of large-tow carbon fibers based on an ultrasonic array according to claim 5, characterized in that: It also includes a multi-channel ultrasonic transducer power control unit, which includes a connected ultrasonic generator and a power amplifier. The power amplifier is provided with several ultrasonic power amplification channels. The multi-channel ultrasonic transducer power control unit controls the actual power of different ultrasonic vibrators in the ultrasonic array in a centrally symmetrical manner.

7. The method for parallel multi-stage large-tow carbon fiber yarn spreading based on ultrasonic array according to claim 1, characterized in that: In step S2, the ultrasonic vibrators are controlled by an ultrasonic generator and a power amplifier. The first channel of the ultrasonic generator and the power amplifier controls the two groups of ultrasonic vibrators on the outermost sides of the web, the second channel controls the two groups of ultrasonic vibrators slightly off the center of the web, and so on. The N-1th channel controls the two groups of ultrasonic vibrators on both sides of the center of the web, and the Nth channel controls the group of ultrasonic vibrators in the center of the web.

8. The method for parallel multi-stage large-tow carbon fiber yarn spreading based on ultrasonic array according to claim 1, characterized in that: In step S3, if there is a yarn bundle gap on the surface of the yarn spread, the distance measurement value returned by the CMOS laser displacement sensor at the yarn bundle gap will increase sharply, and it is judged that this is a yarn bundle gap; if there is a yarn bundle overlap on the surface of the yarn spread, the distance measurement value returned by the CMOS laser displacement sensor at the overlap will decrease, and it is judged that this is a yarn bundle overlap.

9. The method for parallel multi-stage spreading of large-tow carbon fibers based on an ultrasonic array according to claim 1, characterized in that: In step S4, the specific method for adjusting and controlling the drag force at different positions on the yarn spreading surface is as follows: S41. Calculate the mechanical impedance at each ultrasonic vibrator node. The vibration system composed of a single vibrating rod includes the excitation force f Z , elastic force f K , damping force f R , inertial force f M Four forces satisfy the equation: （1） set up K is the elastic coefficient of the vibration system s The reciprocal of K=1 / s , x is the deviation of the vibrating rod from the equilibrium position, v is the linear velocity of the sound wave, then formula (1) can be written as: （2） Where M is the mass of the vibrating rod; R is the mechanical damping coefficient of the vibrating rod; t is the time variable; is the differential time variable; The exciting force of the vibration system can be expressed by the sine function: （3） Where, F Z is the amplitude, ω is the vibration frequency; Substituting equation (3) into equation (2), the exciting force can be rewritten in complex form as: （4） Where, is the complex form of the exciting force; is the complex expression of the velocity response of the vibrating rod; j is the symbol for the imaginary part of a complex number; Therefore, the mechanical impedance of the ultrasonic transducer is: （5） Where, is the mechanical impedance; is the amplitude of mechanical impedance; φ is the phase of mechanical impedance; and φ The specific expression is as follows: （6） （7） Since the vibration velocity V of the vibrating rod is the first-order derivative of the vibration amplitude X, according to formula (5): （8） From formula (8), we can see that the amplitude of mechanical impedance is Z mech Take the minimum value, vibration amplitude X Maximum; According to formula (6), at this time ωM=1 / (ωK), the elastic force f K and inertial force f M Balance, that is: （9） In order to make the excitation force f Z and damping force f R To cancel each other out, the vibration frequency of the external excitation force needs to be ω The natural frequency of the vibration system ω m Equal, that is: （10）； S42, establish the node mechanical impedance matrix of the entire ultrasonic field, establish the quantitative relationship between the driving power of the ultrasonic transducer of each ultrasonic vibrator and the exciting force at different points in the ultrasonic field, and construct a n × n The impedance matrix Z, where n is the number of all ultrasonic vibrators in the entire ultrasonic field, and the node mechanical impedance matrix Z is shown as follows: （11） Each element on the diagonal of the node mechanical impedance matrix Z ii Refers to the self-impedance of the i-th ultrasonic transducer. The self-impedance is the impedance at the i-th node when only the ultrasonic transducer at the i-th node is working and the ultrasonic transducers at the other nodes are in the disconnected state. Z ij (i≠j) Refers to the j When one ultrasonic transducer is working and the other ultrasonic transducers are disconnected, i The mechanical impedance at the node is the mutual impedance, According to the relationship between the node excitation force and the node excitation response shown in Equation (5), the ultrasonic array power adjustment scheme is determined to optimize the distribution of the drag force in the ultrasonic field.

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