Device and method for monitoring the continuous annealing state of cold-rolled strip based on laser ultrasound

Abstract

The present invention belongs to the field of ultrasonic nondestructive monitoring technology, and specifically relates to a device and method for monitoring the continuous annealing state of cold-rolled steel strip based on laser ultrasound. The device for monitoring the continuous annealing state of cold-rolled steel strip based on laser ultrasound includes a monitoring assembly, the monitoring assembly including a monitoring frame, a first linear slide and a second linear slide mounted on the upper and lower inner sides of the monitoring frame, respectively, a third linear slide mounted on the slider of the first linear slide, the third linear slide being arranged perpendicular to the first linear slide, a pulsed laser excitation probe mounted on the slider of the third linear slide, and a TWM monitoring probe mounted on the slider of the second linear slide. The present invention uses laser ultrasonic technology to achieve online, nondestructive, and real-time monitoring of the grain size of the steel strip, without the need for contact with the steel strip surface, thus avoiding damage to the steel strip surface; and can monitor changes in grain size in real time.

Description

Technical Field

[0001] The present invention belongs to the technical field of ultrasonic non-destructive monitoring, and in particular relates to a device and method for monitoring the continuous annealing state of cold-rolled strip steel based on laser ultrasound. Background Art

[0002] With the widespread application of steel in various fields, the demand for steel quality and performance is becoming increasingly stringent. Rolling is a common processing method for plate and strip products. During the cold-rolled strip process, the cold rolling process causes work hardening within the material, resulting in increased hardness and decreased plasticity. To restore the material's plasticity and toughness, continuous annealing is often required. Continuous annealing not only reduces hardness and improves plastic deformation capacity, but also improves the strip's stamping ability, imparting excellent process mechanical properties. However, if the annealing time during the continuous annealing process is insufficient ("under-annealing"), the microstructure within the material cannot fully recrystallize, residual stresses cannot be fully released, and material uniformity is affected. Conversely, if the annealing time is too long ("over-annealing"), grains may merge and grow excessively, resulting in reduced strength and excessive plasticity, which in turn degrades the material's overall performance. Therefore, precise control of the annealing time is crucial to achieving ideal microstructure and properties.

[0003] At present, grain size monitoring can be divided into two categories: destructive monitoring methods and non-destructive monitoring methods. Among them, metallographic methods, transmission electron microscopy, scanning electron microscopy and other methods are destructive monitoring methods, and these methods are all offline monitoring and cannot achieve online real-time monitoring. In addition, there are non-destructive monitoring methods based on ultrasound, such as transmission attenuation method, relative attenuation method, attenuation spectrum method, spectrum analysis method, etc. Although these methods can achieve non-destructive monitoring, they have problems such as insufficient monitoring accuracy or complex operation, and low efficiency. They cannot monitor the grain size online in real time during the production process, affecting quality stability and production efficiency. In addition, the characteristics of plate and strip materials in the production process are fast movement speed and high temperature, which undoubtedly increases the difficulty of online monitoring of grain size. Summary of the Invention

[0004] In view of the above problems, the present invention provides a device and method for monitoring the continuous annealing state of cold-rolled strip steel based on laser ultrasound.

[0005] In order to achieve the above-mentioned purpose, the present invention adopts the following technical solutions:

[0006] The cold-rolled strip continuous annealing state monitoring device based on laser ultrasound comprises two low-position tensioning modules, two high-position tensioning modules and a monitoring component installed behind the annealing heating furnace. The two high-position tensioning modules are respectively located in front of and behind the monitoring component, and the two low-position tensioning modules are respectively located on the outside of the two high-position tensioning modules. The strip is tensioned by the cooperation of the low-position tensioning module and the high-position tensioning module. The monitoring component comprises a monitoring frame. A No. 1 linear slide and a No. 2 linear slide are respectively installed on the upper and lower parts of the inner side of the monitoring frame. A No. 3 linear slide is installed on the slider, and the No. 3 linear slide is arranged perpendicular to the No. 1 linear slide. A pulse laser excitation probe is installed on the slider of the No. 3 linear slide, and a TWM monitoring probe is installed on the slider of the No. 2 linear slide. The TWM monitoring probe is connected to the console for processing the signal received by the TWM monitoring probe. The console is also connected to the No. 1 linear slide, the No. 2 linear slide, the No. 3 linear slide and the pulse laser excitation probe for controlling the operation of the No. 1 linear slide, the No. 2 linear slide, the No. 3 linear slide and the pulse laser excitation probe.

[0007] Furthermore, the low-position tensioning module and the high-position tensioning module have the same structure but different size specifications. The low-position tensioning module includes two low-position tensioning frames symmetrically arranged on the left and right, and a low-position slider is slidingly arranged inside the low-position tensioning frame. A low-position tensioning roller is rotatably installed between the two low-position sliders. A limiting screw is fixedly connected to the upper end of the low-position slider, and a limiting nut is threadedly connected to the limiting screw. The limiting nut is rotatably installed on the low-position tensioning frame, and the limiting screw is raised and lowered by rotating the limiting nut, thereby realizing the adjustment of the position of the low-position slider.

[0008] Furthermore, the lead screws of the No. 1 linear slide and the No. 2 linear slide pass through the monitoring frame and are respectively connected to the commutation output shaft of the T-type commutator and the commutation output shaft of the L-type commutator. The T-type commutator and the L-type commutator are both installed on one side of the monitoring frame. The input shaft of the T-type commutator is connected to the output shaft of the synchronous drive motor. The synchronous drive motor is installed on the monitoring frame. The input shaft of the L-type commutator is connected to the parallel output shaft of the T-type commutator through a detachable sleeve.

[0009] Furthermore, a fixing plate is fixedly connected to the inner side of the monitoring frame by bolts, two fixing bases are fixedly installed on the fixing plate by screws, a support rod is fixedly connected to the fixing base, a fixing frame is provided at the other end of the support rod, and an aperture is installed on the fixing frame.

[0010] Furthermore, a plurality of threaded connection holes are evenly distributed on the fixing plate to facilitate adjustment of the position of the fixing base.

[0011] Furthermore, a 3-RPS parallel mechanism is installed on the slider of the second linear slide, and the TWM monitoring probe is installed on the top plate of the 3-RPS parallel mechanism.

[0012] A method for monitoring the continuous annealing state of cold-rolled strip steel based on laser ultrasound comprises the following steps:

[0013] Step 1: Start the synchronous drive motor and move the TWM monitoring probe to the bottom of the strip. Adjust the inclination angle of the TWM monitoring probe through the 3-RPS parallel mechanism so that the continuous laser emitted by the TWM monitoring probe is perpendicular to the strip surface. At the same time, adjust the height of the TWM monitoring probe through the 3-RPS parallel mechanism so that the continuous laser emitted by the TWM monitoring probe is focused on the strip surface.

[0014] Step 2. After the TWM monitoring probe is adjusted, start the synchronous drive motor and move the pulse laser excitation probe and the TWM monitoring probe to the side close to the aperture for centering. Cover the lens of the pulse laser excitation probe with a lens cap, adjust the aperture to the minimum, and adjust the aperture position so that the continuous laser emitted by the TWM monitoring probe can pass through the two apertures. According to the principle that two points determine a straight line, the straight line determined by the aperture is the optical path of the continuous laser. Cover the lens of the TWM monitoring probe with a lens cap, remove the lens cap on the pulse laser excitation probe, and remove the bushing between the T-shaped commutator and the L-shaped commutator. At this time, the power of the synchronous drive motor cannot be transmitted to the L-shaped commutator and can only control the movement of the pulse laser excitation probe. Use the No. 1 and No. 3 linear slides to adjust the position of the pulse laser excitation probe in the horizontal plane. At the same time, use the angle fine-tuning function of the pulse laser excitation probe to adjust the inclination angle of the pulse laser until the pulse laser can pass through the two apertures at the same time. At this time, the optical paths of the pulse laser excitation probe and the TWM monitoring probe are on the same straight line, and the centering is completed.

[0015] Step 3: Install the sleeve between the T-shaped commutator and the L-shaped commutator, cover the lens of the pulsed laser excitation probe with the lens cap, and remove the lens cap on the TWM monitoring probe;

[0016] Step 4: Start the synchronous drive motor, and the pulse laser excitation probe and the TWM monitoring probe begin to move synchronously. The step distance of the probe is dx. When the continuous laser just hits the strip, the coordinate at this time is recorded as x1. Continue moving. When the continuous laser just leaves the strip, the coordinate at this time is recorded as x2. Move the pulse laser excitation probe and the TWM monitoring probe to the x1 position, and remove the lens cover on the pulse laser excitation probe.

[0017] Step 5: Start the detection. To prevent the lasers emitted by the pulse laser excitation probe and the TWM monitoring probe from colliding and damaging the equipment, limit the movement range of the pulse laser excitation probe and the TWM monitoring probe to (x1, x2-dx). Start the TWM monitoring probe, focus the continuous laser on one side of the strip, start the pulse laser excitation probe, focus the pulse laser on the other side of the strip, align the continuous laser and the pulse laser coaxially, drive the pulse laser excitation probe and the TWM monitoring probe to move synchronously in the horizontal direction through the synchronous drive motor, and record the strip signal detected each time.

[0018] Step 6: receiving the recorded strip steel signal, processing and analyzing the strip steel signal to obtain the annealing state information of the strip steel;

[0019] Step 7: As the strip continues to be fed, repeat steps 5 and 6 until the annealing status monitoring of the entire strip is completed.

[0020] Furthermore, the step 6 specifically includes the following steps:

[0021] Step 6.1, receiving the recorded strip steel signal;

[0022] Step 6.2: Use a Butterworth filter to filter the strip signal to remove noise signals. The filter frequency range is 2-100 MHz.

[0023] Step 6.3, perform variational modal decomposition on the strip signal:

[0024] ;

[0025] in f is the input strip signal, To find the derivative symbol, is the Hilbert transform, t is the time independent variable, u k is the kth modal component function after strip signal decomposition, is the base of natural logarithms, is an imaginary number, ω k is the modal center frequency of the kth modal component function, k=1, 2…M, M is the set mode number;

[0026] The initial value M=1, for the signal f Decompose and obtain the decomposition signal u k , calculate the kurtosis value corresponding to this decomposition Q M , the kurtosis value calculation formula is:

[0027] ;

[0028] in N k is the number of sample points of the kth modal component function, n k is the sample point variable of the kth modal component function, x k is the time domain sequence of the kth modal component function, which is represented by the modal component function u k Calculated, is the mean of the time domain series of the kth modal component function, is the standard deviation of the time domain series of the kth modal component function;

[0029] Step 6.4, change the set mode number, take M=M+1, repeat step 6.3 to get the kurtosis value after changing the set mode number Q M , when M=P, the loop is terminated and the next step is entered. P is the maximum set mode number, and P kurtosis values can be obtained in the end;

[0030] Step 6.5, according to the maximum kurtosis principle, take the kurtosis value Q M The modal number M corresponding to the maximum is the optimal modal number M q , take M= M q , perform variational mode decomposition and obtain M q Modal component function after group decomposition u k , and the corresponding modal center frequency ω k , remove the two groups ω k The modal component function with the largest value u k , the residual mode component function u k Merge, and then perform complex Morlet wavelet transform with a bandwidth parameter of 3 and a center frequency of 3:

[0031] ;

[0032] in, is the scale of wavelet transform, is the translation of the wavelet transform; the time spectrum WN obtained by complex Morlet wavelet transform is analyzed. The frequency corresponding to the signal with the largest amplitude in the time spectrum WN is the center frequency. According to the analysis results, the relationship between the grain size of the target strip material and the center frequency in the time spectrum WN is calibrated to determine the lower cutoff frequency of the strip material in the normal annealing state. f1 and upper cutoff frequency f 2 , if the center frequency is f 1 and f 2 It is normal if the center frequency is less than or equal to f 1 For over-annealing state, if the center frequency is greater than or equal to f 2 Under-annealed state.

[0033] Compared with the prior art, the present invention has the following advantages:

[0034] The present invention realizes online, non-destructive and real-time monitoring of the grain size of the steel strip through laser ultrasonic technology, without contacting the surface of the steel strip, thus avoiding damage to the surface of the steel strip; it can monitor the change of grain size in real time, and then adjust the annealing process parameters in time, improve the yield rate of steel strip forming, and avoid the waste of the entire roll of steel strip material due to unqualified annealing, which cannot be solved by offline methods; and the laser ultrasonic technology has a high spatial resolution, can accurately measure the grain size, and monitor the annealing state of the steel strip through the pre-calibrated upper cutoff frequency and lower cutoff frequency of the steel strip material, is suitable for steel strips of different thicknesses and widths, and has good environmental adaptability.

[0035] The TWM monitoring probe of the present invention is installed on a 3-RPS parallel mechanism, which can realize adjustment of three degrees of freedom and automatic adjustment of the probe posture. At the same time, the present application is equipped with two apertures, which assist the centering of the pulse laser excitation probe and the TWM monitoring probe through the apertures, thereby realizing high-precision coaxial centering adjustment of the optical path.

[0036] The present invention can realize the synchronous movement of the No. 1 linear slide and the No. 2 linear slide through the T-type commutator and the L-type commutator. At the same time, when adjustment is needed, the shaft sleeve can also be disassembled to realize the individual adjustment of the pulse laser excitation probe position.

[0037] The present invention performs variational modal decomposition on the one-dimensional ultrasonic signal of the strip to filter out the noise signal, then performs wavelet transform analysis to extract features, realizes online characterization of the grain size based on the eigenvalues, and achieves online monitoring of the annealing state of the strip. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 It is a structural schematic diagram of the present invention;

[0039] Figure 2 This is a schematic structural diagram of the low-position tensioning module of the present invention;

[0040] Figure 3 It is a structural diagram of the monitoring component of the present invention;

[0041] Figure 4 It is a structural schematic diagram of the fixing plate of the present invention;

[0042] In the figure, there are low-position tensioning module 1, high-position tensioning module 2, monitoring assembly 3, low-position tensioning frame 101, low-position slider 102, low-position tensioning roller 103, limiting screw 104, limiting nut 105, monitoring frame 301, linear slide No. 1 302, linear slide No. 2 303, linear slide No. 304, pulse laser excitation probe 305, TWM monitoring probe 306, sleeve 307, T-type commutator 308, L-type commutator 309, synchronous drive motor 310, fixing plate 311, fixing base 312, support rod 313, fixing frame 314, aperture 315, threaded connection hole 316, 3-RPS parallel mechanism 317. DETAILED DESCRIPTION

[0043] In order to further illustrate the technical solution of the present invention, the present invention is further described below through examples.

[0044] like Figures 1 to 4As shown, a continuous annealing state monitoring device for cold-rolled strip steel based on laser ultrasound comprises two low-position tensioning modules 1, two high-position tensioning modules 2 and a monitoring component 3 installed behind the annealing heating furnace. The two high-position tensioning modules 2 are respectively located in front of and behind the monitoring component 3, and the two low-position tensioning modules 1 are respectively located on the outside of the two high-position tensioning modules 2. The tensioning of the strip steel is achieved by the cooperation of the low-position tensioning module 1 and the high-position tensioning module 2. The monitoring component 3 comprises a monitoring frame 301. A No. 1 linear slide 302 and a No. 2 linear slide 303 are respectively installed on the upper and lower parts of the inner side of the monitoring frame 301. The No. 1 linear slide The lead screws of 302 and the second linear slide 303 pass through the monitoring frame 301 and are connected to the commutation output shaft of the T-type commutator 308 and the commutation output shaft of the L-type commutator 309 respectively. The T-type commutator 308 and the L-type commutator 309 are both installed on one side of the monitoring frame 301. The input shaft of the T-type commutator 308 is connected to the output shaft of the synchronous drive motor 310. The synchronous drive motor 310 is installed on the monitoring frame 301. The input shaft of the L-type commutator 309 is connected to the parallel output shaft of the T-type commutator 308 through a detachable shaft sleeve 307. The third linear slide is installed on the slider of the first linear slide 302. The third linear slide 304 is arranged perpendicular to the first linear slide 302. A pulse laser excitation probe 305 is installed on the slider of the third linear slide 304. A 3-RPS parallel mechanism 317 is installed on the slider of the second linear slide 303. The TWM monitoring probe 306 is installed on the top plate of the 3-RPS parallel mechanism 317. The TWM monitoring probe 306 is connected to the console for processing the signal received by the TWM monitoring probe 306. The console is also connected to the first linear slide 302, the second linear slide 303, the third linear slide 304 and the pulse laser excitation probe 305. , used to control the operation of linear slide No. 1 302, linear slide No. 2 303, linear slide No. 304 and pulse laser excitation probe 305. A fixing plate 311 is fixedly connected to the inner side of the monitoring frame 301 by bolts, and two fixing bases 312 are fixedly installed on the fixing plate 311 by screws. A support rod 313 is fixedly connected to the fixing base 312, and a fixing frame 314 is provided at the other end of the support rod 313. An aperture 315 is installed on the fixing frame 314. A plurality of threaded connection holes 316 are equidistantly distributed on the fixing plate 311 to facilitate the adjustment of the position of the fixing base 312.

[0045] The low-position tensioning module 1 and the high-position tensioning module 2 have the same structure but different dimensions. The low-position tensioning module 1 includes two low-position tensioning frames 101 symmetrically arranged on the left and right. A low-position slider 102 is slidingly arranged inside the low-position tensioning frame 101, and a low-position tensioning roller 103 is rotatably installed between the two low-position sliders 102. A limiting screw 104 is fixedly connected to the upper end of the low-position slider 102, and a limiting nut 105 is threadedly connected to the limiting screw 104. The limiting nut 105 is rotatably installed on the low-position tensioning frame 101, and the limiting screw 104 is raised and lowered by rotating the limiting nut 105, thereby realizing the adjustment of the position of the low-position slider 102.

[0046] A method for monitoring the continuous annealing state of cold-rolled strip steel based on laser ultrasound comprises the following steps:

[0047] Step 1: Start the synchronous drive motor 310 to move the TWM monitoring probe 306 to the bottom of the strip. Adjust the inclination angle of the TWM monitoring probe 306 through the 3-RPS parallel mechanism 317 so that the continuous laser emitted by the TWM monitoring probe 306 is perpendicular to the strip surface. At the same time, adjust the height of the TWM monitoring probe 306 through the 3-RPS parallel mechanism 317 so that the continuous laser emitted by the TWM monitoring probe 306 is focused on the strip surface.

[0048] Step 2: After the TWM monitoring probe 306 is adjusted, start the synchronous drive motor 310, move the pulse laser excitation probe 305 and the TWM monitoring probe 306 to the side close to the aperture 315, and align them; cover the lens of the pulse laser excitation probe 305 with a lens cap, adjust the aperture 315 to the minimum, and adjust the position of the aperture 315 so that the continuous laser emitted by the TWM monitoring probe 306 can pass through the two apertures 315. According to the principle that two points determine a straight line, the straight line determined by the aperture 315 is the optical path of the continuous laser. Cover the lens of the TWM monitoring probe 306 with a lens cap, remove the pulse laser excitation probe 305, and remove the pulse laser excitation probe 305. Remove the lens cover on the lens cover and remove the sleeve 307 between the T-shaped commutator 308 and the L-shaped commutator 309. At this time, the power of the synchronous drive motor 310 cannot be transmitted to the L-shaped commutator 309, and can only control the movement of the pulse laser excitation probe 305. Use the No. 1 linear slide 302 and the No. 3 linear slide 304 to adjust the position of the pulse laser excitation probe 305 in the horizontal plane. At the same time, use the angle fine-tuning function of the pulse laser excitation probe 305 to adjust the tilt angle of the pulse laser until the pulse laser can pass through the two apertures 315 at the same time. At this time, the optical paths of the pulse laser excitation probe 305 and the TWM monitoring probe 306 are on the same straight line, and the centering is completed.

[0049] Step 3: Install the shaft sleeve 307 between the T-shaped commutator 308 and the L-shaped commutator 309, cover the lens of the pulse laser excitation probe 305 with a lens cover, and remove the lens cover on the TWM monitoring probe 306;

[0050] Step 4: Start the synchronous drive motor 310, and the pulse laser excitation probe 305 and the TWM monitoring probe 306 begin to move synchronously. The step distance of the probe is dx. When the continuous laser just hits the strip, the coordinate at this time is recorded as x1. Continue moving. When the continuous laser just leaves the strip, the coordinate at this time is recorded as x2. Move the pulse laser excitation probe 305 and the TWM monitoring probe 306 to the x1 position, and remove the lens cover on the pulse laser excitation probe 305.

[0051] Step 5: Start detection. To prevent the lasers emitted by the pulse laser excitation probe 305 and the TWM monitoring probe 306 from colliding and damaging the equipment, the movement range of the pulse laser excitation probe 305 and the TWM monitoring probe 306 is limited to (x1, x2-dx). The TWM monitoring probe 306 is started, and the continuous laser is focused on one side of the strip. The pulse laser excitation probe 305 is started, and the pulse laser is focused on the other side of the strip. The continuous laser and the pulse laser are coaxially aligned. The pulse laser excitation probe 305 and the TWM monitoring probe 306 are driven by the synchronous drive motor 310 to move synchronously in the horizontal direction, and the strip signal detected each time is recorded.

[0052] Step 6: receiving the recorded strip steel signal, processing and analyzing the strip steel signal to obtain the annealing state information of the strip steel;

[0053] Step 7: As the strip continues to be fed, repeat steps 5 and 6 until the annealing status monitoring of the entire strip is completed.

[0054] Furthermore, the step 6 specifically includes the following steps:

[0055] Step 6.1, receiving the recorded strip steel signal;

[0056] Step 6.2: Use a Butterworth filter to filter the strip signal to remove noise signals. The filter frequency range is 2-100 MHz.

[0057] Step 6.3, perform variational modal decomposition on the strip signal:

[0058] ;

[0059] in f is the input strip signal, To find the derivative symbol, is the Hilbert transform, t is the time independent variable, uk is the kth modal component function after strip signal decomposition, is the base of natural logarithms, is an imaginary number, ω k is the modal center frequency of the kth modal component function, k=1, 2…M, M is the set mode number;

[0060] The initial value M=1, for the signal f Decompose and obtain the decomposition signal u k , calculate the kurtosis value corresponding to this decomposition Q M , the kurtosis value calculation formula is:

[0061] ;

[0062] in N k is the number of sample points of the kth modal component function, n k is the sample point variable of the kth modal component function, x k is the time domain sequence of the kth modal component function, which is represented by the modal component function u k Calculated, is the mean of the time domain series of the kth modal component function, is the standard deviation of the time domain series of the kth modal component function;

[0063] Step 6.4, change the set mode number, take M=M+1, repeat step 6.3 to get the kurtosis value after changing the set mode number Q M , when M=P, the loop is terminated and the next step is entered. P is the maximum set mode number, and P kurtosis values can be obtained in the end;

[0064] Step 6.5, according to the maximum kurtosis principle, take the kurtosis value Q M The modal number M corresponding to the maximum is the optimal modal number M q , take M= M q , perform variational mode decomposition and obtain M q Modal component function after group decomposition u k , and the corresponding modal center frequency ω k , remove the two groups ω k The modal component function with the largest value uk , the residual mode component function u k Merge, and then perform complex Morlet wavelet transform with a bandwidth parameter of 3 and a center frequency of 3:

[0065] ;

[0066] in, is the scale of wavelet transform, is the translation of the wavelet transform; the time spectrum WN obtained by complex Morlet wavelet transform is analyzed. The frequency corresponding to the signal with the largest amplitude in the time spectrum WN is the center frequency. According to the analysis results, the relationship between the grain size of the target strip material and the center frequency in the time spectrum WN is calibrated to determine the lower cutoff frequency of the strip material in the normal annealing state. f 1 and upper cutoff frequency f 2 , if the center frequency is f 1 and f 2 It is normal if the center frequency is less than or equal to f 1 For over-annealing state, if the center frequency is greater than or equal to f 2 Under-annealed state.

[0067] The foregoing shows and describes the principal features and advantages of the present invention. It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above and that the present invention can be embodied in other specific forms without departing from the spirit or essential characteristics of the present invention. Therefore, the embodiments should be considered in all respects as illustrative and non-restrictive, and the scope of the present invention is defined by the appended claims, not the foregoing description, and all variations that come within the meaning and range of equivalents of the claims are intended to be embraced therein.

[0068] In addition, it should be understood that although this specification is described in terms of implementation methods, not every implementation method contains only one independent technical solution. This narrative method of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment can also be appropriately combined to form other implementation methods that can be understood by those skilled in the art.

Claims

1. A method for monitoring the continuous annealing state of cold-rolled strip steel based on laser ultrasound, which uses a device for monitoring the continuous annealing state of cold-rolled strip steel based on laser ultrasound, is characterized by: A continuous annealing state monitoring device for cold-rolled strip steel based on laser ultrasound comprises two low-position tensioning modules (1), two high-position tensioning modules (2) and a monitoring component (3) installed behind an annealing heating furnace, wherein the two high-position tensioning modules (2) are respectively located in front of and behind the monitoring component (3), and the two low-position tensioning modules (1) are respectively located outside the two high-position tensioning modules (2). The tensioning of the strip steel is achieved by the cooperation of the low-position tensioning modules (1) and the high-position tensioning modules (2). The monitoring component (3) comprises a monitoring frame (301), wherein a first linear slide (302) and a second linear slide (303) are respectively installed on the upper and lower parts of the inner side of the monitoring frame (301). The first linear slide (302) is provided with a plurality of linear slides, wherein the ... ) and the lead screws of the second linear slide (303) pass through the monitoring frame (301) and are respectively connected to the commutation output shaft of the T-type commutator (308) and the commutation output shaft of the L-type commutator (309), the T-type commutator (308) and the L-type commutator (309) are both installed on one side of the monitoring frame (301), the input shaft of the T-type commutator (308) is connected to the output shaft of the synchronous drive motor (310), the synchronous drive motor (310) is installed on the monitoring frame (301), the input shaft of the L-type commutator (309) is connected to the parallel output shaft of the T-type commutator (308) through a detachable sleeve (307), and the third linear slide ( 304), the third linear slide (304) is arranged perpendicular to the first linear slide (302), a pulse laser excitation probe (305) is installed on the slider of the third linear slide (304), a 3-RPS parallel mechanism (317) is installed on the slider of the second linear slide (303), a TWM monitoring probe (306) is installed on the top plate of the 3-RPS parallel mechanism (317), the TWM monitoring probe (306) is connected to the console for processing the signal received by the TWM monitoring probe (306), and the console is also connected to the first linear slide (302), the second linear slide (303), the third linear slide (304) and the pulse laser excitation probe (305) for controlling A linear slide No. 1 (302), a linear slide No. 2 (303), a linear slide No. 3 (304) and a pulse laser excitation probe (305) are made to work; a fixing plate (311) is fixedly connected to the inner side of the monitoring frame (301) by bolts, two fixing bases (312) are fixedly installed on the fixing plate (311) by screws, a support rod (313) is fixedly connected to the fixing base (312), a fixing frame (314) is provided at the other end of the support rod (313), an aperture (315) is installed on the fixing frame (314), and a plurality of threaded connection holes (316) are equidistantly distributed on the fixing plate (311) to facilitate adjustment of the position of the fixing base (312); The low-position tensioning module (1) and the high-position tensioning module (2) have the same structure but different size specifications. The low-position tensioning module (1) comprises two low-position tensioning frames (101) symmetrically arranged on the left and right. A low-position slider (102) is slidably arranged inside the low-position tensioning frame (101). A low-position tensioning roller (103) is rotatably installed between the two low-position sliders (102). A limiting screw (104) is fixedly connected to the upper end of the low-position slider (102). A limiting nut (105) is threadedly connected to the limiting screw (104). The limiting nut (105) is rotatably installed on the low-position tensioning frame (101). The limiting screw (104) is lifted and lowered by rotating the limiting nut (105), thereby adjusting the position of the low-position slider (102). The method for monitoring the continuous annealing state of cold-rolled strip steel comprises the following steps: Step 1, start the synchronous drive motor (310), move the TWM monitoring probe (306) to the bottom of the strip, adjust the inclination angle of the TWM monitoring probe (306) by the 3-RPS parallel mechanism (317), so that the continuous laser emitted by the TWM monitoring probe (306) is perpendicular to the strip surface, and at the same time adjust the height of the TWM monitoring probe (306) by the 3-RPS parallel mechanism (317), so that the continuous laser emitted by the TWM monitoring probe (306) is focused on the strip surface; Step 2: After the adjustment of the TWM monitoring probe (306) is completed, the synchronous drive motor (310) is started, and the pulse laser excitation probe (305) and the TWM monitoring probe (306) are moved to the side close to the aperture (315) for centering; the lens of the pulse laser excitation probe (305) is covered with a lens cover, the aperture of the aperture (315) is adjusted to the minimum, and the position of the aperture (315) is adjusted so that the continuous laser emitted by the TWM monitoring probe (306) can pass through the two apertures (315). According to the principle that two points determine a straight line, the straight line determined by the aperture (315) is the optical path of the continuous laser. The lens of the TWM monitoring probe (306) is covered with a lens cover, and the pulse laser excitation probe (305) is removed. The lens cover on the lens cover is removed, and the sleeve (307) between the T-shaped commutator (308) and the L-shaped commutator (309) is removed. At this time, the power of the synchronous drive motor (310) cannot be transmitted to the L-shaped commutator (309), and it can only control the movement of the pulse laser excitation probe (305). The position of the pulse laser excitation probe (305) in the horizontal plane is adjusted by the No. 1 linear slide (302) and the No. 3 linear slide (304). At the same time, the angle fine-tuning function of the pulse laser excitation probe (305) is used to adjust the tilt angle of the pulse laser until the pulse laser can pass through the two apertures (315) at the same time. At this time, the optical paths of the pulse laser excitation probe (305) and the TWM monitoring probe (306) are on the same straight line, and the centering is completed; Step 3, install the shaft sleeve (307) between the T-shaped commutator (308) and the L-shaped commutator (309), cover the lens of the pulse laser excitation probe (305) with a lens cover, and remove the lens cover on the TWM monitoring probe (306); Step 4, start the synchronous drive motor (310), the pulse laser excitation probe (305) and the TWM monitoring probe (306) start to move synchronously, the step distance of the probe is dx, when the continuous laser just hits the strip, the coordinate at this time is recorded as x1, continue to move, when the continuous laser just leaves the strip, the coordinate at this time is recorded as x2, move the pulse laser excitation probe (305) and the TWM monitoring probe (306) to the x1 position, and remove the lens cover on the pulse laser excitation probe (305); Step 5, start detection. To prevent the lasers emitted by the pulse laser excitation probe (305) and the TWM monitoring probe (306) from colliding and damaging the equipment, the moving range of the pulse laser excitation probe (305) and the TWM monitoring probe (306) is limited to (x1, x2-dx). The TWM monitoring probe (306) is started, and the continuous laser is focused on one side of the strip. The pulse laser excitation probe (305) is started, and the pulse laser is focused on the other side of the strip. The continuous laser and the pulse laser are coaxially aligned. The pulse laser excitation probe (305) and the TWM monitoring probe (306) are driven by the synchronous drive motor (310) to move synchronously in the transverse direction, and each monitored strip signal is recorded. Step 6: receiving the recorded strip steel signal, processing and analyzing the strip steel signal to obtain the annealing state information of the strip steel; Step 7: As the strip continues to be fed, repeat steps 5 and 6 until the annealing status monitoring of the entire strip is completed.

2. The method for monitoring the continuous annealing state of cold-rolled strip steel based on laser ultrasound according to claim 1, characterized in that: The step 6 specifically includes the following steps: Step 6.1, receiving the recorded strip steel signal; Step 6.2: Use a Butterworth filter to filter the strip signal to remove noise signals. The filter frequency range is 2-100 MHz. Step 6.3, perform variational modal decomposition on the strip signal: ； in f is the input strip signal, To find the derivative symbol, is the Hilbert transform, t is the time independent variable, u k is the kth modal component function after strip signal decomposition, is the base of natural logarithms, is an imaginary number, ω k is the modal center frequency of the kth modal component function, k=1, 2…M, M is the set mode number; The initial value M=1, for the signal f Decompose and obtain the decomposition signal u k , calculate the kurtosis value corresponding to this decomposition Q M , the kurtosis value calculation formula is: ； in N k is the number of sample points of the kth modal component function, n k is the sample point variable of the kth modal component function, x k is the time domain sequence of the kth modal component function, which is represented by the modal component function u k Calculated, is the mean of the time domain series of the kth modal component function, is the standard deviation of the time domain series of the kth modal component function; Step 6.4, change the set mode number, take M=M+1, repeat step 6.3 to get the kurtosis value after changing the set mode number Q M , when M=P, the loop is terminated and the next step is entered. P is the maximum set mode number, and P kurtosis values can be obtained in the end; Step 6.5, according to the maximum kurtosis principle, take the kurtosis value Q M The modal number M corresponding to the maximum is the optimal modal number M q , take M= M q , perform variational mode decomposition and obtain M q Modal component function after group decomposition u k , and the corresponding modal center frequency ω k , remove the two groups ω k The modal component function with the largest value u k , the residual mode component function u k Merge, and then perform complex Morlet wavelet transform with a bandwidth parameter of 3 and a center frequency of 3: ； in, is the scale of wavelet transform, is the translation of the wavelet transform; the time spectrum WN obtained by complex Morlet wavelet transform is analyzed. The frequency corresponding to the signal with the largest amplitude in the time spectrum WN is the center frequency. According to the analysis results, the relationship between the grain size of the target strip material and the center frequency in the time spectrum WN is calibrated to determine the lower cutoff frequency of the strip material in the normal annealing state. f 1 and upper cutoff frequency f 2 , if the center frequency is f 1 and f 2 It is normal if the center frequency is less than or equal to f 1 For over-annealing state, if the center frequency is greater than or equal to f 2 Under-annealed state.

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