Non-contact online measurement system and measurement method for residual stress of cold-rolled sheet

Abstract

The invention discloses a non-contact online measurement system and method for residual stress of a cold-rolled sheet. The supporting roller, the transmitting measuring roller assembly, the receiving measuring roller assembly and the curling roller are all installed on the bottom supporting frame, the bottom supporting frame is placed on the workbench, one end of a to-be-measured cold-rolled sheet is installed on the supporting roller and sequentially wound around a transmitting ceramic roller of the transmitting measuring roller assembly and a receiving ceramic roller of the receiving measuring roller assembly, and then the other end of the to-be-measured cold-rolled sheet is installed on the curling roller. Guided wave transducers are arranged in the transmitting measuring roller assembly and the receiving measuring roller assembly, and wireless transmission modules in the guided wave transducers are electrically connected with the industrial personal computer. The defect that contact measurement is needed in a traditional measurement method is overcome, damage to the surface of the cold-rolled sheet is reduced, the measurement accuracy and stability are improved, real-time online monitoring and control over the residual stress of the cold-rolled sheet in the industrial production process can be achieved, the intelligence and automation level of a production line is improved, and the production efficiency is improved. The production cost is reduced and the competitiveness is enhanced.

Description

Technical Field

[0001] The invention belongs to the technical field of engineering measurement, and in particular relates to a non-contact online measurement system and a measurement method for residual stress of a cold-rolled plate. Background Art

[0002] The cold-rolled sheet residual stress measurement system can be widely used in the field of thin strip production, especially in production scenarios with high requirements for the flatness of cold-rolled thin sheets such as automotive steel sheets, tin-plated steel sheets, silicon steel sheets, and aviation aluminum sheets. In these fields, plate shape is an important quality indicator of high-precision cold-rolled strip steel. Plate shape control is a key technology, core technology, and high-difficulty technology in the field of plate and strip rolling, and residual stress is one of the important factors affecting the quality of plate shape. In the current cold-rolled strip production process, it is very important to accurately measure the residual stress of the strip, because the residual stress will affect the flatness and deformation of the strip, and thus affect the quality of the product. The commonly used measurement method is to use contact measurement equipment, such as the ABB plate shape meter. During the rolling process, the measuring roller contacts the strip to generate tensile stress. When the electromagnetic sensor contacts the strip, it generates excitation and outputs the corresponding electromagnetic signal. The size of the signal reflects the size of the tensile stress generated by the strip on the measuring roller, and then characterizes the residual stress size and flatness of the cold-rolled sheet being measured. However, this contact measurement method has certain disadvantages, such as being greatly affected by interference, poor stability, and causing damage to the material surface.

[0003] Traditional cold-rolled sheet residual stress measurement methods mainly include contact measurement methods and non-contact measurement methods. The following are some disadvantages of traditional contact measurement methods: 1. Contact measurement method based on pressure sensor: This method sets a pressure sensor on a roller and calculates the axial stress by measuring the normal stress of the steel plate. However, since the contact measurement method requires direct contact with the surface of the steel plate, it is affected by factors such as surface dirt, oil film, and oxide layer, which affects the accuracy of the measurement data. 2. Strain gauge method: The strain gauge method is a commonly used contact measurement method. The strain is measured by pasting strain gauges on the surface of the steel plate to indirectly calculate the residual stress. However, the pasting and removal process of the strain gauge is complicated, the operation is inconvenient, and it is easily affected by factors such as ambient temperature and surface treatment, which affects the accuracy of the measurement data. 3. X-ray diffraction method: The residual stress is measured by using the lattice deformation caused by the elastic scattering of X-rays. However, the disadvantages of this method are: the equipment is expensive and it is not convenient to measure online on the production line; the measurement process is cumbersome, it takes a long time to measure, and it is impossible to achieve fast measurement; in addition, this method measures the average stress, and there is no clear indication for the measurement of stress distribution. 4. Blind hole method: This method mainly changes the stress state by drilling holes on the sample, and then calculates the stress by measuring the deformation of the hole edge. The advantage of this method is that the depth distribution of stress can be measured, but the problem is that this method requires the destruction of the sample and is not suitable for online measurement; in addition, since both the drilling and deformation measurement processes take a certain amount of time, this method cannot be used for rapid measurement. 5. Vibrating wire strain detection method: Stress is calculated by measuring the frequency change of the steel wire surface strain gauge. The disadvantage is that it is inconvenient to install and can only detect the change in stress. 6. Magnetic detection method: Including magnetic strain method, magnetoacoustic emission method and metal magnetic memory method. The magnetic strain method uses the inverse magnetostrictive effect of ferromagnetic objects to detect stress and is suitable for ferromagnetic materials. Metal magnetic memory detection diagnoses defects and stress concentration areas by detecting the magnetic field distribution on the surface of the component. It is only suitable for ferromagnetic materials and can usually only be qualitatively detected.

[0004] In summary, the disadvantages of traditional measurement methods include: 1. Affected by external interference: The contact measurement method is easily affected by external vibrations, temperature changes and other factors, resulting in unstable measurement results. 2. Limited accuracy: The contact measurement equipment is in direct contact with the steel plate during the measurement process, which will be affected by surface conditions, such as surface wear or corrosion, affecting the measurement accuracy. 3. Easy to cause damage: Traditional measurement equipment needs to directly contact the surface of the steel plate for measurement, which may cause surface damage or scratches. It is a destructive test and affects product quality. 4. High maintenance cost: Contact measurement equipment requires frequent maintenance and replacement of sensors and other components during long-term use, which increases maintenance costs and cycles. Therefore, traditional contact and non-contact measurement methods have many shortcomings in terms of measurement accuracy, stability and ease of operation, which limits their application in the field of residual stress measurement of cold-rolled plates. Therefore, it is necessary to introduce a new non-contact online measurement system to solve these problems.

[0005] Traditional residual stress measurement methods cannot meet the needs of rapid, online, non-contact and comprehensive residual stress measurement in cold-rolled sheet production. In order to solve the problems of low accuracy, susceptibility to interference and easy damage to materials in contact measurement methods, some research institutions have begun to explore non-contact measurement methods in recent years. Non-contact measurement using laser technology has been successfully applied in other fields, but its application in the field of cold-rolled sheet production is relatively rare. Summary of the invention

[0006] In order to solve the problems existing in the background technology, the purpose of the present invention is to provide a non-contact online measurement system and method for residual stress of cold-rolled plate, aiming to solve the problems existing in the existing contact measurement method, realize accurate, stable and non-destructive online measurement of residual stress of plate and strip, and meet the needs of plate shape control on the production line.

[0007] The technical solution adopted by the present invention is as follows:

[0008] 1. A non-contact online measurement system for residual stress of cold rolled sheet:

[0009] It includes a supporting roller, a transmitting and measuring roller assembly, a receiving and measuring roller assembly, a curling roller, a bottom supporting frame and an industrial computer. The supporting roller, the transmitting and measuring roller assembly, the receiving and measuring roller assembly and the curling roller are all installed on the bottom supporting frame. The bottom supporting frame is placed on a workbench. One end of the cold-rolled plate to be tested is installed on the supporting roller, and the other end is installed on the curling roller after passing through the transmitting and measuring roller assembly and the receiving and measuring roller assembly in sequence. Waveguide transducers are provided in the transmitting and measuring roller assembly and the receiving and measuring roller assembly. The wireless transmission module in the waveguide transducer is electrically connected to the industrial computer.

[0010] The transmitting and measuring roller assembly comprises a transmitting ceramic roller and a transmitting sound wave transducer, and the receiving and measuring roller assembly comprises a receiving ceramic roller and a receiving sound wave transducer. Both the transmitting sound wave transducer and the receiving sound wave transducer are mainly composed of a plurality of waveguide transducers, and rolling bearings are arranged in the waveguide transducers. A rotating shaft is arranged in the middle of the supporting roller, the transmitting ceramic roller, the receiving ceramic roller and the winding roller, and the rotating shaft is connected to the top end of the bottom supporting frame, and the bottom end of the bottom supporting frame is connected to the workbench, and the rotating shafts of the transmitting ceramic roller and the receiving ceramic roller are connected to the rolling bearings in the waveguide transducer.

[0011] The waveguide transducer includes a wireless transmission module, a magnetic sheet, a permanent magnet, copper foil, iron powder cloth, a spiral electromagnetic coil, a fixed shell, a counterweight and a rolling bearing; the wireless transmission module, the magnetic sheet, the permanent magnet, copper foil, iron powder cloth, the spiral electromagnetic coil and the rolling bearing are all located in the fixed shell, the rolling bearing is installed on the inner top surface of the fixed shell, the counterweight is fixedly installed on the bottom end of the fixed shell, the wireless transmission module is electrically connected to the spiral electromagnetic coil, the magnetic sheet, the permanent magnet, copper foil, iron powder cloth and the spiral electromagnetic coil are stacked and connected in sequence along the radial direction of the waveguide transducer, the spiral electromagnetic coil is fixedly connected to the inner side wall of the fixed shell, and the industrial computer is connected to the mobile hotspot module in the wireless transmission module.

[0012] The wireless transmission module includes an ADC acquisition circuit, a signal filtering circuit, a signal amplifying circuit, a signal source circuit, a power amplifying circuit and a mobile hotspot module; the output end of the mobile hotspot module is connected to the input end of the spiral electromagnetic coil via the signal source circuit and the power amplifying circuit in sequence, and the output end of the spiral electromagnetic coil is connected to the input end of the mobile hotspot module via the signal amplifying circuit, the signal filtering circuit and the ADC acquisition circuit in sequence.

[0013] The bottom of the transmitting ceramic roller and the bottom of the waveguide transducer in the transmitting sound wave transducer have the same curvature, and the bottom of the receiving ceramic roller and the bottom of the waveguide transducer in the receiving sound wave transducer have the same curvature.

[0014] The transmitting sound wave transducer is mainly composed of a plurality of waveguide transducers evenly spaced along the axial direction of the transmitting ceramic roller, and the receiving sound wave transducer is mainly composed of a plurality of waveguide transducers evenly spaced along the axial direction of the receiving ceramic roller. The transmitting ceramic roller and the receiving ceramic roller are arranged in parallel.

[0015] The number and arrangement positions of the waveguide transducers in the transmitting sound wave transducer and the waveguide transducers in the receiving sound wave transducer are identical and aligned.

[0016] 2. A non-contact online measurement method for residual stress of cold-rolled sheet, comprising the following steps:

[0017] Step S1, firstly determine the number of waveguide transducers in the transmitting sound wave transducer and the receiving sound wave transducer according to the size of the cold-rolled sheet to be tested, and use two waveguide transducers in the transmitting sound wave transducer and the receiving sound wave transducer located in the same horizontal direction as a pair of waveguide transducers;

[0018] Step S2: Next, obtain the guided wave velocity v of the cold-rolled sheet to be tested under free boundary conditions. 0 ;

[0019] Step S3, using the wireless transmission module to control the spiral electromagnetic coil in the waveguide transducer, and then setting the waveguide signal excitation parameters of the transmitting sound wave transducer and the waveguide signal receiving parameters of the receiving sound wave transducer, so that N pairs of waveguide transducers are cyclically excited and receive the waveguide signal in turn, and the sampling rate of the waveguide signal is f 0 ;

[0020] Step S4, the N waveguide transducers in the transmitting sound wave transducer sequentially excite the waveguide signals, and the N waveguide transducers in the receiving sound wave transducer sequentially receive the corresponding waveguide signals excited by the N waveguide transducers in the corresponding transmitting sound wave transducers, thereby obtaining N waveguide signals;

[0021] Step S5, transmitting the N waveguide signals received by the N waveguide transducers in the receiving sound wave transducer to the industrial computer through the wireless transmission module, and using the industrial computer to obtain the number of sampling points of each waveguide signal from the transmitting sound wave transducer to the receiving sound wave transducer, and record it as g i , where g i represents the number of sampling points of the ith waveguide signal received by the ith pair of waveguide transducers;

[0022] Step S6: Finally, the residual stress of the cold-rolled sheet to be tested is obtained according to the number of sampling points of the waveguide signal, and the residual stress distribution result of the cold-rolled sheet to be tested is displayed by an industrial computer.

[0023] In step S6, the residual stress of the cold-rolled sheet to be measured is obtained by processing according to the following method:

[0024] σ i =(v i -v 0 ) / Ф

[0025] v i =(S×f 0 ) / g i

[0026] Ф=β / ρ

[0027] Among them, σ i represents the residual stress of the cold-rolled sheet to be tested in the i-th detection area, where the i-th detection area is specifically the sound wave propagation area covered by the i-th pair of guided wave transducers; vi represents the wave velocity of the i-th waveguide signal, Ф represents the acoustic propagation coefficient of the cold-rolled sheet to be tested; β represents the Young's modulus of the cold-rolled sheet to be tested; ρ represents the density of the cold-rolled sheet to be tested; S represents the distance between the transmitting acoustic wave transducer and the receiving acoustic wave transducer.

[0028] Preferably, the transmitting ceramic roller and the receiving ceramic roller are both hollow.

[0029] Preferably, the bottoms of the transmitting sound wave transducer and the receiving sound wave transducer are both arc-shaped, and there are gaps between them and the inner walls of the hollow transmitting ceramic roller and the receiving ceramic roller to ensure that there is no wear during the rotation process.

[0030] Preferably, the direction of the acoustic vector of the waveguide signal generated by the transmitting acoustic wave transducer is perpendicular to the surface of the transmitting ceramic roller.

[0031] Preferably, the conductor of the spiral electromagnetic coil is an enameled wire.

[0032] Preferably, both the transmitting sound wave transducer and the receiving sound wave transducer are mechanically connected to the rotating shaft through rolling bearings. At the same time, a counterweight block is designed inside the waveguide transducer to ensure that the waveguide transducer does not rotate with the corresponding transmitting ceramic roller / receiving ceramic roller, thereby ensuring that the sound vector direction of the waveguide signal is perpendicular to the surface of the transmitting ceramic roller, thereby improving the stability, signal-to-noise ratio and reliability of the waveguide signal.

[0033] The present invention solves the defect of the traditional measurement method that requires contact measurement, reduces the damage to the surface of the cold-rolled plate, and improves the accuracy and stability of the measurement, which helps to realize the real-time online monitoring and control of the residual stress of the cold-rolled plate in the industrial production process, improves the intelligence and automation level of the production line, reduces production costs and enhances competitiveness.

[0034] Through the non-contact online measurement system of the present invention, manufacturers can monitor and control the residual stress of cold-rolled plates in real time, so as to timely discover and solve problems that may affect the quality of plate shape, and improve production efficiency and product quality. The system can help production enterprises achieve precise plate shape control, reduce production costs, improve product competitiveness, and meet the market and customer demand for high-quality cold-rolled thin plates. To this end, the design of a non-contact online measurement system for residual stress of cold-rolled plates of the present invention has important practical significance and engineering application value.

[0035] The beneficial effects of the present invention are:

[0036] 1. The present invention adopts a total of N pairs of waveguide transducers for receiving and for transmitting, thereby dividing the cold-rolled plate to be tested into N regions in the transverse direction (width direction), and finally obtaining N residual stresses, which correspond to the residual stresses of the N regions of the cold-rolled plate to be tested, and has a higher lateral resolution of residual stress, so as to more accurately obtain the detailed distribution of the residual stress of the cold-rolled plate to be tested, and provide important key and accurate information for the subsequent determination of the flatness of the backing cold-rolled plate according to the residual stress.

[0037] 2. The present invention is an online non-contact measurement system. Compared with the traditional offline, contact measurement system, it has better real-time and non-destructive detection characteristics, and is more suitable for and meets the online, high real-time and non-destructive detection requirements of the industry. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 This is a structural block diagram of the non-contact online measurement system for residual stress of cold-rolled plates of the present invention;

[0039] Figure 2 It is a top view of a non-contact online measurement system for residual stress of cold-rolled plates of the present invention;

[0040] Figure 3 It is a schematic diagram of the composition of a transmitting (receiving) acoustic wave transducer of a non-contact online measurement system for residual stress of a cold-rolled plate according to the present invention;

[0041] Figure 4 This is a block diagram of the connection between the transmitting (receiving) acoustic wave transducer and the spiral electromagnetic coil of a non-contact online measurement system for residual stress of cold-rolled plates of the present invention;

[0042] Figure 5 It is a flow chart of a non-contact online measurement system for residual stress of cold-rolled plate of the present invention;

[0043] Figure 6 The present invention is a schematic diagram of N detection areas of N pairs of receiving acoustic wave transducers and transmitting acoustic wave transducers in a non-contact online measurement system for residual stress of cold-rolled plates.

[0044] In the figure: 1-support roller; 2-cold-rolled plate to be tested; 3-transmitting ceramic roller; 4-receiving ceramic roller; 5-transmitting sound wave transducer; 6-receiving sound wave transducer; 7-curling roller; 8-bottom support frame; 9-wireless transmission module; 10-magnetic conductive sheet; 11-permanent magnet; 12-copper foil; 13-iron powder cloth; 14-spiral electromagnetic coil; 15-fixed shell; 16-counterweight; 17-industrial computer; 18-rolling bearing; 19-rotating shaft. DETAILED DESCRIPTION

[0045] The present invention is described in detail below in conjunction with specific implementation cases. The following implementation cases will help those skilled in the art to further understand the present invention, but will not limit the present invention in any form.

[0046] like Figure 1 and Figure 2 As shown, the system includes a support roller 1, a transmitting and measuring roller assembly, a receiving and measuring roller assembly, a curling roller 7, a bottom support frame 8 and an industrial computer 17. The support roller 1, the transmitting and measuring roller assembly, the receiving and measuring roller assembly and the curling roller 7 are all installed on the bottom support frame 8, and the bottom support frame 8 is placed on a workbench. One end of the cold-rolled plate 2 to be measured is installed on the support roller 1, and the other end is installed on the curling roller 7 after passing through the transmitting ceramic roller 3 in the transmitting and measuring roller assembly and the receiving ceramic roller 4 in the receiving and measuring roller assembly in a U-shaped route. Both the transmitting and measuring roller assembly and the receiving and measuring roller assembly are provided with waveguide transducers, and the wireless transmission module 9 in the waveguide transducer is electrically connected to the industrial computer 17.

[0047] Specifically, the cold rolled sheet 2 to be tested is corrugated, and is respectively installed on the support roller 1 and the curling roller 7 at two adjacent wave crest positions, and is respectively installed on the transmitting measuring roller assembly and the receiving measuring roller assembly at two adjacent wave trough positions.

[0048] The transmitting and measuring roller assembly includes a transmitting ceramic roller 3 and a transmitting sound wave transducer 5, and the receiving and measuring roller assembly includes a receiving ceramic roller 4 and a receiving sound wave transducer 6. The transmitting sound wave transducer 5 and the receiving sound wave transducer 6 are mainly composed of a plurality of waveguide transducers. A rolling bearing 18 is arranged in the waveguide transducer. A rotating shaft 19 is arranged in the middle of the supporting roller 1, the transmitting ceramic roller 3, the receiving ceramic roller 4 and the winding roller 7. The rotating shafts 19 in the supporting roller 1, the transmitting ceramic roller 3, the receiving ceramic roller 4 and the winding roller 7 are all connected to the top end of the bottom support frame 8, and the bottom end of the bottom support frame 8 is connected to the workbench, and the rotating shafts 19 of the transmitting ceramic roller 3 and the receiving ceramic roller 4 are connected to the inner rings of the rolling bearings 18 in their respective corresponding waveguide transducers, so that the transmitting ceramic roller 3 / receiving ceramic roller 4 can rotate relative to the waveguide transducer.

[0049] Specifically, the axial directions of the supporting roller 1, the transmitting ceramic roller 3, the receiving ceramic roller 4 and the winding roller 7 are parallel to each other.

[0050] like Figure 3As shown, the waveguide transducer includes a wireless transmission module 9, a magnetic sheet 10, a permanent magnet 11, a copper foil 12, an iron powder cloth 13, a spiral electromagnetic coil 14, a fixed shell 15, a counterweight 16 and a rolling bearing 18; the wireless transmission module 9, the magnetic sheet 10, the permanent magnet 11, the copper foil 12, the iron powder cloth 13, the spiral electromagnetic coil 14 and the rolling bearing 18 are all located in the fixed shell 15, and the fixed shell 15 is provided with a hole for connecting the rolling bearing 18 with the rotating shaft 19 of the ceramic rollers 3 and 4, and the rolling bearing 18 is provided with a hole. The outer ring is installed on the inner top surface of the fixed shell 15, the counterweight 16 is fixedly installed on the bottom end of the fixed shell 15, the wireless transmission module 9 is electrically connected to the spiral electromagnetic coil 14, the magnetic conductive sheet 10, the permanent magnet 11, the copper foil paper 12, the iron powder cloth 13 and the spiral electromagnetic coil 14 are stacked and coupled in sequence from the inside to the outside along the radial direction of the waveguide transducer, the spiral electromagnetic coil 14 is fixedly connected to the inner wall of the fixed shell 15 through an epoxy coupling agent, and the industrial computer 17 is connected to the mobile hotspot module in the wireless transmission module 9.

[0051] The magnetic conductive sheet 10 , the permanent magnet 11 , the copper foil 12 and the iron powder cloth 13 are arranged between the wireless transmission module 9 and the spiral electromagnetic coil 14 .

[0052] like Figure 4 As shown, the wireless transmission module 9 includes an ADC acquisition circuit, a signal filtering circuit, a signal amplifying circuit, a signal source circuit, a power amplifying circuit and a mobile hotspot module (i.e., a 4G or 5G or WiFi wireless module); the output end of the mobile hotspot module is connected to the input end of the spiral electromagnetic coil 14 in sequence through the signal source circuit and the power amplifying circuit, and the output end of the spiral electromagnetic coil 14 is connected to the input end of the mobile hotspot module in sequence through the signal amplifying circuit, the signal filtering circuit and the ADC acquisition circuit.

[0053] The bottom of the transmitting ceramic roller 3 and the bottom of the waveguide transducer in the transmitting acoustic wave transducer 5 have the same curvature, and the bottom of the receiving ceramic roller 4 and the bottom of the waveguide transducer in the receiving acoustic wave transducer 6 have the same curvature.

[0054] The transmitting sound wave transducer 5 is mainly composed of a plurality of waveguide transducers evenly spaced along the axial direction of the transmitting ceramic roller 3, and the receiving sound wave transducer 6 is mainly composed of a plurality of waveguide transducers evenly spaced along the axial direction of the receiving ceramic roller 4. The transmitting ceramic roller 3 and the receiving ceramic roller 4 are arranged in parallel.

[0055] The number and arrangement positions of the waveguide transducers in the transmitting sound wave transducer 5 and the waveguide transducers in the receiving sound wave transducer 6 are the same, and the arrangement positions are aligned one by one in the horizontal direction.

[0056] The bottom of the transmitting acoustic wave transducer 5 and the receiving acoustic wave transducer 6 are both arc-shaped, the curvature of the bottom of the transmitting ceramic roller 3 and the transmitting acoustic wave transducer 5 is the same, the curvature of the bottom of the receiving ceramic roller 4 and the receiving acoustic wave transducer 6 is the same, the spacing between the counterweight block 16 at the bottom of the waveguide transducer in the transmitting acoustic wave transducer 5 and the transmitting ceramic roller 3 is 1mm to 4mm, the spacing between the counterweight block 16 at the bottom of the waveguide transducer in the receiving acoustic wave transducer 6 and the receiving ceramic roller 4 is 1mm to 4mm, and the thickness of the transmitting ceramic roller 3 and the receiving ceramic roller 4 are both 2mm to 3mm; the transmitting acoustic wave transducer 5 and the receiving acoustic wave transducer 6 are The number of acoustic transducers 5 and 6 is N, wherein the value range of N is 1 to 350. The acoustic transducers 5 and 6 in the same row are arranged along the width direction of the cold-rolled plate 2 to be tested. The spacing M between the acoustic transducers 5 and 6 in the same row is 50 mm. The specific value of N is determined by the width L of the cold-rolled plate 2 to be tested, that is, N is the integer part of L / M. The distance between the transmitting acoustic transducer 5 and the receiving acoustic transducer 6 is S=300 mm. The sampling rate of the ADC (analog-to-digital converter) acquisition circuit is at least 1 GHZ. The spiral electromagnetic coil 14 is a planar spiral winding structure with a line spacing of 0.5 mm to 2 mm and at least 10 spiral turns. Figure 6 As shown, N pairs of waveguide transducers correspond to N detection areas in total, and each pair of waveguide transducers corresponds to one detection area, that is, the sound wave propagation area covered by the waveguide transducers from each pair of transmitting sound wave transducers 5 to the receiving sound wave transducers 6.

[0057] The embodiment of the present invention includes the following steps: Figure 5 As shown:

[0058] During operation, this embodiment uses a cold-rolled plate as the object to be measured. The length of the cold-rolled plate is about 12 meters and the width is 3 meters. The waveguide working mode is a single-transmit and single-receive mode.

[0059] Step S1, first determine the number of waveguide transducers in the transmitting sound wave transducer 5 and the receiving sound wave transducer 6 according to the size of the cold-rolled sheet 2 to be tested, and use the two waveguide transducers in the transmitting sound wave transducer 5 and the receiving sound wave transducer 6 located in the same horizontal direction (i.e., the extension direction of the cold-rolled sheet 2 to be tested) as a pair of waveguide transducers;

[0060] In a specific implementation, the number N of waveguide transducers in the transmitting sound wave transducer and the receiving sound wave transducer, that is, N pairs of waveguide transducers, is determined according to the actual width L of the cold-rolled sheet 2 to be tested and the waveguide transducer spacing M=50 mm;

[0061] Step S2: Next, the guided wave velocity v of the cold-rolled sheet 2 to be tested under free boundary conditions is obtained by using a semi-analytical finite element method. 0 , the guided wave velocity is a fixed value;

[0062] Starting the power supply of the measurement system of the present invention, and the system completes power-on initialization;

[0063] Step S3, using the industrial computer 17 and the wireless transmission module 9 to control the magnetic field of the spiral electromagnetic coil 14 in the waveguide transducer, and then setting the waveguide signal excitation parameters of the transmitting acoustic wave transducer 5 and the waveguide signal receiving parameters of the receiving acoustic wave transducer 6, so that N pairs of waveguide transducers are cyclically excited and receive the waveguide signal in turn, and the sampling rate of the waveguide signal is f 0 ;

[0064] Step S4, the N waveguide transducers in the transmitting acoustic wave transducer 5 sequentially excite the waveguide signals, and at the same time, the N waveguide transducers in the receiving acoustic wave transducer 6 sequentially receive the corresponding waveguide signals excited by the N waveguide transducers in the corresponding transmitting acoustic wave transducer 5, thereby obtaining N waveguide signals;

[0065] Step S5, the N waveguide signals received by the N waveguide transducers in the receiving sound wave transducer 6 are transmitted to the industrial computer 17 through the wireless transmission module 9, and the number of sampling points of each waveguide signal from the transmitting sound wave transducer 5 to the receiving sound wave transducer 6 is obtained by the industrial computer 17, and recorded as g i , i=1,2…,N, where g i represents the number of sampling points of the ith waveguide signal received by the ith pair of waveguide transducers;

[0066] Step S6. Finally, the residual stress of the cold-rolled sheet 2 to be tested is obtained according to the number of sampling points of the waveguide signal, and the residual stress distribution result of the cold-rolled sheet 2 to be tested is displayed by an industrial computer.

[0067] In step S6, the residual stress of the cold-rolled sheet 2 to be measured is obtained by processing according to the following method:

[0068] σ i =(v i -v 0 ) / Ф

[0069] v i =(S×f 0 ) / g i

[0070] Ф=β / ρ

[0071] Among them, σ i represents the residual stress of the cold-rolled sheet 2 to be tested in the i-th detection area, where the i-th detection area is specifically the sound wave propagation area covered by the i-th pair of guided wave transducers; v i represents the wave velocity of the i-th waveguide signal, Ф represents the acoustic propagation coefficient of the cold-rolled sheet 2 to be tested; β represents the Young's modulus of the cold-rolled sheet to be tested; ρ represents the density of the cold-rolled sheet to be tested; S represents the distance between the transmitting acoustic wave transducer 5 and the receiving acoustic wave transducer 6.

[0072] Specifically, the sampling points g of each waveguide signal can be i and sampling rate f 0 Get the actual wave velocity v of these N guided wave signals i , where S is the distance between the transmitting acoustic wave transducer and the receiving acoustic wave transducer, that is, S = 300 mm; then the residual stresses of the N detection areas of the cold-rolled sheet 2 obtained by the N guided wave signals are σ i Thus, the residual stresses of N detection areas of the cold-rolled sheet to be tested are obtained from the N groups of waveguide signals obtained by the above-mentioned N pairs of waveguide transducers; the industrial computer gives and displays the N residual stress results.

[0073] The present invention adopts N pairs of waveguide transducers for receiving and transmitting, thereby dividing the transverse direction (width direction) of the cold-rolled sheet to be tested into N regions, such as Figure 6 As shown, each pair of two waveguide transducers corresponds to one region, and each pair of waveguide transducers of the receiving acoustic wave transducer and the transmitting acoustic wave transducer work in a single-transmitting and single-receiving mode, that is, a waveguide transducer of a transmitting acoustic wave transducer excites to generate a waveguide signal, and the waveguide transducer of the corresponding receiving acoustic wave transducer collects the waveguide signal, thereby obtaining N groups of waveguide signals, and finally obtaining N residual stresses, corresponding to the residual stresses of N regions of the cold-rolled sheet being tested. Compared with the traditional method of measuring the residual stress of only one region, the present invention can obtain N residual stresses, with a higher lateral resolution of residual stress, so as to more accurately obtain the detailed distribution of the residual stress of the cold-rolled sheet being tested, and provide important key and accurate information for the subsequent determination of the flatness of the backing cold-rolled sheet according to the residual stress.

[0074] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein by equivalents. However, these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A non-contact online measurement system for residual stress of cold-rolled sheet, characterized by: The invention comprises a support roller (1), a transmitting and measuring roller assembly, a receiving and measuring roller assembly, a curling roller (7), a bottom support frame (8) and an industrial control computer (17). The support roller (1), the transmitting and measuring roller assembly, the receiving and measuring roller assembly and the curling roller (7) are all mounted on the bottom support frame (8). The bottom support frame (8) is placed on a workbench. One end of the cold-rolled plate (2) to be measured is mounted on the support roller (1). The other end of the cold-rolled plate (2) to be measured is mounted on the curling roller (7) after passing through the transmitting and measuring roller assembly and the receiving and measuring roller assembly in sequence. The transmitting and measuring roller assembly and the receiving and measuring roller assembly are both provided with a waveguide transducer. The waveguide transducer is electrically connected to the industrial control computer (17).

2. According to claim 1, a non-contact online measurement system for residual stress of cold-rolled sheet is characterized in that: The transmitting and measuring roller assembly comprises a transmitting ceramic roller (3) and a transmitting sound wave transducer (5), and the receiving and measuring roller assembly comprises a receiving ceramic roller (4) and a receiving sound wave transducer (6). The transmitting sound wave transducer (5) and the receiving sound wave transducer (6) are mainly composed of a plurality of waveguide transducers, and a rolling bearing (18) is arranged in the waveguide transducer. A rotating shaft (19) is arranged in the middle of the supporting roller (1), the transmitting ceramic roller (3), the receiving ceramic roller (4) and the winding roller (7). The rotating shaft (19) is connected to the top end of the bottom support frame (8), and the bottom end of the bottom support frame (8) is connected to the workbench. The rotating shafts (19) of the transmitting ceramic roller (3) and the receiving ceramic roller (4) are connected to the rolling bearings (18) in the waveguide transducers.

3. The non-contact online measurement system for residual stress of cold-rolled sheet according to claim 2, characterized in that: The waveguide transducer comprises a wireless transmission module (9), a magnetic sheet (10), a permanent magnet (11), copper foil (12), iron powder cloth (13), a spiral electromagnetic coil (14), a fixed shell (15), a counterweight (16) and a rolling bearing (18); the rolling bearing (18) is mounted on the inner top surface of the fixed shell (15), the counterweight (16) is fixedly mounted on the bottom end of the fixed shell (15), the wireless transmission module (9) is electrically connected to the spiral electromagnetic coil (14), the magnetic sheet (10), the permanent magnet (11), the copper foil (12), the iron powder cloth (13) and the spiral electromagnetic coil (14) are sequentially stacked and connected along the radial direction of the waveguide transducer, and the industrial computer (17) is connected to the mobile hotspot module in the wireless transmission module (9).

4. The non-contact online measurement system for residual stress of cold-rolled sheet according to claim 2, characterized in that: The wireless transmission module (9) comprises an ADC acquisition circuit, a signal filtering circuit, a signal amplifying circuit, a signal source circuit, a power amplifying circuit and a mobile hotspot module; the output end of the mobile hotspot module is connected to the input end of the spiral electromagnetic coil (14) after passing through the signal source circuit and the power amplifying circuit in sequence, and the output end of the spiral electromagnetic coil (14) is connected to the input end of the mobile hotspot module after passing through the signal amplifying circuit, the signal filtering circuit and the ADC acquisition circuit in sequence.

5. The non-contact online measurement system for residual stress of cold-rolled sheet according to claim 2, characterized in that: The bottom of the transmitting ceramic roller (3) and the bottom of the waveguide transducer in the transmitting sound wave transducer (5) have the same curvature, and the bottom of the receiving ceramic roller (4) and the bottom of the waveguide transducer in the receiving sound wave transducer (6) have the same curvature.

6. The non-contact online measurement system for residual stress of cold-rolled sheet according to claim 2, characterized in that: The number and arrangement positions of the waveguide transducers in the transmitting sound wave transducer (5) and the waveguide transducers in the receiving sound wave transducer (6) are identical and aligned.

7. A non-contact online measurement method for residual stress of cold-rolled sheet applied to the system described in any one of claims 1 to 6, characterized in that: The following steps are involved: Step S1, firstly determining the number of waveguide transducers in the transmitting sound wave transducer (5) and the receiving sound wave transducer (6) according to the size of the cold-rolled sheet (2) to be tested, and taking two waveguide transducers in the transmitting sound wave transducer (5) and the receiving sound wave transducer (6) located in the same horizontal direction as a pair of waveguide transducers; Step S2, then, obtaining the guided wave velocity v0 of the cold-rolled sheet (2) to be tested under free boundary conditions; Step S3, using the wireless transmission module (9) to set the signal excitation parameters of the transmitting sound wave transducer (5) and the signal receiving parameters of the receiving sound wave transducer (6) so that the sampling rate of the waveguide signal is f0; Step S4, the N waveguide transducers in the transmitting sound wave transducer (5) sequentially excite the waveguide signals, and at the same time, the N waveguide transducers in the receiving sound wave transducer (6) sequentially receive the corresponding waveguide signals excited by the N waveguide transducers in the corresponding transmitting sound wave transducer (5), thereby obtaining N waveguide signals; Step S5, transmitting the N waveguide signals received by the N waveguide transducers in the receiving sound wave transducer (6) to the industrial control computer (17) via the wireless transmission module (9), and obtaining the number of sampling points of each waveguide signal from the transmitting sound wave transducer (5) to the receiving sound wave transducer (6) by the industrial control computer (17), and recording it as g i ; Step S6: Finally, the residual stress of the cold-rolled sheet (2) to be tested is obtained according to the number of sampling points of the waveguide signal, and the residual stress distribution result of the cold-rolled sheet (2) to be tested is displayed using an industrial computer.

8. The non-contact online measurement method for residual stress of cold-rolled sheet according to claim 7, characterized in that: In the step S6, the residual stress of the cold-rolled sheet (2) to be measured is obtained by processing according to the following method: s i =(((S×f0) / g i )-v0) / (b / r) Among them, σ i represents the residual stress of the cold-rolled sheet (2) to be tested in the i-th detection area, and the i-th detection area is specifically the sound wave propagation area covered by the i-th pair of waveguide transducers; β represents the Young's modulus of the cold-rolled sheet to be tested; ρ represents the density of the cold-rolled sheet to be tested; S represents the distance between the transmitting sound wave transducer (5) and the receiving sound wave transducer (6).

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