Online real-time detection device for thickness of color-coated sheet

Abstract

The invention relates to an online real-time detection device for the thickness of a color-coated sheet. The online real-time detection device comprises a unit steering roller, an upper stabilizing roller, a lower stabilizing roller, a stabilizing roller mounting bearing, a middle thickness detection assembly, a WS thickness detection assembly, a DS thickness detection assembly, a detection bracket and a control system, the detection device is installed in a relatively stable operation area of a color-coated sheet production line and used for detecting the total thickness of a sheet after a coating is prepared, the detection device is provided with three groups of detection probes including an edge (WS side), a middle (CL side) and an edge (DS side), the three groups of detection probes are used for detecting the thicknesses of the edges, the middle and the edges respectively, and the middle thickness detection assembly, the WS thickness detection assembly and the DS thickness detection assembly are all installed on the detection support. A pair of upper and lower stabilizing rollers are respectively arranged at the front and back positions of the color-coated sheet in-out detection device, the stabilizing rollers are arranged on rolling bearings, and the height of the bearings can be adjusted. The initial positions of the three groups of detection probes are located at the edge part of the strip steel, and after the control system receives a detection instruction, the three groups of probes are driven by a servo motor to move at required detection positions to continuously output the thickness of the edge-middle edge position. According to the technical scheme, the surface color correction model of the color-coated sheet is provided, so that the laser thickness detection precision is improved, the real thickness of the color-coated sheet is obtained in real time, and technical guarantee is provided for intelligent production of the color-coated sheet.

Description

Technical Field

[0001] This invention relates to a detection device, specifically an online real-time detection device for the thickness of color-coated steel sheets, belonging to the field of metallurgical machinery technology. Background Technology

[0002] Color-coated steel sheet is a type of steel substrate coated with one or more layers of liquid coating, followed by baking and cooling. It possesses corrosion resistance and high strength, making it an important basic industrial material widely used in construction, home appliances, and decoration industries. The substrates for color-coated steel sheets are mainly hot-dip galvanized steel, aluminized zinc steel, aluminum-magnesium-manganese steel, zinc-aluminum-magnesium steel, and stainless steel. The coatings used include polyester, modified polyester, polyvinylidene fluoride, epoxy, and others, to meet the performance requirements of different applications.

[0003] The unfolded area of ​​pre-coated steel sheets is an important evaluation indicator. Since these sheets are typically delivered by weight, their thickness directly affects the unfolded area and consequently, construction costs. Therefore, thickness is a crucial indicator for pre-coated steel sheets. Currently, the thickness of pre-coated steel sheets produced by steel mills is measured manually offline using a spiral micrometer. This manually measured thickness serves as the basis for quality inspection, and there is currently no online testing equipment. The thickness of pre-coated steel sheets consists of the steel (aluminum) substrate, the plating, and the coating. For steel sheets or steel sheets with plating, a radiographic thickness gauge is typically used to monitor the thickness. However, because the types and thicknesses of coatings on pre-coated steel sheets vary, existing radiographic methods require establishing curves or correction coefficients for different coating types, which is cumbersome and ineffective. No cases of using radiographic methods for online thickness testing of pre-coated steel sheets have been found.

[0004] Strip steel production equipment is highly automated, requiring real-time online measurement of strip steel thickness. Methods for online strip steel thickness measurement are generally categorized as contact and non-contact. Patent CN222579250U proposes an "Automatic Dedicated Thickness Measurement Device for Hot-Rolled Strip Steel." The proposed method is used for thickness measurement of hot-rolled plates. The device consists of a base, a base plate, a connecting column, a welding sleeve, and an electrically telescopic column. This device prevents the hot-rolled strip steel body from shifting position during thickness measurement, increasing the accuracy of the measurement value and improving the practicality of the device. Contact thickness measurement involves contact with the high-speed running strip steel, posing a significant quality risk for cold-rolled plates with high surface quality requirements. Therefore, contact thickness measurement is rarely used in cold-rolling production. For non-contact thickness measurement, most cold-rolling production uses radiographic methods, judging strip steel thickness by the attenuation of radiation as it penetrates the steel plate. This method suffers from radiation contamination, high cost, and high energy consumption. Furthermore, the reliability of the measurement results is affected by the chemical composition of the strip steel, requiring continuous correction and calibration. For example, patent CN107702667A proposes "A Method for Establishing a Material Compensation System for an X-ray Thickness Gauge." This patent presents a method for establishing a material compensation system for an X-ray thickness gauge, which consists of five steps: Step 1: Sampling of the strip steel and making a template; Step 2: Actual measurement of the template thickness; Step 3: Placing the template on the standard frame of the thickness gauge to measure the thickness; Step 4: Calculation of the material compensation coefficient; Step 5: Application of the material compensation coefficient. This method can effectively establish a material compensation system for an X-ray thickness gauge, solving the problem that even when the specific composition and proportion of the strip steel being measured cannot be obtained, the X-ray thickness gauge can still accurately measure the actual thickness value of strip steel of various steel grades.

[0005] In non-contact detection methods, low-energy laser ranging can be used to predict the thickness of the strip by detecting the height of its upper surface. This method directly obtains the total thickness of the strip, making it a direct thickness measurement method. However, this method suffers from data fluctuations. To address this issue, patent CN115127458A proposes a "data processing method for laser thickness measurement of strip." This patent, based on the initial laser thickness measurement data of the strip, filters out data anomalies and strip edge data to obtain preprocessed data. The preprocessed data undergoes a first filtering to extract surface roughness data, resulting in first-filtered data. The first-filtered data undergoes a second filtering to extract waviness data, resulting in second-filtered data. Finally, the second-filtered data is calculated based on at least one preset profile index, outputting data corresponding to that index. While this data processing method reduces data fluctuations in laser thickness measurement, it does not fundamentally improve detection accuracy.

[0006] For online thickness measurement of color-coated steel sheets, the thickness of the sheet cross-section consists of three parts: the upper and lower coatings, the plating layer, and the steel (aluminum) material. Since these three materials have different attenuation rates for X-rays, it is difficult to obtain an accurate thickness. To address this, patent CN113074646A proposes a "Method for Measuring the Paint Layer Thickness of Zinc-Aluminum-Magnesium Coated Steel Sheets." This patent discloses a method for preparing N standard galvanized color-coated steel sheets of the same color but different paint layer thicknesses. The standard paint layer thickness of these N sheets is measured. X-ray fluorescence spectroscopy is used to measure the paint layer thickness of the standard galvanized color-coated steel sheets with known paint layer thicknesses, recording the spectral intensity of characteristic elements and plotting a working curve. X-ray fluorescence spectroscopy is also used to measure the spectral intensity of Ti element in the zinc-aluminum-magnesium coated steel sheet to be tested. The paint layer thickness of the zinc-aluminum-magnesium coated steel sheet to be tested is calculated based on the working curve. This patent can measure coating thickness, and the results are not affected by the substrate's magnetism or roughness. However, it is affected by variations in the titanium content in the coating formulation, limiting its application to users testing the coating thickness of different product lines and varieties, and it cannot measure the total thickness of the color-coated steel sheet.

[0007] For color-coated steel sheets, achieving online real-time thickness detection presents certain challenges. Currently, the only method for online real-time thickness detection is manual inspection. However, manual methods are susceptible to human error, involve a large workload, and are unsuitable for online operation. Manual thickness detection cannot meet the requirements of modern intelligent manufacturing, necessitating the development of online real-time thickness detection equipment. Summary of the Invention

[0008] This invention addresses the technical problems existing in the prior art by providing an online real-time detection device for the thickness of color-coated steel sheets. This technical solution mainly refers to the online real-time detection of the thickness of color-coated steel sheets. The detection method is pollution-free and the detection results are stable and reliable.

[0009] To achieve the above objectives, the technical solution of the present invention is as follows: an online real-time detection device for the thickness of color-coated steel sheet, the detection device comprising a unit steering roller 1, a color-coated steel sheet 2, upper and lower stabilizing rollers 3, a stabilizing roller mounting bearing 4, a middle thickness detection component 5, a WS thickness detection component 6, a DS thickness detection group 7, and a detection bracket 8.

[0010] The detection device is installed in a relatively stable area of ​​the color-coated sheet (2) production line, such as the middle of a pair of steering rollers (1), and as close as possible to one side of the rollers. The detection device is equipped with three sets of detection probes: edge (WS side), middle (CS side), and edge (DS side), which respectively realize the thickness detection of the edge, middle, and edge. The middle thickness detection component 5, the WS thickness detection component 6, and the DS thickness detection group 7 are all installed on the detection bracket (8). A pair of upper and lower stabilizing rollers 3 are respectively set at the front and rear positions of the color-coated sheet entering and exiting the detection device. The stabilizing rollers are installed on rolling bearings, and the bearings can adjust the height. The stabilizing rollers are used to prevent the vibration of the color-coated sheet from causing the detection probes to exceed the range and generate invalid detection data.

[0011] Each detection component includes a U-shaped frame (9), a servo motor (10), a mounting plate (11), a linear module (12), and a magnetic scale (13). The U-shaped frame is mounted on the linear module via the mounting plate. The linear module is connected to the servo motor to control the movement of the U-shaped frame. The magnetic scale is used to measure the position of the U-shaped frame.

[0012] Each set of detection probes includes an upper detection probe (15) and a lower detection probe (16). The upper and lower detection probes are respectively installed on the upper coordinate platform (14) and the lower coordinate platform (17). The upper and lower coordinate platforms are installed on the upper and lower parts of the opening end of the U-shaped frame.

[0013] Among them, the groove width W of the U-shaped frame is determined according to the effective detection range HH of the probe, W=(1.5-3.0)HH; the installation distance WW of the upper and lower coordinate platforms is determined according to the installation height H of the probe, WW=(2.5-3.0)H; the groove depth L of the U-shaped frame for measuring the thickness of the edge is 100mm; the groove depth L of the U-shaped frame for measuring the middle part is 100+maximum bandwidth of the unit / 2.

[0014] The U-shaped frame is made of carbon fiber material with a thickness of 20-30mm.

[0015] The detection probe is a multi-spot coaxial laser displacement gauge. It detects the laser illuminating four points in the measurement area, using four CMOS sensors to receive the reflected light. Based on the light spectrum obtained from each CMOS sensor, the measurement is converted into a distance value. A built-in algorithm combines the four CMOS measurements to form the distance value for that point, eliminating the influence of surface unevenness on thickness and thus improving the stability of the measurement. Different probe models have different installation heights H, and their corresponding detection ranges HH also vary.

[0016] A method for online real-time detection of the thickness of color-coated steel sheets, the method comprising the following steps:

[0017] Step 1: After the device is powered on, the system PLC performs a self-test on the detection system. The self-test includes checking whether the communication with the host computer is correct, whether the communication with the PC is normal, whether the servo motor is working properly, and whether the probes of the detection instruments (thickness probe, magnetic ruler, position sensor, etc.) are in normal condition.

[0018] Step 2: With the probe at the origin, measure the thickness of the standard sample. Compare the measured value with the nominal value of the standard sample to obtain the thickness correction factor Δ1.

[0019] Step 3: Calculate the coating color correction factor Δ2 based on the coating code sent by the unit.

[0020] Step 4: The detection device receives the start detection command from the unit. Upon receiving the command, the three sets of probes (edge, center, and edge) simultaneously move into the color-coated steel sheet. The two sets of edge probes locate the edge based on the detected thickness change value. After locating the edge, the servo motor moves the probe 5-20mm into the strip. Once the probe reaches the designated position, the servo motor is activated and released. The center set of probes automatically moves to the middle position of the color-coated steel sheet. Once the probe reaches the designated position, the servo motor is activated and released.

[0021] Step 5: When the probe is at the designated position, the PLC notifies the PC to start collecting the thickness data sent by the probe. The PC adds a correction value to the received thickness value to obtain the actual thickness of the color-coated steel sheet, which is then sent to the PLC in real time. Simultaneously, based on the position information of the color-coated steel sheet provided by the unit, the thickness of the edge-to-edge at different positions is obtained, forming a thickness variation curve along the length of the color-coated steel sheet. This detection result is saved on the PC under the name of the steel coil number.

[0022] Step 6: The PLC sends the thickness detection value along the corresponding length direction to the host computer. The host computer evaluates the product quality based on the actual requirements for product thickness control. The thickness detection results can also be used to adjust the working parameters of the coating machine, realizing closed-loop control of the color-coated sheet thickness.

[0023] Step 7: After receiving the detection signal from the unit, the servo motor moves the three sets of detection probes back to the initial position, and the detection work ends.

[0024] Compared with the prior art, the present invention has the following advantages: the technical solution rationally designs the detection device and provides a color correction model for the surface of the color-coated sheet, thereby improving the accuracy of laser thickness detection, meeting the unit's requirements for three-point thickness measurement of the edge, center and side of the color-coated sheet, obtaining the true thickness of the color-coated sheet in real time, and providing technical support for the intelligent production of color-coated sheets. Attached Figure Description

[0025] Figure 1 This is a schematic diagram of the overall structure of the detection device.

[0026] Figure 2 This is a schematic diagram of the detection component.

[0027] Figure 3 This is a schematic diagram of the U-shaped frame and probe structure.

[0028] Figure 4 This is a schematic diagram illustrating the principle of the detection probe.

[0029] Figure 5 This is a schematic diagram of the thickness measurement principle.

[0030] Figure 6 This is a schematic diagram of the operation mode of the detection device.

[0031] In the diagram: 1. Unit steering roller; 2. Color-coated sheet; 3. Upper and lower stabilizing rollers; 4. Stabilizing roller mounting bearing; 5. Middle thickness detection assembly; 6. WS thickness detection assembly; 7. DS thickness detection assembly; 8. Detection bracket; 9. U-shaped bracket; 10. Linear motor; 11. Mounting connection plate; 12. Linear module; 13. Magnetic scale; 14. Upper coordinate measuring machine platform; 15. Upper detection probe; 16. Lower detection platform; 17. Lower detection probe; 21. Upper distance sensor; 22. U-shaped bracket; 23. Strip steel under test; 24. Lower distance sensor; 25. Data processing unit. Detailed Implementation

[0032] To enhance understanding of the present invention, the embodiments will be described in detail below with reference to the accompanying drawings.

[0033] Example 1: See Figure 1 , Figure 2 A real-time online detection device for the thickness of color-coated steel sheets, the detection device includes a unit steering roller 1, a color-coated steel sheet 2, upper and lower stabilizing rollers 3, a stabilizing roller mounting bearing 4, a middle thickness detection component 5, a WS thickness detection component 6, a DS thickness detection group 7, and a detection bracket 8.

[0034] The detection device is installed in a relatively stable area of ​​the color-coated sheet production line 2, such as the middle of a pair of guide rollers 1, and as close as possible to one side of the rollers. The detection device is equipped with three sets of detection probes: edge (WS side), middle (CS side), and edge (DS side), which respectively realize the thickness detection of the edge, middle, and edge. The middle thickness detection component 5, the WS thickness detection component 6, and the DS thickness detection component 7 are all installed on the detection bracket 8. A pair of upper and lower stabilizing rollers 3 are respectively installed at the front and rear positions of the color-coated sheet entering and exiting the detection device. The stabilizing rollers are mounted on rolling bearings, and the bearings can be adjusted in height. The stabilizing rollers are used to prevent the vibration of the color-coated sheet from causing the detection probes to exceed the range and generate invalid detection data.

[0035] Each detection component includes a U-shaped frame 9, a servo motor 10, a mounting plate 11, a linear module 12, and a magnetic scale 13. The U-shaped frame is mounted on the linear module via the mounting plate. The linear module is connected to the servo motor to control the movement of the U-shaped frame. The magnetic scale is used to measure the position of the U-shaped frame.

[0036] Each set of detection probes includes an upper detection probe 15 and a lower detection probe 16. The upper and lower detection probes are respectively installed on the upper coordinate platform 14 and the lower coordinate platform 17. The upper and lower coordinate platforms are installed at the upper and lower parts of the opening end of the U-shaped frame.

[0037] Among them, the groove width W of the U-shaped frame is determined according to the effective detection range HH of the probe, W=(1.5-3.0)HH; the installation distance WW of the upper and lower coordinate platforms is determined according to the installation height H of the probe, WW=(2.5-3.0)H; the groove depth L of the U-shaped frame for measuring the thickness of the edge is 100mm; the groove depth L of the U-shaped frame for measuring the middle part is 100+maximum bandwidth of the unit / 2.

[0038] The U-shaped frame is made of carbon fiber material with a thickness of 20-30mm.

[0039] The detection probe is a multi-spot coaxial laser displacement gauge. It detects the laser illuminating four points in the measurement area, using four CMOS sensors to receive the reflected light. Based on the light spectrum obtained from each CMOS sensor, the measurement is converted into a distance value. A built-in algorithm combines the four CMOS measurements to form the distance value for that point, eliminating the influence of surface unevenness on thickness and thus improving the stability of the measurement. Different probe models have different installation heights H, and their corresponding detection ranges HH also vary.

[0040] The testing principle of the detection device is that the positions of the upper and lower laser coaxial displacement gauges are fixed (WW). The distance measured by the upper surface laser coaxial displacement gauge is H1, and the distance measured by the lower surface laser coaxial displacement gauge is H2. The thickness of the strip can be calculated by measuring these two heights.

[0041] h=WW-H1-H2

[0042] For thickness measurements using through-beam lasers, the optical axes of the upper and lower coaxial laser displacement gauges must be aligned. The data processing unit includes an optical axis alignment detection module. Before the equipment is put into use, the planar position and angle of the probe need to be adjusted using a three-dimensional platform. Only after the alignment degree set by the data processing unit is achieved can the measured thickness result be valid.

[0043] The thickness obtained from probe testing cannot truly represent the actual thickness of the color-coated steel sheet. The test values ​​need to be corrected, which includes two aspects: first, systematic error; and second, the color of the coating.

[0044] For systematic errors, the measured value is compared with the standard sample for correction. Specifically, a standard sample module is embedded at the origin of the detection probe. The thickness of the standard sample is determined by the thickness of the color-coated steel sheet of the unit, with an actual thickness range of 0.5-2.0 mm. The standard sample is made of ceramic material. The standard sample is located at the physical midpoint between the upper and lower coaxial laser displacement gauges. After each detection, the probe must return to the origin. The thickness of the standard sample is measured during this return, yielding the system's measured thickness. This measured thickness is then compared with the nominal thickness of the standard sample to obtain the systematic error Δ1.

[0045] The correction of coating color involves extracting the RGB values ​​of the color coating from the color-coated steel sheet based on the coating code sent by the unit, and then providing the characteristic coefficient (D) of the coating based on different RGB values. The formula for calculating the characteristic coefficient is as follows:

[0046] D=0.0047×R+0.0032×G-0.0012×B

[0047] Based on the coating characteristic coefficient, calculate the correction coefficient for the coating color;

[0048] Δ2==0.0035×D 2 +0.0011×D+0.0197

[0049] The actual output thickness (t) of the color coating is the measured value (h) obtained by the thickness probe plus the systematic error (Δ1) and the coating color correction value (Δ2).

[0050] t = h + Δ1 + Δ2

[0051] The operation mode of detection transposition is as follows: Figure 6As shown, after the device is powered on, the system PLC performs a self-test. This self-test includes verifying the correctness of communication with the host computer, the normality of communication with the PC, the proper functioning of the servo motor, and the normal operation of the detection instruments (thickness probe, magnetic ruler, position sensor, etc.). Once all these are normal, the "Return to Origin" button on the device is manually activated. The laser coaxial displacement gauge returns to its origin position under the drive of the servo motor. After the probe returns to its origin position, the thickness of the standard sample is measured. The measured value is compared with the nominal value of the standard sample to obtain the thickness correction coefficient Δ1. Based on the coating code sent by the unit, the coating color correction coefficient Δ2 is calculated. After completing these tasks, the detection system waits for the unit to issue a detection command. Upon receiving the command to start detection from the unit, the three probes (edge, center, and edge) simultaneously move into the color-coated plate. For the two edge probes, the detected thickness value is invalid if there is no color-coated plate between them. Only when there is a color-coated plate between the two probes can a valid thickness value be obtained. This characteristic allows for automatic edge finding by the probes, with the edge position serving as the coordinate for the first thickness value. Once the edge is located, the servo motor moves the probe 5-20mm further into the strip. After the probe reaches the designated position, the servo motor is released, and the probe continuously sends thickness detection signals to the PC at the designated position. For probes in the middle, the servo motor directly moves the probe to the centerline of the unit. After reaching the centerline, the servo motor is released, and the probe remains in the middle position, continuously sending thickness detection signals to the PC. The PC, based on the detected thickness value sent by the probe and adding a correction value, outputs the actual thickness of the color-coated sheet. Simultaneously, based on the color-coated sheet position information provided by the unit, it obtains the thickness of the edge at different positions, forming a thickness variation curve of the strip along its length. This detection result is sent to the host computer for product quality assessment. It can also be used to adjust the working parameters of the coating machine in real time, achieving closed-loop control of the color-coated sheet thickness.

[0052] Example 2:

[0053] A method for online real-time detection of the thickness of color-coated steel sheets, the method comprising the following steps:

[0054] Step 1: After the device is powered on, the system PLC performs a self-test on the detection system. The self-test includes checking whether the communication with the host computer is correct, whether the communication with the PC is normal, whether the servo motor is working properly, and whether the probes of the detection instruments (thickness probe, magnetic ruler, position sensor, etc.) are in normal condition.

[0055] Step 2: With the probe at the origin, measure the thickness of the standard sample. Compare the measured value with the nominal value of the standard sample to obtain the thickness correction factor Δ1.

[0056] Step 3: Calculate the coating color correction factor Δ2 based on the coating code sent by the unit.

[0057] Step 4: The detection device receives the start detection command from the unit. Upon receiving the command, the three sets of probes (edge, center, and edge) simultaneously move into the color-coated steel sheet. The two sets of edge probes locate the edge based on the detected thickness change value. After locating the edge, the servo motor moves the probe 5-20mm into the strip. Once the probe reaches the designated position, the servo motor is activated and released. The center set of probes automatically moves to the middle position of the color-coated steel sheet. Once the probe reaches the designated position, the servo motor is activated and released.

[0058] Step 5: When the probe is at the designated position, the PLC notifies the PC to start collecting the thickness data sent by the probe. The PC adds a correction value to the received thickness value to obtain the actual thickness of the color-coated steel sheet, which is then sent to the PLC in real time. Simultaneously, based on the position information of the color-coated steel sheet provided by the unit, the thickness of the edge-to-edge at different positions is obtained, forming a thickness variation curve along the length of the color-coated steel sheet. This detection result is saved on the PC under the name of the steel coil number.

[0059] Step 6: The PLC sends the thickness detection value along the corresponding length direction to the host computer. The host computer evaluates the product quality based on the actual requirements for product thickness control. The thickness detection results can also be used to adjust the working parameters of the coating machine, realizing closed-loop control of the color-coated sheet thickness.

[0060] Step 7: After receiving the detection signal from the unit, the servo motor moves the three sets of detection probes back to the initial position, and the detection work ends.

[0061] Example 3:

[0062] The color-coated steel sheet thickness detection device enables real-time online thickness detection of color-coated steel sheets. The detected thickness can be used for product quality assessment. By connecting the detected thickness value to the coating machine, the machine's operating parameters can be adjusted in real time. The device can meet the real-time thickness detection requirements at a machine speed of 250 mpm, achieving a static thickness detection accuracy of 0.003 mm and a production line accuracy of 0.01 mm. The device can be controlled by the machine for automatic detection. The device requires minimal investment, offers high detection efficiency, and provides the required accuracy for color-coated steel sheet inspection.

[0063] A certain color-coated steel sheet production unit has a maximum speed of 160 mpm, produces color-coated steel sheets with a thickness of 0.3-1.0 mm and a width of 700-1250 mm, and has an annual output of 200,000 tons. This patented technology has been implemented on this unit.

[0064] The detection device is installed between the two guide rollers in front of the winding shearing machine in the outlet area of ​​the unit, closer to the outlet guide roller. The detection device has three sets of detection probes: edge (WS side), center, and edge (DS side), which respectively realize the thickness detection of the edge, center, and edge. A pair of stabilizing rollers are set in front of and behind the detection device. The lower stabilizing roller is fixed, and the upper stabilizing roller can be moved by a cylinder. When the detection device is in use, the upper stabilizing roller is pressed down. When the device is not running, the stabilizing roller is raised to facilitate operations such as threading. When the stabilizing roller is pressed down, the gap between the two stabilizing rollers is 15mm.

[0065] Each testing assembly includes a U-shaped frame, a servo motor, a mounting plate, a linear module, and a magnetic scale. The U-shaped frame is mounted on the linear module via the mounting plate. The linear module is connected to the servo motor to control the movement of the U-shaped frame. The magnetic scale is used to precisely measure the position of the probe.

[0066] The detection probe uses a multi-spot coaxial laser displacement meter. The probe's installation height H = 7cm, and the effective detection range HH = 3cm. The upper and lower coaxial laser displacement meters are installed on the upper and lower coordinate measuring machines (CMMs), respectively. The CMMs are installed at the upper and lower openings of the U-shaped frame. The groove width of the U-shaped frame is W = 2 × HH = 3cm. The installation distance between the upper and lower CMMs is WW = 20cm. The groove depth L of the U-shaped frame for measuring the edge thickness is 100mm, and the groove depth L of the U-shaped frame for measuring the middle thickness is 650mm.

[0067] The U-shaped frame is made of carbon fiber material with a thickness of 25mm.

[0068] The actual output thickness (t) of the color coating is the measured value (h) obtained by the thickness probe plus the systematic error (Δ1) and the coating color correction value (Δ2).

[0069] t = h + Δ1 + Δ2

[0070] After the transposer is powered on, the system PLC performs a self-test. If the self-test is successful, manually press the "Return to Origin" button on the control box. The laser coaxial displacement gauge, driven by the servo motor, returns to its origin position. At the origin, the probe is calibrated to obtain the thickness correction coefficient Δ1. Based on the coating code sent by the unit, the coating color correction coefficient Δ2 is calculated. Then, wait for the unit to issue a detection command. Upon receiving the command to start detection, all three probes move simultaneously into the color-coated sheet. When the two edge probes detect the edge of the color-coated sheet, the width of the sheet is calculated based on the detected edge coordinates. Simultaneously, the probes are moved to a position 20mm from the edge, the servo motor is released, and the probes begin continuously sending thickness detection signals to the PC. For the central probe, the servo motor moves it to the centerline position of the unit. After reaching the position, the servo motor is released, and it begins continuously sending thickness detection signals to the PC. The PC, based on the thickness value sent by the probe and after adding a correction value, gives the actual thickness of the color-coated steel sheet. Simultaneously, based on the position information of the color-coated steel sheet provided by the unit, it obtains the thickness at different positions of the edge-to-edge, forming a thickness variation curve of the strip along its length. The thickness measurement accuracy of this device can be achieved within ±0.01mm. The detection results are simultaneously sent to the host computer, which evaluates the quality of the product. This detection result can also be used to adjust the working parameters of the coating machine in real time, realizing closed-loop control of the thickness of the color-coated steel sheet.

[0071] It should be noted that the above embodiments are not intended to limit the scope of protection of the present invention. Equivalent transformations or substitutions made based on the above technical solutions all fall within the scope of protection of the claims of the present invention.

Claims

1. A device for online real-time detection of the thickness of color-coated steel sheets, characterized in that, The detection device includes a unit steering roller (1), upper and lower stabilizing rollers (3), stabilizing roller mounting bearings (4), a middle thickness detection component (5), a WS thickness detection component (6), a DS thickness detection group (7), a detection bracket (8), and a control system. The detection device is installed in a relatively stable area of ​​the color-coated steel sheet (2) production line. The detection device is equipped with three sets of detection probes: edge (WS side), middle (CL side), and edge (DS side), which respectively realize the thickness detection of the edge, middle, and edge. The middle thickness detection component (5), the WS thickness detection component (6), and the DS thickness detection group (7) are all installed on the detection bracket (8). A pair of upper and lower stabilizing rollers (3) are respectively set at the front and rear positions of the color-coated steel sheet entering and exiting the detection device. The stabilizing rollers are installed on rolling bearings, and the bearings can adjust the height. The initial position of the three sets of detection probes is located at the edge of the strip steel, and the position control of the detection probes is realized by the control system.

2. The online real-time detection device for the thickness of color-coated steel sheets according to claim 1, characterized in that, Each detection assembly includes a U-shaped frame (9), a servo motor (10), a mounting plate (11), a linear module (12), and a magnetic scale (13). The U-shaped frame is mounted on the linear module via the mounting plate. The linear module is connected to the servo motor to control the movement of the U-shaped frame. The magnetic scale is used to measure the position of the U-shaped frame.

3. The online real-time detection device for the thickness of color-coated steel sheets according to claim 2, characterized in that, Each set of detection probes includes an upper detection probe (15) and a lower detection probe (16). The upper and lower detection probes are respectively installed on the upper coordinate platform (14) and the lower coordinate platform (17). The upper and lower coordinate platforms are installed on the upper and lower parts of the opening end of the U-shaped frame.

4. The online real-time detection device for the thickness of color-coated steel sheets according to claim 2, characterized in that, The groove width W of the U-shaped frame is determined according to the effective detection range HH of the probe, W = (1.5-3.0)HH; the installation distance WW of the upper and lower coordinate platforms is determined according to the installation height H of the probe, WW = (2.5-3.0)H; the groove depth L of the U-shaped frame for measuring the edge thickness is 100mm; the groove depth L of the U-shaped frame for measuring the middle part is 100 + the maximum bandwidth of the unit / 2.

5. The online real-time detection device for the thickness of color-coated steel sheets according to claim 3, characterized in that, The U-shaped frame is made of carbon fiber material with a thickness of 20-30mm.

6. The online real-time detection device for the thickness of color-coated steel sheets according to claim 2, characterized in that, The detection probe is a multi-spot coaxial laser displacement meter. It detects the laser illuminating four points in the measurement area and uses four CMOS sensors to receive the reflected light. Based on the light spectrum obtained by each CMOS sensor, it converts the light into a distance value. Through a built-in algorithm, the four CMOS measurement values ​​are combined into the distance value of that point, eliminating the influence of surface unevenness on the thickness, thereby improving the stability of the measurement value.

7. A method for online real-time detection of the thickness of color-coated steel sheets, characterized in that, Using the detection device according to any one of claims 1-6, the method includes the following steps: Step 1: After the device is powered on, the system PLC performs a self-test on the detection system. The self-test includes checking whether the communication with the host computer is correct, whether the communication with the PC is normal, whether the servo motor is working properly, and whether the detection instrument probe is in a normal state. Step 2: With the probe at the origin, measure the thickness of the standard sample. Compare the measured value with the nominal value of the standard sample to obtain the thickness correction factor Δ1. Step 3: Calculate the coating color correction factor Δ2 based on the coating code sent by the unit. Step 4: The detection device receives the start detection command from the unit. Upon receiving the command, the three sets of probes (edge, center, and edge) simultaneously move into the color-coated steel sheet. The two sets of edge probes locate the edge based on the detected thickness change value. After locating the edge, the servo motor moves the probe 5-20mm into the strip. Once the probe reaches the designated position, the servo motor is activated and released. The center set of probes automatically moves to the middle position of the color-coated steel sheet. Once the probe reaches the designated position, the servo motor is activated and released. Step 5: When the probe is at the designated position, the PLC notifies the PC to start collecting the thickness data sent by the probe. The PC adds a correction value to the received thickness value to obtain the actual thickness of the color-coated steel sheet, which is then sent to the PLC in real time. Simultaneously, based on the position information of the color-coated steel sheet provided by the unit, the thickness of the edge-to-edge at different positions is obtained, forming a thickness variation curve along the length of the color-coated steel sheet. This detection result is saved on the PC under the name of the steel coil number. Step 6: The PLC sends the thickness detection value along the corresponding length direction to the host computer. The host computer evaluates the product quality based on the actual requirements for product thickness control. The thickness detection results can also be used to adjust the working parameters of the coating machine, realizing closed-loop control of the color-coated sheet thickness. Step 7: After receiving the detection signal from the unit, the servo motor moves the three sets of detection probes back to the initial position, and the detection work ends.

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