TW202018284A - Steel strip crease detection method including a preparation step, a measurement step, a conversion step, and a reading step - Google Patents

Abstract

A steel strip crease detection method which is suitable for detecting creases on the surface of a steel strip, and includes a preparation step, a measurement step, a conversion step, and a reading step. When the preparation step is conducted, the flatness and evenness of the steel strip is confirmed and a measurement location is set. When the measurement step is conducted, an axis passing through the measurement location is defined, a magnetic stress measurement device is used to measure the steel strip along the axis direction to obtain a plurality of stress values along the axis direction and to summarize a stress curve showing a composite waveform. When the conversion step is conducted, a spectrum analytic method is used to separate the composite waveform and convert the stress curve into a conversion curve of bending amplitude and crease defect spacing. The reading step is conducted last, in which a plurality of crease defect spacings respectively corresponding to the stresses in the conversion curve is determined.

Description

Steel belt crease detection method

The invention relates to a detection method, in particular to a detection method of a steel strip crease.

When a steel factory manufactures materials such as steel belts or coils, due to factors such as extrusion or collision during the manufacturing process, the steel belt may produce creases that are not easily visible to the naked eye. Therefore, the factory needs to carry out Tube inspection. When the inspector wants to inspect the creases of the steel belt, he will first grind the surface of the steel belt with oil stone, remove the convex points of the surface, increase the reflectivity, and form a bright and dark texture on the surface. A standardized sample prepared in advance to distinguish the obvious degree of the lines, thereby dividing the severity of the crease into several levels.

However, this method is mainly based on manual judgment, from the method and strength of grinding the steel belt, the type of oil stone, to the different benchmarks when comparing the limit samples, all will affect the judgment of the severity of the crease. That is to say, this method lacks standardization, and the results obtained may vary from person to person, and cannot be reproduced or can only be reproduced randomly. Assuming that the steel strip is delivered to the customer, due to the customer's grinding technique or the type of oil stone If the results are different and the two parties cannot reach a consensus, both parties will suffer. Moreover, relying solely on the inspection of the inspectors, even if the differences caused by individual subjective judgments are different, directly adopting the method of pure manpower will also cause problems of low efficiency and high labor costs, and the judgment of the inspectors may also follow Mental power is reduced and affected, which in turn affects the results of the test.

Therefore, the purpose of the present invention is to provide a standardized method for detecting creases in steel belts that is accurate, accurate and feasible, and can reduce labor costs.

Therefore, the method for detecting the crease of the steel strip of the present invention is suitable for detecting the crease on the surface of the steel strip, and includes a preparation step, a measurement step, a conversion step, and a reading step.

When performing this preparation step, the steel belt is placed on a standard plane, and a measurement position is set on the steel belt.

When performing the measurement step, an axis passing through the measurement position is defined, and a magnetic stress measurement device is used to measure the steel strip along the axis direction to obtain a plurality of stress values along the axis direction, and a composite Wave stress diagram.

And the conversion step is to use a spectrum analysis method to perform the separation of the composite waveform, and convert the stress curve into a conversion curve of bending amplitude and crease defect spacing.

Finally, the reading step is performed to determine the pitches of multiple crease defects corresponding to the stresses in the conversion curve.

The effect of the present invention is to measure the steel strip by the magnetic stress measuring device, and use the frequency spectrum analysis method to present the creases as standardized data, eliminating errors that may be caused by manual judgment, and having accuracy and At the same time as feasibility, it can also reduce labor costs.

Referring to FIG. 1, an embodiment of the method for detecting the creases of the steel strip of the present invention is suitable for detecting the creases on the surface of a steel strip 1, and includes a preparation step 2, a measurement step 3, a conversion step 4, and a Read step 5. It should be explained first that in this embodiment, the steel strip 1 rolled by a roll is used as the detection object to help explain the effectiveness of the present invention, but in actual implementation, the method for detecting the crease of the steel strip of the present invention is also possible Measure other kinds of workpieces, such as steel coils, etc.

Referring to FIG. 2, the preparation step 2 is first performed. In order to prevent the steel strip 1 from being placed in a rough or skewed area, which causes new creases, thereby reducing the quality of the steel strip and affecting the measurement results, the steel strip 1 must be Place on a standard plane 11. The standard plane 11 is a horizontal plane measured by a level meter. After confirming that the steel belt 1 is flatly arranged, a measurement position 12 to be measured can be set on the steel belt 1 as shown in FIG. 2.

Next, the measurement step 3 is performed. Since the creases mainly come from the stress that the steel strip is subjected to during the manufacturing process due to compression or collision, when the surface of the steel strip is stressed, its magnetic permeability will be affected. Taking advantage of this type of change and the corresponding change in permeability, the industry often uses a magnetic stress measurement device (not shown in the figure) for measurement.

Before performing the measurement, an axis A passing through the measurement position 12 is defined. Considering the technical limitations of the magnetic stress measurement device and the accuracy of the measurement, it is preferable to run every 2 mm along the direction parallel to the axis A Make a mark 131, and then form a mark line 13 as shown in FIG. 2, and then use the magnetic stress measuring device to measure individually along the mark 131. It should be noted that the interval of each mark 131 is limited by the current measurement equipment technology. However, with the breakthrough of the measurement equipment technology later, the distance of each mark 131 will change, so it is not 2 Mm only.

分別代表X軸與Y軸之磁通量，

分別代表X軸與Y軸之條件函數，其中，該等磁通量與該等應力值的關係式為

。要特別說明的是，

、

皆為向量，得以同時呈現方向以及量值。After the measurement, a plurality of axial magnetic fluxes of the marking line 13 of the steel strip 1 are obtained, and the equivalent magnetic fluxes can be converted into a plurality of stress values, respectively. Define F as stress,

Represent the magnetic flux of X axis and Y axis,

Respectively represent the condition function of X axis and Y axis, where the relationship between the magnetic flux and the stress value is

. In particular,

,

All are vectors, which can show the direction and magnitude at the same time.

It is worth noting that the condition function varies with the magnetic permeability of the steel strip. For example, the carbon content, the content of various metal components, and the quenching time and other parameters that may affect the magnetic permeability will affect the value of the function. Therefore, steel strips with different compositions or processes will have different conditional functions. Conversely, the conditional function of steel strips of the same material and manufacturing process will be the same. Therefore, after measuring the magnetic flux of the steel strip, the manufacturer and the customer can calculate the same result by the same condition function.

Referring to FIG. 3 and FIG. 4, after measuring the stress values, the distance moved by the magnetic stress measuring device along the marking line 13 is taken as the X axis, and the corresponding stress values corresponding to the distance are the Y axis. A stress curve as shown in FIG. 3 is shown. A stress curve 6 shown in FIG. 3 can record the crease changes on the surface of the steel strip 1 at a fine scale. However, the reasons for the creases on the surface of the steel strip are complicated, which may come from extrusion, collision, or scratching, and each factor will be represented by a waveform signal, so the stress curve 6 will be a composite waveform . For the factory, in addition to finding the location of the crease, it is also hoped that the cause of the crease can be analyzed from the stress curve 6 and used as the basis for improving the process and equipment adjustment.

Therefore, in this conversion step 4, the factory can use the Fast Fourier Transform (FFT) to analyze the stress curve 6, and convert the stress curve 6 shown in FIG. 3 into the X-axis as a crease For the defect spacing, the Y axis is the bending amplitude, and a conversion curve 7 as shown in FIG. 4 is depicted to facilitate analysis of the bending information contained in the original composite waveform.

Finally, the reading step 5 is performed. By judging the interval corresponding to the peak on the conversion curve 7, it can be understood that the steel strip 1 has a crease at the interval, and then, according to the rule of thumb, the value of the interval value To determine the cause of the crease and determine the severity of the crease from the size of the peak. For example, as shown in FIG. 4, when the pitch is 10-16 mm, there is a peak P1, and when the pitch is 23 mm, there is a peak P2, the corresponding position of the peak P1 and P2 can be used to determine the corresponding discount Possible causes of marks.

However, the judgment method is different according to the steel belt process and material, so the factory and the customer can use the standardized data to agree on a judgment standard, and then can perform standard interactive inspection based on the agreed judgment standard nuclear.

In the following, the reproducibility of the steel strip crease detection method of the present invention will be described, and the steel strip test strip 14, the crease-free reference steel strip 15 and the image comparison steel strip 16 which are currently manually detected are compared with each other. , Examine the executability and accuracy of the detection method of the steel strip crease of the present invention.

Referring to FIGS. 2 and 5, the magnetic stress measuring device is used to repeatedly measure the steel strip 1 shown in FIG. 2 three times along the marking line 13, and three stress curves as shown in FIG. 5 can be depicted respectively. These are a first stress curve 61 indicated by a solid line, a second stress curve 62 indicated by a dotted line, and a third stress curve 63 indicated by a dotted line. It can be seen from FIG. 5 that the change of the stress curve measured by the three measurements tends to be consistent, and it can be seen that multiple measurements will get the same trend results, and the measurement reproducibility is good. The stress curves are converted into three conversion curves as shown in FIG. 6, which are a first conversion curve 71 indicated by a solid line, a second conversion curve 72 indicated by a dotted line, and a one-point chain line.之第3 Transformation curve 73. As shown in FIG. 6, the change trends of the conversion curves are approximately the same, so it can be proved that the steel strip crease detection method of the present invention is reproducible.

Referring to FIGS. 7, 8 and 9, the crease spacing S of the steel strip test piece 14 in FIG. 7 is 10 to 15 mm. Use the magnetic stress measuring device to measure the steel strip test piece 14 as shown in FIG. 8 A stress curve 64 of a test piece is depicted as shown. After the fast Fourier transform of the test piece stress curve 64, a test piece conversion curve 74 as shown in FIG. 9 is obtained. It can be seen from FIG. 9 that there is a peak P3 at a position of 11 to 15 millimeters, indicating that the steel strip test piece 14 is at a spacing From 11 to 15 mm, there is a change in magnetic force, which shows that there is a crease at this location, which is the same as the observation result at the macroscopic scale.

Referring to FIGS. 10 and 11, the reference steel strip 15 without creases in FIG. 10 is set as a control group, and the reference steel strip 15 is analyzed using the method for detecting the crease of the steel strip of the present invention to depict a reference steel as shown in FIG. 11 With the conversion curve 75, it can be seen that there is no signal with a particularly large distance between them, and the signal amplitude is relatively weak, which means that the magnetic permeability of the surface of the reference steel strip 15 does not change much. Since the reference steel strip 15 has no creases, it means that its surface is not affected by stress, and there is no obvious peak-valley change in magnetic permeability, which is the same as that described in the reference steel strip conversion curve 75.

Referring to FIG. 12 and FIG. 13, one of the current detection methods is to judge the comparison with the naked eye according to the prepared reference map after grinding to make the lightness and darkness more obvious. In order to confirm the correspondence between the detection method of the steel strip crease of the present invention and the current detection method, first use the magnetic stress measuring device, the axial vector measures an image comparison steel strip 16 and draws an image comparison stress curve 65, After grinding the image comparison steel strip 16, and taking a photo 8 as a record, and then converting the photo 8 to grayscale, it can be seen that the surface folds of the image comparison steel strip 16 are divided into brighter and darker traces. A preliminary comparison of Fig. 12 with Fig. 13 shows that the image compares the ups and downs of the stress curve 65, the peak corresponds to the brighter trace, and the valley corresponds to the darker trace. It matches the bright and dark traces in this photo 8. Then, the 8-axis of the photo is converted into a 0-255 gray scale curve 81 according to the shade of the tone, and then compared with the image to the stress curve 65. For the convenience of comparison, the gray-scale curve 81 and the image-comparison stress curve 65 are placed together to form a gray-scale-stress curve comparison diagram as shown in FIG. 13. After the comparison results, it can be more clearly seen that the image comparison stress curve 65 and the gray scale curve 81 have almost the same fluctuation tendency. Based on the above two paragraphs, it can be confirmed that the method for detecting the crease of the steel strip of the present invention can indeed describe the crease pattern, and it is feasible.

In summary, the method for detecting the crease of the steel strip according to the present invention can provide standardized, accurate results and can explain the stress curve of the surface crease by using the magnetic stress measurement device as long as the magnetic stress measurement device is used And, the fast Fourier transform method can be used to analyze the stress curves to explore the cause and severity of the creases. More importantly, the steel strip crease detection method of the present invention does not need to be ground, which is enough to eliminate errors that may be caused by different grinding methods or different judgment standards, and at the same time reduce labor costs. Therefore, the purpose of cost invention can indeed be achieved.

However, the above are only examples of the present invention, and should not be used to limit the scope of the present invention. Any simple equivalent changes and modifications made according to the scope of the patent application of the present invention and the content of the patent specification are still classified as This invention covers the patent.

1: steel strip 11: standard plane 12: measurement position 13: mark line 131: mark 14: steel strip test piece 15: reference steel strip 16: image comparison steel strip 2: preparation step 3: measurement step 4: conversion Step 5: Reading step 6: Stress curve 61: First stress curve 62: Second stress curve 63: Third stress curve 64: Test piece stress curve 65: Image comparison stress curve 7: Conversion curve 71: First conversion Curve 72: Second conversion curve 73: Third conversion curve 74: Test piece conversion curve 75: Reference steel strip conversion curve 8: Photo 81: Gray scale curve A: Axis P1: Peak P2: Peak P3: Peak S: Spacing

Other features and effects of the present invention will be clearly presented in the embodiment with reference to the drawings, in which: FIG. 1 is a block flow diagram illustrating an embodiment of the method for detecting the crease of the steel strip of the present invention; FIG. 2 is a A schematic diagram illustrating a preparation step of the embodiment; FIG. 3 is a graph illustrating a stress curve drawn by measuring the steel strip; FIG. 4 is a graph illustrating the stress curve through fast Fourier transform One conversion curve is depicted; FIG. 5 is a graph similar to FIG. 3, illustrating the three stress curves respectively depicted by repeatedly measuring the steel strip three times; FIG. 6 is a graph similar to FIG. 4, illustrating The three transformation curves are depicted by the fast Fourier transformation of these stress curves; FIG. 7 is a partial front view illustrating the surface crease pattern of a steel strip test piece; FIG. 8 is a graph similar to FIG. 3, illustrating Measuring the steel strip test piece and drawing a stress curve of one test piece; FIG. 9 is a graph similar to FIG. 4, illustrating that the stress curve of the test piece depicts a test piece conversion curve through fast Fourier transform Fig. 10 is a partial front view illustrating the surface crease pattern of a reference steel strip; FIG. 11 is a graph similar to FIG. 4 illustrating that the reference steel strip depicts a reference steel strip through this embodiment Conversion graph; FIG. 12 is a partial front view illustrating the surface crease pattern of an image comparison steel strip; and FIG. 13 is a graph illustrating the comparison of a gray scale curve and an image comparison stress curve.

2: preparation steps

3: Measurement steps

4: Conversion steps

5: Reading steps

Claims (4)

A steel belt crease detection method, suitable for detecting creases on the surface of the steel belt, and includes: a preparation step, placing the steel belt on a standard plane, and setting a measurement position on the steel belt; A measuring step, defining an axis passing through the measuring position, using a magnetic stress measuring device to measure the steel strip along the axis direction, obtaining a plurality of stress values along the axis direction, and summing up a complex waveform A stress curve; a conversion step, using a spectrum analysis method to perform the separation of the composite waveform, converting the stress curve into a conversion curve of bending amplitude and crease defect spacing; and a reading step, from the conversion curve In the figure, the distance between multiple crease defects corresponding to these stresses is determined. The steel belt crease detection method according to claim 1, wherein, in the measuring step, the magnetic stress measuring device measures a plurality of axial magnetic fluxes at the measurement position along the axis direction, and compares these The axial magnetic flux is converted into a plurality of stress values respectively, and then the distance moved by the magnetic stress measurement device along the axis direction is the X axis, and the corresponding stress values corresponding to the distance are the Y axis to form the stress curve. According to the method for detecting creases in steel strip as described in claim 2, F is defined as stress,

Represent the magnetic flux of X axis and Y axis,

Respectively represent the condition functions of the X axis and the Y axis, and the condition function changes with the material of the steel strip, wherein the relationship between the magnetic flux and the stress in the stress curve is

. The method for detecting creases in a steel strip according to claim 1, wherein the spectrum analysis method in the analysis step is fast Fourier transform.

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