A method for detecting the bonding layer of rolls

Abstract

This invention discloses a method for detecting the bonding layer of rolls, comprising the following steps: determining the state of the roll bonding layer based on independent point defects and planar defects within the bonding layer; the state of the roll bonding layer includes a safety level, a tracking level, and a warning level. Rolls in the safety level are used normally; rolls in the tracking level are continuously monitored for defect development within the tracking period; rolls in the warning level are suspended from use. A roll bonding layer detection method based on secondary and multiple reflected waves is established for independent point defects, and a roll bonding layer detection method with bottom wave attenuation is designed for planar defects, improving the detection accuracy of the roll bonding layer; classifying the state of the roll bonding layer and adopting different measures for different states can effectively avoid roll accidents, rolling line downtime, or equipment damage caused by bonding layer defects.

Description

Technical Field

[0001] This invention belongs to the field of roll inspection technology, and more specifically, this invention relates to a method for inspecting the roll bonding layer. Background Technology

[0002] Rolls are key large-scale tools in hot-rolled sheet mills, coming into direct contact with the sheet material. Their safe use is crucial to the mill's production, quality, planning, and cost.

[0003] Due to the high efficiency of hot-rolled thin plate production, the extremely thin product thickness, and the high performance enhancement, higher requirements are placed on the performance of the rolls. To meet the high requirements of the rolling mill, the alloy content of the working layer is optimized and the microstructure is refined to improve the hardness and wear resistance of the working layer. The working layer and the core have two different microstructures, which increases the difficulty of fusing the bonding layer between the working layer and the core of the work roll. During repeated use, under the action of rolling force and shear force, the bonding layer of the roll is prone to separation, resulting in defects and ultimately roll failure.

[0004] The national standard GB / T 1503-2008 "Cast Steel Rolls" only specifies the number and size equivalent of independent point defects and the density of planar defects in the evaluation of bonding layer defects of strip finishing work rolls. Due to the current development of new roll materials, the national standard for single point and planar defects can no longer effectively support the judgment of bonding layer defects, which may lead to roll accidents. Summary of the Invention

[0005] This invention provides a method for detecting the bonding layer of rolls, aiming to improve the above-mentioned problems.

[0006] This invention is implemented as follows: a method for detecting the bonding layer of a roll, the method comprising the following steps:

[0007] The state of the roll bonding layer is determined based on independent point defects and surface defects within the roll bonding layer.

[0008] The status of the roll bonding layer includes safety level, tracking level and warning level. Rolls in the safety level are used normally, rolls in the tracking level are continuously monitored during the tracking period to see if defects in the bonding layer develop, and rolls in the warning level are suspended from use.

[0009] In some embodiments, the method for determining the state of the roll bonding layer based on independent point defects is as follows:

[0010] (1) When the reflected wave equivalent of the roll bonding layer is below the Φ4mm distance amplitude curve, the roll bonding layer is considered to be at the safety level;

[0011] (2) When the reflected wave equivalent of the roll bonding layer is between the Φ4mm-Φ5mm+6dB distance amplitude curve, the state of the roll bonding layer is detected based on the number of reflections of the defect reflected wave and the wave height ratio of the secondary defect reflected wave to the primary defect reflected wave.

[0012] (3) When the reflected wave equivalent of the roll bonding layer is above the Φ5mm+6dB distance amplitude curve, the roll bonding layer is considered to be in a warning state.

[0013] In some embodiments, when the reflected wave equivalent of the roll bonding layer is between the Φ4mm-Φ5mm distance amplitude curve, the specific method for determining the state of the roll bonding layer is as follows:

[0014] (21) Detect the reflected waves of each independent point defect;

[0015] (22) If all independent point defects have only one defect reflection wave, then the roll is considered to be in the safe level;

[0016] (23) When there is a secondary reflection wave of an independent defect, calculate the ratio F / B of the wave height F of the secondary defect reflection wave to the wave height B of the primary defect reflection wave. If there are two or more independent point defects with a ratio F / B greater than 20%, the roll bonding layer is considered to be in the warning level. If there are none, it is in the safe level.

[0017] (24) If at least one independent point defect has three or more reflected waves, and the size of the corresponding independent point defect is relatively large, then the roll is considered to be in the warning level.

[0018] In some embodiments, when the ratio F / B of the secondary defect reflection wave height F of an independent point defect to the primary defect reflection wave height B is less than 20%, the roll bonding layer is considered to be in the tracking level.

[0019] During the tracking period, continue to track the ratio F / B of the secondary defect reflection wave height F to the primary defect reflection wave height B of the independent point defect. If the ratio F / B increases to 20% during the tracking period, it is considered that the ratio F / B of the secondary defect reflection wave height F to the primary defect reflection wave height B of the independent point defect is greater than 20%.

[0020] In some embodiments, when the reflected wave equivalent of the roll bonding layer is between the Φ5mm-Φ5mm+6dB distance amplitude curve, the specific method for determining the state of the roll bonding layer is as follows:

[0021] (31) If there is only one independent point defect, and the independent point defect has a second or more defect reflection wave, the roll bonding layer is considered to be in the warning level. If the independent point defect has a first defect reflection wave, the roll bonding layer is considered to be in the tracking level.

[0022] (32) When there are two or more independent point defects, the roll bonding layer is considered to be in the warning level.

[0023] In some embodiments, the independent point defect is tracked during the tracking period to see if secondary or higher defect reflection waves occur. If they do, the roll bonding layer is considered to be in the warning level; if they do not, the roll bonding layer is considered to be in the safe level.

[0024] In some embodiments, the method for determining the state of the roll bonding layer based on planar defects is as follows:

[0025] (1) When the echo equivalent of the planar defect is below the amplitude curve of the φ4mm distance, the roll bonding layer is considered to be in the safe level;

[0026] (2) The echo equivalent of the planar defect is between the φ4mm-φ5mm distance amplitude curve. The state of the roll bonding layer is determined based on the attenuation degree of the defect bottom wave.

[0027] (3) When the echo equivalent of the planar defect is above the amplitude curve of the φ5mm distance, the roll bonding layer is considered to be in the warning level.

[0028] In some embodiments, the process of determining the state of the roll bonding layer based on the attenuation degree of the defect bottom wave is as follows:

[0029] (61) Detect the bottom surface reflection wave of the planar defect. When the attenuation of the bottom surface reflection wave of the planar defect relative to the normal bottom surface reflection wave is less than 75%, the roll bonding layer is considered to be in the safe level.

[0030] (62) When the attenuation of the bottom surface reflected wave of the planar defect relative to the normal bottom surface reflected wave is in the range of 75-90%, the roll bonding layer is considered to be in the tracking level.

[0031] (63) If the attenuation of the bottom surface reflected wave of the planar defect is greater than 90% compared with the normal bottom surface reflected wave, the roll bonding layer is considered to be in the warning level.

[0032] In some embodiments, during the tracking period, the attenuation of the bottom surface reflection wave of the planar defect relative to the normal bottom surface reflection wave reaches 90%. If the detection result is yes, the roll bonding layer is identified as being in the warning level; if the detection result is no, the roll bonding layer is identified as being in the safety level.

[0033] This invention provides a roll bonding layer detection method based on secondary and multiple reflected waves for independent point defects, and a roll bonding layer detection method with bottom wave attenuation for planar defects, thereby improving the detection accuracy of roll bonding layers. The invention also classifies the state of roll bonding layers and adopts different measures for different states, which can effectively avoid roll accidents, rolling line failures, downtime, or equipment damage caused by bonding layer defects. Attached Figure Description

[0034] Figure 1 A schematic diagram of the wave height of the secondary defect reflection wave and the primary defect reflection wave of an independent point defect provided in an embodiment of the present invention;

[0035] Figure 2 The following is a comparison diagram of bottom wave attenuation of planar defects provided in an embodiment of the present invention, wherein (a) is the bottom surface reflection wave of the normal (defect-free) area, and (b) is the bottom surface reflection wave of the defective area. Detailed Implementation

[0036] The specific embodiments of the present invention will be further described in detail below with reference to the accompanying drawings, so as to help those skilled in the art to have a more complete, accurate and in-depth understanding of the inventive concept and technical solution of the present invention.

[0037] Ultrasonic testing is used to detect defects in the bonding layer of rolls (roughing and finishing mills). Defect types include independent point defects and area defects. If the density F of independent point defects in a certain area exceeds a set density threshold, then area defects are considered to exist in that area. The ultrasonic testing instrument has the following parameters: probe frequency: 2MHz-2.5MHz; probe diameter: Φ10mm-Φ25.4mm; probe sensitivity: Φ4, Φ5mm; gain: 45.5dB; and bottom echo or bottom echo height (100% full screen height). This invention classifies the state of the roll bonding layer into three levels: safety level, tracking level, and warning level. Rolls in the safety level can be used normally. Rolls in the tracking level track the bonding layer for a period of time to observe whether defects develop. Rolls in the warning level are suspended from use. The detection method for the bonding layer state based on independent point defects and area defects is as follows:

[0038] (a) Independent point defects

[0039] (1) When the reflected wave equivalent of the roll bonding layer is below the Φ4mm distance amplitude curve, the roll bonding layer is considered to be in the safe level and can be used normally.

[0040] The Φ4mm distance-amplitude curve refers to the AVG curve plotted using ultrasonic testing of a 4mm artificial regular reflector. The horizontal axis represents the actual sound path, and the vertical axis represents the wave height of the regular reflector. This curve describes the relationship between distance, amplitude, and equivalent size. The same principle applies to the Φ5mm distance-amplitude curve and Φ...

[0041] 5mm++6dB distance amplitude curve.

[0042] The equivalent of the defect emission wave (echo) of an independent point defect is between the amplitude curve of the distance φ4mm-φ5mm. Although the defect echo equivalent is small, it meets the national standard. When an independent point defect exhibits multiple reflections due to the acoustic impedance of the defect being much smaller than that of the bonding layer material, it is necessary to track the independent point defect. Therefore, it is necessary to track the number of echoes of the point defect, as well as the wave height ratio of the secondary defect emission wave to the primary defect reflection wave.

[0043] Example 1: In workshop 2250, roll FW51366 had a point-independent defect smaller than φ5mm. A secondary reflected wave appeared, and the wave height ratio F / B of the secondary reflected wave to the primary reflected wave was 8%. The roll continued to be used. During the third use, the roll peeled off and was scrapped, causing certain equipment losses and downtime. When the accident occurred, the wave height ratio of the secondary reflected wave to the primary reflected wave had reached 23%.

[0044] (2) When the equivalent reflected wave of the roll bonding layer is between the Φ4mm-Φ5mm distance amplitude curve, the state of the roll bonding layer is detected based on the number of reflections of the defect reflected wave and the wave height ratio of the secondary defect reflected wave to the primary defect reflected wave. The secondary defect reflected wave and the primary defect reflected wave of independent point defects are as follows: Figure 1 As shown:

[0045] (21) Detect the reflected waves of each independent point defect;

[0046] (22) If all independent point defects have only one defect reflection wave, then the roll is considered to be in the safe level;

[0047] (23) When there is a secondary reflection wave of an independent defect, calculate the ratio F / B of the wave height F of the secondary defect reflection wave to the wave height B of the primary defect reflection wave. If there are two or more independent point defects with a ratio F / B greater than 20%, the roll bonding layer is considered to be in the warning level; otherwise, it is in the safe level.

[0048] If the ratio F / B of the secondary defect reflection wave height F to the primary defect reflection wave height B is less than 20%, the roll bonding layer is considered to be in the tracking level. During the tracking period, the ratio F / B of the independent existing defect is continued to be tracked. If the ratio F / B increases to 20% or more, the independent point defect has developed, and the ratio F / B of the secondary defect reflection wave height F to the primary defect reflection wave height B of the independent point defect is considered to be greater than 20%.

[0049] (24) If at least one independent point defect has three or more reflected waves, and the size of the corresponding independent point defect is relatively large, then the roll is considered to be in the warning level.

[0050] (3) When the reflected wave equivalent of the roll bonding layer is between the Φ5mm-Φ5mm+6dB distance amplitude curve, the specific method for determining the state of the roll bonding layer is as follows:

[0051] (31) If there is only one independent point defect, and the independent point defect has two or more defect reflection waves, the roll bonding layer is directly identified as being in the warning level; if the independent point defect has a single defect reflection wave, the roll bonding layer is identified as being in the tracking level. The independent point defect is tracked to see if two or more defect reflection waves appear within the tracking period. If they appear, the roll bonding layer is directly identified as being in the warning level; if they do not appear, the roll bonding layer is identified as being in the safety level.

[0052] (32) When there are two or more independent point defects, the roll bonding layer is directly identified as being in the warning level.

[0053] (4) When the reflected wave equivalent of the roll bonding layer is above the Φ5mm+6dB distance amplitude curve, the roll bonding layer is considered to be in a warning state.

[0054] (ii) Planar defects

[0055] (5) When the echo equivalent of the planar defect is below the amplitude curve of the φ4mm distance, the roll bonding layer is considered to be in the safe level;

[0056] (6) The echo equivalent of planar defects is between the amplitude curves of the φ4mm-φ5mm distance. The state of the roll bonding layer is determined based on the attenuation degree of the defect bottom wave. The determination process is as follows:

[0057] Despite the surface defect echo equivalent falling within the φ4mm-φ5mm range of the amplitude curve, roll accidents still occur. Analysis revealed that although the surface defect equivalent of φ4mm-φ5mm is within the national standard range, the dense morphology of the surface defects causes them to expand during use due to internal stress or external pressure, leading to failure. Since dense defects cause bottom wave scattering attenuation, bottom wave attenuation is used to evaluate surface defects at the roll joint surface, as detailed below:

[0058] (61) Detecting the bottom surface reflection wave of planar defects, if the attenuation of the bottom surface reflection wave of the planar defect relative to the normal bottom surface reflection wave is less than 75%, the roll bonding layer is considered to be in a safe level. The normal bottom surface reflection wave and the bottom surface reflection wave of the planar defect are respectively as follows: Figure 2 As shown in (a) and (b).

[0059] (62) When the attenuation of the bottom surface reflected wave of the planar defect relative to the normal bottom surface reflected wave is in the range of 75-90%, the roll bonding layer is identified as being in the tracking level. During the tracking period, the attenuation of the bottom surface reflected wave of the planar defect relative to the normal bottom surface reflected wave is tracked to see if it reaches 90%. If the detection result is yes, the roll bonding layer is identified as being in the warning level. If the detection result is no, the roll bonding layer is identified as being in the safety level.

[0060] (63) If the attenuation of the bottom surface reflected wave of the planar defect is greater than 90% compared with the normal bottom surface reflected wave, the roll bonding layer is considered to be in the warning level.

[0061] (7) When the echo equivalent of a planar defect is above the amplitude curve of a φ5mm distance, the roll bonding layer is considered to be in the warning level:

[0062] Example 2: During inspection, defects smaller than φ5mm were found in roll FW10277 in workshop 2250. However, it was confirmed by penetration with a 1MHz Φ24mm probe. The bottom wave of the normal area was taken as 100%, and the defect area was inspected. The bottom wave attenuation was 100%-15%=85%. After a second use, the bottom wave attenuated to 90%, and the bonding layer had separated. The defect had extended and changed. If it continued to be used, a serious rolling accident would occur.

[0063] Example 3: The FW51363 roll in workshop 2250 has a defect equivalent of φ5mm+1dB. However, the nature of this defect is that graphite aggregates at the bonding layer, which weakens the bonding force of the bonding layer. Due to the influence of thermal expansion and contraction, continued use will easily cause the bonding layer to separate and cause roll accidents.

[0064] The present invention has been described by way of example. Obviously, the specific implementation of the present invention is not limited to the above-described manner. Any non-substantial improvements made using the inventive concept and technical solution of the present invention, or the direct application of the inventive concept and technical solution of the present invention to other occasions without modification, are all within the protection scope of the present invention.

Claims

1. A method for detecting the bonding layer of a rolling mill roll, characterized in that, The method includes the following steps: The state of the roll bonding layer is determined based on independent point defects and surface defects within the roll bonding layer. The status of the roll bonding layer includes safety level, tracking level and warning level. Rolls in the safety level are used normally, rolls in the tracking level are continuously monitored during the tracking period to see if defects in the bonding layer develop, and rolls in the warning level are suspended from use. The specific method for determining the state of the roll bonding layer based on independent point defects is as follows: (1) When the reflected wave equivalent of the roll bonding layer is below the Φ4mm distance amplitude curve, the roll bonding layer is considered to be at the safety level; (2) When the reflected wave equivalent of the roll bonding layer is between the Φ4mm-Φ5mm+6dB distance amplitude curve, the state of the roll bonding layer is detected based on the number of reflections of the defect reflected wave and the wave height ratio of the secondary defect reflected wave to the primary defect reflected wave. (3) When the reflected wave equivalent of the roll bonding layer is above the Φ5mm+6dB distance amplitude curve, the roll bonding layer is considered to be in a warning state.

2. The method for detecting the roll bonding layer as described in claim 1, characterized in that, When the reflected wave equivalent of the roll bonding layer is between the Φ4mm-Φ5mm distance amplitude curve, the specific method for determining the state of the roll bonding layer is as follows: Detecting the reflected waves from individual point defects; If all independent point defects have only one defect reflection wave, the roll is considered to be in the safe level. When an independent defect has a secondary defect reflection wave, calculate the ratio F / B of the secondary defect reflection wave height F to the primary defect reflection wave height B. If there are two or more independent point defects with a ratio F / B greater than 20%, the roll bonding layer is considered to be in the warning level; otherwise, it is in the safe level. (24) If at least one independent point defect has three or more reflected waves, and the size of the corresponding independent point defect is relatively large, then the roll is considered to be in the warning level.

3. The method for detecting the roll bonding layer as described in claim 2, characterized in that, When the ratio F / B of the secondary defect reflection wave height F to the primary defect reflection wave height B of an independent point defect is less than 20%, the roll bonding layer is identified as being in the tracking level. During the tracking period, the ratio F / B of the secondary defect reflection wave height F to the primary defect reflection wave height B of the independent point defect is continued to be tracked. If the ratio F / B increases to 20% during the tracking period, the roll bonding layer is identified as being in the warning level.

4. The method for detecting the roll bonding layer as described in claim 1, characterized in that, When the reflected wave equivalent of the roll bonding layer falls within the range of the Φ5mm-Φ5mm+6dB distance amplitude curve, the specific method for determining the state of the roll bonding layer is as follows: If there is only one independent point defect, and the independent point defect has secondary or higher defect reflection waves, the roll bonding layer is considered to be in the warning level. If the independent point defect has a primary defect reflection wave, the roll bonding layer is considered to be in the tracking level. When two or more independent point defects exist, the roll bonding layer is considered to be at the warning level.

5. The method for detecting the roll bonding layer as described in claim 4, characterized in that, During the tracking period, the independent point defect is tracked to see if secondary or higher defect reflection waves appear. If they do, the roll bonding layer is considered to be in the warning level; if they do not, the roll bonding layer is considered to be in the safe level.

6. The method for detecting the roll bonding layer as described in claim 1, characterized in that, The specific method for determining the state of the roll bonding layer based on planar defects is as follows: (1) When the echo equivalent of the planar defect is below the amplitude curve of the φ4mm distance, the roll bonding layer is considered to be in the safe level; (2) The echo equivalent of the planar defect is between the φ4mm-φ5mm distance amplitude curve. The state of the roll bonding layer is determined based on the attenuation degree of the defect bottom wave. (3) When the echo equivalent of the planar defect is above the amplitude curve of the φ5mm distance, the roll bonding layer is considered to be in the warning level.

7. The method for detecting the roll bonding layer as described in claim 6, characterized in that, The process of determining the state of the roll bonding layer based on the attenuation degree of the defect bottom wave is as follows: When detecting the bottom surface reflection wave of a planar defect, if the attenuation of the bottom surface reflection wave of the planar defect relative to the normal bottom surface reflection wave is less than 75%, the roll bonding layer is considered to be in a safe level. When the attenuation of the bottom surface reflected wave from a planar defect relative to the normal bottom surface reflected wave is in the 75-90% range, the roll bonding layer is considered to be in the tracking level. If the attenuation of the bottom surface reflected wave of a planar defect is greater than 90% compared to the normal bottom surface reflected wave, the roll bonding layer is considered to be in the warning level.

8. The method for detecting the roll bonding layer as described in claim 7, characterized in that, During the tracking period, the attenuation of the bottom surface reflected wave of the planar defect relative to the normal bottom surface reflected wave is monitored to see if it reaches 90%. If the detection result is yes, the roll bonding layer is identified as being in the warning level; if the detection result is no, the roll bonding layer is identified as being in the safe level.

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