Ultrasonic flaw detection method for functional area of bearing
By using comparative test blocks and critical curves in ultrasonic flaw detection in the bearing functional area, the problem of inaccurate detection results in the prior art is solved, and accurate detection and cost reduction of bearing functional area is achieved.
Patent Information
- Application Number
- CN202510151402.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-02-11
- Publication Date
- 2025-05-09
AI Technical Summary
In the prior art, the ultrasonic flaw detection method detects the bearing functional area inaccurate results, and the water immersion detection equipment is expensive and has a high cost of use.
A method of ultrasonic flaw detection in the bearing functional area is adopted, including making a comparison test block, processing flat bottom holes of different depths on the comparison test block to simulate the maximum defect at different depths of the functional area, using an ultrasonic probe to detect the comparison test block to obtain a critical curve, and then detect the functional area from the raceway of the bearing to be tested to determine whether the defect is within the critical value.
Accurate detection of bearing functional areas is achieved, the accuracy of detection results is ensured, the detection cost is reduced, and it is suitable for larger bearing inspections.
Smart Images
Figure CN119959355A_ABST
Abstract
Description
Technical Field
[0001] The invention relates to the technical field of ultrasonic flaw detection, and in particular to a method for ultrasonic flaw detection of a bearing functional area. Background Art
[0002] Traditional ultrasonic flaw detection methods for bearing rings include contact method single straight probe detection and water immersion detection. Among them, contact method single straight probe detection is more commonly used. The detection steps of this method are: first use Figure 7-8 The DAC curve is made by using the comparison test block shown in the figure, and then the bearing ring to be tested is tested. When testing the bearing ring, if Figure 5-6 As shown, an ultrasonic probe is used to scan the outside of the bearing outer ring 1 and then scan the inside of the bearing inner ring 2, so that defects inside the bearing ring can be detected.
[0003] When using the water immersion method for testing, there is currently no standard in the bearing industry for using the water immersion method for ultrasonic flaw detection of bearings. Therefore, most bearing ring water immersion flaw detection test blocks are made in accordance with the requirements of Appendix B of GB / T 25770-2024 "Rolling Bearings Railway Freight Car Bearings", such as Figure 7-8 As shown, the test is carried out according to the requirements of EN 12080:2017 standard, such as Fig. 9 As shown, the bearing ring to be tested is placed in a water tank 7, a fulcrum 8 is provided at the bottom of the water tank 7, the bearing ring to be tested is in contact with the fulcrum 8, water 6 is filled in the water tank 7, and the water immersion focusing probe 5 is located on the non-raceway surface. It can be deflected at a certain angle to allow the ultrasonic wave to enter the bearing ring, and the direction of the refracted sound beam is perpendicular to the raceway surface of the bearing ring. In this way, defects inside the bearing ring can also be detected.
[0004] Due to the high reliability requirements for wind turbine main shaft and gearbox bearings, the concept of functional zone is proposed, that is, the area within the range of 10% roller diameter depth from the contact point between the bearing ring and the roller (the raceway surface of the bearing ring) to the inside of the ring is the functional zone, such as Figure 1-2 As shown, the functional area of the gearbox bearing is 3mm to 6mm from the bearing ring to the raceway surface, and the functional area of the main shaft bearing is 6mm to 13mm from the bearing ring to the raceway surface. The current ultrasonic flaw detection requirements for functional areas are: gearbox bearing functional area defect equivalent ≤φ0.8mm flat bottom hole equivalent, some customers require ≤φ0.6mm flat bottom hole equivalent, spindle bearing functional area defect equivalent ≤φ1.0mm flat bottom hole equivalent, large megawatt wind turbine main shaft bearing functional area defect equivalent can be relaxed to ≤φ1.2mm flat bottom hole equivalent, the inspection requirements are in accordance with EN12080:2017 A.4.3, that is, the equivalent flat bottom hole bottom surface is parallel to the raceway surface.
[0005] In the prior art, the following are proposed for ultrasonic flaw detection of the functional area of the bearing ring: Figure 3-4 The comparison test block shown in the figure has a flat-bottomed hole whose bottom is parallel to the raceway surface, which can more accurately simulate the internal defects that may exist in the functional area and characterize the internal defect equivalent. However, when using the contact method single straight probe to detect this test block, the direction of the sound wave incident is not perpendicular to the raceway surface of the bearing ring, which will lead to inaccurate detection results of the functional area of the bearing ring. When using the water immersion method to detect the bearing ring, adjusting the angle of the sound wave incident can make the direction of the sound wave incident perpendicular to the raceway surface of the bearing ring, but there are still blind areas that cannot be detected during the detection, which will also lead to inaccurate final detection results. In addition, the equipment required for water immersion detection is expensive and the cost of use is high. Summary of the invention
[0006] The object of the present invention is to provide a method for ultrasonic flaw detection of a bearing functional zone, so as to solve the problem that the ultrasonic flaw detection method in the prior art provides inaccurate detection results when detecting a bearing functional zone.
[0007] In order to solve the above technical problems, the present invention adopts the following technical solutions.
[0008] A method for ultrasonic flaw detection of a bearing functional area comprises: (1) making a comparison test block, processing flat-bottom holes of different depths on the comparison test block to simulate the maximum defects allowed at different depths of the functional area, and the distance range between the bottom of the flat-bottom holes of different depths and the side of the comparison test block facing away from the flat-bottom hole opening is not less than the depth range of the functional area of the bearing ring to be tested; (2) using an ultrasonic probe to detect the side of the comparison test block facing away from the flat-bottom hole opening; (3) fitting a critical curve reflecting the relationship between the sound path and the defect reflection amplitude based on the detection results of each flat-bottom hole on the comparison test block; (4) using an ultrasonic probe to detect the functional area from the raceway surface of the bearing to be tested; (5) comparing the defect reflection amplitude appearing when detecting the raceway surface of the bearing to be tested with the value at the corresponding depth of the critical curve to determine whether the defect at the location is within the critical value of the defect reflection amplitude.
[0009] Furthermore, the distance between the bottom of the flat-bottom holes of different depths and the side of the comparison test block facing away from the flat-bottom hole opening ranges from 3 mm to 16 mm.
[0010] Furthermore, the ultrasonic probe uses a double crystal straight probe, and the probe diameter does not exceed φ14mm.
[0011] Furthermore, the wafer of the ultrasonic probe adopts a 5mm*5mm square wafer or a round wafer.
[0012] Furthermore, the probe focal length F is not less than half of the functional area depth and does not exceed the functional area depth, and the probe frequency f is set to 5 MHz to 6 MHz.
[0013] Furthermore, the scanning speed of the ultrasonic probe on the raceway surface of the bearing to be tested is not greater than 75 mm / s.
[0014] Furthermore, when making the comparison test block, the material with the same material and heat treatment state as the bearing ring is used.
[0015] Furthermore, the diameter of the comparison test block is not less than 60 mm, and the depth of the flat-bottom hole is not less than 5 mm.
[0016] Furthermore, the surface roughness of the side surface of the comparison test block facing away from the flat-bottomed hole is the same as the surface roughness of the ferrule.
[0017] Furthermore, the surface roughness of the side surface of the comparison test block facing away from the flat-bottomed hole is not greater than Ra3.2 μm.
[0018] Furthermore, a plurality of comparison test blocks are arranged in groups, and only one flat-bottom hole is processed on each comparison test block.
[0019] The above technical scheme has the following beneficial effects: the present invention innovatively proposes a method for ultrasonic flaw detection of bearing functional areas, including making a comparison test block, processing flat-bottom holes of different depths on the comparison test block to simulate the maximum defect allowed at different depths of the functional area, and the distance range between the bottom of the flat-bottom holes of different depths and the side of the comparison test block facing away from the flat-bottom hole opening, that is, the buried depth of the flat-bottom hole is not less than the depth range of the functional area of the bearing ring to be tested, using an ultrasonic probe to detect the comparison test block to obtain a critical curve, and then using an ultrasonic probe to detect the functional area from the raceway surface of the bearing ring to be tested, the defect reflection wave within the depth range of the functional area can be accurately obtained, and the defect reflection wave is compared with the critical curve to determine whether the bearing ring is qualified. In this way, the functional area of the bearing ring can be detected, the accuracy of the detection result can be guaranteed, and it is also more convenient to detect larger bearings with lower cost. BRIEF DESCRIPTION OF THE DRAWINGS
[0020] Figure 1 This is a schematic diagram of the functional area of the bearing outer ring; Figure 2 This is a schematic diagram of the functional area of the inner ring of the bearing; Figure 3 This is a schematic diagram of the requirements for the flat bottom hole of the outer ring comparison test block of the bearing for the main shaft and gearbox of the wind turbine; Figure 4 This is a schematic diagram of the requirements for the flat bottom hole of the inner ring comparison test block of the bearing for the main shaft and gearbox of the wind turbine; Figure 5 It is a schematic diagram of the contact method ultrasonic flaw detection of the outer ring of the bearing in the prior art; Figure 6 It is a schematic diagram of the contact method ultrasonic flaw detection of the inner ring of the bearing in the prior art; Figure 7 It is a schematic diagram of a flat bottom hole of a comparison test block of a bearing outer ring during contact method ultrasonic flaw detection in the prior art; Figure 8 It is a schematic diagram of a flat bottom hole of a comparison test block of a bearing inner ring during contact method ultrasonic flaw detection in the prior art; Fig. 9 A schematic diagram of the blind area of a bearing raceway detected by ultrasonic flaw detection using water immersion method in the prior art; Fig.10 A schematic diagram of using the method of the present invention to perform ultrasonic flaw detection on the functional area of the outer ring of a bearing; Fig.11 A schematic diagram of using the method of the present invention to perform ultrasonic flaw detection on the functional area of the inner ring of a bearing; Fig.12 A schematic diagram of a comparative test block of a bearing for a wind turbine gearbox of the present invention; Fig.13 It is a schematic diagram of another comparative test block of the bearing for the wind turbine gearbox of the present invention; Fig.14 This is a schematic diagram of another comparative test block of the bearing for the wind turbine gearbox of the present invention; Fig.15 A schematic diagram of a comparative test block of a bearing for a main shaft of a wind turbine generator according to the present invention; Fig.16 It is a schematic diagram of another comparative test block of the main shaft bearing for a wind turbine generator of the present invention; Fig.17 This is a schematic diagram of another comparative test block for the main shaft bearing of a wind turbine generator according to the present invention; Fig.18 It is a schematic diagram for comparing DAC curves fitted by different numbers of flat-bottom holes within the functional area of the present invention.
[0021] In the figure: 1. outer ring of bearing; 2. inner ring of bearing; 3. single crystal straight probe; 4. double crystal straight probe; 5. water immersion focusing probe; 6. water; 7. water tank; 8. fulcrum; 9. flat-bottom hole; M, DAC curve made from 5 flat-bottom holes of different depths; N, DAC curve made from 3 flat-bottom holes of different depths. DETAILED DESCRIPTION
[0022] The features and performance of the present invention are further described in detail below in conjunction with the embodiments.
[0023] The present invention proposes a method for ultrasonic flaw detection of bearing functional areas, comprising making a comparison test block, processing flat-bottom holes of different depths on the comparison test block to simulate the maximum defects allowed at different depths of the functional area, and the distance range between the bottom of the flat-bottom holes of different depths and the side of the comparison test block facing away from the flat-bottom hole opening, that is, the buried depth of the flat-bottom hole is not less than the depth range of the functional area of the bearing ring to be tested, using an ultrasonic probe to detect the comparison test block to obtain a critical curve, and then using the ultrasonic probe to detect the functional area from the raceway surface of the bearing ring to be tested, so that the defect reflection wave within the depth range of the functional area can be accurately obtained, and the defect reflection wave is compared with the critical curve to determine whether the bearing ring is qualified. In this way, the functional area of the bearing ring is detected, the accuracy of the detection result can be guaranteed, and the detection of larger bearings is also more convenient and the cost is lower.
[0024] Based on the above concept, the present invention provides various embodiments of the method for ultrasonic flaw detection of bearing functional areas for illustration.
[0025] In a basic embodiment, the method for ultrasonic flaw detection of the functional area of a bearing mainly includes: (1) making a comparison test block, processing flat-bottom holes 9 of different depths on the comparison test block to simulate the maximum defect that can be allowed at different depths of the functional area, and the distance range between the bottom of the flat-bottom holes 9 of different depths and the side of the comparison test block facing away from the flat-bottom hole opening, that is, the buried depth of the flat-bottom hole is not less than the depth range of the functional area of the bearing ring to be tested; (2) using an ultrasonic probe to detect the side of the comparison test block facing away from the flat-bottom hole opening; (3) fitting a critical curve reflecting the relationship between the sound path and the defect reflection amplitude based on the detection results of each flat-bottom hole 9 on the comparison test block; (4) using an ultrasonic probe to detect the functional area from the raceway surface of the bearing to be tested; (5) comparing the defect reflection amplitude that appears when detecting the raceway surface of the bearing to be tested with the value at the corresponding depth of the critical curve to determine whether the defect at that location is within the critical value of the defect reflection amplitude.
[0026] When processing the comparison test block, the comparison test block needs to be made of the same material and heat-treated state as the bearing ring to be tested. Preferably, it can be cut from a defect-free bearing ring, so as to ensure the accuracy of the test results.
[0027] On the basis of the above embodiments, the diameter of the comparison test block can be 60mm, 55mm, 50mm, and the hole depth of the flat bottom hole 9 processed on the comparison test block can be 5mm, 4mm, 3mm. In a preferred embodiment, the diameter of the comparison test block is not less than 60mm, and the hole depth of the flat bottom hole 9 processed on the comparison test block is not less than 5mm, so that the interference of the reflection wave of the side wall of the comparison test block on the reflection wave of the flat bottom hole can be reduced, and at the same time, it can be convenient to distinguish the reflection wave of the bottom surface of the comparison test block from the reflection wave of the flat bottom hole.
[0028] The shape of the comparison block can be set as follows Fig.13 , 16 The test block shown, or set as Fig.14 , 17 As the diameter of the flat bottom hole 9 is very small, the processing of small diameter deep holes is difficult and costly. Preferably, in order to reduce the processing difficulty and the processing cost of the test block, the flat bottom holes 9 with different buried depths can be made separately. The shape of the comparison test block is set as follows Fig.12 , 15 The test block shape is shown.
[0029] The surface roughness of the contact surface of the comparison test block can be different from the surface roughness of the bearing ring to be tested. When the surface roughness of the two is different, a comparison experiment is required to perform coupling compensation. Preferably, the surface roughness of the contact surface of the comparison test block is the same as the surface roughness of the bearing ring to be tested.
[0030] Due to the high detection sensitivity of the functional area, in a preferred embodiment, in order to improve the ultrasonic coupling effect and reduce the amplitude of the grass-like wave reflected on the surface of the bearing ring to be tested when the probe moves, the surface roughness of the bearing ring to be tested shall not exceed Ra3.2μm.
[0031] The ultrasonic probe may be a single crystal straight probe 3 , preferably, a double crystal straight probe 4 , with a probe diameter not exceeding φ14 mm, which can further reduce the detection blind area.
[0032] The wafer of the probe may be a round wafer. Preferably, the wafer of the probe may be a square wafer, and preferably a 5 mm×5 mm square wafer.
[0033] In the above embodiment, the parameters of the ultrasonic probe are adjusted, the focal length F of the probe is not less than half of the depth of the functional area and does not exceed the depth of the functional area, the probe frequency f is set to 5MHz~6MHz, according to the longitudinal wave wavelength λ=V / f in steel, the wavelength range is 1.184mm~0.986mm, and the detection sensitivity is half of the wavelength, that is, 0.592mm~0.493mm. Due to the focusing effect of the dual crystal straight probe, the actual detection sensitivity is higher than 0.592mm~0.493mm, which meets the requirement that the defect in the functional area is not greater than the equivalent of a flat-bottom hole with a diameter of 0.6mm.
[0034] When selecting an ultrasonic flaw detector, you can choose a digital ultrasonic flaw detector. When selecting an imported ultrasonic flaw detector, you can choose an ultrasonic flaw detector with a DGS curve function, and use a comparison test block to calibrate the DGS curve. Preferably, when selecting a domestic ultrasonic flaw detector, it is necessary to ensure that the instrument has a DAC curve function and a dual crystal straight probe channel, and can use a comparison test block to make a dual crystal straight probe DAC curve, which can reduce the cost of the equipment. These ultrasonic flaw detectors are all existing products, and their curve generation functions are all functions of the instrument itself.
[0035] After selecting the ultrasonic flaw detection instrument, the timing of testing the bearing ring to be tested is set after the forging and finishing of the bearing ring to be tested is completed and before quenching and heat treatment. This can reduce the subsequent processing losses caused by the unqualified internal quality of the bearing ring. At the same time, before quenching, there is a processing allowance of 1mm to 2.5mm on one side of the bearing ring raceway, and the finished bearing ring needs to remove the processing allowance, which can effectively reduce the detection blind area of the finished bearing ring.
[0036] To make a DAC critical curve, use a digital portable ultrasonic flaw detector equipped with a dual crystal straight probe to perform flaw detection on the contact surface of the comparison test block, and then make a DAC curve. The GB / T 6402-2008 standard requires that the comparison test block contain at least three reflectors that can cover the entire detection depth, that is, take three points to make a DAC curve. The more points you take, the more realistic the DAC curve will be, but the test block investment cost will be higher. Fig.18 As shown in the figure, the DAC curve N made by taking 3 flat-bottom holes of different depths and the DAC curve M made by taking 5 flat-bottom holes of different depths are fitted with the flat-bottom hole amplitude and the sound path as the coordinate axes. The sound path represents the depth of the defect in the functional area, and the flat-bottom hole amplitude represents the amplitude of the maximum defect that can be allowed at the corresponding position.
[0037] Combined with the functional area depth range of the current wind turbine main shaft bearing and gearbox bearing ring, it is stipulated that the gearbox bearing DAC curve has 5 points and the main shaft bearing DAC curve has 7 points. Therefore, when ultrasonic flaw detection is performed on the gearbox bearing, a total of 5 flat bottom hole test blocks are made, such as Figure 13-14 As shown in the figure, the distances between the bottom of the five flat-bottom holes 9 and the side of the comparison test block facing away from the flat-bottom hole opening are 3mm, 5mm, 7mm, 9mm, and 11mm respectively. The buried depth of the flat-bottom holes 9 is 2mm. A total of 7 flat-bottom hole test blocks are made for ultrasonic flaw detection of the spindle bearings. Figure 16-17 As shown, the distances between the bottoms of the seven flat-bottom holes 9 and the side of the comparison test block facing away from the flat-bottom hole opening are 3mm, 5mm, 7mm, 9mm, 11mm, 13mm, and 15mm, respectively. The buried depths of the flat-bottom holes 9 are spaced 2mm apart. The buried depths of the flat-bottom holes 9 set in this way can further make the critical curve more accurate and improve the accuracy of detection.
[0038] After the DAC critical curve is prepared, use an ultrasonic flaw detector to detect the raceway surface of the bearing to be tested. Use an ultrasonic flaw detector to scan the raceway surface. Figure 10-11 As shown in the figure, the scanning speed shall not be greater than 75mm / s, and the direction of the sound insulation layer of the ultrasonic probe must be perpendicular to the moving direction of the probe during scanning. The ultrasonic probe must have a 15% overlap rate each time it moves, which can further improve the accuracy of flaw detection.
[0039] In the above embodiment, a coupling agent is required when an ultrasonic flaw detector is used to perform flaw detection on a comparison test block and a bearing ring to be tested, and the same coupling agent needs to be used. Generally, 46# anti-wear hydraulic oil commonly used in factories is used as the coupling agent.
[0040] When a defect reflection signal appears on the screen of the ultrasonic flaw detector during the scanning process, move the probe to find the largest reflection amplitude of the defect and compare it with the DAC critical curve on the screen of the ultrasonic flaw detector. If the defect reflection amplitude is below the corresponding depth position of the DAC critical curve, it is determined that the defect here is allowed to exist; when the defect wave reflection amplitude is above the corresponding depth position of the DAC critical curve, it is determined that the defect here is not allowed to exist, that is, the bearing ring to be tested is unqualified.
[0041] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. The patent protection scope of the present invention shall be based on the claims. All equivalent structural changes made using the contents of the description and drawings of the present invention should also be included in the protection scope of the present invention.
Claims
1. A method for ultrasonic flaw detection of a bearing functional area, characterized in that: The method comprises: (1) making a comparison test block, machining flat-bottom holes of different depths on the comparison test block to simulate the maximum defects allowed at different depths of the functional zone, and the distance range between the bottom of the flat-bottom holes of different depths and the side of the comparison test block facing away from the flat-bottom hole opening is not less than the depth range of the functional zone of the bearing ring to be tested; (2) using an ultrasonic probe to detect the side of the comparison test block facing away from the flat-bottom hole opening; (3) fitting a critical curve reflecting the relationship between the sound path and the defect reflection amplitude based on the detection results of each flat-bottom hole on the comparison test block; (4) using an ultrasonic probe to detect the functional zone from the raceway surface of the bearing to be tested; and (5) comparing the defect reflection amplitude appearing when detecting the raceway surface of the bearing to be tested with the value at the corresponding depth of the critical curve to determine whether the defect at that location is within the critical value of the defect reflection amplitude.
2. The method for ultrasonic flaw detection of bearing functional areas according to claim 1 is characterized in that: The distance between the bottom of the flat-bottom holes of different depths and the side of the comparison test block facing away from the flat-bottom hole opening ranges from 3 mm to 16 mm.
3. The method for ultrasonic flaw detection of bearing functional areas according to claim 1 is characterized in that: The ultrasonic probe shall be a twin-crystal straight probe with a probe diameter not exceeding φ14mm.
4. The method for ultrasonic flaw detection of bearing functional areas according to claim 3 is characterized in that: The chip of the ultrasonic probe uses a 5mm*5mm square chip or a round chip.
5. The method for ultrasonic flaw detection of bearing functional areas according to claim 4 is characterized in that: The focal length F of the probe is not less than half of the depth of the functional area and does not exceed the depth of the functional area. The probe frequency f is set to 5MHz to 6MHz.
6. The method for ultrasonic flaw detection of a bearing functional area according to claim 1 is characterized in that: The scanning speed of the ultrasonic probe on the raceway surface of the bearing to be tested shall not exceed 75mm / s.
7. The method for ultrasonic flaw detection of a bearing functional area according to any one of claims 1 to 6, characterized in that: When making the comparison test block, the material with the same material and heat treatment status as the bearing ring is used.
8. The method for ultrasonic flaw detection of a bearing functional area according to claim 7 is characterized in that: The diameter of the comparison test block shall not be less than 60mm, and the depth of the flat-bottom hole shall not be less than 5mm.
9. The method for ultrasonic flaw detection of a bearing functional area according to claim 7, characterized in that: The surface roughness of the side surface of the comparison test block facing away from the flat-bottomed hole is the same as the surface roughness of the ferrule.
10. The method for ultrasonic flaw detection of a bearing functional area according to claim 9, characterized in that: The surface roughness of the side surface of the comparison test block facing away from the flat-bottomed hole is not greater than Ra3.2μm.
11. The method for ultrasonic flaw detection of a bearing functional area according to any one of claims 1 to 6, characterized in that: A plurality of comparison test blocks are arranged in groups, and only one flat-bottom hole is processed on each comparison test block.