A train wheel flaw detection method based on phased array ultrasonic wave

Abstract

The application discloses a train wheel flaw detection method based on a phased array ultrasonic wave, which is composed of wheel rim axial wheel flaw detection, wheel rim radial wheel flaw detection and wheel rim flaw detection. The application performs flaw detection on the wheel rim axial direction, the wheel rim radial direction and the wheel rim, so that the detection area is more comprehensive, the risk of missing detection is reduced, and the flaw detection precision of the three parts is improved.

Description

Technical Field

[0001] This invention belongs to the field of wheel manufacturing technology, and more specifically, this invention relates to a flaw detection method for train wheels based on phased array ultrasonic waves. Background Technology

[0002] Wheels are critical components of vehicles, directly contacting the rails. Their continuous rotation on the wheel-rail system propels the train, subjecting it to alternating stresses. With the rapid development of railway transportation, increased train loads and speeds have led to a rise in the risk of wheel rim cracking. From a causal perspective, rim cracking primarily results from fatigue fracture caused by manufacturing defects within the wheel-rail contact zone initiating and expanding under alternating stresses. Therefore, increasingly stringent requirements are placed on the internal quality of wheel rims, necessitating ultrasonic testing to minimize missed and false defects.

[0003] Currently, most domestic and international standards for train wheel flaw detection generally require scanning from the inner rim surface and tread surface of the wheel. The criterion for evaluating the equivalent quality of ultrasonic flaw detection in domestic and international wheel standards is based on comparison with standard flat-bottomed hole defects, such as the requirements of ISO 5948 standard (which is the same as domestic railway standards), for preparing test blocks. Figure 1 A DAC curve is created based on the flat-bottomed hole in the test block. If the defect wave reflection reaches the DAC curve or above, it is judged as an excessive defect.

[0004] According to ISO 5948 standard, the actual requirements for the axial and radial scanning areas of the wheel rim are as follows: Figure 2 The shaded area lacks specific quantitative indicators. For wheels with thicker rims, there are many blind spots if the above requirements are followed for scanning. In addition, when scanning the rim radially, the sound field distribution varies under different tread shapes due to the influence of the tread shape, resulting in uneven sound field distribution. Furthermore, the sound enters under the tread after refraction, and the reflection angle of the flat-bottom hole at different positions under the tread is different. The larger the reflection angle, the smaller the reflected sound pressure received by the probe, leading to inaccurate quantitative analysis of the flat-bottom hole. Summary of the Invention

[0005] This invention provides a method for flaw detection of train wheels based on phased array ultrasonic waves, aiming to improve the above-mentioned problems.

[0006] The present invention is implemented as follows: a method for flaw detection of train wheels based on phased array ultrasonic waves, the method consisting of three parts: wheel flaw detection along the rim axis, wheel flaw detection along the rim radial direction, and wheel flange flaw detection.

[0007] Furthermore, wheel flaw detection along the rim axis includes:

[0008] A scanning with a focusing depth of 70 mm is used for detecting equivalent defects of flat-bottomed holes with a diameter of 1 mm and a diameter of 1 mm in the 10 mm downward region of the inner rim surface; and a scanning with a focusing depth of 10 mm is used for detecting equivalent defects of flat-bottomed holes with a diameter of 1 mm and a diameter of 1 mm in the 5 mm-10 mm region of the inner rim surface.

[0009] Furthermore, wheel flaw detection is performed in radial sections along the rim, and the DAC curve is adaptively adjusted for the tread shape of each section to set the radial flat bottom hole of the rim.

[0010] Furthermore, the specific methods for dividing the region are as follows:

[0011] At the sampling points on the tread, the slope of each sampling point is calculated, and then the slope change rate of each sampling point is determined. The two points with the largest slope change rate are used as the dividing points, and the tread is divided into three regions in sequence, namely region one, region two and region three, where region three is close to the rolling circle of the tread.

[0012] Furthermore, the two ends of Region 2 extend towards Region 1 and Region 3 by a set distance, so that the scanning areas of Region 2 and Region 1 and Region 3 partially overlap along the tread direction.

[0013] Furthermore, during the wheel flaw detection process in regions one to three, the deflection angle θ of the ultrasonic probe crystal adaptively changes with the tread slope k to ensure that the ultrasonic waves are incident perpendicularly into the flat-bottomed hole inside the wheel.

[0014] Furthermore, the specific method for controlling the deflection angle θ of the ultrasonic probe wafer is as follows:

[0015] At each sampling point on the tread surface, the slope of each sampling point is determined. Based on the slope of each sampling point on the tread surface, the required deflection angle θ of the ultrasonic probe crystal at each sampling point is calculated when the ultrasonic wave is injected perpendicularly into the flat-bottom hole, so as to ensure that all ultrasonic waves inside the tread surface are injected perpendicularly into the flat-bottom hole.

[0016] Furthermore, the specific formula for calculating the ultrasonic probe crystal deflection angle θ is as follows:

[0017] θ=β-α=arctan(k)-arcsin(sin(arctan(k))c 水 / c 钢 )

[0018] Where θ is the deflection angle of the ultrasonic probe crystal, k is the slope of the tread sampling point, and c 水 c 钢 These represent the sound speeds of ultrasound in steel wheel and water, respectively.

[0019] Furthermore, folding defects cause chipping of the rim. The flaw detection area of ​​the rim is offset by 5mm-10mm from the rim tip and from the rim throat, based on the axis of the flat bottom hole, and covers the entire throat area.

[0020] This invention performs flaw detection on three parts of the wheel rim: axial, radial, and flange. The detection area is more comprehensive, reducing the risk of missed defects. In addition, it improves the defect detection accuracy of the three parts. Attached Figure Description

[0021] Figure 1 The test blocks provided in this embodiment of the invention are in accordance with the requirements of ISO5948 standard, wherein (a) is a rim axial test block and (b) is a rim radial test block;

[0022] Figure 2 The scanning area according to the ISO5948 standard provided for the embodiments of the present invention, wherein (a) is the axial region of the rim and (b) is the radial region of the rim;

[0023] Figure 3 This is a schematic diagram of a 70mm axial focusing depth scan of a wheel rim provided in an embodiment of the present invention, wherein (a) is the DAC curve set for the axial flat-bottom hole of the wheel rim, and (b) is the sound field distribution during axial scanning of the wheel rim;

[0024] Figure 4 This is a schematic diagram of a 10mm axial focusing depth scan of a wheel rim provided in an embodiment of the present invention, wherein (a) is the DAC curve set for the flat-bottomed hole in the axial blind zone of the wheel rim, and (b) is the sound field distribution during the axial blind zone scan of the wheel rim.

[0025] Figure 5 A schematic diagram of a typical tread shape provided in an embodiment of the present invention;

[0026] Figure 6 This is a schematic diagram of the tread surface scanning zones provided in an embodiment of the present invention;

[0027] Figure 7 This is a schematic diagram of the rim diameter deflection rule provided in an embodiment of the present invention;

[0028] Figure 8 A DAC curve is set for the radial flat-bottom hole of the wheel rim provided in the embodiments of the present invention;

[0029] Figure 9 A schematic diagram of the sound field distribution in the radial region of the rim provided for an embodiment of the invention, wherein (a) is region one, (b) is region two, (c) is region three, and (d) is a combination of region one, region two, and region three;

[0030] Figure 10 A schematic diagram of the rim scanning area provided in an embodiment of the present invention;

[0031] Figure 11 This is a schematic diagram of the sound field distribution during rim scanning provided in an embodiment of the present invention;

[0032] Figure 12 A schematic diagram of the sound field distribution of the entire wheel rim provided for an embodiment of the present invention;

[0033] Figure 13 This is a schematic diagram of the radial sound field distribution when an ultrasonic wave is incident on a vertical tread surface, as provided in an embodiment of the present invention. Detailed Implementation

[0034] 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.

[0035] The train wheel flaw detection method based on phased array ultrasonic waves provided in this invention comprises three parts: wheel flaw detection along the rim axis, wheel flaw detection along the rim radial direction, and wheel flange flaw detection.

[0036] (1) Wheel flaw detection along the rim axis:

[0037] 11) A 70mm deep scan is used to scan for equivalent defects of Φ1mm flat-bottomed holes in a 10mm downward area on the inner rim surface;

[0038] With a spacing of one wafer, 14 wafer groups are excited each time, and the number of excitations is set according to the rim thickness. The focus depth is set to 70mm, and the design is as follows. Figure 3 (a) The DAC curve is set for the six axial flat-bottomed holes of the rim. The diameter of the flat-bottomed holes is 1mm. Among them, the flat-bottomed holes RAD1 (hole depth 20mm), RAD2 (hole depth 40mm), RAD3 (hole depth 60mm), RAD4 (hole depth 80mm), RAD5 (hole depth 100mm), and RAD6 (hole depth 120mm) are circumferentially spaced 15 degrees apart. The distances of the flat-bottomed holes RAD1, RAD2, RAD3, RAD4, RAD5, and RAD6 from the rolling circle of the tread surface are 15mm, 22.5mm, 30mm, 37.5mm, 45mm, and 52.5mm, respectively. Figure 3 (b) shows the sound field distribution of the corresponding ultrasound.

[0039] The rim thickness of various types of iron wheels is generally around 120-150mm. According to field tests, with a phased array focusing depth set within 50-90mm, it is difficult to detect flat-bottomed holes with a depth of less than 10mm at a sensitivity of Φ1mm. Therefore, this invention uses a scanning depth of 10mm to scan for equivalent defects of flat-bottomed holes with a depth of Φ1mm in a 5mm-10mm area on the inner rim surface, so that the blind zone is ≤5mm at a sensitivity of Φ1mm.

[0040] 12) A 10mm focusing depth scan is used to scan for equivalent defects of Φ1mm flat-bottomed holes within a 5mm-10mm area on the inner rim surface;

[0041] Spacing out one wafer, 14 wafer groups are excited each time, with the number of excitations set according to the rim thickness. The focus depth is set to 10mm, as shown below. Figure 4 (a) The DAC curve is set in the three axial flat-bottom holes of the rim. The diameter of the flat-bottom hole is 1mm. The axial DAC curve holes of the rim are drilled on the outer rim surface: 14 sets of crystals are excited each time, and the focus depth is set to 10mm. The flat-bottom holes RAD7 (10mm depth), RAD8 (5mm depth), and RAD9 (3mm depth) are 15mm, 30mm, and 45mm away from the rolling circle of the tread surface, respectively. Figure 4 (b) shows the sound field distribution of the corresponding ultrasound.

[0042] (2) Wheel flaw detection in the radial direction of the rim.

[0043] In embodiments of the present invention, such as Figure 5 These are some of the more typical tread shapes, including LM type, LMA type, EN13715, and AAR-1B. Figure 5 As can be seen, the slope is relatively gentle in the middle, while the slopes on both sides vary considerably. Therefore, the radial scan of the wheel rim is divided into three regions, and the specific division method is as follows:

[0044] At the sampling points on the tread, the slope of each sampling point is calculated, and then the slope change rate of each sampling point is determined. The two points with the largest slope change rate are used as the dividing points, and the tread is divided into three regions in sequence, namely region one, region two and region three, where region three is close to the rolling circle of the tread.

[0045] Based on the characteristics of the tread surface, we can deduce that: Region 1 is generally a diagonal line segment; Region 2 is a relatively flat area in the middle, which is generally composed of two arcs or one arc and one straight line segment; Region 3 is generally an arc that extends to the rolling circle, such as... Figure 6 As shown.

[0046] In order to ensure that the sound field at the transition between the three regions can be completely covered, the two ends of Region 2 are extended to Region 1 and Region 3 by a set distance (e.g., 10mm), that is, the scanning areas of Region 2 and Region 1, and Region 2 and Region 3 overlap by 10mm along the tread direction.

[0047] like Figure 13 This is a schematic diagram of the ultrasonic sound field distribution inside the wheel when an ultrasonic wave is incident perpendicularly to the tread surface. Figure 13It is known that due to the influence of tread shape, the sound field cannot be uniformly covered in the inspection area, posing a risk of missed detections. This invention designs a phased array with a deflection law applicable to tread shape. During radial scanning, the sound beam is incident from water, and the longitudinal wave refracted in the steel is perpendicular to the designed flat-bottomed hole surface. Simultaneously, a zoned scanning design is implemented to reduce the significant impact of tread shape on quantitative analysis. Based on this, during wheel inspection in regions one to three, the ultrasonic probe crystal deflection angle θ adaptively changes with the tread slope to ensure that the ultrasonic waves are incident perpendicularly to the flat-bottomed hole inside the wheel. The method for determining the incident angle of the tread is as follows:

[0048] At each sampling point on the tread surface, the slope of each sampling point is determined. Based on the slope of each sampling point on the tread surface, the required deflection angle θ of the ultrasonic probe crystal at each sampling point is calculated when the ultrasonic wave is injected perpendicularly into the flat-bottom hole, so as to ensure that all ultrasonic waves inside the tread surface are injected perpendicularly into the flat-bottom hole.

[0049] In this embodiment of the invention, the slope of the tread sampling points is k, based on Figure 7 It can be seen that as long as the angle of refraction is kept consistent with the slope of the tread surface, it will be fine, according to the formula:

[0050] sinα / c 水 =sin(arctan(k)) / c 钢

[0051] Therefore, the deflection rule is:

[0052] θ=β-α=arctan(k)-arcsin(sin(arctan(k))c 水 / c 钢 )

[0053] Where θ is the deflection angle of the ultrasonic probe crystal, α represents the incident angle in the water, β is the refraction angle under the tread surface, and the ultrasonic wave refracted by the tread surface is perpendicular to the flat-bottomed hole, c 水 c 钢 These represent the sound speeds of ultrasound in steel wheel and water, respectively.

[0054] Wheel flaw detection process in Area 1: One crystal is spaced apart, 10 crystals are excited each time, the focusing depth is set to 25mm, and the sound beam focusing direction is vertically propagating under the tread surface according to its shape (the sound beam and propagation direction are perpendicular to the flat bottom hole). Design as follows... Figure 8 The DAC curve is set for the six axial flat-bottom holes of the rim. Flat-bottom holes RRC1 (hole depth 10mm), RRC2 (hole depth 20mm), RRC3 (hole depth 10mm), RRC4 (hole depth 10mm), RRC5 (hole depth 10mm), and RRC6 (embedded depth 10mm) are drilled with a diameter of 1mm at 4 degrees circumferentially and 15mm away from the outer rim surface.

[0055] The wheel flaw detection process in Area 2: Ten sets of crystals are excited at intervals of one crystal. The focusing depth is set to 25mm, and the sound beam focusing direction is vertically transmitted below the tread surface according to its shape. According to... Figure 6 The DAC curve is set for the 6 axial flat-bottom holes of the wheel rim. Flat-bottom holes RRC7 (hole depth 10mm), RRC8 (hole depth 20mm), RRC9 (hole depth 10mm), RRC10 (hole depth 10mm), RRC11 (hole depth 10mm), and RRC12 (embedded depth 10mm) are drilled with a diameter of 1mm at a distance of 4 degrees and 15mm from the outer rim surface.

[0056] The wheel flaw detection process in Region 3: 10 wafers are excited at a time, spaced one wafer apart. The focusing depth is set to 25mm. The design is as follows: Figure 8 The DAC curve is set for the six axial flat-bottomed holes of the wheel rim. Flat-bottomed holes RRC13 (hole depth 10mm), RRC14 (hole depth 20mm), RRC15 (hole depth 10mm), RRC16 (hole depth 10mm), RRC17 (hole depth 10mm), and RRC18 (embedding depth 10mm) are drilled with a diameter of 1mm, 4 degrees apart and 15mm away from the outer rim surface.

[0057] in, Figure 9 Figures (a), (b), (c), and (d) show schematic diagrams of the sound field distribution in Region 1, Region 2, Region 3, and the composite sound field of the three regions, respectively. According to standard requirements, DAC curves were established using the standard flat-bottom hole equivalent for scanning under different tread slopes. CIVA simulation results show that the slope variation has a maximum impact of 6dB on the scanning sensitivity of the φ1 flat-bottom hole. Designing zoned scanning and designing quantitative flat-bottom holes for different regions can reduce the impact of slope variation on quantitative analysis, making the quantitative analysis more accurate.

[0058] (3) Wheel flange inspection.

[0059] During wheel operation, especially during cornering, the wheel flange is subjected to stress, leading to flange chipping. Analysis shows that this chipping is mainly caused by folding defects. To reduce the probability of flange chipping, a flaw detection method for the wheel flange has been implemented.

[0060] Spacing out one wafer, 10 wafers are excited each time, and the number of excitations is set to cover the rim area. The design is as follows: Figure 10 Flat-bottomed aperture on the rim. Focusing depth set to 10mm, the transmitted beam is perpendicular to the bottom surface of the flat-bottomed aperture; Scanning area: Using the axis of the flat-bottomed aperture as a reference, offset 5mm-10mm towards the rim tip, and offset towards the rim throat to cover the entire throat area, i.e. Figure 10 The area marked with bold lines is the scanning area for the wheel rim. Figure 11The corresponding ultrasonic sound field distribution;

[0061] The phased array deflection law is designed so that the sound beam, incident from water, refracts into longitudinal waves in the steel and is perpendicular to the flat-bottomed surface of the wheel rim, allowing for more accurate detection of folding defects in the wheel rim. The deflection law is designed as follows:

[0062]

[0063] In the formula: θ is the deflection angle of the ultrasonic probe crystal, α represents the incident angle in water, β is the refraction angle below the inner rim surface, and the ultrasonic wave refracted by the inner rim surface is perpendicular to the flat-bottomed hole, c 水 c 钢 These represent the sound speeds of ultrasound in steel wheel and water, respectively.

[0064] Based on the aforementioned method for flaw detection of train wheels using phased array ultrasonic waves, the detection ultrasonic waves are evenly distributed throughout the wheel rim during production. Figure 12 As shown, a flat-bottomed hole is designed for calibration, enabling the method to be applied in the field. Therefore, the beneficial effects of this invention are as follows:

[0065] 1) The maximum detection area in the circumferential direction of the rim, and the blind zone of the rim is controlled within 5mm under the sensitivity of φ1mm flat-bottom hole; 2) The radial tread deflection law design and the zoned scanning design of the rim make the sound field distribution under the tread uniform, and the sound beam is parallel to the flat-bottom hole, reducing the influence of tread shape on defect quantification and making defect quantification more accurate; 3) The deflection law design and flat-bottom hole position design of the flange effectively prevent the flange from falling off due to overlapping defects during train operation.

[0066] 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 flaw detection of train wheels based on phased array ultrasonic waves, characterized in that, The method consists of three parts: wheel flaw detection along the rim axis, wheel flaw detection along the rim radial direction, and wheel flange flaw detection. Wheel flaw detection is performed in radial sections along the rim, and the DAC curve is adaptively adjusted for the tread shape of each section to set the radial flat bottom hole of the rim. The specific method for dividing the region is as follows: At each sampling point on the tread surface, the slope of each sampling point is calculated to determine the rate of change of the slope. The two points with the largest rate of change of slope are used as dividing points to divide the tread surface into three regions: Region 1, Region 2, and Region 3. Region 3 is closer to the rolling circle of the tread surface. The two ends of Region 2 extend towards Region 1 and Region 3 by a set distance, so that the scanning areas of Region 2, Region 1, and Region 3 partially overlap along the tread surface direction. During wheel flaw detection in areas one through three, the ultrasonic probe crystal deflection angle It adapts to the slope k of the tread surface to ensure that the ultrasonic waves are incident vertically through the flat-bottomed hole inside the wheel. Ultrasonic probe crystal deflection angle The specific control methods are as follows: At each sampling point on the tread surface, the slope of each sampling point is determined. Based on the slope of each sampling point on the tread surface, the required ultrasonic probe wafer deflection angle at each sampling point is calculated when the ultrasonic wave is injected perpendicularly into the flat-bottomed hole. This ensures that all ultrasonic waves inside the tread are injected perpendicularly to the flat-bottomed hole. Ultrasonic probe crystal deflection angle The specific calculation formula is as follows: ； in, This refers to the deflection angle of the ultrasonic probe crystal. The slope of the tread sampling point. , These represent the sound speeds of ultrasound in steel wheel and water, respectively.

2. The method for flaw detection of train wheels based on phased array ultrasonic waves as described in claim 1, characterized in that, Wheel flaw detection along the rim axis includes: A scanning with a focusing depth of 70 mm is used for detecting equivalent defects of flat-bottomed holes with a diameter of 1 mm (Φ1 mm) in the area 10 mm downward from the inner rim surface; and a scanning with a focusing depth of 10 mm is used for detecting equivalent defects of flat-bottomed holes with a diameter of 1 mm (Φ1 mm) in the area 5 mm to 10 mm from the inner rim surface.

3. The method for flaw detection of train wheels based on phased array ultrasonic waves as described in claim 1, characterized in that, Flaw inspection includes: Folding defects cause chipping of the rim. The inspection area of ​​the rim is based on the axis of the flat bottom hole, offset 5mm-10mm towards the tip of the rim, and offset towards the throat of the rim to cover the entire throat area.

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