A phased array dynamic focusing detection method and system for a variable cross-section shaft end

Abstract

The application relates to the field of phased array ultrasonic nondestructive testing technology, and discloses a phased array dynamic focusing detection method and system for a variable cross-section shaft end portion. The method divides a detection zone according to shaft end structure information and determines a target focusing position sequence, screens an effective array element range according to a propagation path and a propagation sound path, determines a focusing delay, switches focusing control information according to the target focusing position sequence before ultrasonic wave emission, obtains dynamic focusing echo data, identifies and removes structure echoes, and determines a defect position according to echo amplitude and continuity of adjacent target focusing positions. The application can improve the focusing effect and defect positioning accuracy of different shaft sections and cross-section transition regions.

Description

Technical Field

[0001] This invention relates to the field of phased array ultrasonic nondestructive testing technology, and in particular to a phased array dynamic focusing testing method and system for the end of a variable cross-section shaft. Background Technology

[0002] Shafts are crucial load-bearing and transmission components in mechanical transmission systems. To meet the installation and positioning requirements of bearings, gears, couplings, and other functional components, shafts typically have multiple segments of varying diameters at their ends, forming variable cross-section structures such as shoulders, fillets, tapered transition sections, or annular grooves between adjacent segments. During operation, shafts are usually subjected to torque, bending moment, axial loads, and alternating impact loads. Stress concentration easily occurs in areas of cross-sectional change, leading to fatigue cracks or other internal defects. If these defects are not detected in time and continue to propagate, they may reduce the load-bearing capacity of the shaft or even cause it to fracture.

[0003] Existing non-destructive testing methods for shaft parts mainly include magnetic particle testing, penetrant testing, eddy current testing, radiographic testing, and ultrasonic testing. Among these, magnetic particle testing, penetrant testing, and eddy current testing are primarily suitable for surface or near-surface defects; radiographic testing, when applied to large, thick-walled shaft parts, is easily limited by workpiece thickness, testing direction, and radiation protection conditions. Ultrasonic testing, with its advantages of greater penetration depth, higher testing safety, and ease of automation, is therefore well-suited for detecting internal defects in shaft parts.

[0004] Traditional shaft-end ultrasonic testing typically uses a single-crystal probe to emit ultrasonic waves from the shaft end face into the shaft body, or scans the shaft end face point by point by moving the probe. Because the beam angle and focal length of a single-crystal probe are relatively fixed, repeatedly adjusting the probe position or replacing the probe is often necessary when testing different axial depths and radial positions. Furthermore, manually moving the probe makes it difficult to ensure the beam direction remains in the predetermined state, easily leading to missed defects or positioning errors. Phased array ultrasonic testing, by controlling the excitation and reception delays of multiple array elements, can achieve electronic deflection, electronic scanning, and focusing of the ultrasonic beam. Compared to traditional single-probe testing, it offers advantages such as flexible beam control, a larger detection range, and more intuitive imaging results.

[0005] Patent CN109060954A discloses an ultrasonic array detection method and system for detecting cracks in stepped shafts. This method detects and evaluates cracks by arranging multiple array elements on the end face of the stepped shaft and acquiring array echo signals. However, this method does not dynamically adjust the array element aperture and focusing delay according to the geometry of different shaft segments and the target detection position, making it difficult to ensure that different axial depths and cross-sectional transition regions are all in an effective focusing state.

[0006] For example, patent CN104335038A discloses a system and method for ultrasonic testing of solid turbine shafts using a phased array probe. This method acquires internal echoes of the shaft through fan-shaped scanning and evaluates the location and size of defects. However, this method is mainly applicable to scanning regular solid shafts from the outer periphery of the shaft. It does not dynamically adjust the focusing parameters to account for cross-sectional changes and acoustic path differences when testing shafts with varying cross-sections from the shaft end face, making it difficult to guarantee focusing accuracy for different shaft segments and cross-sectional transition areas.

[0007] Therefore, the key technical problem that the existing technology needs to solve is: how to dynamically adjust the focusing parameters of the phased array according to the geometry of different shaft segments and the target detection position when performing phased array ultrasonic testing on a variable cross-section shaft from the shaft end face, so that effective focusing can be maintained in different axial depths and cross-sectional transition areas, thereby improving the detection sensitivity and positioning accuracy of internal defects at the end of the variable cross-section shaft. Summary of the Invention

[0008] To address the shortcomings of existing technologies, the present invention aims to provide a phased array dynamic focusing detection method and system for the end of a variable cross-section shaft. This method dynamically adjusts the focusing parameters of the phased array based on the geometry of different shaft segments and the target detection position, ensuring effective focusing across different axial depths and cross-sectional transition regions. This improves the detection sensitivity and positioning accuracy of internal defects at the end of the variable cross-section shaft. To solve the above technical problem, the present invention provides the following technical solution: The first aspect of this application relates to a phased array dynamic focusing detection method for the end of a variable cross-section shaft, comprising the following steps: Step P1: Obtain the position of the shaft end face, the position of the axis, and the axial section profile of the axisymmetric variable cross-section shaft to be tested in the predetermined axial detection plane. Establish the shaft end detection coordinates based on the shaft end face and the axis to obtain the shaft end structure information. Step P2: Determine the cross-sectional change position based on the shaft end structure information, divide the detection zone with the cross-sectional change position as the boundary, and determine the target focusing position within each detection zone to obtain the target focusing position sequence; Step P3: Couple the phased array probe to the end face of the shaft, determine the position of each array element in the detection coordinates of the end face, and obtain the propagation path and propagation sound path of each array element to each target focusing position based on the array element position, the end face structure information and the target focusing position sequence. Step P4: Based on the positional relationship between the propagation path and the cross-sectional boundary of the corresponding detection partition, eliminate propagation paths that exceed any corresponding cross-sectional boundary, continuously merge the array elements corresponding to the remaining propagation paths according to the arrangement order, select the effective array element range based on the radial projection position of the target focusing position on the axial end face, determine the focusing delay based on the propagation path difference of each array element, and obtain the focusing control information. Step P5: Determine the current target focus position sequentially according to the target focus position sequence, pre-call the corresponding effective array element range and focus delay to control ultrasonic wave transmission and echo reception, match the echo propagation time with the expected echo arrival time determined according to the propagation sound path to determine the reception position, when the next target focus position is located in the next detection zone, switch the corresponding effective array element range and focus delay before the next transmission to obtain dynamic focus echo data; Step P6: Match the dynamic focusing echo data with the shaft end detection coordinates and target focusing position sequence. Calibrate the structure reflection position according to the shaft end structure information. Determine the expected structure echo arrival time according to the propagation path of each array element to the structure reflection position. Identify and remove structure echoes. Determine abnormal echoes according to the echo amplitude of the remaining echoes and the continuity of adjacent target focusing positions. Determine the axial and radial positions corresponding to the abnormal echoes as the defect positions to obtain the defect detection results.

[0009] Further, step P1 includes: Obtain the shaft end face profile and axial section profile of the axisymmetric variable cross section shaft to be detected in the predetermined axial detection plane; The center position of the shaft end face contour is calibrated to obtain the center of the shaft end face; The center positions of the two contour boundaries of the axial section profile are calibrated to obtain the axis of the variable cross-section shaft to be detected; The shaft end detection coordinates are established with the center of the shaft end face as the coordinate starting point, the axial direction within the predetermined axial detection plane as the axial direction, and the direction perpendicular to the axial line within the predetermined axial detection plane as the radial direction. By mapping the axial cross-sectional profile to the shaft end detection coordinates, the shaft end structure information, including the axial position and the corresponding radial boundary, is obtained.

[0010] Further, step P2 includes: The radial boundary in the shaft end structure information is extracted sequentially along the axial direction; The radial boundaries corresponding to adjacent axial positions are compared and the axial position of the radial boundary abrupt change is determined as the cross-sectional abrupt change boundary. The starting position and ending position of the continuous change range of the radial boundary are determined as the cross-sectional transition starting boundary and cross-sectional transition ending boundary, respectively. The cross-sectional abrupt change boundary, the cross-sectional transition starting boundary and the cross-sectional transition ending boundary are combined to form a cross-sectional change boundary set. Using each cross-sectional change boundary in the set of cross-sectional change boundaries as an axial boundary, the area to be detected is divided into partitions to obtain axial segment detection partitions and cross-sectional transition detection partitions. Within the shaft segment detection zone, the target focusing positions are sequentially set along the axial and radial directions, with the starting boundary of the zone's axial direction as the starting point and the ending boundary of the zone's axial direction as the ending point. Within the cross-section transition detection zone, the target focusing positions are sequentially set along the extension direction of the cross-section transition profile in the solid area between the axis and the cross-section transition profile. Based on the shaft end structure information, structural markers are set for the target focus positions corresponding to the shaft shoulder, fillet, and cross-sectional change boundary, and the target focus positions are arranged in order according to the axial position and radial position to obtain the target focus position sequence.

[0011] Further, step P3 includes: The acoustic center position of each array element is mapped to the detection coordinates at the axis end to obtain the array element coordinate sequence; Candidate propagation paths are constructed from the positions of each array element in the array element coordinate sequence to the focal positions of each target in the target focal position sequence; Based on the shaft end structure information, the entity contour range of the candidate propagation path is determined to obtain the propagation path located within the entity contour range of the variable cross section shaft to be detected; The path length of the propagation path is determined to obtain the propagation path from each array element to the focusing position of each target. Each propagation path is associated with its corresponding array element, target focusing position, and propagation path.

[0012] Further, step P4 includes: Determine the detection zone where the target focusing position is located, and extract the cross-sectional boundary corresponding to the detection zone from the shaft end structure information; The radial boundary of the propagation path from each array element to the target focusing position is compared to obtain the positional relationship between the axial position of each propagation path and the corresponding cross-sectional boundary. Based on the aforementioned positional relationship, propagation paths that exceed the boundary of any corresponding cross section are eliminated to obtain reachable propagation paths; The array elements corresponding to the reachable propagation paths are continuously merged according to the array element arrangement order to obtain candidate array element groups; Based on the radial projection position of the target focusing position on the end face of the shaft, the candidate array elements are selected to obtain the effective array element range corresponding to the target focusing position.

[0013] Furthermore, step P4 also includes: Obtain the propagation path of each array element within the effective array element range to the same target focusing position; The maximum value of each propagation path is determined to obtain the maximum propagation path. The propagation path difference of each array element is calculated by comparing the propagation path of each array element with the maximum propagation path. Based on the propagation path difference and the propagation speed of the ultrasonic wave in the variable cross-section shaft to be detected, the focusing delay corresponding to each array element is determined according to the following formula: ; in, Indicates the first The element corresponds to the first Focusing delay at each target focus position Indicates the first Individual formation to the first The propagation path of sound at the target focal point This indicates that each element within the effective array element range is up to the [number]th [element]. The maximum propagation range of a target focusing location c This indicates the propagation speed of the ultrasonic wave in the variable cross-section shaft under test; The focusing delay is associated with the corresponding array element, the effective array element range, and the target focusing position to obtain the focusing control information.

[0014] Further, step P5 includes: The current target focus position is determined according to the target focus position sequence, and the effective array element range and focus delay corresponding to the current target focus position are pre-called from the focus control information; According to the effective array element range and focusing delay, each array element is controlled to emit ultrasonic waves and receive echoes. The propagation time of the echoes received by each array element is marked to obtain echo time information. For each target focusing position, the common transmission focusing arrival time is determined based on the maximum propagation path and ultrasonic propagation speed within the corresponding effective array element range. The common transmission focusing arrival time is added to the return propagation time from the corresponding target focusing position to each receiving array element to obtain the expected echo arrival time corresponding to each target focusing position. Using half of the minimum interval between adjacent expected echo arrival times as the time matching window, the echo time information is compared with the expected echo arrival time. The target focusing position corresponding to the expected echo arrival time with the shortest time interval within the time matching window is determined as the receiving position. When the time interval between the same echo and two expected echo arrival times is the same, the target focusing position that appears first in the target focusing position sequence is determined as the receiving position. Echoes that exceed the entire time matching window are marked as unmatched echoes and excluded. The receiving position is compared with the current target focusing position. If they match, the corresponding echo is retained. If they do not match, the corresponding echo is marked as a position mismatch echo and excluded. When the next target focus position determined according to the target focus position sequence is located in the next detection zone, the effective array element range and focus delay corresponding to the next target focus position are switched before the next ultrasonic wave transmission.

[0015] Furthermore, step P5 also includes: According to the effective array element range corresponding to the current target focusing position, select array elements to participate in echo reception from the array elements corresponding to the echoes retained after position verification to obtain the receiving array element group. According to the focusing delay corresponding to the current target focusing position, the echo received by the receiving array element is time-aligned to obtain the aligned echo; The aligned echoes are superimposed to obtain the focused echo corresponding to the current target focusing position; By associating each of the focused echoes with the corresponding target focusing positions, the corresponding relationship between the focused echo positions is obtained; The dynamic focused echo data is obtained by sequentially arranging the corresponding relationships of the focused echo positions according to the target focused position sequence.

[0016] Further, step P6 includes: Based on the shaft end structure information, determine the positions of the shaft shoulder, fillet, and cross-sectional change boundary in the shaft end detection coordinates, obtain the structure reflection position, and set a structure mark at the target focusing position corresponding to the structure reflection position; Based on the propagation path of each array element to the reflection position of the structure, the echo time of the reflection position of the structure is converted to obtain the expected arrival time of the echo of the structure. Using half of the minimum interval between the arrival times of adjacent expected structural echoes as the structural echo time matching window, the echo propagation time in the dynamic focusing echo data is compared with the arrival time of the expected structural echo to obtain the structural matching echo located within the structural echo time matching window. The structure matching echo corresponding only to the target focusing position with the structure mark is determined as the structure echo. The structure matching echo corresponding to the same internal position on consecutive adjacent target focusing positions is retained as the overlapping candidate defect echo. The structure echo is removed from the dynamic focusing echo data, and the remaining echo and the overlapping candidate defect echo are combined to form candidate defect echo data. The continuous time period between the end of the transmitted pulse and the earliest expected arrival time of the effective echo is selected as the noise reference period, and the average value of the absolute value of the echo amplitude within the noise reference period is determined as the noise benchmark. Candidate echoes with peak values ​​not less than three times the noise reference are identified as amplitude anomalous echoes. Anomalous echoes with amplitude values ​​corresponding to three consecutive adjacent target focusing positions and whose axial position difference and radial position difference do not exceed half the distance between the corresponding target focusing positions are identified as anomalous echoes, and the remaining candidate echoes are excluded. The abnormal echo is mapped to the shaft end detection coordinates to obtain the axial and radial positions of the abnormal echo in the predetermined axial detection plane, and the axial and radial positions are determined as the defect positions to obtain the defect detection results.

[0017] A second aspect of this application relates to a phased array dynamic focusing detection system for the end of a variable cross-section shaft, comprising: The shaft end structure calibration module is used to obtain the position of the shaft end face, the position of the axis, and the axial section profile of the axisymmetric variable cross-section shaft to be tested in a predetermined axial detection plane, and to establish shaft end detection coordinates based on the shaft end face and the axis to obtain shaft end structure information. The detection area partitioning module is used to determine the cross-sectional change position based on the shaft end structure information, divide the detection area into detection partitions with the cross-sectional change position as the boundary, and determine the target focusing position within each detection partition to obtain a target focusing position sequence; The propagation path determination module is used to determine the position of each array element in the phased array probe in the detection coordinates at the axial end, and to obtain the propagation path and propagation path of each array element to each target focusing position based on the array element position, axial end structure information and target focusing position sequence; The focusing parameter generation module is used to eliminate propagation paths that exceed the cross-sectional boundary based on the positional relationship between the propagation path and the cross-sectional boundary of the corresponding detection partition, continuously merge the array elements corresponding to the remaining propagation paths, select the effective array element range based on the radial projection position of the target focusing position on the axial end face, and determine the focusing delay based on the propagation path difference of each array element to obtain focusing control information. The dynamic focusing acquisition module is used to determine the current target focusing position according to the target focusing position sequence, pre-call the corresponding effective array element range and focusing delay to control ultrasonic wave transmission and echo reception, determine the receiving position according to the echo propagation time, and switch the corresponding effective array element range and focusing delay before the next ultrasonic wave transmission when the next target focusing position is located in the next detection zone to obtain dynamic focusing echo data. The defect location and determination module is used to match the dynamic focused echo data with the shaft end detection coordinates and target focused position sequence, determine the structural reflection position according to the shaft end structural information and identify and eliminate structural echoes, determine abnormal echoes according to the echo amplitude of the remaining echoes and the continuity of adjacent target focused positions, determine the axial position and radial position corresponding to the abnormal echo as the defect position, and obtain the defect detection result.

[0018] Compared with the prior art, the present invention has the following beneficial effects: (1) The present invention divides the detection zone according to the cross-sectional change position in the predetermined axial detection plane, sets the target focusing position according to the focusing beam coverage relationship, selects the effective array element range through cross-sectional boundary constraints, continuous array element merging and radial projection, and determines the focusing delay according to the propagation path difference, so that the axial section and the cross-sectional transition area can obtain a focusing beam that matches the geometric contour, thereby improving the signal-to-noise ratio and detection sensitivity of the defect echo.

[0019] (2) The present invention calls up the focusing control information before ultrasonic wave is emitted according to the target focusing position sequence, and completes the switching of effective array element range and focusing delay when crossing detection zones. The structure echo is identified by the target focusing position with structural mark and the expected arrival time of the structure echo. Then, the abnormal echo is determined by combining the noise reference and the continuity of adjacent target focusing positions, thereby reducing structural reflection and isolated noise interference and improving the axial and radial positioning accuracy of the defect position in the predetermined axial detection plane. Attached Figure Description

[0020] Figure 1 This is a schematic flowchart of a phased array dynamic focusing detection method for the end of a variable cross-section shaft provided in an embodiment of the present invention; Figure 2 This is a schematic diagram of the shaft end detection coordinates and the predetermined axial detection plane provided in an embodiment of the present invention; Figure 3 This is a schematic diagram of the layout of detection zones, cross-sectional change boundaries, and target focusing positions according to an embodiment of the present invention; Figure 4 This is a schematic diagram illustrating the propagation path filtering and effective array element range determination according to an embodiment of the present invention; Figure 5 This is a schematic diagram of cross-detection zone focus control switching provided in an embodiment of the present invention; Figure 6 This is a functional block diagram of a phased array dynamic focusing detection system for the end of a variable cross-section shaft, provided in an embodiment of the present invention.

[0021] The realization of the objective, functional features and advantages of the present invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0022] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions in the embodiments of this invention will be described more clearly and completely below. Obviously, the described embodiments are only some embodiments of this invention, and not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0023] The variable cross-section shaft to be detected referred to in this application is an axisymmetric variable cross-section shaft in which each axial cross-section forms a rotationally symmetric profile around the same axis. The shaft end detection coordinates, target focusing position and defect position are all limited to a predetermined axial detection plane formed by the phased array probe element arrangement direction and the axis. The axial position and radial position output in this embodiment are used to represent the two-dimensional defect position in the predetermined axial detection plane.

[0024] Reference Figure 1 The diagram shown is a flowchart illustrating a phased array dynamic focusing detection method for a variable cross-section shaft end according to an embodiment of the present invention. In this embodiment, the phased array dynamic focusing detection method for a variable cross-section shaft end includes: Step P1: Obtain the position of the shaft end face, the position of the axis, and the axial section profile of the axisymmetric variable cross-section shaft to be tested in the predetermined axial detection plane. Establish the shaft end detection coordinates based on the shaft end face and the axis to obtain the shaft end structure information. In this embodiment of the invention, step P1 includes: Obtain the shaft end face profile and axial section profile of the axisymmetric variable cross section shaft to be detected in the predetermined axial detection plane; The center position of the shaft end face contour is calibrated to obtain the center of the shaft end face; The center positions of the two contour boundaries of the axial section profile are calibrated to obtain the axis of the variable cross-section shaft to be detected; The shaft end detection coordinates are established with the center of the shaft end face as the coordinate starting point, the axial direction within the predetermined axial detection plane as the axial direction, and the direction perpendicular to the axial line within the predetermined axial detection plane as the radial direction. By mapping the axial cross-sectional profile to the shaft end detection coordinates, the shaft end structure information, including the axial position and the corresponding radial boundary, is obtained.

[0025] The axisymmetric variable cross-section shaft to be tested is fixed at the testing position and the shaft end face is fully exposed. A predetermined axial testing plane is determined by the arrangement direction of the phased array probe elements and the axis. The positions of each edge are continuously recorded along the outer peripheral edge of the shaft end face. Adjacent edge positions are connected and closed sequentially according to their arrangement order on the shaft end face to form the shaft end face profile characterizing the outer edge shape of the shaft end face. At the same time, the outer surfaces on both sides of the shaft are synchronously profiled along the predetermined axial testing plane so that the outer surfaces on both sides form corresponding profile boundaries at the same axial position. The starting position of the shaft end face, the positions of the outer surfaces of each shaft segment, the position of the shaft shoulder, the position of the cross-section transition, and the profile positions in the internal extension direction of the shaft are continuously arranged according to the actual connection relationship to form the axial cross-section profile characterizing the shape change of the axisymmetric variable cross-section shaft to be tested along the length direction. The shaft end face profile and the axial cross-section profile of the axisymmetric variable cross-section shaft to be tested are obtained.

[0026] Two mutually perpendicular contour extension directions are determined within the contour of the shaft end face. The boundary positions opposite to each other on both sides of the shaft end face contour are determined along each contour extension direction. Each set of opposite boundary positions is directly connected to form a boundary line that runs through the shaft end face contour. An intermediate position is determined on each boundary line that is equidistant from the two end boundary positions. A center reference line perpendicular to the corresponding boundary line is established through each intermediate position. The intersection of the two center reference lines is determined as the center position of the shaft end face contour. The center position corresponds to the geometric intermediate position of the shaft end face contour in two mutually perpendicular directions, thus obtaining the center of the shaft end face.

[0027] Multiple axial corresponding positions are sequentially determined along the length extension direction of the axial cross-section profile. At each axial corresponding position, the contour boundary positions on both sides of the axial cross-section profile are read. The two contour boundary positions at the same axial corresponding position are connected to form a radial line. On each radial line, the contour center position is determined at the same distance from the contour boundary positions on both sides, so that each contour center position corresponds to the cross-section center of the variable cross-section shaft to be tested at different axial positions. All contour center positions are connected according to their arrangement order along the axial cross-section profile to form a center extension line that runs through each shaft segment and cross-section transition position. The center extension line is determined as the axis of the variable cross-section shaft to be tested, thus obtaining the axis of the variable cross-section shaft to be tested.

[0028] The center of the shaft end face is determined as the coordinate starting point. The direction extending from the center of the shaft end face along the axis of the variable cross-section shaft to be tested into the shaft body is determined as the axial direction. The direction passing through the center of the shaft end face and perpendicular to the axis is determined as the radial direction. The position of any position in the variable cross-section shaft to be tested along the axis relative to the center of the shaft end face is recorded as the axial position. The position of this position along the direction perpendicular to the axis relative to the axis is recorded as the radial position. The position on the shaft end face, the position on the axis, and the position on the axial cross-section profile are all expressed according to the same coordinate starting point, axial direction, and radial direction, thus establishing the shaft end detection coordinate.

[0029] According to the front-to-back arrangement of each contour position in the axial cross-section profile relative to the center of the shaft end face, each contour position is mapped to the shaft end detection coordinate along the axial direction and the axial position of each contour position is determined. Then, each contour position is pointed towards the axial direction along the direction perpendicular to the axial direction, and the radial interval between the contour position and the axial direction is recorded as the radial boundary corresponding to the axial position. For shaft segment positions, the same radial boundary is continuously recorded in the axial extension order. For shaft shoulder positions, the radial boundaries before and after the cross-section change are recorded in the contour connection order. For cross-section transition positions, the change process of the radial boundary is continuously recorded in the contour extension order. A fixed correspondence is established between each axial position and the radial boundary corresponding to that axial position. All correspondences are arranged in the order of extension from the shaft end face into the shaft body to obtain the shaft end structure information including the axial position and the corresponding radial boundary.

[0030] The beneficial effect is that by acquiring and processing the shaft end face contour and axial section contour position by position, the center of the shaft end face and the axis of the variable cross-section shaft to be tested can be accurately determined. A unified shaft end detection coordinate is established with the center of the shaft end face and the axis. Different shaft segments, shaft shoulders and cross-section transition positions are recorded in the shaft end structure information in the form of axial position and corresponding radial boundary. This provides a clear geometric position reference for subsequent determination of cross-section change position, division of detection zones, layout of target focusing position, judgment of the positional relationship between ultrasonic propagation path and cross-section boundary and identification of structural echo, thereby reducing focusing position deviation and defect location deviation caused by inconsistent expression of variable cross-section structure position.

[0031] Reference Figure 2As shown, PA represents a phased array probe coupled to the end face of the axisymmetric variable cross-section shaft to be tested; O represents the center of the end face and serves as the starting point of the end face detection coordinates; Z represents the axial direction extending from the center of the end face along the axis of the axisymmetric variable cross-section shaft to be tested into the shaft body; R represents the radial direction perpendicular to the axis and pointing from the axis to the radial boundary of the shaft body within the predetermined axial detection plane; P represents the target focusing position within the contour range of the axisymmetric variable cross-section shaft to be tested; the array element arrangement direction of the phased array probe is consistent with the radial direction; the target focusing position and the defect position are both represented by their axial position relative to the starting point of the coordinates and their radial position relative to the axis; the radial position is the vertical distance between the target focusing position or the defect position and the axis; based on the rotational symmetry structure of the axisymmetric variable cross-section shaft to be tested, the radial position takes a non-negative value; positions located on both sides of the axis and at the same vertical distance from the axis have the same radial position.

[0032] Step P2: Determine the cross-sectional change position based on the shaft end structure information, divide the detection zone with the cross-sectional change position as the boundary, and determine the target focusing position within each detection zone to obtain the target focusing position sequence; In this embodiment of the invention, step P2 includes: The radial boundary in the shaft end structure information is extracted sequentially along the axial direction; The radial boundaries corresponding to adjacent axial positions are compared and the axial position of the radial boundary abrupt change is determined as the cross-sectional abrupt change boundary. The starting position and ending position of the continuous change range of the radial boundary are determined as the cross-sectional transition starting boundary and cross-sectional transition ending boundary, respectively. The cross-sectional abrupt change boundary, the cross-sectional transition starting boundary and the cross-sectional transition ending boundary are combined to form a cross-sectional change boundary set. Using each cross-sectional change boundary in the set of cross-sectional change boundaries as an axial boundary, the area to be detected is divided into partitions to obtain axial segment detection partitions and cross-sectional transition detection partitions. Within the shaft segment detection zone, the target focusing positions are sequentially set along the axial and radial directions, with the starting boundary of the zone's axial direction as the starting point and the ending boundary of the zone's axial direction as the ending point. Within the cross-section transition detection zone, the target focusing positions are sequentially set along the extension direction of the cross-section transition profile in the solid area between the axis and the cross-section transition profile. Based on the shaft end structure information, structural markers are set for the target focus positions corresponding to the shaft shoulder, fillet, and cross-sectional change boundary, and the target focus positions are arranged in order according to the axial position and radial position to obtain the target focus position sequence.

[0033] Along the axial direction, starting from the shaft end facing the interior of the variable cross-section shaft to be detected, the axial positions and radial boundaries that have established corresponding relationships in the shaft end structure information are read one by one. The radial boundaries corresponding to each axial position are continuously recorded in the reading order, so that the radial boundary corresponding to the previous axial position and the radial boundary corresponding to the next axial position form an adjacent relationship, and the correspondence between each radial boundary and the corresponding axial position is retained, thus obtaining the radial boundaries arranged along the axial direction.

[0034] The radial boundary corresponding to each axial position is compared with the radial boundary corresponding to the next adjacent axial position. When the two radial boundaries are in the same position in the radial direction, the corresponding axial range is determined as the cross-section holding range. When the two radial boundaries jump directly between adjacent axial positions, the axial position corresponding to the jump is determined as the cross-section change position. When the radial boundary changes continuously at multiple consecutive axial positions, the starting position and ending position of the continuously changing range are determined as the cross-section transition starting position and cross-section transition ending position, respectively. The cross-section change position, the cross-section transition starting position, and the cross-section transition ending position are jointly determined as the cross-section change position, thus obtaining the cross-section change position.

[0035] Using the cross-sectional change positions as axial boundaries, the area to be detected is continuously divided along the axial direction. The area where the radial boundaries between adjacent cross-sectional change positions remain consistent is determined as the shaft segment detection zone. The area where the radial boundary continuously transitions from one shaft segment corresponding position to another shaft segment corresponding position is determined as the cross-sectional transition detection zone. Each shaft segment detection zone corresponds to a shaft area with consistent radial boundaries, and each cross-sectional transition detection zone corresponds to a shaft area where the shoulder, fillet, or cross-sectional profile continuously changes, thus obtaining the shaft segment detection zone and the cross-sectional transition detection zone.

[0036] Within the shaft segment detection zone, the axial starting boundary of the zone is determined as the axial layout start point, and the axial ending boundary of the zone is determined as the axial layout end point. Axial layout positions are sequentially determined along the axial direction, and at each axial layout position, radial layout positions are sequentially determined from the axial direction towards the corresponding radial boundary, ensuring that the distance between adjacent axial layout positions and adjacent radial layout positions does not exceed half the width of the corresponding focused sound beam. The internal positions corresponding to each axial layout position and each radial layout position are determined as the target focused positions within the shaft segment detection zone. Within the cross-section transition detection zone, the radial boundary continuously extending between the cross-section transition start position and the cross-section transition end position is determined as the cross-section transition profile. Profile positions are sequentially determined along the cross-section transition profile, ensuring that the profile distance between adjacent profile positions does not exceed half the width of the corresponding focused sound beam. Multiple target focused positions are sequentially arranged from each profile position along the profile normal pointing towards the inside of the shaft body, ensuring that the first layer of target focused positions is located within the cross-section transition profile and the distance between adjacent layers does not exceed half the width of the corresponding focused sound beam, thereby covering the interior of the cross-section transition detection zone.

[0037] Structural markers are set for the target focus positions corresponding to the shaft shoulder, fillet, abrupt change position, start position of section transition, and end position of section transition. Each target focus position is arranged sequentially from the shaft end to the inside of the variable section shaft to be detected according to its axial position in the shaft end detection coordinate. Target focus positions at the same axial position are arranged sequentially from the axis to the corresponding radial boundary according to their radial position. Multi-layer target focus positions set along the normal of the section transition contour within the section transition detection zone are arranged sequentially according to their contour position and inward level, so that each target focus position has a unique arrangement position and structural marker state. All the arranged target focus positions are connected sequentially to form a detection sequence, thus obtaining the target focus position sequence.

[0038] The beneficial effect is that by extracting the radial boundary along the axis and comparing the radial boundaries corresponding to adjacent axial positions one by one, the cross-sectional change position can be accurately determined based on the shaft end structure information. The shaft body area with consistent radial boundaries and the cross-sectional transition area with continuously changing radial boundaries are respectively divided into shaft segment detection zones and cross-sectional transition detection zones. Then, according to the contour characteristics of different detection zones, the corresponding target focusing position layout method is adopted so that the target focusing position sequence simultaneously covers the interior of each shaft segment and the cross-sectional transition contour. This provides a clear detection position sequence for subsequently determining the propagation path from each array element to each target focusing position, screening the effective array element range, and switching the focusing delay, thereby reducing the omission of detection areas caused by the inability of fixed focusing positions to adapt to variable cross-sectional structures.

[0039] Reference Figure 3As shown, I, II, and IV represent shaft segment detection zones arranged sequentially along the axial direction, III represents the cross-section transition detection zone located between the cross-section transition start boundary B2 and the cross-section transition end boundary B3, B1 represents the cross-section abrupt boundary formed by the abrupt change of the radial boundary between adjacent shaft segments, B2 and B3 represent the axial positions where the radial boundary begins and ends its continuous change, respectively, Z represents the axial direction extending from the shaft end face into the shaft body, the hollow circles in the figure represent ordinary target focusing positions arranged within the physical contour range of each detection zone, and the hollow circles with intersecting lines represent target focusing positions with structural markings corresponding to the shaft shoulder, cross-section abrupt boundary, cross-section transition start boundary, and cross-section transition end boundary. Among them, the target focusing positions in each shaft segment detection zone are arranged sequentially along the axial and radial directions, and the target focusing positions in the cross-section transition detection zone are arranged inside the shaft body along the extension direction of the cross-section transition contour, so that the target focusing positions cover the shaft segment detection zone and the cross-section transition detection zone, and establish a positional correspondence between the target focusing positions with structural markings and the corresponding structural reflection positions.

[0040] Step P3: Couple the phased array probe to the end face of the shaft, determine the position of each array element in the detection coordinates of the end face, and obtain the propagation path and propagation sound path of each array element to each target focusing position based on the array element position, the end face structure information and the target focusing position sequence. In this embodiment of the invention, step P3 includes: The acoustic center position of each array element is mapped to the detection coordinates at the axis end to obtain the array element coordinate sequence; Candidate propagation paths are constructed from the positions of each array element in the array element coordinate sequence to the focal positions of each target in the target focal position sequence; Based on the shaft end structure information, the entity contour range of the candidate propagation path is determined to obtain the propagation path located within the entity contour range of the variable cross section shaft to be detected; The path length of the propagation path is determined to obtain the propagation path of each array element to the focusing position of each target. Each propagation path is associated with its corresponding array element, target focusing position, and propagation path.

[0041] The coupling surface of the phased array probe is attached to the axial end face. A coupling medium is continuously laid between the coupling surface and the axial end face, and the air gap between them is eliminated. The array center of the phased array probe is aligned with the center of the axial end face, and the array element arrangement direction is consistent with the radial direction of the axial end detection coordinate. According to the arrangement position of the acoustic center of each array element relative to the array center, the acoustic center of each array element is sequentially mapped to the axial end detection coordinate. The axial position and radial position corresponding to each acoustic center are recorded. The mapping results are arranged according to the arrangement order of each array element in the phased array probe to obtain the array element coordinate sequence.

[0042] One array element position is extracted sequentially from the array element coordinate sequence, and one target focus position is extracted sequentially from the target focus position sequence. The array element position is used as the propagation start position, and the target focus position is used as the propagation end position. The propagation start position and the propagation end position are directly connected in the axis-end detection coordinates to form a continuous connection path from the corresponding array element to the corresponding target focus position. Each array element position and each target focus position are connected in the same way so that each array element position has a corresponding connection path to each target focus position, thus obtaining the candidate propagation path.

[0043] Along each candidate propagation path, the axial positions traversed by the path are determined sequentially from the corresponding array element position to the corresponding target focusing position. The corresponding radial positions are determined based on the distance of the candidate propagation path from each axial position to the axis. The radial boundary corresponding to the same axial position is extracted from the axis end structure information. The radial position of the candidate propagation path is compared with the corresponding radial boundary position point by point. When the candidate propagation path is located between the axis and the corresponding radial boundary at all the positions it passes through, the candidate propagation path is retained. When the candidate propagation path crosses the corresponding radial boundary at any position it passes through, the candidate propagation path is excluded. This ensures that the entire part of the retained path from the corresponding array element position to the corresponding target focusing position is located inside the variable cross section axis to be detected, thus obtaining the propagation path within the solid contour range of the variable cross section axis to be detected.

[0044] For each propagation path, the corresponding array element position and target focusing position are determined. According to the path extension direction from the array element position to the target focusing position in the axis-end detection coordinates, the propagation path is continuously traced from the starting position to the ending position. The position changes of the propagation path in the axial and radial directions are mapped to the same distance reference. The complete distance formed along the propagation path between the array element position and the target focusing position is determined as the path length from the array element to the target focusing position. The path lengths of all propagation paths are determined in the same way to obtain the propagation sound path from each array element to each target focusing position.

[0045] Using each propagation path as an associated object, the starting position of the propagation path is mapped to an array element in the array element coordinate sequence, the ending position of the propagation path is mapped to a target focus position in the target focus position sequence, and the path length of the propagation path is mapped to the propagation path between the array element and the target focus position, so that each propagation path has a unique corresponding array element, target focus position, and propagation path. Then, the propagation paths are arranged according to the arrangement order of the target focus position sequence, and the propagation paths are arranged according to the arrangement order of the array element coordinate sequence under the same target focus position, forming an association relationship between each propagation path and its corresponding array element, target focus position, and propagation path.

[0046] The beneficial effect is that by uniformly mapping the acoustic center of each element in the phased array probe to the detection coordinates at the axial end, the element positions can be aligned with the axial end structure information and the target focusing position sequence at the same positional reference. By judging the physical contour range of each candidate propagation path from each element position to each target focusing position, invalid propagation paths that penetrate the physical contour of the variable cross-section shaft to be detected can be eliminated, and the propagation path corresponding to the retained propagation path can be accurately determined. This provides a clear data basis for subsequently determining the effective element range based on the positional relationship between the propagation path and the cross-sectional boundary, and for determining the focusing delay based on the difference in propagation path, thereby reducing the interference caused by the variable cross-section structure on the ultrasonic propagation path and dynamic focusing position.

[0047] Step P4: Based on the positional relationship between the propagation path and the cross-sectional boundary of the corresponding detection partition, eliminate propagation paths that exceed any corresponding cross-sectional boundary, continuously merge the array elements corresponding to the remaining propagation paths according to the arrangement order, select the effective array element range based on the radial projection position of the target focusing position on the axial end face, determine the focusing delay based on the propagation path difference of each array element, and obtain the focusing control information. In this embodiment of the invention, step P4 includes: Determine the detection zone where the target focusing position is located, and extract the cross-sectional boundary corresponding to the detection zone from the shaft end structure information; The radial boundary of the propagation path from each array element to the target focusing position is compared to obtain the positional relationship between the axial position of each propagation path and the corresponding cross-sectional boundary. Based on the aforementioned positional relationship, propagation paths that exceed the boundary of any corresponding cross section are eliminated to obtain reachable propagation paths; The array elements corresponding to the reachable propagation paths are continuously merged according to the array element arrangement order to obtain candidate array element groups; Based on the radial projection position of the target focusing position on the end face of the shaft, the candidate array elements are selected to obtain the effective array element range corresponding to the target focusing position.

[0048] The target focus positions are extracted sequentially from the target focus position sequence. The axial position of the target focus position is matched with the axial start position and axial end position of each detection zone. The detection zone whose axial range includes the target focus position is determined as the detection zone where the target focus position is located. Then, according to the axial start position and axial end position of the detection zone, the radial boundary corresponding to each axial position in the axial range is continuously extracted from the shaft end structure information. The radial boundaries are connected according to the arrangement order of each radial boundary along the axis direction to obtain the cross-sectional boundary corresponding to the detection zone.

[0049] One propagation path is extracted sequentially from the propagation paths from each array element to the target focusing position. Along the propagation path, the axial positions traversed by the propagation path from the corresponding array element position to the target focusing position are continuously determined. At each axial position, the radial position of the propagation path relative to the axis is determined. The radial boundary corresponding to the same axial position is read from the cross-sectional boundary corresponding to the detection partition. The radial position of the propagation path is compared with the radial boundary at each point. The comparison results of whether the propagation path is located between the axis and the corresponding cross-sectional boundary, on the corresponding cross-sectional boundary, or beyond the corresponding cross-sectional boundary are recorded. The positional relationship between the axial positions traversed by each propagation path and the corresponding cross-sectional boundary is obtained.

[0050] Based on the positional relationship between the axial positions traversed by each propagation path and the corresponding cross-sectional boundary, all axial positions traversed by each propagation path are continuously checked. When the radial position of the propagation path at any axial position exceeds the corresponding cross-sectional boundary, the propagation path is determined as a propagation path that cannot reach the target focusing position from the corresponding array element and is discarded. When the propagation path is located between the axis and the corresponding cross-sectional boundary or on the corresponding cross-sectional boundary at all axial positions, the propagation path is retained, so that all paths of the retained propagation path from the corresponding array element position to the target focusing position are within the solid contour range of the variable cross-section axis to be detected, thus obtaining a reachable propagation path.

[0051] Each reachable propagation path is mapped to an element in the phased array probe. The elements are read one by one from the beginning to the end of the arrangement according to their order in the phased array probe. When two adjacent elements both correspond to reachable propagation paths, the two elements are grouped into the same continuous element range. When there are elements between two adjacent elements that do not correspond to reachable propagation paths, the continuous element range is broken at that position. Each range consisting of continuously arranged elements that all correspond to reachable propagation paths is determined as a candidate element group, thus obtaining the candidate element group.

[0052] The target focusing position is extended toward the axial end face along a direction parallel to the axis. The intersection of the extension direction and the axial end face is determined as the radial projection position of the target focusing position on the axial end face. The radial projection position is mapped to the array element arrangement direction of the phased array probe. The radial interval between the acoustic center position of the array element in each candidate array element group and the radial projection position is determined. The array element with the shortest radial interval is determined as the projection corresponding array element. When the radial intervals of two array elements are the same, the array element that appears earlier in the array element arrangement order is determined as the projection corresponding array element. The candidate array element group containing the projection corresponding array element is determined as the effective array element range corresponding to the target focusing position.

[0053] The beneficial effects are as follows: by determining the detection zone where the target focusing position is located and extracting the corresponding cross-sectional boundary, the ultrasonic propagation space can be defined for different axial segments and cross-sectional transition areas. By comparing the positional relationship between the propagation path and the corresponding cross-sectional boundary at each point and eliminating propagation paths that exceed any corresponding cross-sectional boundary, it is possible to avoid using array elements that penetrate the outline of the variable cross-section axial entity to be detected for ultrasonic transmission and echo reception. Furthermore, by continuously merging the array elements corresponding to the reachable propagation paths and selecting candidate array element groups based on the radial projection position of the target focusing position on the axial end face, the effective array element range corresponds to the target focusing position and the variable cross-section structure. This provides an accurate array element selection basis for subsequently determining the focusing delay based on the propagation path difference of each array element within the effective array element range, thereby reducing the impact of cross-sectional boundary occlusion and invalid array element participation on the dynamic focusing effect.

[0054] Reference Figure 4As shown, P represents the target focusing position. The solid line represents the reachable propagation path from the corresponding array element to the target focusing position P, and all of them are within the outline of the axisymmetric variable cross-section of the entity to be detected. The dashed line represents the propagation path that exceeds the boundary of the corresponding cross-section and is eliminated during the propagation process. The array elements corresponding to each reachable propagation path and continuously arranged along the array element arrangement direction form a candidate array element group. The target focusing position P is projected onto the axis end face in a direction parallel to the axis to obtain the radial projection position. The array element corresponding to the radial projection position is determined as the projection corresponding array element. In the figure, EA represents the candidate array element group containing the projection corresponding array element, and the candidate array element group is determined as the effective array element range corresponding to the target focusing position P.

[0055] Step P4 further includes: Obtain the propagation path of each array element within the effective array element range to the same target focusing position; The maximum value of each propagation path is determined to obtain the maximum propagation path. The propagation path difference of each array element is calculated by comparing the propagation path of each array element with the maximum propagation path. Based on the propagation path difference and the propagation speed of the ultrasonic wave in the variable cross-section shaft to be detected, the focusing delay corresponding to each array element is determined according to the following formula: ; in, Indicates the first The element corresponds to the first Focusing delay at each target focus position Indicates the first Individual formation to the first The propagation path of sound at the target focal point This indicates that each element within the effective array element range is up to the [number]th [element]. The maximum propagation range of a target focusing location c This indicates the propagation speed of the ultrasonic wave in the variable cross-section shaft under test; The focusing delay is associated with the corresponding array element, the effective array element range, and the target focusing position to obtain the focusing control information.

[0056] Extract the same target focusing position from the target focusing position sequence, and read the effective array element range corresponding to the same target focusing position. Determine each array element in sequence according to the arrangement order of the array elements within the effective array element range. Map the established propagation path between each array element and the same target focusing position to the propagation path association relationship. Extract the path length of the array element along the corresponding propagation path to the same target focusing position from the propagation path association relationship, and determine the path length as the propagation sound path from the array element to the same target focusing position. Obtain the propagation sound path from each array element within the effective array element range to the same target focusing position.

[0057] The propagation path of each array element within the effective array element range is read sequentially according to the arrangement order of the array elements. The propagation path of the array element corresponding to the starting position of the arrangement is used as the current comparison reference. The current comparison reference is compared with the propagation path of the next array element. When the propagation path of the next array element exceeds the current comparison reference, the propagation path is replaced with the new current comparison reference. When the propagation path of the next array element does not exceed the current comparison reference, the current comparison reference remains unchanged. The propagation path of all array elements within the effective array element range is traversed in the same comparison method. The current comparison reference retained after the traversal is completed is determined as the maximum propagation path.

[0058] The propagation path of each array element within the effective array element range is matched with the maximum propagation path. The maximum propagation path is used as a unified path alignment benchmark. The propagation path of the current array element is subtracted from the maximum propagation path. The resulting difference is determined as the propagation distance that the current array element needs to compensate for so that the ultrasonic wave and the ultrasonic wave corresponding to the maximum propagation path reach the same target focusing position at the same time. The same path difference calculation is performed on all array elements according to the array element arrangement order to obtain the propagation path difference corresponding to each array element.

[0059] The propagation speed of ultrasonic waves in the variable cross-section shaft to be tested is read according to the material type of the shaft to be tested, and the propagation speed is kept constant during the same testing process. The propagation path difference corresponding to each array element is converted into the propagation time required for ultrasonic waves to pass through the propagation path difference according to the propagation speed. The propagation time is determined as the transmission waiting time and reception alignment time of the corresponding array element relative to the array element with the largest propagation path. The array element with the shorter propagation path participates in ultrasonic wave transmission later and its received echo is aligned according to the same time relationship, so that the ultrasonic waves emitted by each array element within the effective array element range arrive at the same target focusing position at the same time, and the focusing delay corresponding to each array element is obtained.

[0060] The propagation path of each array element to the same target focusing position is derived from the propagation path association established in step P3. Specifically, each array element is read sequentially from the effective array element range corresponding to the target focusing position. Then, the propagation path of each array element to the target focusing position is extracted according to the correspondence between array elements and propagation paths. The complete path length extending from the acoustic center of the array element to the target focusing position is determined as the corresponding propagation path. The maximum propagation path is derived from the comparison result obtained by comparing all propagation paths within the effective array element range item by item. Specifically, the propagation path of the array element corresponding to the starting position is taken as the current retained value. Then, the current retained value is compared with the propagation path corresponding to the next array element, and the propagation path with the higher value is retained. This process continues until all propagation paths are compared. The final retained propagation path is determined as the maximum propagation path. The propagation path difference is derived from the difference between the maximum propagation path and the propagation path corresponding to the current array element. Specifically, the maximum propagation path is used as... A unified sound path alignment benchmark is used. The sound path corresponding to the current array element is subtracted from the maximum sound path to obtain the required compensation for the current array element to achieve a unified sound path distance. This sound path difference is defined as the sound path difference corresponding to the current array element. The propagation speed of the ultrasonic wave in the variable cross-section shaft under test is derived from the calibration results of a standard test block made of the same material as the variable cross-section shaft under test. Specifically, the ultrasonic wave is made to propagate along the determined propagation path in the standard test block. The time taken for the ultrasonic wave to complete the propagation path is recorded, and the propagation speed is determined according to the correspondence between the propagation path length and the propagation time. The focusing delay indicates the time that the current array element needs to delay emitting the ultrasonic wave relative to the array element with the maximum sound path. Specifically, it is determined based on the time required for the ultrasonic wave to pass through the sound path difference corresponding to the current array element. Array elements with shorter sound paths are emitted later, and array elements with longer sound paths are emitted earlier, so that the ultrasonic waves emitted by each array element within the effective array element range simultaneously reach the same target focusing position and form a focus at that target focusing position.

[0061] Under the condition that the propagation speed of the ultrasonic wave remains constant in the variable cross-section shaft to be detected, the closer the propagation path of the current array element to the same target focusing position is to the maximum propagation path, the shorter the propagation path difference corresponding to the current array element, the shorter the time required for the ultrasonic wave to pass through the propagation path difference, and the smaller the focusing delay corresponding to the current array element. When the propagation path of the current array element is equal to the maximum propagation path, the propagation path difference corresponding to the current array element is zero, and the current array element, as a propagation time reference, does not need to be delayed in transmission. As the propagation path of the current array element to the same target focusing position gradually moves away from the maximum propagation path, the propagation path difference corresponding to the current array element gradually increases. As the time required for the ultrasonic wave to pass through the propagation path difference gradually increases, the focusing delay corresponding to the current array element also increases. Under the condition that the propagation path difference remains constant, when the propagation speed of the ultrasonic wave in the variable cross-section axis to be detected increases, the time required for the ultrasonic wave to pass through the same propagation path difference shortens, and the focusing delay decreases accordingly. When the propagation speed of the ultrasonic wave in the variable cross-section axis to be detected decreases, the time required for the ultrasonic wave to pass through the same propagation path difference lengthens, and the focusing delay increases accordingly. Thus, the focusing delay of each array element is simultaneously controlled by the propagation path difference and the propagation speed, and the ultrasonic waves corresponding to different propagation paths reach a consistent arrival time at the same target focusing position.

[0062] Each focusing delay is mapped to the array element that generates the focusing delay. All array elements and their corresponding focusing delays are included in the effective array element range corresponding to the same target focusing position. A fixed association relationship is established between the effective array element range, each array element within the effective array element range, the focusing delay corresponding to each array element, and the same target focusing position. Then, the association relationship corresponding to each target focusing position is established sequentially according to the arrangement order of the target focusing position sequence. This allows the effective array element range participating in transmission and reception and the focusing delay corresponding to each array element to be directly determined based on the current target focusing position during the detection process, thereby obtaining the focusing control information.

[0063] The beneficial effect is that by using the maximum propagation path of each array element within the effective array element range to the same target focusing position as a unified alignment benchmark, determining the propagation path difference corresponding to each array element one by one, and converting the propagation path difference into focusing delay, it is possible to compensate for the propagation path difference between different array elements to the same target focusing position, so that the ultrasonic waves emitted by each array element are synchronously superimposed at the same target focusing position and the echoes received by each array element are aligned according to the same propagation relationship. At the same time, by establishing a fixed association between each focusing delay and the corresponding array element, effective array element range, and target focusing position, it provides a clear focusing control basis for subsequently calling and switching the effective array element range and focusing delay according to the receiving position, thereby improving the ultrasonic focusing intensity and echo reception consistency in different axial depths and cross-sectional transition regions.

[0064] Step P5: Determine the current target focus position sequentially according to the target focus position sequence, pre-call the corresponding effective array element range and focus delay to control ultrasonic wave transmission and echo reception, match the echo propagation time with the expected echo arrival time determined according to the propagation sound path to determine the reception position, when the next target focus position is located in the next detection zone, switch the corresponding effective array element range and focus delay before the next transmission to obtain dynamic focus echo data; In this embodiment of the invention, step P5 includes: The current target focus position is determined according to the target focus position sequence, and the effective array element range and focus delay corresponding to the current target focus position are pre-called from the focus control information; According to the effective array element range and focusing delay, each array element is controlled to emit ultrasonic waves and receive echoes. The propagation time of the echoes received by each array element is marked to obtain echo time information. For each target focusing position, the common transmission focusing arrival time is determined based on the maximum propagation path and ultrasonic propagation speed within the corresponding effective array element range. The common transmission focusing arrival time is added to the return propagation time from the corresponding target focusing position to each receiving array element to obtain the expected echo arrival time corresponding to each target focusing position. Using half of the minimum interval between adjacent expected echo arrival times as the time matching window, the echo time information is compared with the expected echo arrival time. The target focusing position corresponding to the expected echo arrival time with the shortest time interval within the time matching window is determined as the receiving position. When the time interval between the same echo and two expected echo arrival times is the same, the target focusing position that appears first in the target focusing position sequence is determined as the receiving position. Echoes that exceed the entire time matching window are marked as unmatched echoes and excluded. The receiving position is compared with the current target focusing position. If they match, the corresponding echo is retained. If they do not match, the corresponding echo is marked as a position mismatch echo and excluded. When the next target focus position determined according to the target focus position sequence is located in the next detection zone, the effective array element range and focus delay corresponding to the next target focus position are switched before the next ultrasonic wave transmission.

[0065] The current target focus position is determined sequentially according to the target focus position sequence. Before each ultrasonic wave transmission, the effective array element range and focus delay corresponding to the current target focus position are read from the focus control information. The effective array element range and focus delay are respectively mapped to the array element channels of the transmit and receive circuit. Each array element within the effective array element range is controlled to transmit ultrasonic waves according to the corresponding focus delay, and each array element within the effective array element range enters the echo reception state after transmission. The time when the earliest array element starts transmitting is taken as the echo propagation timing start point. The received waveforms of each array element are continuously recorded according to the array element arrangement order. The echo peak position that exceeds the noise reference in the received waveform is determined as the echo arrival position. The time between the reception time corresponding to the echo arrival position and the echo propagation timing start point is determined as the propagation time of the corresponding echo. Then, the echo propagation time is associated with the array element that receives the echo to obtain the echo time information.

[0066] Extract the propagation path from each transmitting array element within the effective array element range to the current target focusing position from the propagation path association established in step P3, and read the maximum propagation path within the effective array element range. Determine the time required for the ultrasonic wave to pass through the maximum propagation path as the common transmission focusing arrival time relative to the earliest transmission time. Then, extract the return propagation path from the current target focusing position to each receiving array element. Add the time required for the ultrasonic wave to pass through each return propagation path to the common transmission focusing arrival time in sequence to obtain the expected echo arrival time of each receiving array element corresponding to the current target focusing position. Establish the correspondence between each target focusing position, receiving array element, and expected echo arrival time in sequence according to the target focusing position sequence.

[0067] The propagation time of the current echo is extracted from the echo time information. The arrival times of each expected echo corresponding to the same receiving array element are arranged in chronological order. The minimum interval between adjacent expected echo arrival times is determined, and half of the minimum interval is determined as the time matching window. The propagation time of the current echo is compared with each expected echo arrival time one by one. When the time interval is within the time matching window, the target focusing position corresponding to the expected echo arrival time with the shortest time interval is determined as the target focusing position corresponding to the current echo and is determined as the receiving position. When the propagation time of the current echo exceeds the entire time matching window, the current echo is marked as an unmatched echo and excluded from the position association processing.

[0068] The receiving position is matched with the current target focusing position. When they are the same target focusing position, the current echo is associated with the current target focusing position. When they are not the same, the current echo is reassigned according to the receiving position, but the effective array element range and focusing delay that were called before this transmission are not changed. Thus, the receiving position is only used for echo position verification and data association, and does not participate in the calling of focusing control information before this ultrasonic transmission.

[0069] The axial position of the current target focus position is read from the axis end detection coordinates, and the axial start boundary and axial end boundary of each detection partition formed in step P2 are extracted sequentially. The axial position of the current target focus position is compared with the axial start boundary and axial end boundary of each detection partition. When the current target focus position is located between the axial start boundary and axial end boundary of a detection partition, the detection partition is determined as the detection partition where the current target focus position is located. When the current target focus position coincides with the common axial boundary between two adjacent detection partitions, the detection partition located after the common axial boundary along the extension direction of the target focus position sequence is determined as the detection partition where the current target focus position is located, thus obtaining the detection partition where the current target focus position is located.

[0070] The detection zone where the current target focus position is located is compared with the detection zone where the previous target focus position is located. When the two target focus positions are in the same detection zone, the focus control information corresponding to the current detection zone continues to be used. When the current target focus position crosses the axial termination boundary of the previous detection zone and enters the next detection zone arranged along the target focus position sequence, the effective array element range and focus delay corresponding to the previous detection zone are stopped. The effective array element range and focus delay corresponding to the current target focus position in the next detection zone are read from the focus control information. The switching of the effective array element range and focus delay is completed before the next ultrasonic wave transmission. The focus echoes corresponding to each target focus position are continuously recorded according to the target focus position sequence to obtain dynamic focus echo data.

[0071] The beneficial effects are as follows: by pre-calling the corresponding effective array element range and focus delay according to the target focus position sequence before each ultrasonic transmission, the sequential loop between the receiving position and the focus control information call is eliminated. The expected echo arrival time is determined by the common transmission focus arrival time and the return propagation time of each receiving array element. Unmatched echoes are excluded by using a time matching window, so that the echo position association is consistent with the multi-array element transmission and reception mode. When the current target focus position enters the next detection zone, the effective array element range and focus delay are switched before the next ultrasonic transmission, thereby improving the position correspondence accuracy and cross-zone acquisition continuity of the dynamic focus echo data.

[0072] Reference Figure 5 As shown, P1 represents the current target focus position within the previous detection zone, P2 represents the next target focus position arranged after P1 and located within the next detection zone according to the target focus position sequence, B2 represents the axial boundary between the previous and next detection zones, Z represents the axial direction extending from the end of the shaft towards the inside of the shaft body, EA1 represents the first effective array element range corresponding to P1, EA2 represents the second effective array element range corresponding to P2, the solid line pointing to P1 represents the propagation path from each array element within the first effective array element range to P1, and the dashed line pointing to P2 represents the propagation path from each array element within the second effective array element range to P2. After completing the ultrasonic wave transmission and echo reception corresponding to P1, the dynamic focus acquisition module determines the next detection zone after B2 for P2 according to the target focus position sequence, and stops calling the first effective array element range and focus delay corresponding to P1 before the next ultrasonic wave transmission corresponding to P2, instead calling the second effective array element range and focus delay corresponding to P2 to control the array elements within the second effective array element range to transmit ultrasonic waves to P2 and receive echoes, thus completing the focus control switching across detection zones.

[0073] Step P5 further includes: According to the effective array element range corresponding to the current target focusing position, select array elements to participate in echo reception from the array elements corresponding to the echoes retained after position verification to obtain the receiving array element group. According to the focusing delay corresponding to the current target focusing position, the echo received by the receiving array element is time-aligned to obtain the aligned echo; The aligned echoes are superimposed to obtain the focused echo corresponding to the current target focusing position; By associating each of the focused echoes with the corresponding target focusing positions, the corresponding relationship between the focused echo positions is obtained; The dynamic focused echo data is obtained by sequentially arranging the corresponding relationships of the focused echo positions according to the target focused position sequence.

[0074] The effective array element range corresponding to the current target focusing position is read from the focusing control information. The array elements participating in echo reception are checked sequentially according to the arrangement order of each array element in the phased array probe. The array elements located within the effective array element range and establishing a focusing control association with the current target focusing position are determined as the array elements participating in echo reception. The array elements located outside the effective array element range are excluded from the current echo reception process. The array elements participating in echo reception are then arranged continuously according to their arrangement order in the phased array probe, and the correspondence between each array element and its received echo is retained to obtain the receiving array element group.

[0075] The focusing delay corresponding to the current target focusing position is read from the focusing control information, and each focusing delay is mapped to the echo received by the corresponding array element according to the arrangement order of each array element in the receiving array element group. Taking the common transmission focusing arrival time as the transmission time reference, the echo received by each array element is moved along the time extension direction according to the return propagation time from the current target focusing position to each receiving array element, so that the echo arrival part corresponding to the current target focusing position in the echo received by each array element falls at a unified time alignment position, while keeping the waveform arrangement relationship and amplitude of each echo unchanged during the movement process, thus obtaining an aligned echo.

[0076] The aligned echoes are extracted sequentially according to the arrangement order of the array elements in the receiving array group. The aligned echoes corresponding to each array element are placed under the same time reference, so that the echo arrival parts corresponding to the current target focusing position in each aligned echo overlap with each other. Then, the echo amplitudes of each aligned echo at the same time position are merged item by item. The merged echo amplitudes are arranged continuously in chronological order to form an echo record, so that the in-phase echoes from the current target focusing position are concentrated and the echoes that do not arrive at the same time position do not form a synchronous concentration, thus obtaining the focused echo corresponding to the current target focusing position.

[0077] Each focused echo is mapped to a pre-determined current target focus position before this acquisition, and the correspondence is verified using the receiving position. The echo propagation time, echo amplitude, and receiving array elements of the focused echo are established with the target focus position, so that each target focus position corresponds to a focused echo formed by time alignment and superposition of its receiving array elements, and each focused echo can determine its target focus position in the axis-end detection coordinates according to the fixed association, thus obtaining the focus echo position correspondence.

[0078] According to the target focus position sequence, each target focus position is read sequentially from the position near the shaft end face into the interior of the variable cross-section shaft to be detected. The focus echo associated with the current target focus position is extracted from the focus echo position correspondence. The focus echoes are arranged in the recording position of the corresponding target focus position. For target focus positions in the same axial position, the corresponding focus echoes are arranged in the order of radial position from the axis to the corresponding radial boundary. For target focus positions located in the cross-section transition detection zone, the corresponding focus echoes are arranged in the extension order of the cross-section transition contour. The correlation between each focus echo and the target focus position is retained to obtain the dynamic focus echo data.

[0079] The beneficial effects are as follows: by selecting the receiving array element group according to the effective array element range corresponding to the current receiving position, array element echoes that do not belong to the current focusing aperture can be excluded; by aligning the echoes received by the receiving array element group according to the focusing delay corresponding to the current receiving position, the propagation time difference between different array elements and the current receiving position can be compensated; by superimposing the aligned echoes, the echoes from the current receiving position can be concentrated at a unified time and position to form a focused echo; and by establishing the position correspondence of the focused echoes and arranging them in sequence according to the target focusing position sequence, each focused echo has a clear target focusing position and detection order, thereby enhancing the concentration of the echoes corresponding to the current receiving position, suppressing the influence of asynchronous echoes on the detection results, and providing dynamic focused echo data with clear positional relationships for subsequent identification of structural echoes and determination of defect positions.

[0080] Step P6: Match the dynamic focusing echo data with the shaft end detection coordinates and target focusing position sequence. Calibrate the structure reflection position according to the shaft end structure information. Determine the expected structure echo arrival time according to the propagation path of each array element to the structure reflection position. Identify and remove structure echoes. Determine abnormal echoes according to the echo amplitude of the remaining echoes and the continuity of adjacent target focusing positions. Determine the axial and radial positions corresponding to the abnormal echoes as the defect positions to obtain the defect detection results.

[0081] In this embodiment of the invention, step P6 includes: Based on the shaft end structure information, determine the positions of the shaft shoulder, fillet, and cross-sectional change boundary in the shaft end detection coordinates to obtain the structural reflection position, and set a structural mark at the target focusing position corresponding to the structural reflection position; Based on the propagation path of each array element to the reflection position of the structure, the echo time of the reflection position of the structure is converted to obtain the expected arrival time of the echo of the structure. Using half of the minimum interval between the arrival times of adjacent expected structural echoes as the structural echo time matching window, the echo propagation time in the dynamic focusing echo data is compared with the arrival time of the expected structural echo to obtain the structural matching echo located within the structural echo time matching window. The structure matching echo corresponding only to the target focusing position with the structure mark is determined as the structure echo. The structure matching echo corresponding to the same internal position on consecutive adjacent target focusing positions is retained as the overlapping candidate defect echo. The structure echo is removed from the dynamic focusing echo data, and the remaining echo and the overlapping candidate defect echo are combined to form candidate defect echo data. The continuous time period between the end of the transmitted pulse and the earliest expected arrival time of the effective echo is selected as the noise reference period, and the average value of the absolute value of the echo amplitude within the noise reference period is determined as the noise benchmark. Candidate echoes with peak values ​​not less than three times the noise reference are identified as amplitude anomalous echoes. Anomalous echoes with amplitude values ​​corresponding to three consecutive adjacent target focusing positions and whose axial position difference and radial position difference do not exceed half the distance between the corresponding target focusing positions are identified as anomalous echoes, and the remaining candidate echoes are excluded. The abnormal echo is mapped to the shaft end detection coordinates to obtain the axial and radial positions of the abnormal echo in the predetermined axial detection plane, and the axial and radial positions are determined as the defect positions to obtain the defect detection results.

[0082] The axial and radial positions of the shoulder, fillet, abrupt cross-section boundary, transition start boundary, and transition end boundary within the predetermined axial detection plane are sequentially extracted from the shaft end structural information. Each position is mapped to the shaft end detection coordinates to obtain the actual geometric positions corresponding to the shoulder, fillet, and cross-section change boundary. Each actual geometric position is determined as a structural reflection position. Then, each structural reflection position is mapped to the target focus position in the target focus position sequence. A structural mark is set on the target focus position whose detection range covers the structural reflection position, so that the structural reflection position represents the actual structural position of the axisymmetric variable cross-section shaft to be detected, and the structural mark represents the correspondence between the target focus position and the actual structural position, thus obtaining the structural reflection position and the target focus position with the structural mark.

[0083] From the propagation path association established in step P3, the propagation path from each array element to each of the structure reflection positions is extracted sequentially. The propagation path length from the acoustic center position of the array element to the structure reflection position is determined as the transmission propagation path, and the return propagation path length from the structure reflection position to the corresponding receiving array element is determined as the return propagation path. Based on the propagation speed of the ultrasonic wave in the axis of the axis of the variable cross section to be detected, the propagation time of the ultrasonic wave to complete the transmission propagation path and the return propagation path are determined respectively. The transmission propagation time and the return propagation time are added together to obtain the expected structure echo arrival time between the corresponding structure reflection position and the corresponding receiving array element. The expected structure echo arrival time is then associated with the corresponding structure reflection position, target focusing position, and receiving array element.

[0084] The echo propagation time of the focused echo corresponding to each target focusing position is extracted sequentially from the dynamic focused echo data. The receiving array element that receives the echo is determined according to the correspondence of the focused echo positions. The arrival times of each expected structure echo corresponding to the same receiving array element are arranged in chronological order. The time interval between the arrival times of two adjacent expected structure echoes is determined sequentially. Half of the shortest time interval is determined as the structure echo time matching window corresponding to the receiving array element. The echo propagation time of the current echo is compared with the arrival times of each expected structure echo corresponding to the same receiving array element one by one. When the time interval between the current echo propagation time and the arrival time of any expected structure echo is within the structure echo time matching window, the structure reflection position corresponding to the arrival time of the expected structure echo with the shortest time interval is determined as the candidate structure source of the current echo, and the current echo is determined as the structure matching echo, thus obtaining the structure matching echo.

[0085] Based on the target focusing position and structural mark status corresponding to each structural matching echo, the structural matching echoes are classified. When a structural matching echo appears only at a target focusing position with a structural mark, and no echo corresponding to the same internal position appears at an adjacent target focusing position, the structural matching echo is identified as a structural echo generated by a shoulder, fillet, or cross-sectional change boundary. When a structural matching echo appears not only at a target focusing position with a structural mark but also continuously at adjacent target focusing positions, and the axial and radial positions calculated from the propagation time of each echo correspond to the same internal position, the structural matching echoes at adjacent target focusing positions are retained as overlapping candidate defect echoes. The structural echoes are removed from the dynamic focusing echo data, and the remaining echoes that have not been identified as structural echoes are retained. The remaining echoes are then merged with the overlapping candidate defect echoes to obtain candidate defect echo data.

[0086] Using the start time of each ultrasonic transmission as a reference, the end time of the transmission pulse and the earliest expected effective echo arrival time are determined. The time range between the two is defined as the noise reference selection range. Within the noise reference selection range, the continuous time portion occupied by the probe residual vibration and the shaft end face coupling interface response is identified, and the time portion occupied by the probe residual vibration and the shaft end face coupling interface response is excluded. The continuous time period after exclusion is defined as the noise reference period. The absolute value of the echo amplitude at each sampling position within the noise reference period is read sequentially. All the absolute values ​​of the echo amplitude are added together and averaged according to the number of echo amplitudes read to obtain the average value of the absolute values ​​of the echo amplitude within the noise reference period. The average value is defined as the noise reference.

[0087] The echo peak value of each candidate echo is extracted sequentially from the candidate defect echo data. The echo peak value of each candidate echo is compared with the noise reference. When the echo peak value of the candidate echo is not less than three times the noise reference, the candidate echo is determined to be an amplitude abnormal echo. When the echo peak value of the candidate echo is less than three times the noise reference, the candidate echo is excluded from the candidate defect echo data, thus obtaining an amplitude abnormal echo. According to the target focusing position sequence, the target focusing positions corresponding to each amplitude abnormal echo are read sequentially. Every three consecutive adjacent target focusing positions are taken as a continuity judgment group. The axial and radial positions of each amplitude abnormal echo are determined according to the echo propagation time and propagation path. The axial and radial position differences between adjacent amplitude abnormal echoes within the same continuity judgment group are determined respectively. The axial and radial distances between adjacent target focusing positions are read respectively. When the axial position difference between each amplitude abnormal echo within the same continuity judgment group does not exceed half of the axial distance between the corresponding adjacent target focusing positions, and the radial position difference does not exceed half of the radial distance between the corresponding adjacent target focusing positions, the amplitude abnormal echoes in the continuity judgment group are determined to be abnormal echoes corresponding to the same internal position. When any axial position difference or radial position difference exceeds half of the corresponding distance, the amplitude abnormal echoes in the continuity judgment group are determined to be echoes that do not meet the continuity requirements and are excluded, thus obtaining abnormal echoes.

[0088] Based on the correlation between the abnormal echo and the target focusing position, the abnormal echoes belonging to the same echo group are compared from high to low according to their echo amplitude. The abnormal echo with the highest echo amplitude is identified as the defect location echo. The target focusing position corresponding to the defect location echo is read and mapped to the shaft end detection coordinates. The position of the target focusing position relative to the center of the shaft end face along the axis direction in the predetermined axial detection plane is extracted from the shaft end detection coordinates as the axial position of the abnormal echo. The position of the target focusing position relative to the axis along the direction perpendicular to the axis in the predetermined axial detection plane is extracted as the radial position of the abnormal echo. The axial position and the radial position are determined as the defect position. The defect position is correlated with the echo propagation time and echo amplitude of the corresponding abnormal echo to obtain the defect detection result.

[0089] The beneficial effects are as follows: by determining the actual geometric positions of the shoulder, fillet, and cross-sectional change boundary in the shaft end detection coordinates based on the shaft end structure information, the structural reflection position is obtained, and a structural mark is set for the target focusing position corresponding to the structural reflection position. This maintains a clear correspondence between the actual structural position and the detection position. The structural matching echo is determined by the expected structural echo arrival time and the structural echo time matching window. The structural matching echo corresponding to the same internal position on consecutive adjacent target focusing positions is retained as overlapping candidate defect echoes. This reduces the situation where defect echoes near the shoulder, fillet, and cross-sectional change boundary are rejected as structural echoes. By determining the noise reference period after excluding probe residual vibration and shaft end face coupling interface response, and combining three times the noise reference, three consecutive adjacent target focusing positions, and axial and radial position difference constraints to determine abnormal echoes, the interference of structural reflection and isolated noise on defect judgment can be eliminated, improving the positioning stability of the defect detection result in the predetermined axial detection plane.

[0090] like Figure 6 The diagram shown is a functional block diagram of a phased array dynamic focusing detection system at the end of a variable cross-section shaft provided in an embodiment of the present invention.

[0091] In this embodiment of the invention, the phased array dynamic focusing detection system for the end face of a variable cross-section shaft is applied to a phased array ultrasonic testing device. The phased array ultrasonic testing device emits ultrasonic waves to the end face of the axisymmetric variable cross-section shaft to be tested through a phased array probe and receives the echoes. The array elements participating in the emission and echo reception in the phased array probe are selected, and the ultrasonic wave emission is controlled according to the focusing delay corresponding to each array element. The propagation time of the echoes received by each array element is recorded, time-aligned, and superimposed. The system completes the dynamic focusing detection of each detection zone according to the shaft end structure information, target focusing position sequence, propagation path, propagation sound path, and focusing control information, and outputs the defect detection results.

[0092] The phased array dynamic focusing detection system 100 for a variable cross-section shaft end as described in this invention can be installed in an electronic device. Depending on the functions implemented, the phased array dynamic focusing detection system 100 for a variable cross-section shaft end may include a shaft end structure calibration module 101, a detection area partitioning module 102, a propagation sound path determination module 103, a focusing parameter generation module 104, a dynamic focusing acquisition module 105, and a defect location judgment module 106.

[0093] The shaft end structure information output by the shaft end structure calibration module is transmitted to the detection area partitioning module, the propagation sound path determination module, the focusing parameter generation module, and the defect location determination module, respectively. The target focusing position sequence output by the detection area partitioning module is transmitted to the propagation sound path determination module, the focusing parameter generation module, the dynamic focusing acquisition module, and the defect location determination module, respectively. The propagation path and propagation sound path output by the propagation sound path determination module are transmitted to the focusing parameter generation module, and the propagation sound path is transmitted to the dynamic focusing acquisition module and the defect location determination module. The focusing control information output by the focusing parameter generation module is transmitted to the dynamic focusing acquisition module. The dynamic focusing echo data output by the dynamic focusing acquisition module is transmitted to the defect location determination module. The defect location determination module generates the defect detection result based on the dynamic focusing echo data, the shaft end structure information, and the target focusing position sequence.

[0094] In this embodiment, the functions of each module are as follows: The shaft end structure calibration module 101 is used to obtain the shaft end face position, axis position and axial section profile of the axisymmetric variable cross section shaft to be tested in a predetermined axial detection plane, and to establish shaft end detection coordinates based on the shaft end face and axis to obtain shaft end structure information. The detection area partitioning module 102 is connected to the shaft end structure calibration module 101. It is used to determine the cross-sectional change position according to the shaft end structure information, divide the detection area with the cross-sectional change position as the boundary, and determine the target focusing position in each detection area to obtain the target focusing position sequence. The propagation path determination module 103 is connected to the detection area partitioning module 102. It is used to determine the position of each array element in the phased array probe in the detection coordinates at the axial end, and to obtain the propagation path and propagation path of each array element to each target focusing position based on the array element position, the axial end structure information and the target focusing position sequence. The focusing parameter generation module 104 is connected to the propagation path determination module 103. It is used to eliminate propagation paths that exceed the cross-sectional boundary based on the positional relationship between the propagation path and the cross-sectional boundary of the corresponding detection partition, continuously merge the array elements corresponding to the remaining propagation paths, select the effective array element range based on the radial projection position of the target focusing position on the axial end face, and determine the focusing delay based on the difference in propagation path of each array element to obtain focusing control information. The dynamic focusing acquisition module 105 is connected to the focusing parameter generation module 104. It is used to determine the current target focusing position according to the target focusing position sequence, pre-call the corresponding effective array element range and focusing delay to control ultrasonic wave transmission and echo reception, determine the receiving position according to the echo propagation time, and switch the corresponding effective array element range and focusing delay before the next ultrasonic wave transmission when the next target focusing position is located in the next detection zone to obtain dynamic focusing echo data. The defect location determination module 106 is connected to the dynamic focusing acquisition module 105. It is used to match the dynamic focusing echo data with the shaft end detection coordinates and target focusing position sequence, determine the structural reflection position according to the shaft end structural information and identify and eliminate structural echoes, determine abnormal echoes according to the echo amplitude of the remaining echoes and the continuity of adjacent target focusing positions, and determine the axial and radial positions corresponding to the abnormal echoes as the defect positions to obtain the defect detection results.

[0095] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention.

Claims

1. A phased array dynamic focusing detection method for the end of a variable cross-section shaft, characterized in that, Includes the following steps: Step P1: Obtain the position of the shaft end face, the position of the axis, and the axial section profile of the axisymmetric variable cross-section shaft to be tested in the predetermined axial detection plane. Establish the shaft end detection coordinates based on the shaft end face and the axis to obtain the shaft end structure information. Step P2: Determine the cross-sectional change position based on the shaft end structure information, divide the detection zone with the cross-sectional change position as the boundary, and determine the target focusing position within each detection zone to obtain the target focusing position sequence; Step P3: Couple the phased array probe to the end face of the shaft, determine the position of each array element in the detection coordinates of the shaft end, and obtain the propagation path and propagation sound path of each array element to each target focusing position based on the array element position, the shaft end structure information and the target focusing position sequence; Step P4: Based on the positional relationship between the propagation path and the cross-sectional boundary of the corresponding detection partition, eliminate propagation paths that exceed any corresponding cross-sectional boundary, continuously merge the array elements corresponding to the remaining propagation paths according to the arrangement order, select the effective array element range based on the radial projection position of the target focusing position on the axial end face, determine the focusing delay based on the propagation path difference of each array element, and obtain the focusing control information. Step P5: Determine the current target focus position sequentially according to the target focus position sequence, pre-call the corresponding effective array element range and focus delay to control ultrasonic wave transmission and echo reception, match the echo propagation time with the expected echo arrival time determined according to the propagation sound path to determine the reception position, when the next target focus position is located in the next detection zone, switch the corresponding effective array element range and focus delay before the next transmission to obtain dynamic focus echo data; Step P6: Match the dynamic focusing echo data with the shaft end detection coordinates and target focusing position sequence. Calibrate the structure reflection position according to the shaft end structure information. Determine the expected structure echo arrival time according to the propagation path of each array element to the structure reflection position. Identify and remove structure echoes. Determine abnormal echoes according to the echo amplitude of the remaining echoes and the continuity of adjacent target focusing positions. Determine the axial and radial positions corresponding to the abnormal echoes as the defect positions to obtain the defect detection results.

2. The phased array dynamic focusing detection method for the end of a variable cross-section shaft according to claim 1, characterized in that, Step P1 includes: Obtain the shaft end face profile and axial section profile of the axisymmetric variable cross section shaft to be detected in the predetermined axial detection plane; The center position of the shaft end face contour is calibrated to obtain the center of the shaft end face; The center positions of the two contour boundaries of the axial section profile are calibrated to obtain the axis of the variable cross-section shaft to be detected; The shaft end detection coordinates are established with the center of the shaft end face as the coordinate starting point, the axial direction within the predetermined axial detection plane as the axial direction, and the direction perpendicular to the axial line within the predetermined axial detection plane as the radial direction. By mapping the axial cross-sectional profile to the shaft end detection coordinates, the shaft end structure information, including the axial position and the corresponding radial boundary, is obtained.

3. The phased array dynamic focusing detection method for the end of a variable cross-section shaft according to claim 1, characterized in that, Step P2 includes: The radial boundary in the shaft end structure information is extracted sequentially along the axial direction; The radial boundaries corresponding to adjacent axial positions are compared and the axial position of the radial boundary abrupt change is determined as the cross-sectional abrupt change boundary. The starting position and ending position of the continuous change range of the radial boundary are determined as the cross-sectional transition starting boundary and cross-sectional transition ending boundary, respectively. The cross-sectional abrupt change boundary, the cross-sectional transition starting boundary and the cross-sectional transition ending boundary are combined to form a cross-sectional change boundary set. Using each cross-sectional change boundary in the set of cross-sectional change boundaries as an axial boundary, the area to be detected is divided into partitions to obtain axial segment detection partitions and cross-sectional transition detection partitions. Within the shaft segment detection zone, the target focusing positions are sequentially set along the axial and radial directions, with the starting boundary of the zone's axial direction as the starting point and the ending boundary of the zone's axial direction as the ending point. Within the cross-section transition detection zone, the target focusing positions are sequentially set along the extension direction of the cross-section transition profile in the solid area between the axis and the cross-section transition profile. Based on the shaft end structure information, structural markers are set for the target focus positions corresponding to the shaft shoulder, fillet, and cross-sectional change boundary, and the target focus positions are arranged in order according to the axial position and radial position to obtain the target focus position sequence.

4. The phased array dynamic focusing detection method for the end of a variable cross-section shaft according to claim 1, characterized in that, Step P3 includes: The acoustic center position of each array element is mapped to the detection coordinates at the axis end to obtain the array element coordinate sequence; Candidate propagation paths are constructed from the positions of each array element in the array element coordinate sequence to the focal positions of each target in the target focal position sequence; Based on the shaft end structure information, the entity contour range of the candidate propagation path is determined to obtain the propagation path located within the entity contour range of the variable cross section shaft to be detected; The path length of the propagation path is determined to obtain the propagation path of each array element to the focusing position of each target. Each propagation path is associated with its corresponding array element, target focusing position, and propagation path.

5. The phased array dynamic focusing detection method for the end of a variable cross-section shaft according to claim 1, characterized in that, Step P4 includes: Determine the detection zone where the target focusing position is located, and extract the cross-sectional boundary corresponding to the detection zone from the shaft end structure information; The radial boundary of the propagation path from each array element to the target focusing position is compared to obtain the positional relationship between the axial position of each propagation path and the corresponding cross-sectional boundary. Based on the aforementioned positional relationship, propagation paths that exceed the boundary of any corresponding cross section are eliminated to obtain reachable propagation paths; The array elements corresponding to the reachable propagation paths are continuously merged according to the array element arrangement order to obtain candidate array element groups; Based on the radial projection position of the target focusing position on the end face of the shaft, the candidate array elements are selected to obtain the effective array element range corresponding to the target focusing position.

6. The phased array dynamic focusing detection method for the end of a variable cross-section shaft according to claim 5, characterized in that, Step P4 further includes: Obtain the propagation path of each array element within the effective array element range to the same target focusing position; The maximum value of each propagation path is determined to obtain the maximum propagation path. The propagation path difference of each array element is calculated by comparing the propagation path of each array element with the maximum propagation path. Based on the propagation path difference and the propagation speed of the ultrasonic wave in the variable cross-section shaft to be detected, the focusing delay corresponding to each array element is determined according to the following formula: ； in, Indicates the first The element corresponds to the first Focusing delay at each target focus position Indicates the first Individual formation to the first The propagation path of sound at the target focal point This indicates that each element within the effective array element range is up to the [number]th [element]. The maximum propagation range of a target focusing location c This indicates the propagation speed of the ultrasonic wave in the variable cross-section shaft under test; The focusing delay is associated with the corresponding array element, the effective array element range, and the target focusing position to obtain the focusing control information.

7. The phased array dynamic focusing detection method for the end of a variable cross-section shaft according to claim 1, characterized in that, Step P5 includes: The current target focus position is determined according to the target focus position sequence, and the effective array element range and focus delay corresponding to the current target focus position are pre-called from the focus control information; According to the effective array element range and focusing delay, each array element is controlled to emit ultrasonic waves and receive echoes. The propagation time of the echoes received by each array element is marked to obtain echo time information. For each target focusing position, the common transmission focusing arrival time is determined based on the maximum propagation path and ultrasonic propagation speed within the corresponding effective array element range. The common transmission focusing arrival time is added to the return propagation time from the corresponding target focusing position to each receiving array element to obtain the expected echo arrival time corresponding to each target focusing position. Using half of the minimum interval between adjacent expected echo arrival times as the time matching window, the echo time information is compared with the expected echo arrival time. The target focusing position corresponding to the expected echo arrival time with the shortest time interval within the time matching window is determined as the receiving position. When the time interval between the same echo and two expected echo arrival times is the same, the target focusing position that appears first in the target focusing position sequence is determined as the receiving position. Echoes that exceed the entire time matching window are marked as unmatched echoes and excluded. The receiving position is compared with the current target focusing position. If they match, the corresponding echo is retained. If they do not match, the corresponding echo is marked as a position mismatch echo and excluded. When the next target focus position determined according to the target focus position sequence is located in the next detection zone, the effective array element range and focus delay corresponding to the next target focus position are switched before the next ultrasonic wave transmission.

8. The phased array dynamic focusing detection method for the end of a variable cross-section shaft according to claim 7, characterized in that, Step P5 further includes: According to the effective array element range corresponding to the current target focusing position, select array elements to participate in echo reception from the array elements corresponding to the echoes retained after position verification to obtain the receiving array element group. According to the focusing delay corresponding to the current target focusing position, the echo received by the receiving array element is time-aligned to obtain the aligned echo; The aligned echoes are superimposed to obtain the focused echo corresponding to the current target focusing position; By associating each of the focused echoes with the corresponding target focusing positions, the corresponding relationship between the focused echo positions is obtained; The dynamic focused echo data is obtained by sequentially arranging the corresponding relationships of the focused echo positions according to the target focused position sequence.

9. The phased array dynamic focusing detection method for the end of a variable cross-section shaft according to claim 1, characterized in that, Step P6 includes: Based on the shaft end structure information, determine the positions of the shaft shoulder, fillet, and cross-sectional change boundary in the shaft end detection coordinates to obtain the structural reflection position, and set a structural mark at the target focusing position corresponding to the structural reflection position; Based on the propagation path of each array element to the reflection position of the structure, the echo time of the reflection position of the structure is converted to obtain the expected arrival time of the echo of the structure. Using half of the minimum interval between the arrival times of adjacent expected structural echoes as the structural echo time matching window, the echo propagation time in the dynamic focusing echo data is compared with the arrival time of the expected structural echo to obtain the structural matching echo located within the structural echo time matching window. The structure matching echo corresponding only to the target focusing position with the structure mark is determined as the structure echo. The structure matching echo corresponding to the same internal position on consecutive adjacent target focusing positions is retained as the overlapping candidate defect echo. The structure echo is removed from the dynamic focusing echo data, and the remaining echo and the overlapping candidate defect echo are combined to form candidate defect echo data. The continuous time period between the end of the transmitted pulse and the earliest expected arrival time of the effective echo is selected as the noise reference period, and the average value of the absolute value of the echo amplitude within the noise reference period is determined as the noise benchmark. Candidate echoes with peak values ​​not less than three times the noise reference are identified as amplitude anomalous echoes. Anomalous echoes with amplitude values ​​corresponding to three consecutive adjacent target focusing positions and whose axial position difference and radial position difference do not exceed half the distance between the corresponding target focusing positions are identified as anomalous echoes, and the remaining candidate echoes are excluded. The abnormal echo is mapped to the shaft end detection coordinates to obtain the axial and radial positions of the abnormal echo in the predetermined axial detection plane, and the axial and radial positions are determined as the defect positions to obtain the defect detection results.

10. A phased array dynamic focusing detection system for the end of a variable cross-section shaft, characterized in that, A phased array dynamic focusing detection method for the end of a variable cross-section shaft as described in claim 1 includes: The shaft end structure calibration module is used to obtain the position of the shaft end face, the position of the axis, and the axial section profile of the axisymmetric variable cross-section shaft to be tested in a predetermined axial detection plane, and to establish shaft end detection coordinates based on the shaft end face and the axis to obtain shaft end structure information. The detection area partitioning module is used to determine the cross-sectional change position based on the shaft end structure information, divide the detection area into detection partitions with the cross-sectional change position as the boundary, and determine the target focusing position within each detection partition to obtain a target focusing position sequence; The propagation path determination module is used to determine the position of each array element in the phased array probe in the detection coordinates at the axial end, and to obtain the propagation path and propagation path of each array element to each target focusing position based on the array element position, axial end structure information and target focusing position sequence; The focusing parameter generation module is used to eliminate propagation paths that exceed the cross-sectional boundary based on the positional relationship between the propagation path and the cross-sectional boundary of the corresponding detection partition, continuously merge the array elements corresponding to the remaining propagation paths, select the effective array element range based on the radial projection position of the target focusing position on the axial end face, and determine the focusing delay based on the propagation path difference of each array element to obtain focusing control information. The dynamic focusing acquisition module is used to determine the current target focusing position according to the target focusing position sequence, pre-call the corresponding effective array element range and focusing delay to control ultrasonic wave transmission and echo reception, determine the receiving position according to the echo propagation time, and switch the corresponding effective array element range and focusing delay before the next ultrasonic wave transmission when the next target focusing position is located in the next detection zone to obtain dynamic focusing echo data. The defect location and determination module is used to match the dynamic focused echo data with the shaft end detection coordinates and target focused position sequence, determine the structural reflection position according to the shaft end structural information and identify and eliminate structural echoes, determine abnormal echoes according to the echo amplitude of the remaining echoes and the continuity of adjacent target focused positions, determine the axial position and radial position corresponding to the abnormal echo as the defect position, and obtain the defect detection result.

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