阅读说明：本技术 曲面零件超声全聚焦缺陷定量检测方法及系统 (Curved surface part ultrasonic full-focusing defect quantitative detection method and system ) 是由 华林 关山月 汪小凯 钱东升 李一轩 于 2021-08-17 设计创作，主要内容包括：本发明公开了一种曲面零件超声全聚焦缺陷定量检测方法,包括步骤：首先根据曲面零件的几何特征,制作相同曲率的凸面和凹面标准试块；采用水浸相控阵全聚焦系统检测曲面试块,绘制缺陷定量判定DAC三维曲面；将待测曲面零件浸入水中,采用相同参数检测待测曲面零件的相应曲面区域,获得全矩阵数据并生成全聚焦图像,根据缺陷出现的位置在曲面极坐标系中找到在缺陷距离-幅值DAC曲线中的标定值,若缺陷回波幅值超过缺陷距离-幅值DAC曲面高度,则判定该缺陷尺寸超过标定尺寸,记录该缺陷位置和尺寸。本发明有效解决了曲面零件超声全聚焦缺陷回波幅值不均匀,缺陷定量评价困难等问题。(The invention discloses a quantitative detection method for curved surface part ultrasonic full-focus defects, which comprises the following steps: firstly, manufacturing convex and concave standard test blocks with the same curvature according to the geometric characteristics of a curved part; detecting a curved surface test block by adopting a water immersion phased array full-focusing system, and drawing a DAC three-dimensional curved surface for quantitatively judging defects; immersing the curved surface part to be detected in water, detecting the corresponding curved surface area of the curved surface part to be detected by adopting the same parameters, obtaining full matrix data and generating a full focus image, finding a calibration value in a defect distance-amplitude DAC curve in a curved surface polar coordinate system according to the position where the defect appears, judging that the size of the defect exceeds the calibration size if the defect echo amplitude exceeds the height of the curved surface of the defect distance-amplitude DAC, and recording the position and the size of the defect. The invention effectively solves the problems of non-uniform echo amplitude of the ultrasonic full-focusing defect of the curved surface part, difficulty in quantitative evaluation of the defect and the like.)

1. The quantitative detection method for the ultrasonic full-focusing defects of the curved surface part is characterized by comprising the following steps of:

manufacturing a curved surface standard test block which is the same as a convex surface or a concave surface on a curved surface part to be measured by using the same material, processing n same curved surfaces and defects on the same curved surface standard test block, and increasing the distance between each defect and the circle center of the corresponding curved surface according to real-time precision;

placing the curved surface standard test block on a rotating platform, enabling one of the curved surfaces in the curved surface standard test block to be concentric with the rotating platform and rotate around the center of the circle, moving the ultrasonic phased array probe to be above the central axis of the curved surface standard test block, enabling the distance between the ultrasonic phased array probe and the arc center point of the curved surface to be a certain water layer height, and calibrating n defects on the curved surface standard test block respectively to obtain a defect distance-amplitude DAC curve for defect equivalent judgment;

immersing the curved surface part to be detected in water, detecting the corresponding curved surface area of the curved surface part to be detected by adopting the same parameters, obtaining full matrix data and generating a full focus image, finding a calibration value in a defect distance-amplitude DAC curve in a curved surface polar coordinate system according to the position where the defect appears, judging the equivalent weight of the size of the defect, judging that the size of the defect exceeds the calibration size if the defect echo amplitude exceeds the height of the curved surface of the defect distance-amplitude DAC, and recording the position and the size of the defect.

2. The curved surface part ultrasonic full-focusing defect quantitative detection method as claimed in claim 1, wherein during calibration, an appropriate ultrasonic phased array probe and detection parameters are selected specifically according to material properties and curved surface curvature of the curved surface part to be detected, the probe array width covers the curved surface region to be detected, and the water layer height h satisfies:h is the maximum depth of detection, c₁Is the speed of sound in water, c₂Is the speed of sound in the metal part.

3. The method for quantitatively detecting the ultrasonic full-focusing defects of the curved surface part as claimed in claim 2, wherein the curved surface part to be detected is assumed to comprise a plurality of geometrical characteristics of convex surfaces and concave surfaces, and the corresponding central angles of the arc sections of the convex surfaces and the concave surfaces areThe calibration process comprises the following steps:

the rotating platform is used for driving the curved surface standard test block to rotate around the circle center of the curved surface, and the stepping degree is theta₀From the leftmost endRotated to the rightPer revolution theta₀Acquiring full matrix data once, and acquiring N groups of full matrix data of one defect at different positions on corresponding circular arc linesRecording a set of maximum amplitude values of the defects on the circular arc lineData;

sequentially detecting n defects on the curved surface standard test block, sequentially obtaining maximum amplitude data of the n defects with different depths on corresponding circular arc lines, and completing the defect amplitude detection of all grid point positions in the curved surface polar coordinate system;

and carrying out interpolation operation and surface fitting on the defect amplitude values of all grid points of the curved surface polar coordinate system to obtain a defect distance-amplitude DAC three-dimensional curved surface for defect equivalent judgment in two directions of a central angle and a polar radius.

4. The curved surface part ultrasonic full-focusing defect quantitative detection method as claimed in any one of claims 1-3, characterized in that defects are machined at positions with a depth of 2mm to 8mm and a spacing of 1mm on a curved surface standard test block, according to aviation detection standards and requirements, the equivalent size of the machined defects is 0.8mm, and the number of the defects is 7.

5. The curved surface part ultrasonic full-focusing defect quantitative detection method as claimed in any one of claims 1-3, characterized in that according to the detection depth range H, n transverse through hole defects with the same diameter as the curved surface diameter on the curved surface part to be detected are processed at the depth position of the interval H/n.

6. A water immersion ultrasonic full-focusing detection system is characterized by being used for realizing the quantitative detection method for the ultrasonic full-focusing defect of the curved surface part in claim 1, and comprising a computer, an ultrasonic phased array detector, an ultrasonic phased array probe and a water tank filled with a coupling agent; the ultrasonic phased array detector acquires full matrix data through an ultrasonic phased array probe and transmits the full matrix data to the computer;

the system also comprises a rotary platform, wherein a four-jaw chuck is arranged on the rotary platform and used for fixing and centering the curved surface standard test block and the curved surface part to be detected, and the rotary platform drives the curved surface standard test block or the curved surface part to be detected to rotate around the circle center; the curved surface standard test block is a curved surface which is made of the same material and has the same convex surface or concave surface as the curved surface part to be measured, n identical curved surfaces and defects are machined on the same curved surface standard test block, and the distance between each defect and the circle center of the corresponding curved surface is increased progressively according to real-time precision.

Technical Field

The invention belongs to the technical field of ultrasonic nondestructive testing, and particularly relates to a quantitative detection method for curved surface part ultrasonic full-focusing defects, which is suitable for the quantitative detection of metal part defects with different curvature convex/concave geometric characteristics.

Background

With the rapid development of industries such as aerospace, wind power bearings, petrochemical engineering and the like, the requirements on parts with complex curved surfaces are more and more, and the quality nondestructive testing of the parts with the curved surface shapes plays an important role in the reliability and the service life safety of equipment. The ultrasonic phased array is composed of a plurality of array elements, can receive multi-angle reflection echo signals, has higher detection sensitivity and adaptability, and has advantages for ultrasonic detection of curved surface parts. However, when the ultrasonic phased array is used for detecting a curved surface component, due to the fact that sound beam incident angles of array elements on a curved surface interface are different, sound fields inside the curved surface are not uniformly distributed, and sound field intensities at different central angle positions are different, so that defect amplitude values are different, and at present, research on measurement and calibration of a curved surface full-focus sound field is not carried out, so that the defect quantitative evaluation difficulty of curved surface full-focus imaging is higher.

At present, an ultrasonic phased array flexible probe or a curved surface array probe is generally adopted for a complex curved surface component, the probes adopt contact type detection, the problems of unstable coupling conditions, low detection efficiency and the like exist, and ultrasonic automatic detection cannot be realized. Therefore, how to develop a quantitative detection method for the full focus defect of the water immersion ultrasonic phased array and realize the industrial automatic rapid detection is an urgent problem to be solved. In ultrasonic inspection, a defect distance-amplitude (DAC) curve is generally used to describe the relationship between defect distance, amplitude and equivalent size for quantitative inspection of defects. The defect amplitude of the defect with the same equivalent is gradually reduced along with the increase of the depth, so that the reflected echo amplitudes of the defect with the same equivalent size at different depths are connected into a curve, and the curve can be used for judging the equivalent size of the defect at different depth positions. For ultrasonic full-focus detection of curved surface parts, defects are attenuated not only in the depth direction but also in the circumferential direction, so that the traditional DAC curve defect quantitative evaluation method cannot be applied to detection of the curved surface parts, and the ultrasonic quantitative detection difficulty of the curved surface parts is higher. Currently, there is no specific method for evaluating the size of the full focus defect, so that the industrial application is difficult to realize.

Disclosure of Invention

Aiming at the defects or improvement requirements of the prior art, the invention provides the quantitative detection method for the ultrasonic full-focusing defects of the curved surface parts, which has higher detection sensitivity and more visual detection results and can realize the geometrical characteristics of the sections of the convex surface/the concave surface with different curvatures.

In order to achieve the aim, the invention provides a quantitative detection method for the ultrasonic full-focusing defects of curved surface parts, which comprises the following steps:

manufacturing a curved surface standard test block which is the same as a convex surface or a concave surface on a curved surface part to be measured by using the same material, processing n same curved surfaces and defects on the same curved surface standard test block, and increasing the distance between each defect and the circle center of the corresponding curved surface according to real-time precision;

placing the curved surface standard test block on a rotating platform, enabling one of the curved surfaces in the curved surface standard test block to be concentric with the rotating platform and rotate around the center of the circle, moving the ultrasonic phased array probe to be above the central axis of the curved surface standard test block, enabling the distance between the ultrasonic phased array probe and the arc center point of the curved surface to be a certain water layer height, and calibrating n defects on the curved surface standard test block respectively to obtain a defect distance-amplitude DAC curve for defect equivalent judgment;

immersing the curved surface part to be detected in water, detecting the corresponding curved surface area of the curved surface part to be detected by adopting the same parameters, obtaining full matrix data and generating a full focus image, finding a calibration value in a defect distance-amplitude DAC curve in a curved surface polar coordinate system according to the position where the defect appears, judging the equivalent weight of the size of the defect, judging that the size of the defect exceeds the calibration size if the defect echo amplitude exceeds the height of the curved surface of the defect distance-amplitude DAC, and recording the position and the size of the defect.

According to the technical scheme, during calibration, a proper ultrasonic phased array probe and detection parameters are selected according to the material properties and the curvature of the curved surface part to be detected, the width of the probe array covers the area to be detected of the curved surface, and the height h of a water layer meets the following requirements:h is the maximum depth of detection, c₁Is the speed of sound in water, c₂Is the speed of sound in the metal part.

According to the technical scheme, the curved surface part to be measured is assumed to comprise a plurality of convex surfaces and a plurality of concave surface geometrical characteristics, and the arc sections of the convex surfaces and the concave surfaces correspond to central angles ofThe calibration process comprises the following steps:

the rotating platform is used for driving the curved surface standard test block to rotate around the circle center of the curved surface, and the stepping degree is theta₀From the leftmost end-Rotated to the rightPer revolution theta₀Acquiring full matrix data once, and acquiring N groups of full matrix data of one defect at different positions on corresponding circular arc linesRecording a group of defect maximum amplitude data on the arc line;

sequentially detecting n defects on the curved surface standard test block, sequentially obtaining maximum amplitude data of the n defects with different depths on corresponding circular arc lines, and completing the defect amplitude detection of all grid point positions in the curved surface polar coordinate system;

and carrying out interpolation operation and surface fitting on the defect amplitude values of all grid points of the curved surface polar coordinate system to obtain the defect distance-amplitude DAC three-dimensional curved surface judged by the defect equivalent values in the two directions of the central angle and the polar radius.

According to the technical scheme, the defects are machined at the positions with the depth of 2mm to 8mm and the interval of 1mm on the curved surface standard test block respectively, the equivalent size of the machined defects is 0.8mm according to the aviation detection standard and requirements, and the number of the defects is 7.

According to the technical scheme, according to the detection depth range H, n transverse through hole defects with the diameter the same as that of the curved surface on the curved surface part to be detected are machined at the depth position with the interval of H/n.

The invention also provides a water immersion ultrasonic full-focusing detection system which is characterized by being used for realizing the quantitative detection method of the ultrasonic full-focusing defect of the curved surface part, and the water immersion ultrasonic full-focusing detection system comprises a computer, an ultrasonic phased array detector, an ultrasonic phased array probe and a water tank filled with a coupling agent; the ultrasonic phased array detector acquires full matrix data through an ultrasonic phased array probe and transmits the full matrix data to the computer;

the system also comprises a rotary platform, wherein a four-jaw chuck is arranged on the rotary platform and used for fixing and centering the curved surface standard test block and the curved surface part to be detected, and the rotary platform drives the curved surface standard test block or the curved surface part to be detected to rotate around the circle center; the curved surface standard test block is a curved surface which is made of the same material and has the same convex surface or concave surface as the curved surface part to be measured, n identical curved surfaces and defects are machined on the same curved surface standard test block, and the distance between each defect and the circle center of the corresponding curved surface is increased progressively according to real-time precision.

The invention achieves the following beneficial effects: the quantitative detection method for the ultrasonic full-focusing defects of the curved surface parts can realize the ultrasonic full-focusing imaging and the quantitative detection of the sizes of the defects of the metal parts with different curvature convex/concave geometric characteristics. According to the arc radius of the convex surface and the concave surface, a curved surface standard test block with artificial defects is designed, and the provided method for detecting the rotation of the curved surface standard test block can acquire a series of defect amplitude values of the defects at different positions on an arc line, greatly save the defect processing quantity and avoid the problem of mutual interference of a plurality of defect ultrasonic signals on one test block; the proposed defect calibration method can cover all grid points of the curved surface polar coordinate system; the provided curved surface full-focusing defect size determination DAC three-dimensional curved surface can determine the defect equivalent size of any position in a two-dimensional polar coordinate system of different depths and different central angles of a curved surface part. The method effectively solves the problems of uneven echo amplitude of the curved surface full-focus imaging defect, difficulty in quantitative detection of the defect and the like.

Drawings

FIG. 1 is a water immersion ultrasonic full focus detection system of the present invention;

FIG. 2 is a schematic view of polar meshing for curved surface regions in accordance with the present invention;

FIG. 3 is a schematic diagram of a curved standard test block design according to the present invention;

FIG. 4 is a schematic diagram of the rotation detection of the standard test block with curved surface according to the present invention;

FIG. 5 is a dimensional view of a swage of a specific embodiment of the present invention;

FIG. 6 is a graph of standard test block dimensions for a curved surface designed in accordance with an embodiment of the present invention;

FIG. 7 is a three-dimensional surface diagram of a defect quantitative determination DAC in an embodiment of the present invention.

In the figure: the test system comprises a computer 1, an ultrasonic phased array detector 2, an ultrasonic phased array probe 3, a water tank 4, a curved surface standard test block 5, a four-jaw chuck 6 and a rotary platform 7.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention. In addition, the technical features involved in the embodiments of the present invention described below may be combined with each other as long as they do not conflict with each other.

The invention relates to an ultrasonic full-focus defect quantitative detection method for curved surface parts, which is used for calibrating artificial defects in two directions of a central angle and a polar radius by establishing a curved surface polar coordinate system, measuring the maximum amplitude of the defects by using a full-focus experiment and drawing a distance-amplitude (DAC) three-dimensional curved surface for quantitative defect judgment. The specific method comprises the following steps: firstly, manufacturing convex and concave standard test blocks with the same curvature according to the geometric characteristics of a curved part; a curved surface test block is detected by adopting a water immersion phased array full focusing system, a series of maximum amplitude values of defects on a circular arc line are obtained by rotating the curved surface test block, maximum amplitude value data sets of the defects in two directions of a central angle and a polar radius are sequentially obtained according to the method, and a DAC three-dimensional curved surface for quantitatively judging the defects is drawn by utilizing data interpolation and three-dimensional curved surface fitting. The method utilizes the DAC three-dimensional curved surface to realize the defect equivalent size judgment of the curved surface part at any position in the circumferential and radial polar coordinate systems, effectively solves the problems of non-uniform ultrasonic full-focusing defect echo amplitude, difficult defect quantitative evaluation and the like of the curved surface part, and has important application value for the ultrasonic automatic industrial detection of the curved surface part.

As shown in fig. 1, the water immersion ultrasonic full-focus detection system adopted in the embodiment of the present invention includes a computer 1, an ultrasonic phased array detector 2, an ultrasonic phased array probe 3, and a water tank 4 filled with a coupling agent; the ultrasonic phased array detector 2 collects full matrix data through the ultrasonic phased array probe 3, transmits the full matrix data to the computer 1 for storage, and utilizes ultrasonic detection software to realize full focus imaging and extract the maximum amplitude of the defect position. A four-jaw chuck 6 is arranged on the rotary platform 7 and used for fixing and centering the curved surface standard test block 5 and the curved surface part to be detected, and artificial defects are machined on the curved surface standard test block 5; the rotary platform 7 drives the curved surface standard test block 5 to rotate around the circle center, and a series of echo amplitudes of the defects on the circular arc lines of different circle center angles can be acquired. And acquiring full-matrix ultrasonic signals by using a computer, an ultrasonic phased array detector and an ultrasonic phased array probe and carrying out full-focus imaging.

The invention provides a quantitative detection method for ultrasonic full-focus defects of curved surface parts, which comprises the following steps:

step (1): selecting proper probes and detection parameters according to the material properties and the curvature of the curved surface part to be detected, wherein the width of the probe array needs to cover the area to be detected of the curved surface, and the height h of a water layer needs to satisfy the following conditions:h is the maximum depth of detection, c₁Is the speed of sound in water, c₂Is the speed of sound in the metal part;

step (2): it is assumed that the curved surface part to be measured includes a plurality of convex surfaces (radius r respectively)_iI-1, 2,3) and a plurality of concave surfaces (radii R, respectively)_iI 1,2,3) geometric characteristics, the arc segments of the convex and concave surfaces corresponding to the central angle beingRespectively manufacturing curved surface standard test blocks with the same material and the same curvature, namely a convex surface and a concave surface; as shown in fig. 6, if the standard block with the same convex surface includes n same convex surfaces, and each convex surface corresponds to a defect with one depth, the defect can be made into a through hole. The curved standard test block with the same concave surface comprises n same concave surfaces, and each concave surface corresponds to a defect with one depth. And the defect depth on each curved surface standard test block is sequentially increased or decreased according to the measurement precision.

And (3): placing the curved surface standard test block on a rotary platform, enabling the curved surface standard test block to be concentric with the rotary platform, moving the ultrasonic phased array probe to be above the central axis of the curved surface standard test block, and enabling the height of a water layer of the probe from the central point of the curved surface circular arc to be h;

and (4): detecting a curved surface standard test block by adopting ultrasonic phased array equipment, collecting full matrix data of the position of the curved surface standard test block, carrying out full focus imaging by using the full matrix data, extracting the maximum amplitude of the position of a defect in an image, and recording the polar coordinate position of the defect as (rho)₁θ) of maximum amplitude of the position defect

And (5): as shown in fig. 4, on the premise of ensuring that other detection parameters are not changed, the rotating platform is used to drive the curved surface standard test block to rotate around the center of a circle, and the stepping degree is θ₀From the leftmost end-Rotated to the rightPer revolution theta₀Collecting once full matrix data, and obtaining the radius rho of the defect in total₁N groups of full matrix data at different positions on arc lineAll data are collected under the same gain condition, and the radius is obtained as rho by adopting full-focus imaging₁A set of maximum amplitude data of defects on a circular arc, i.e.

And (6): repeating the step (3-5) to sequentially detect n curved surface standard test blocks and sequentially obtain the maximum amplitude data of the defects on the arc lines of n different depthsFinishing the defect amplitude values of all grid point positions in the curved surface polar coordinate system;

and (7): carrying out interpolation operation and surface fitting on the defect amplitude values of all grid points of the curved surface polar coordinate system to obtain defect equivalent judgment DAC three-dimensional curved surfaces in two directions of a central angle and a polar radius;

and (8): immersing the curved surface part to be detected in water, detecting convex and concave surface areas of the part by adopting the same parameters, obtaining full matrix data and generating a full focus image, and determining the position (rho) of the defect according to the position_i,θ_x) And finding a DAC curve calibration value in a polar coordinate system, judging the equivalent weight of the defect size, judging that the defect size exceeds the calibration size if the defect echo amplitude exceeds the height of the DAC curved surface, and recording the position and the size of the defect.

The ultrasonic phased array full-focus imaging algorithm collects full-matrix data through ultrasonic detection software, combines all transmitting-receiving array elements at a focus point in sequence, and carries out amplitude superposition, and the algorithm belongs to the prior art and is not detailed here.

As a preferable embodiment of the present invention, in the step (2), the design method of the curved standard test block is as follows:

as shown in fig. 2, a polar coordinate system is established in the curved surface region to be measured, meshes are divided, and the sound pressure values of the mesh points on the circular arc lines at different depths of the curved surface polar coordinate system are respectively measured, so that the measurement of the curved surface full-focusing sound field can be completed;

as shown in fig. 3, in order to measure the sound pressure values of the grid points of the curved polar coordinate system, the maximum amplitudes of the same defect at the positions of the grid points need to be collected. And designing a convex standard test block with curvature R and a concave standard test block with curvature R by adopting the same material as the curved surface part to be detected, and processing n transverse through hole defects with diameter d at the depth position at the interval of H/n according to the detection depth range H. The method can ensure the independent detection of each defect, and avoid the mutual interference of signals of a plurality of defects in a test block to influence the calibration precision of the amplitude of the defect; in addition, the defect amplitude of the defect at different circle center angle positions on the arc line can be detected through the rotation detection of the test block, and the processing quantity of the defects on the arc line is saved. The diameter d of the artificial defect transverse through hole is determined according to the detection standard and requirements of the part.

As a preferred embodiment of the present invention, in step (7), the method for drawing the three-dimensional curved surface of the DAC for determining the defect equivalent in the polar coordinate system is as follows:

step (2) - (6), under the condition of unified gain, acquiring the defect echo amplitudes of all grid points in the curved surface region polar coordinate system, and obtaining the maximum amplitude data of the defects on n arc lines with different depthsFirstly, in order to ensure the smoothness of the curve, a 3-order spline difference method is adopted to align polar coordinate two-dimensional dataInterpolation is carried out, the data quantity of the defect amplitude is expanded, and the surface fitting precision is improved. Then, the interpolated polar defect amplitude data is processedFitting the curved surface to obtain the defectsAnd quantitatively judging the DAC three-dimensional curved surface, wherein the fitted DAC three-dimensional curved surface covers the curved surface polar coordinate area of the curved surface part to be detected and contains information in two directions of a central angle and a polar radius.

In another embodiment of the invention, as shown in fig. 5, in the target aircraft engine case ring forging of this embodiment, the curved surface part has a large number of regions to be measured for concave chamfer, the radius of the concave surface is 5mm, and the central angle corresponding to the arc of the concave surface isThe material is high-temperature alloy, and the coupling agent is water.

Step (1): aiming at a small-size concave arc with the R being 5mm, selecting a small linear phased array probe with 16 array elements, the frequency being 10MHz and the array element spacing being 0.25mm, wherein the maximum detection depth H is 8mm, and the height H of a water layer is 5 mm;

step (2): as shown in fig. 6, the same material of the curved surface part to be detected is adopted to manufacture a concave standard test block, defects are processed at the positions with the depth of 2mm to 8mm and the interval of 1mm respectively, the equivalent size of the processed defects is 0.8mm according to the aviation detection standard and requirement, and the number of the defects is 7;

and (3): placing the curved surface standard test block 5 on a rotating platform 7, enabling the curved surface standard test block 5 and the rotating platform 7 to be concentric, and moving the ultrasonic phased array probe 3 to be above the center of a concave surface circular arc of the curved surface standard test block 5, so that the height h of a water layer of the probe from the center point of the curved surface circular arc is 5 mm;

and (4): detecting a curved surface standard test block 5 by adopting an ultrasonic phased array detector 2, acquiring full matrix data of the position of the curved surface standard test block, recording the central angle of a defect deviating from the central axis, and calculating a full focus image of the position by utilizing the full matrix data, wherein the polar coordinate position of the defect is (rho)₁θ), then the maximum amplitude of the defect at that location is recorded as

And (5): as shown in FIG. 3, on the premise of ensuring other detection parameters to be unchanged, the rotary platform is used to drive the curved surface standard test block to rotate around the center of the circle,the degree of stepping is 2.5 °, rotating from-22.5 ° at the leftmost end to 22.5 ° at the right end. Acquiring full matrix data once per 2.5 degrees of rotation, and acquiring the radius rho of the defect in total₁N-19 groups of full matrix data at different positions on the circular arc line, wherein all the data are acquired under the same gain condition, and full focus imaging is adopted to acquire the rho radius₁A set of maximum amplitude data of defects on a circular arc, i.e.

And (6): repeating the steps (3) to (5) to sequentially detect 7 defects of the curved surface standard test block and sequentially obtain maximum amplitude data of the defects on the arc lines of 7 different depthsAs shown in the following table 1, the defect amplitude acquisition of all grid point positions in the curved polar coordinate system is completed, and statistics is shown in table 1:

table 1: defect amplitude data of each position in curved surface polar coordinate system

And (7): as shown in fig. 7, a 3-order spline difference method is adopted to perform three-dimensional surface interpolation and surface fitting on the defect amplitudes of all grid points of the curved surface polar coordinate system, so as to obtain a DAC three-dimensional curved surface determined in terms of defect equivalent, wherein the three-dimensional curved surface contains information of defects in two directions, namely a central angle and a polar radius;

and (8): immersing the curved surface part to be detected in water, detecting the concave surface area of the part by adopting the same parameters, obtaining full matrix data, generating a full focus image, extracting the maximum amplitude of the defect, and obtaining the position (rho) of the defect according to the position (rho) of the defect_i,θ_x) And finding a DAC curve calibration value in a polar coordinate system, judging the equivalent weight of the defect size, judging that the defect size exceeds the calibration size if the defect echo amplitude exceeds the height of the DAC curved surface, and recording the position and the size of the defect.

In conclusion, the invention adopts the water immersion ultrasonic full-focus detection method to detect the curved surface part, and manufactures the defect judgment DAC three-dimensional curved surface of the curved surface area in the polar coordinate system by designing the convex surface standard test block and the concave surface standard test block, thereby realizing the defect quantitative detection and evaluation of the complex curved surface part, having high detection sensitivity and being easy to realize the industrial automatic detection and evaluation.

It should be noted that, according to the implementation requirement, each step/component described in the present application can be divided into more steps/components, and two or more steps/components or partial operations of the steps/components can be combined into new steps/components to achieve the purpose of the present invention.

It will be understood by those skilled in the art that the foregoing is only a preferred embodiment of the present invention, and is not intended to limit the invention, and that any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the scope of the present invention.