CN105699492A - An ultrasonographic method used for weld seam detection - Google Patents

Abstract

An ultrasonographic method used for weld seam detection is provided. Aiming at weld seam ultrasonic phased array detection situations, the method includes collecting echo data of ultrasonic waves emitted separately in order by each array element by utilization of a full array, and performing pixel point-by-point focusing imaging treatment to obtain echo intensity corresponding to each pixel. The method improves imaging quality for weld seam detection and sensitivity for small-size detect detection for weld seams, further ensures performance and reliability of ultrasonic nondestructive testing for weld seams, and avoids accidents caused by unqualified welding quality of the weld seams.

Description

A kind of ultrasonic imaging method for weld seam detection

Technical field

The present invention relates to the ultrasonic non-destructive inspection techniques field of weld seam, particularly relate to a kind of ultrasonic imaging method for weld seam detection。

Background technology

In recent years, the ultrasonic application in Non-Destructive Testing (NDT) field is more and more extensive, for weld seam, is generally divided into the traditional detection method of based single crystal sheet transducer and based on the ultrasonic imaging method of array。The former includes again diffraction time difference method and pulse reflection method etc.。

The diffraction energy that ultrasonic wave diffraction time difference method is a kind of dependence to be obtained from weld seam internal structure " end angle " and " end points " method to detect defect, for the detection, quantitatively and location of defect。Adopting defect quantitative in the middle part of diffraction time difference of arrival technique butt welded seam, its quantitative accuracy is significantly larger than pulse reflection method ultrasound examination。And based on Ultrasonic NDT the having important advantages in that relative to traditional Ultrasonic NDT adopting single-chip transducer of array: electronic system can be passed through and control deflection and the focusing of acoustic beam, and then acoustic beam can be controlled be scanned along specific region, detecting speed and image quality thus improve, finally making the quantitative of defect and location more directly perceived, quick and accurate。

Traditional array ultrasonic is imaged on the coupled modes between phased array probe and measurand interface, generally comprises employing couplant direct-coupling or couples by placing voussoir。The former mainly adopts compressional wave to detect；And when adopt voussoir be tapered wedges couple time, can in order to change the direction of propagation and the conversion wave mode of acoustic beam, shear wave so can be adopted to detect those weld seams that can not directly place phased array probe on surface or surface, by time delay superposition Beamforming Method, defect area is carried out imaging。In imaging process, currently mainly adopt the method launched and receive point-by-point focusing that focuses, to improve imaging effect。But the transmitting that focuses often causes imaging resolution to decline。Ultrasonic phase array for weld seam detects, and owing to imaging region is near especially, the acoustic wave diffraction problem that the transmitting that focuses brings has been further exacerbated by the decline of imaging resolution, thus reducing the sensitivity of small-sized defects detection。

As shown in the above, for the phased array ultrasonic detection of weld seam, it is necessary to improve image quality further, to ensure the reliability of ultrasonic phase array weld seam Non-Destructive Testing, reduce because of the defective accident brought of weld seam welding quality。

Summary of the invention

It is an object of the invention to, in order to solve, the quantitative of above-mentioned existing weld joint ultrasound detection method existence and location are inaccurate, detection speed is not high, or the technical problem that the imaging resolution of defect area is low, the present invention provides a kind of ultrasonic imaging method for weld seam detection, it is different from above-mentioned traditional ultrasonic imaging method, the present invention is directed to the particularity of weld seam detection, adopting goes directly involves multiple reflection joint-detection, adopt and launch successively with single array element, full aperture gathers data, each imaging point all realizes transmitting-receiving and focuses on。And for the situation using tapered wedges to produce shear wave, it is precisely calculated each array element and propagates the time delay to test point through tapered wedges, and carry out pointwise imaging, in conjunction with physical size and the position of weld seam, carry out automatically identifying and mark, to improve sensitivity and the efficiency of the small-sized defects detection in butt welded seam。

To achieve these goals, the invention provides a kind of ultrasonic imaging method for weld seam detection, comprise the following steps:

Step 1) according to position on workpiece of the shape of workpiece for measurement, size and weld seam, physical dimension in conjunction with ultrasonic phase array probe, it is determined that the areas imaging of the position of ultrasonic phase array probe, hyperacoustic wave mode, the echo times of detection and object detection area；

Step 2) by step 1) in the areas imaging determined become some pixels by stress and strain model, using the centre coordinate of each pixel as the position coordinates of focus point；

Step 3) according to step 1) in determine ultrasound phase-control probe position place probe, in excitation ultrasound phased array, each array element individually launches ultrasound wave successively, and utilizes whole array element to receive this hyperacoustic echo-signal simultaneously；

Step 4) relative position according to each array element and pixel, by step 3) in the echo-signal that obtains carry out point-by-point focusing imaging processing, obtain the echo strength corresponding to each pixel；

Step 5) according to step 4) in echo strength corresponding to each pixel that obtain, be normalized, logarithmic compression, dynamic range restriction obtain ultrasound detection image after processing；

Step 6) according to step 1) in determine the position of ultrasonic phase array probe, hyperacoustic wave mode and object detection area areas imaging, it is arranged in step 5 by geometric position labelling) welded seam area in the ultrasound detection image that obtains, to determine defect image in welded seam area and to show。

As the further improvement of technique scheme, described step 4) in point-by-point focusing imaging process specifically include following steps:

Step 401) described echo-signal is filtered；

Step 402) record hyperacoustic transmission path that each array element is individually launched successively, and the RX path of this hyperacoustic echo-signal is individually received by each array element；

Step 403) according to step 402) in obtain hyperacoustic transmission path that each array element is individually launched successively, and the RX path of the echo-signal of correspondence calculates transmission delay；

Step 404) according to step 403) in calculated transmission delay, by corresponding with this transmission delay through step 401) filtered echo-signal carries out coherent superposition, and obtains the echo strength that each pixel is corresponding after taking envelope。

As the further improvement of technique scheme, described hyperacoustic wave mode is shear wave or compressional wave。

Further improvement as technique scheme, described ultrasonic phase array probe is attached at the surface of the work near weld seam, or it is attached at the side of the tapered wedges of the confession ultrasonic transmission being provided with, the opposite side of this tapered wedges contacts with surface of the work, and described tapered wedges is used for changing hyperacoustic direction of propagation and realizing shape transformation by interfacial refraction。

A kind of ultrasonic imaging method for weld seam detection of the present invention is in that:

The present invention is directed to welding line ultrasonic phased array detection situation, each array element of full array acquisition is utilized individually to launch hyperacoustic echo data successively, and carry out pixel point-by-point focusing imaging processing, thus obtaining the echo strength corresponding to each pixel, improve the sensitivity of small-sized defects detection in the image quality of weld seam detection and butt welded seam, it is further ensured that the Performance And Reliability of the Ultrasonic NDT of weld seam, it is to avoid the accident brought because weld seam welding quality is defective。

Accompanying drawing explanation

Fig. 1 is the ultrasonic imaging method flow chart for weld seam detection in the embodiment of the present invention。

Fig. 2 is the geometric representation utilizing tapered wedges to carry out the docking V-weld detection of plate plate。

Fig. 3 is the structural representation of the plate plate docking V-weld in Fig. 2。

Fig. 4 is the imaging geometry schematic diagram utilizing tapered wedges to carry out weld seam detection。

Fig. 5 is the corresponding relation figure that each array element of full array acquisition individually launches hyperacoustic echo-signal successively。

Fig. 6 is the imaging results utilizing the ultrasonic imaging method for weld seam detection in the embodiment of the present invention to carry out defects detection。

Detailed description of the invention

Below in conjunction with drawings and Examples, a kind of ultrasonic imaging method for weld seam detection of the present invention is described in detail。

A kind of ultrasonic imaging method for weld seam detection of the present invention, this ultrasonic imaging method includes:

Step 1) according to position on workpiece of the shape of workpiece for measurement, size and weld seam, physical dimension in conjunction with ultrasonic phase array probe, it is determined that the areas imaging of the position of ultrasonic phase array probe, hyperacoustic wave mode, the echo times of detection and object detection area；When utilizing ultrasonic phase array that workpiece weld seam is detected, owing to being subject to the impact of the many factors such as workpiece shapes and size, beam width, near-field interference, detection environment, it is necessary to select the probe of supersonic sounding according to practical situation, determine the order of reflection of the geometry echo of the wave mode of detection use, detecting location, scanning mode and employing。And the relative position according to workpiece shapes and size, probe detection position and weld seam may further determine that employing direct wave or adopts several times echo to carry out ultra sonic imaging。

Step 2) by step 1) in the areas imaging determined become some pixels by stress and strain model, using the centre coordinate of each pixel as the position coordinates of focus point；

Step 3) according to step 1) in determine ultrasonic phase array probe position place probe, in excitation ultrasound phased array, each array element individually launches ultrasound wave successively, and utilizes whole array element to receive this hyperacoustic echo-signal simultaneously。

Step 4) relative position according to each array element and pixel, by step 3) in the echo-signal that obtains carry out point-by-point focusing imaging processing, obtain the echo strength corresponding to each pixel；

Step 5) according to step 4) in echo strength corresponding to each pixel that obtain, be normalized, logarithmic compression and dynamic range restriction obtain ultrasound detection image after processing。

Step 6) according to step 1) in determine the position of ultrasonic phase array probe, hyperacoustic wave mode and object detection area areas imaging, it is arranged in step 5 by geometric position labelling) welded seam area in the ultrasound detection image that obtains, to determine defect image in welded seam area and to show。

Based on above-mentioned ultrasonic imaging method, as it is shown in figure 1, be a kind of supersonic array formation method flow process for weld seam detection in the embodiment of the present invention, this ultrasonic imaging method comprises the following steps:

Step 1), according to position on workpiece of the shape of workpiece for measurement, size and weld seam, in conjunction with the physical dimension of ultrasonic phase array probe, it is determined that the placement location of ultrasound phase-control probe, areas imaging for the hyperacoustic characteristic detected and object detection area。Described hyperacoustic characteristic comprises wave mode (shear wave or compressional wave), hyperacoustic order of reflection。

Due to the restriction of detectable position, sometimes can directly utilizing phased array probe and adopt compressional wave mode to detect, now ultrasonic phase array probe is often placed near face of weld or surface, again or be positioned over the position such as surface of the work of weld seam offside；Sometimes shear wave mode can be adopted to detect, now need to place tapered wedges between ultrasonic phase array probe and measurand, to change the direction of propagation of acoustic beam and to realize shape transformation by interfacial refraction, shear wave so can be adopted to detect those and directly cannot place the weld seam that ultrasonic phase array probe carries out detecting on workpiece。

When weld seam upper and lower surface all out-of-flatnesses or directly place on workpiece ultrasonic phase array probe cannot butt welded seam detect time, can be selected for tapered wedges and use ultrasonic transverse wave to carry out weld seam detection。Direct wave or multiple reflection the areas imaging in hard objectives detection region is clearly adopted according to the relative position that the shape of workpiece, physical dimension and weld seam and ultrasound phase-control are popped one's head in。As in figure 2 it is shown, owing to the upper and lower surface of weld seam is all uneven, it is impossible to directly place probe；And when directly placing probe on the surface of the work of weld seam side, restriction due to acoustic beam scanning angle, whole section of weld joint cannot be carried out scanning by possibly, therefore select here to place tapered wedges between ultrasonic phase array probe and measured workpiece, to change the direction of propagation of acoustic beam and the compressional wave that probe is launched is converted to shear wave。Owing to direct wave still scanning can not dock V-weld cross section to whole plate plate completely, therefore select direct wave to be used in combination and primary reflection butt welded seam carries out scanning。Wherein, the structure of plate plate docking V-weld is as shown in Figure 3。

Step 2), by step 1) in the areas imaging of object detection area determined become some pixels by stress and strain model, as shown in Figure 4。The centre coordinate of each pixel is using the position coordinates as focus point。

Step 3), according to step 1) in the position of ultrasound phase-control probe determined place tapered wedges and probe, record and arbitrary launch that to receive array element combination be g to corresponding echo-signal_i,jT (), specific operation process is as shown in Figure 5。Namely in excitation ultrasound phased array, each array element individually launches ultrasound wave successively, and receives this hyperacoustic echo-signal with whole array elements when receiving simultaneously, obtains all transmitting and receives array element combination to corresponding echo-signal。

Step 4), in the areas imaging of object detection area, the position according to array element and pixel, described launching is received array element combination corresponding echo-signal is carried out point-by-point focusing imaging processing, obtain the echo strength corresponding to each pixel。

Described step 4) in point-by-point focusing imaging process specifically include following steps:

Step 401) described arbitrary transmitting is received array element combination to corresponding echo-signal g_i,jT () is filtered processing, obtain filtered echo-signal h_i,j(t)；

Step 402) determine that ultrasound wave is launched by array element i as shown in Figure 4, reflect at tapered wedges and measurand interface, then through scattering source P (x_pn,z_pn) scattering, the transmission path finally received by array element j and RX path；

Step 403) according to step 402) in obtain calculated transmission delay ti by the transmission path of array element i to j and RX path_j；

Step 404) as shown in Figure 4, according to any pixel point P (x in the target area to weld seam to be detected_pn,z_pn) the computed transmission delay drawn, by corresponding with this transmission delay through step 401) filtered echo-signal coherent superposition, and obtain the echo strength corresponding to this pixel after taking envelope。

In above-mentioned steps 403, it is determined that by the transmission path of array element i to j and RX path it is crucial that determine ultrasound wave tapered wedges and the incidence point Q on measurand interface in such as Fig. 4_ti(x_bi,z_bi) and Q_rj(x_bj,z_bj) location parameter。The position of incidence point in conjunction with the coordinate system of foundation, from ray acoustics angle, can be set up equation according to snell law and solve。For incidence point Q_ti(x_bi,z_bi), solution procedure is as follows:

Set up equation:

$\frac{{(x_{\mathrm{bi}}-x_i)}^2}{{c_1}^2[{(x_{\mathrm{bi}}-x_i)}^2+{(z_{\mathrm{bi}}-z_i)}^2]}=\frac{{(x_{\mathrm{pn}}-x_{\mathrm{bi}})}^2}{{c_2}^2[{(x_{\mathrm{pn}}-x_{\mathrm{bi}})}^2+{(z_{\mathrm{pn}}-z_{\mathrm{bi}})}^2]}---\left(1\right)$

Wherein, c₁And c₂Represent the velocity of sound that ultrasound wave is propagated in tapered wedges and measurand, x respectively_iAnd z_iRepresent the position coordinates of array element i, x_pnAnd z_pnRepresent the position coordinates of any pixel point P。Due to the curved surface that the interface of voussoir Yu measurand is known, if surface equation is: z=f (x, y), owing to the equivalent incidence point that each array element is corresponding is positioned in xoz plane, therefore can obtain according to the surface equation of actual voussoir with measurand:

z_bi=f (x_bi,0)(2)

(2) formula is substituted into (1) formula, only x in (1) formula_biFor unknown parameter, other are known parameters。

When the interface of voussoir Yu measurand is plane, and when when setting up coordinate system, interface is located exactly in xoz plane, z_bi=0, i.e. situation as shown in Figure 4。Aforesaid equation (1) can utilize analytic method, numerical method or iterative method to solve, by x after solving_biNamely (2) formula of substitution determines a Q_ti(x_bi,z_bi) particular location coordinate。In like manner can calculate and obtain incidence point Q_rj(x_bj,z_bi) position coordinates。

Utilize the incidence point Q that aforesaid equation (1) obtains_ti(x_bi,z_bi) and Q_rj(x_bj,z_bj) position coordinates, calculate further transmission delay t_ij, specific as follows:

t_ij=t_i+t_j(3)

$t_i=\frac{\sqrt{{(x_{\mathrm{bi}}-x_i)}^2+{(z_{\mathrm{bi}}-z_i)}^2}}{c_1}+\frac{\sqrt{{(x_{\mathrm{pn}}-x_{\mathrm{bi}})}^2+{(z_{\mathrm{pn}}-z_{\mathrm{bi}})}^2}}{c_2}---\left(4\right)$

$t_j=\frac{\sqrt{{(x_{\mathrm{bj}}-x_{\mathrm{pn}})}^2+{(z_{\mathrm{bj}}-z_{\mathrm{pn}})}^2}}{c_2}+\frac{\sqrt{{(x_j-x_{\mathrm{bj}})}^2+{(z_j-z_{\mathrm{bj}})}^2}}{c_1}---\left(5\right)$

Utilize above-mentioned calculated any pixel point P (x_pn,z_pn) corresponding to transmission delay t_ij, by corresponding with this transmission delay through step 401) and the analytic signal coherent superposition of filtered echo-signal, and take envelope, the echo strength result corresponding to this pixel can be calculated by following formula (6):

$I=\left|\underset{j=1}{\overset{N}{\mathrm{\Σ}}}\underset{i=1}{\overset{N}{\mathrm{\Σ}}}{h}_{i,j}\left(t_{\mathrm{ij}}\right)\right|---\left(6\right)$

Step 5), the echo strength I of each pixel is carried out post processing and shows, namely according to step 4) in echo strength corresponding to each pixel that obtain, be normalized, logarithmic compression and dynamic range restriction obtain ultrasound detection image after processing。

Step 6), according to step 1) placement location of the ultrasound phase-control determined probe, hyperacoustic wave mode and object detection area areas imaging, it is arranged in step 5 by geometric position labelling) weld seam relevant range in the ultrasound detection image that obtains, thus the defect image in detection region is identified, with the image-region that identification defect image is corresponding。As shown in Figure 6, figure has marked the scope of weld seam and mirror image figure (can labelling repeatedly mirror image figure), to detection region in and neighbouring image be identified and process, the direct wave of this detection region internal flaw and primary reflection imaging can be obtained, by rough the caused primary reflection imaging of face of weld and " chevron echo " imaging results of being caused by leg, thus having efficiently differentiated out the defect imaging within the false defect imaging of various weld seam and weld seam。

Situation is detected for welding line ultrasonic phased array, each array element of full array acquisition is utilized individually to launch hyperacoustic echo-signal successively, and carry out pixel point-by-point focusing imaging processing through tapered wedges, thus obtaining the echo strength corresponding to each pixel, the weld defect utilizing the formation method butt welded seam of the present invention detects, focus relative to traditional employing launch and receive point-by-point focusing method detection for, improve image quality, improve the resolution of detection and the sensitivity to small-sized defects detection。

It should be noted last that, above example is only in order to illustrate technical scheme and unrestricted。Although the present invention being described in detail with reference to embodiment, it will be understood by those within the art that, technical scheme being modified or equivalent replacement, without departure from the spirit and scope of technical solution of the present invention, it all should be encompassed in the middle of scope of the presently claimed invention。

Claims (4)

1. the ultrasonic imaging method for weld seam detection, it is characterised in that this ultrasonic imaging method includes:

Step 1) according to position on workpiece of the shape of workpiece for measurement, size and weld seam, physical dimension in conjunction with ultrasonic phase array probe, it is determined that the areas imaging of the position of ultrasonic phase array probe, hyperacoustic wave mode, the echo times of detection and object detection area；

Step 2) by step 1) in the areas imaging determined become some pixels by stress and strain model, using the centre coordinate of each pixel as the position coordinates of focus point；

Step 3) according to step 1) in determine ultrasonic phase array probe position place probe, in excitation ultrasound phased array, each array element individually launches ultrasound wave successively, and utilizes whole array element to receive this hyperacoustic echo-signal simultaneously；

Step 4) relative position according to each array element and pixel, by step 3) in the echo-signal that obtains carry out point-by-point focusing imaging processing, obtain the echo strength corresponding to each pixel；

Step 5) according to step 4) in echo strength corresponding to each pixel that obtain, be normalized, logarithmic compression and dynamic range restriction obtain ultrasound detection image after processing；

Step 6) according to step 1) in determine the position of ultrasonic phase array probe, hyperacoustic wave mode and object detection area areas imaging, it is arranged in step 5 by geometric position labelling) welded seam area in the ultrasound detection image that obtains, to determine defect image in welded seam area and to show。

2. the ultrasonic imaging method for weld seam detection according to claim 1, it is characterised in that described step 4) in point-by-point focusing imaging processing include:

Step 401) described echo-signal is filtered；

Step 402) determine hyperacoustic transmission path that each array element is individually launched successively, and the RX path of this hyperacoustic echo-signal is individually received by each array element；

Step 403) according to step 402) in obtain hyperacoustic transmission path that each array element is individually launched successively, and the RX path of the echo-signal of correspondence calculates transmission delay；

Step 404) according to step 403) in calculated transmission delay, by corresponding with this transmission delay through step 401) filtered echo-signal coherent superposition, and obtain the echo strength corresponding to each pixel after taking envelope。

3. method according to claim 1, it is characterised in that described hyperacoustic wave mode is shear wave or compressional wave。

4. the ultrasonic imaging method for weld seam detection according to claim 1, it is characterized in that, described ultrasonic phase array probe is attached at the surface of the work near weld seam, or it is attached at the side of the tapered wedges of the confession ultrasonic transmission being provided with, the opposite side of this tapered wedges contacts with surface of the work, and described tapered wedges is used for changing hyperacoustic direction of propagation and realizing shape transformation by interfacial refraction。