Patent Translate Powered by EPO and Google Notice This translation is machine-generated. It cannot be guaranteed that it is intelligible, accurate, complete, reliable or fit for specific purposes. Critical decisions, such as commercially relevant or financial decisions, should not be based on machine-translation output. DESCRIPTION JPS63274860 [0001] This invention relates to a method for appropriately determining the surface shape of an ultrasonic lens used in ultrasonic flaw detection and the like. (Conventional technology and its problems) In performing ultrasonic flaw detection, it is necessary to make an ultrasonic wave into a focused wave using an ultrasonic lens and to focus it on a target point of the inspection material itself. In this case, the ultrasonic waves focused by the ultrasonic lens are refracted when they enter from inside to outside of the material to be inspected. For this reason, in order to obtain a focused wave that is actually focused at the target point, it is necessary to determine the surface shape of the ultrasonic lens (and thus its focusing characteristics) while taking into consideration such refraction and the like. FIG. 9 is an explanatory view of a conventional method for determining the surface shape of an ultrasonic lens in such a position. In the figure, an ultrasonic wave US is emitted from a probe 2 provided with an ultrasonic transducer (not shown) and an ultrasonic lens 3. The ultrasonic waves uS are focused waves by the action of the ultrasonic lens 3. And, in this example, a round bar 1 immersed in water (not shown) is assumed as a material to be inspected to be subjected to ultrasonic flaw detection, and ultrasonic waves are applied to a target point A inside the round bar 1. Consider the case of focusing. At this time, the probe 2 is disposed such that its central axis U intersects perpendicularly with the axis V of the round rod 1 and the central axis U passes through the target point A. Under this arrangement, the surface shape of the ultrasonic lens 3 is determined as follows. First, consider a plane PA which includes the central axis U and which is perpendicular to the axis 1 of the round rod 1. Then, the radius of curvature r (FIG. 10) of the surface 4 of the ultrasonic lens 3 is set so that each of the sound rays SL of the ultrasonic wave US which travels on the plane PA from the probe 2 pass through the target point A. It is decided. However, the refraction angle of the sound ray SL on the surface of the round rod 1 is determined based on Snell's law. As described above, the surface shape of the ultrasonic lens 3 can be determined with relatively high accuracy only 03-05-2019 1 by the sound ray analysis on the plane PA because of the geometric symmetry in the case of the arrangement as shown in FIG. It is because it is expensive. By the way, such a surface shape determination method is premised on making the central axis U of the probe 2 perpendicular to the axis V of the material to be inspected. However, in fact, there are not a few cases where flaw detection is performed (that is, oblique incidence is made) by setting the angle between the central axis U of the probe 2 and the axis 3 of the test material as an angle other than vertical. At this time, geometrical symmetry as shown in FIGS. 9 and 10 is lost. For this reason, if the surface shape of the ultrasonic lens 3 is determined based only on the conventional two-dimensional analysis (that is, sound ray analysis on the plane PA), the focusing error becomes large, and the focusing degree of the ultrasonic waves decreases. There is a problem of doing it. And as a result, S / N of ultrasonic flaw detection will also fall. In order to solve this problem, it is conceivable to determine the surface shape of the ultrasonic lens 3 based on three-dimensional sound ray analysis. However, when performing three-dimensional sound ray analysis, a large number of Another problem arises that the operation has to be performed. And such a problem is a problem that occurs not only in the above case but also when the geometric symmetry of the shape of the test material itself is low, etc., and an ultrasonic lens is used for applications other than ultrasonic flaw detection It is also a common problem if you (Object of the Invention) The present invention is intended to overcome the above-mentioned problems in the prior art, and relates to the spatial positional relationship between an object to be irradiated with an ultrasonic wave and an ultrasonic lens, and the geometry of the object itself. An object of the present invention is to provide a method of determining the surface shape of an ultrasonic lens that can increase the focusing degree of ultrasonic waves with a relatively small amount of calculation even when the target symmetry is low. (Means for achieving the object) In order to achieve the above object, the present invention is characterized in that the ultrasonic wave generated outside the target object is made incident as the focusing wave to the inside of the object, and the inside of the object is In focusing the ultrasonic wave on a predetermined target point, as a method of determining the surface shape of the ultrasonic lens used when making the ultrasonic wave into a focusing wave, ■ super emitted from the central point of the ultrasonic lens A first step of determining an arrangement position and an arrangement attitude of the ultrasonic lens so that a sound ray of a sound wave passes through the target point, and specifying a sound ray from the central point as a reference sound ray; A second step of assuming a value of a predetermined shape parameter representing the shape of the surface of the acoustic lens; and a field where the surface shape of the ultrasonic lens is configured according to the assumed value of the shape parameter The position of each intersection point of each sound ray of ultrasonic waves respectively emitted from a predetermined number of minute sound sources assumed on the surface of the ultrasonic lens and the reference sound ray on a predetermined projection plane A third step of calculating a sum of positional deviations between each of the intersection points and the target point; and repeating the second and third steps while sequentially changing the value of the shape parameter; A fourth step of adopting the value of the shape parameter with 03-05-2019 2 which is the smallest as the actual shape parameter value of the ultrasonic lens, thereby determining the surface shape of the neck ultrasonic lens. (Embodiment) FIG. 1 is a flow chart showing the procedure of an ultrasonic lens surface shape determination method according to an embodiment of the present invention. Further, in FIG. 2, when performing ultrasonic flaw detection using the cylindrical material 8 immersed in water (not shown) as the inspection material, the surface shape of the ultrasonic lens is determined according to the procedure shown in FIG. It is a conceptual diagram of a case. And FIG. 3 is a figure which projected the sound ray of the ultrasonic wave shown in FIG. 2 on xy plane perpendicular | vertical to the central axis of a cylindrical material. The procedure for determining the surface shape of the ultrasonic lens will be described below with reference to these figures. However, for the purpose of clarifying the features of the invention, in the ultrasonic flaw detection of FIG. 2, a plano-concave lens 7 having a cylindrical surface 6 as shown in FIG. 4 is used. Further, the case where the radius of curvature R in the I-I cross section passing through the center point R8 of the surface 6 will be described. A, Determination of the lens 1 · and the foundation First, the cylindrical material 8 to be inspected for internal defects (Fig. 2). A target point Z at which the ultrasound US should be focused inside of FIG. 3). Set Next, when the ultrasonic wave is made to enter the inside of the cylindrical material 8, an incident point Po which is an incident center position is determined. This incident point P. The target point Z along the direction of the central axis 2 of the cylindrical material 8. Are set at positions separated by a predetermined distance l. Also, as shown in FIG. 3, a target point Z. And incident point P. The directions of the X-axis and the y-axis are determined such that the projection of the line segment connecting the X-axis and Y-axis into the x-y plane is parallel to the X-axis. Next, the sound ray a of the ultrasonic wave emitted from the central point R8 of the ultrasonic lens 7. But the incident point P. , And enters the inside of the cylindrical material 8 and this acoustic ray a. The placement position and the placement posture of the ultrasonic lens 7 are determined so that the target point Z0 passes through the target point Zo. In this process, the angle of refraction of sound rays at the surface of the cylindrical material 8 is determined based on Snell's law. Further, the distance between the center point R6 of the ultrasonic lens 7 and the surface of the cylindrical member 8, the diameter of the ultrasonic lens 7, and the like are determined in advance. Furthermore, sound ray a specified as described above. Is rat in the following process! ! It is treated as "ray". This reference sound line a. Is a sound ray of the ultrasonic wave from the center point of the ultrasonic lens 7 and therefore has nothing to do with the value of the curvature radius R of the surface 6 of the ultrasonic lens 7. Therefore, even if the radius of curvature R is changed in the following process, this reference sound ray a. Is unchanged. B, Calculation of shape parameter temporary and total of positional displacement amount As described above, reference sound ray a. Is determined, and an arbitrary value (for example, R = 25 m) is assumed as the radius of curvature R as the shape parameter of the surface 6. Next, on this surface 6, it is assumed that n minute sound sources R (i = 1.2, ..., n) arranged at equal intervals on an arc passing through the center point R8. The sound ray a H (i = 1. 2..., N) of the 03-05-2019 3 ultrasonic wave emitted from the lens is calculated by using Snell's law. Also, each sound line a. And the reference sound line a. Find the position of the intersection point c, (i = 1.2..., N) on the x-y projection plane PI of and. Then, the snow intersection C1 and the target point Z. Which positional deviation Δx− (i = 1.2..., N) on the x−y projection plane P1 is obtained. This misregistration mother ΔX is the target point Z. Assuming that the X coordinate of X is Xo, and the X coordinate of the intersection point C, is X, it is defined as the absolute value of these differences 1xo-x, l. However, when the intersection C1 can not be obtained, or when the intersection C8 is positioned outside the cylindrical member 8, the positional deviation amount ΔX is not calculated. By the way, this positional deviation amount ΔX indicates only the deviation between the intersection point C1 and the target point 2 ° in the X axis direction, but the reference sound ray a. And the X axis are parallel, there is no positional deviation in the y axis direction between the intersection point C · and the target point 7 °. Further, since the positional deviation in the direction of the central axis 2 of the cylindrical material 8 is in proportion to Δxi, it can be said that the smaller the ΔX, the smaller the positional deviation in the central axis Z direction. Therefore, the I3-dimensional positional deviation amount between the intersection point C1 and the target point Zo is sufficiently expressed only by the positional deviation amount ΔX · in the X-axis direction. Then, the above processing is repeated for all the n small sound sources R, and the sum ΣΔX of the positional deviation amount ΔX obtained by the calculation is calculated. Also, the sum Σ is the sum of i. This sum ΣΔX is the target point Z, as is apparent from its definition. It is four that reflects the degree of focusing of the ultrasonic waves in Determination of C0 Surface Shape In this way, after the sum ΣΔXi of positional displacement amounts when the curvature radius R of the surface 6 is 25 am, a new value (for example, R = 30 tnts) is assumed as the curvature radius R Then, in the same procedure as described above, the sum of the amounts of deviation when the curvature radius R is 301 RM is obtained. In this manner, repetitive processing is performed to obtain the sum of displacement amounts for various values of the radius of curvature R (for example, 25 m to 60 M). Then, the radius of curvature R such that the sum of the positional displacement amounts is minimum is adopted as the actual radius of curvature of the surface 6, thereby determining the surface shape of the ultrasonic lens 7. The above method does not use the premise that the central axis U of the ultrasonic lens is perpendicular to the axis 2 of the material to be inspected. For this reason, the target point Z also when these axes are not perpendicular to one another and are inclined at an arbitrary angle. The surface shape of the ultrasonic lens 7 can be determined so that the degree of focusing of the ultrasonic waves at the point. The same applies to the case where the symmetry of the shape of the test material is low. That is, in the above case, originally, three-dimensional analysis is required, but if the surface shape is determined as in the above-mentioned embodiment, evaluation of the degree of focusing is simple and accurate. Thus, the surface shape of the ultrasonic lens can be determined with a 03-05-2019 4 relatively small amount of calculation. FIG. 5 is a figure which shows the example of an experiment which detects the artificial defect provided in the inside of a sample by ultrasonic flaw detection. In this figure, this sample 9 is a cylindrical material having an outer diameter of 123 s + and an inner diameter of 83.6 m, and the artificial defect 10a provided on the inner wall of the welded portion 9a has a depth of 1/3 of the thickness of the welded portion 9a. Have. Further, another artificial defect 10b having a depth of 1/2 of the thickness of the welded portion 9a is also provided on the inner wall opposite to this. The positions of these artificial defects 10a and 10b in the circumferential direction are 90 ° and 270 ′ ′, respectively, and the position of the ultrasonic wave emitted from the probe 2a is a half depth of the thickness of the welded portion 9a ( Focusing at the target point), the reflection intensity of the ultrasonic wave from this position is measured by the probe 2b. FIG. 6 is an ultrasonic wave when the surface shape of the ultrasonic lens incorporated in the probe 2a, 2b of FIG. 5 is determined by the method shown in the above embodiment (curvature radius R = 30 m) It is a graph which shows angular distribution of reflective intensity of. 7 and 8 show the case where parallel ultrasonic waves are incident without using an ultrasonic lens (without a lens), and the case of using an ultrasonic lens having an inappropriate surface shape (curvature) It is a graph which each shows angular distribution of the reflective intensity of the ultrasonic wave of radius R = 50 m). The horizontal axis represents the circumferential position (angle) of the artificial defects 10a and 10b, and the vertical axis represents the reflection intensity. In these graphs, when the ultrasonic lens whose surface shape is determined by the method described in the above embodiment is used (FIG. 6), the positions where the artificial defects 10a and 10b are provided (position 90 ° in the circumferential direction, The reflection intensity of the ultrasonic wave at 270 ") is extremely large compared to that at the position without the artificial defects 10a and 10b, and as a result, the S / N is also sufficiently large. This is because the ultrasonic wave emitted from the probe 2a is sufficiently focused at the target point. On the other hand, when an ultrasonic lens is not used (FIG. 7) and when an inappropriate ultrasonic lens is used (FIG. 8), focusing of the ultrasound at the target point is not sufficient. Not only the degree of focusing at the point is reduced, but also the ultrasonic waves that are not focused become noises, making it difficult to specify the circumferential position of the artificial defects 10a and 10b, and the S / N also decreases. As described above, in the ultrasonic lens configured according to the present invention, the S / N can be made sufficiently large as compared with the conventional method. By the way, the method of determining the surface shape of the ultrasonic lens according to the present invention is not limited to the above-described embodiment, and the following modifications are possible. {Circle over (3)} In this embodiment, a cylindrical material is used as a target object on which ultrasonic waves are incident, but the present invention is also effective when an object having an arbitrary shape is used. The surface of the ultrasonic lens is not limited to a cylindrical surface, and may be various curved surfaces, for example, a spherical surface. Of course, the invention is not limited to the aspect of ultrasonic flaw detection (reflection method, transmission 03-05-2019 5 method, etc.), and can be applied to ultrasonic lenses other than those for ultrasonic flaw detection. (2) As the shape parameter, not only the radius of curvature but, for example, in the case of a parabolic lens or the like, the eccentricity of the objective surface may be used as a parameter. The position may be adopted, and the degree of convergence may be evaluated by the magnitude of the sum Σ (Xo-X). (Effects of the Invention) As described above, in the method of determining the surface shape of the ultrasonic lens according to the present invention, attention is paid to the intersection of the reference sound ray and another sound ray, and the positional deviation between this intersection and the target point By using the sum of the two as a parameter of the degree of focusing, even when the spatial relationship between the object on which the ultrasonic wave is to be incident and the ultrasonic lens and the geometrical symmetry such as the shape of the object itself are relatively low, It is possible to obtain a method of determining the surface shape of the ultrasonic lens that can increase the degree of focusing of the ultrasonic wave with a small amount of calculation. [0002] Brief description of the drawings [0003] FIG. 1 is a flow chart showing the procedure of the method for determining the surface shape of an ultrasonic lens according to an embodiment of the present invention, and FIGS. 2 and 3 show the surface shape of an ultrasonic lens used for ultrasonic flaw detection. 4 is a schematic view of an ultrasonic lens for determining the surface shape in this embodiment, and FIG. 5 is a layout of an experimental example for detecting an artificial defect by ultrasonic flaw detection. FIGS. 6 to 8 are graphs showing the results of the experiment shown in FIG. 5, and FIGS. 9 and 10 are explanatory views of a conventional method for determining the surface shape of the ultrasonic lens. 6 ... surface of ultrasonic lens, 7 ... ultrasonic lens, ao ... reference sound ray, al, a2, ..., fa line, C1, C2 '' intersection point, Ro ... of ultrasonic lens Center point, R, R2, ..., Ro ... Minute sound source, Zo ... Target point 03-05-2019 6

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