JP5064280B2 - Ultrasonic inspection apparatus and ultrasonic inspection method - Google Patents

Description

  The present invention relates to an ultrasonic inspection apparatus and an ultrasonic inspection method for nondestructive inspection for the presence or absence of internal defects in an inspection object.

  Ultrasonic inspection is performed for soundness evaluation inside a material of an inspection object, for example, a rotating part for an aero engine. In particular, a water immersion method is used in which an ultrasonic inspection is performed by immersing the inspection object in water.

  In addition, when the inspection object is a thick material such as a billet (for example, φ200 mm × 1 to 3 m), the attenuation of the ultrasonic wave is large, and it becomes difficult to inspect the central portion. Therefore, for thick materials, the use of a focusing probe is effective in suppressing the spread of ultrasonic waves and inspecting deep layers with high sensitivity.

  When a focusing probe is used, an ordinary probe has one focal point (single focal point), and thus ultrasonic inspection is limited to a limited range in the thickness direction. For this reason, when performing ultrasonic inspection in the entire thickness direction, prepare multiple probes with different focal lengths, perform ultrasonic inspection for each probe, and in the entire thickness direction of the inspection object. It was inspected for defects.

  When such a single-focus probe is used, the object to be measured must be subjected to ultrasonic inspection multiple times, and the probe must be replaced for each inspection. There was a problem that the ultrasonic inspection time was increased and workability was poor.

  In addition, when the inspection object becomes large, the transducer of the probe becomes large, and there is a problem that the capacitance increases and the frequency of the ultrasonic wave decreases.

  On the other hand, there is an array type ultrasonic deep touch element having a plurality of focal lengths or capable of adjusting the focal length.

  The array-type ultrasonic probe is composed of a required number of transducers into which a probe is divided into small pieces, and includes a control device that oscillates each transducer by performing phase control individually. By individually controlling the oscillation timing (phase), the entire probe has one focal length, the focal length is changed, and the probe has a plurality of focal lengths. Some are phase controlled.

  In such an array type ultrasonic deep probe, even if the probe becomes large, there is no decrease in the frequency of the ultrasonic wave, and it is not necessary to replace the probe every time the focal length is changed. It is also possible to inspect the presence or absence of defects over the entire thickness direction by ultrasonic inspection. On the other hand, in order to perform ultrasonic inspection using the array type ultrasonic deep touch element, there is a problem that an expensive control device for the array type ultrasonic deep touch element is required.

JP 2006-292697 A

  In view of such circumstances, the present invention provides a probe having a plurality of focal lengths, and allows the oscillation control of the probe to be performed by a probe control device for a single focal point.

  The present invention relates to an ultrasonic inspection apparatus in which a transducer membrane of a probe is divided into a plurality of areas, and the curved surface of each area is set so that each area has a different focal length.

  The present invention also relates to an ultrasonic inspection apparatus configured such that the area is connected to a control device via switching means, and the control device selects and drives one of the plurality of areas.

  The present invention also relates to an ultrasonic inspection apparatus in which the vibrator film is divided into concentric rings to form the area.

  The present invention also relates to an ultrasonic inspection apparatus in which the vibrator film is divided into strips to form the area, and the vibrator film is arranged in order along the traveling direction.

  Further, the present invention relates to an ultrasonic inspection apparatus in which the area is connected to the control apparatus via matching means.

  Further, the present invention is an ultrasonic inspection method using the ultrasonic inspection apparatus, wherein after the entire length of the inspection object is detected in one area, the other areas are sequentially selected to extend the entire length in the entire thickness direction. The present invention relates to an ultrasonic inspection method for flaw detection.

  Furthermore, the present invention relates to an ultrasonic inspection method using the ultrasonic inspection apparatus, in which the entire length of the inspection object is flawed while repeatedly driving a plurality of areas.

  According to the present invention, the transducer membrane of the probe is divided into a plurality of areas, and the curved surface of each area is set so that each area has a different focal length. In addition, the probe may be driven for each area, and the probe control device for a single focus can be used. Also, in response to the increase in the size of the inspection object, the area is divided even when the probe is enlarged, so that it is possible to prevent the ultrasonic frequency from being lowered and the detection sensitivity at a short distance is not impaired. Exhibits excellent effects.

  The best mode for carrying out the present invention will be described below with reference to the drawings.

  The probe used in the present invention will be described with reference to FIGS.

  The probe 1 is held at a position away from the surface of the inspection object 2 by a predetermined distance. Although not shown, the probe 1 and the inspection object 2 are disposed in water.

  A transducer film 3 that is a piezoelectric element is provided on the surface of the probe 1 that faces the inspection object 2. The vibrator film 3 has a planar shape and a curved surface adapted to the shape of the inspection object 2, and the vibrator film 3 has a circular cross-sectional shape as the inspection object 2. The cross-sectional shape is an ellipse having a long axis parallel to the axis of the inspection object 2 or a substantially ellipse (hereinafter referred to as an ellipse), and a curved surface along the surface of the inspection object 2. It has become.

  Here, the shape of the curved surface of the vibrator film 3 is formed so that the curve indicated by the cross section of the vibrator film 3 becomes a parabola when the cross section is taken along an arbitrary plane including an elliptical centroid.

  The vibrator film 3 is divided into a required number of areas in a concentric ring shape (four divisions in the drawing), and each ring is further divided in the circumferential direction. The divided parts are physically separated from each other, and the area of each part may be equal.

  Each part constitutes a vibrator 4, and a control device (described later) is electrically connected to each vibrator 4.

  In addition, the vibrators 4 belonging to each ring form a vibrator group, that is, an A group 5, a B group 6, a C group 7, and a D group 8, and each vibrator group includes matching circuits 10, 11, 12 respectively. , 13 and the switching means 14 are connected to the control device 15.

  The matching circuits 10, 11, 12, and 13 adjust the oscillation state of the vibrator 4 so that the vibrator 4 of each vibrator group oscillates under the same conditions. The switching means 14 turns ON / OFF the changeover switches 16, 17, 18, and 19 so that any one of the vibrator groups is connected to the control device 15.

  The control device 15 applies a pulse current to each transducer 4 of one transducer group selected by the switching means 14 to oscillate the transducer 4 and generate an ultrasonic wave. Further, the ultrasonic wave received by the vibrator 4 is detected as an electric signal.

  By simultaneously oscillating each transducer group under the same conditions, each transducer group is driven as one transducer and generates ultrasonic waves.

  As described above, the transducer 4 of each transducer group generates ultrasonic waves under the same conditions. In order to focus the ultrasonic waves at a predetermined distance (predetermined focal length), the transducer 4 It is necessary that the oscillation surface has a concave curved surface, the transducer film 3 or each transducer group is required to form a continuous concave curved surface, and the curvature of the concave curved surface depends on the focal length. , The curvature state is set.

  In the present invention, as shown in FIG. 1, each vibrator group is configured to have a different focal length, and the A group 5 located at the center of the vibrator film 3 is formed of the inspection object 2. A set including the A group 5, the B group 6, the C group 7, and the D group 8 having a focal length at a position in the vicinity of the surface including the surface and located around the transducer film 3 is the inspection. The set is set so as to have a focus at the center of the object 2, and the set of the A group 5 and the B group 6 is combined, and the set of the A group 5, the B group 6 and the C group 7 is the inspection It has a focal point in the middle of the surface of the object 2 and the center.

  In addition, the ultrasonic focusing portion has a width in the depth direction, and the ultrasonic focusing portions emitted from each transducer group are flaw detection zones 21, 22, 23, and 24 for detecting flaws. The flaw detection zones 21, 22, 23, and 24 overlap in a required range.

  The curved surface of the vibrator film 3 is determined so that the divided A group 5, B group 6, C group 7, and D group 8 of the vibrator film 3 have different focal lengths. The curved surface has a short focal length at the center and a longer focal length as it goes to the periphery.

  Thus, when the inspection object 2 is a long object having a cross-sectional circle, the curved surface shape of the vibrator film 3 is an arbitrary plane including the centroid of the vibrator film 3 as described above. When the cross section is taken, the curve shown by the cross section of the vibrator film 3 is formed to be a parabola.

  The curved surface shape of the vibrator film 3 will be described with reference to FIGS.

  FIG. 4A shows the inspection object (billet) 2 having a circular cross section and a long object, and the vibrator film 3 is crossed at an angle of φ with respect to the axis of the inspection object 2. FIG. 4B shows the relationship between the inspection object 2 and the vibrator film 3 in this case.

  In the figure, a: intersection of the short axis of the AA ′ cross section and the surface of the billet 2; b: intersection of an arbitrary ultrasonic wave traveling direction and the surface of the billet 2; c: arbitrary ultrasonic wave traveling direction and probe. D: intersection of the major axis of the AA ′ section and the surface of billet 2, f: focal length, o: center of billet 2 (origin), D: probe radius, F: depth of focus (metal) Travel), R: length of short axis (billet radius), R / cosφ: length of long axis, WP: water distance (distance between probe and billet 2), k: connecting point b and origin o Straight line, l: close contact at point b, m: straight line parallel to straight line oa and passing through point b, n: normal line at point b, α: ultrasonic refraction angle, β: ultrasonic incident angle , Γ: an angle formed by the normal line n with the billet center axis oa, θ: an angle formed by the straight lines k and m.

  Thus, in FIG. 4B, with respect to the origin o, the curve f (x, y) indicated by the cross section of the vibrator film 3 is represented by the equation shown in FIG.

  The operation of the ultrasonic inspection apparatus according to the present invention will be described below.

  First, the changeover switch 16 is turned ON, and the group A 5 and the control device 15 are connected. Note that the operation of the changeover switch 16 may be performed automatically by a command from the control device 15 or may be performed manually.

  The inspection object 2 is rotated, and the probe 1 is moved relative to the inspection object 2.

  At predetermined time intervals, current pulses are applied to the transducers 4 of the A group 5 to generate ultrasonic waves and perform flaw detection. Regarding the relationship between the time interval of the current pulse and the moving speed, the flaw detection zones 21 and 21 formed for each current pulse overlap each other within a required range.

  When flaw detection is completed over the entire length of the inspection object 2, the changeover switch 16 is turned off and the changeover switch 17 is turned on, or the changeover switch 16 is turned on while the changeover switch 17 is turned on. Similarly, flaw detection is performed on the flaw detection zone 22. Further, if the flaw detection zones 23 and 24 are sequentially flawed by the C group 7 and the D group 8, ultrasonic flaw detection can be performed on the entire area inside the inspection object 2.

  The moving speed of the probe 1 is slowed down, and the A group 5, the B group 6, the C group 7, and the D group 8 are repeatedly switched to perform ultrasonic flaw detection over the entire interior at once. May be.

  FIG. 6 (A) shows the flaw detection result of the probe 1 according to the present invention, and FIG. 6 (B) shows that all the transducers 4 are subjected to phase control by the controller for the array type ultrasonic deep probe. It shows the flaw detection results when inspected. In the drawing, L25 to L100 indicate the depth at which the inspection scratch is provided. For example, L25 is provided with an inspection flaw at a depth of 25 mm. Taking the example of L25, in both cases (A) and (B), there is reflection of ultrasonic waves on the surface and bottom surface of the inspection object 2, and reflection of ultrasonic waves is seen at a depth of 25 mm. Further, in both (A) and (B), the magnitude of the ultrasonic wave at a depth of 25 mm is the same. In addition, the magnitude | size of the reflected wave which shows a crack is the same also in the case of L50, L75, and L100, and the flaw detection performance of the probe 1 of this invention is control for an array type ultrasonic deep probe. It turns out that it is equivalent to the case where an apparatus is used.

  Next, another embodiment will be described with reference to FIG.

  In the other embodiment, the vibrator film 3 is divided into strip-shaped areas, and the areas are further divided to form vibrator groups. A group 5, B group 6, C group 7, D group 8 Are arranged in order along the advancing direction, and each of the transducer groups has a curved surface with a different curvature, and the A group 5, the B group 6, the C group 7, and the D group 8 are respectively Each area has flaw detection zones 21, 22, 23, and 24 having different focal lengths and different depths.

  In this embodiment, it is assumed that the traveling direction pitch P between the areas is a relative speed v, and the A group 5 → the B group 6 → the C group 7 → the D group 8 → the A group 5 are sequentially repeated. P = vt, where t is the time interval for applying the pulse current.

  By matching the relative speed with the time interval during which the pulse current is applied, it is possible to detect flaws at different positions in the same traveling direction.

  Note that the shape of the curved surface of the vibrator film 3 varies depending on the cross-sectional shape of the inspection object 2, and the curve indicated by the cross section of the vibrator film 3 is not limited to a parabola. Further, the number of divisions in each area is arbitrary, and each area may be constituted by one vibrator 4 that is not divided.

  According to the present invention, when the probe 1 is enlarged in response to the increase in the size of the inspection object 2, it is possible to prevent a decrease in the frequency of the ultrasonic wave and the detection sensitivity at a short distance is not impaired. . Furthermore, the probe 1 having a plurality of focal lengths can be driven by a control device for a single-focus probe.

It is a schematic diagram which shows embodiment of this invention. The transducer film of the probe which concerns on this invention is shown, (A) is a top view, (B) is a right view, (C) is a front view. It is a schematic block diagram which shows the ultrasonic inspection apparatus which concerns on this invention. It is explanatory drawing which shows the relationship between a test object and a vibrator film. It is explanatory drawing which shows the type | formula of the curved surface of a vibrator film. (A) is a graph which shows the test result of the ultrasonic inspection apparatus of this invention, (B) is a graph which shows the test result of the conventional array type ultrasonic deep touch element. It is explanatory drawing which shows other embodiment of this invention, (A) is a side view, (B) is a front view, (C) is a top view.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Probe 2 Test object 3 Vibrator film | membrane 4 Vibrator 5 A group 6 B group 7 C group 8 D group 10 Matching circuit 11 Matching circuit 12 Matching circuit 13 Matching circuit 14 Switching means 15 Control apparatus

Claims (6)

A continuous concave curved surface is formed by the transducer film of the probe, the transducer film is divided into concentric rings to form an area, and the area is further divided in the circumferential direction. The vibrators constituting each vibrator form a vibrator group, and the vibrators belonging to one vibrator group are simultaneously oscillated under the same conditions and have the same focal length. An ultrasonic inspection apparatus characterized in that the curved surface of each area is set so that the child groups have different focal lengths.   The ultrasonic inspection apparatus according to claim 1, wherein the area is connected to a control device via a switching unit, and the control device is configured to select and drive one of the plurality of areas.   The ultrasonic inspection apparatus according to claim 2, wherein the area is connected to the control apparatus via a matching unit. The transducer film of the probe is composed of a plurality of strip-shaped areas, the areas are arranged at a predetermined pitch with respect to the traveling direction, and each area is further divided in a direction perpendicular to the traveling direction, The required divided parts constitute a vibrator, and the vibrators belonging to each area form a vibrator group and a continuous concave curved surface, and the vibrators belonging to one vibrator group are simultaneously subjected to the same conditions. The curved surface of each area is set so that each vibrator group is oscillated and has the same focal length, and each vibrator group has a different focal length, and the traveling speed of the vibrator film and the current interval applied to the vibrator group are determined. An ultrasonic inspection apparatus characterized in that matching is performed to sequentially detect parts having different depths at the same position in the traveling direction .   An ultrasonic inspection method using the ultrasonic inspection apparatus according to claim 1, wherein after the entire length of the inspection object is detected in one area, the other areas are sequentially selected to cover the entire length in the thickness direction. An ultrasonic inspection method characterized by performing flaw detection. An ultrasonic inspection method using the ultrasonic inspection apparatus according to claim 4 , wherein the entire length of the inspection object is detected while repeatedly driving a plurality of areas.

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