JP4972678B2 - Ultrasonic measuring device, ultrasonic sensor and ultrasonic measuring method used therefor - Google Patents

Description

  The present invention relates to an ultrasonic measurement apparatus, an ultrasonic sensor used therefor, and an ultrasonic measurement method, and more particularly, an ultrasonic measurement apparatus suitable for using an array sensor in which ultrasonic vibration elements are two-dimensionally arranged, and an ultrasonic sensor used therefor And an ultrasonic measurement method.

2. Description of the Related Art In recent years, research and development have been actively conducted on three-dimensional ultrasonic technology that can transmit and receive ultrasonic waves in three dimensions using a matrix array sensor in which ultrasonic vibration elements are two-dimensionally arranged. This technique makes it possible to perform omnidirectional measurement with a high S / N ratio in a short time without mechanical rotation scanning (see, for example, Patent Document 1).
Therefore, the present inventors are considering applying a three-dimensional ultrasonic technique using a matrix array sensor to inspection of a thick plate material.
In order to determine the presence or absence of a crack located in a deep portion of a thick plate material by an inspection method using a three-dimensional ultrasonic technique, it is necessary to enlarge a sensor opening for transmitting and receiving ultrasonic waves. For this reason, if the size of the sensor aperture is increased with a matrix array sensor composed of ultrasonic transducer elements having a substantially constant area, such as a conventional rectangular matrix sensor or segment array sensor, two sensor apertures are obtained. The number of ultrasonic vibration elements increases in proportion to the power.
However, there is a technical limit to the total number of ultrasonic vibration elements that can be controlled by the phased array device, and even if the number of ultrasonic vibration elements that can be controlled is increased, the device becomes large and expensive. It was difficult to increase the size of the sensor opening.
On the other hand, among the ultrasonic vibration elements constituting the array sensor equally divided in the angular direction, a method of using only the ultrasonic vibration element group arranged in the electronic scanning direction for transmission / reception of ultrasonic waves is known. (For example, refer to Patent Document 2).

JP-A-2005-351718 JP-A-5-244691

However, as described in Patent Document 2, in an array sensor that is simply divided at an equal angle or an array sensor that uses only the innermost ultrasonic vibration element as a disk, the ultrasonic vibration on the inner peripheral side depends on the divided angle. There is a problem that not only the element size is reduced and processing becomes difficult at the time of sensor wiring, but also sufficient sensitivity cannot be obtained on the inner peripheral side of the sensor, and noise such as side lobes increases.
Furthermore, in the sensor shape and measurement method described in Patent Document 2, since the range of the ultrasonic vibration element used in the inner peripheral portion is narrow, the sound directivity deteriorates, and the SN ratio of the flaw detection image cannot be improved. was there.

  An object of the present invention is to provide an ultrasonic measuring device that is suitable for flaw detection in a deep part of a thick plate material, can increase the size of a sensor opening, and has an improved S / N ratio, an ultrasonic sensor used therefor, and an ultrasonic measuring method. There is to do.

(1) In order to achieve the above object, the present invention provides a two-dimensional array sensor in which a plurality of ultrasonic vibration elements are two-dimensionally arranged, and transmits and measures ultrasonic waves from the two-dimensional array sensor. An ultrasonic measurement apparatus having a transmission / reception unit that receives a reflected wave from the inside of a target, and a control unit that controls transmission / reception of ultrasonic waves by the transmission / reception unit, wherein the two-dimensional array sensor is an ultrasonic transducer element A conditional expression that includes an inner peripheral portion and an outer peripheral portion having different arrangement patterns, and the outer peripheral portion of the two-dimensional array sensor is such that the distance between the gravity center positions of the adjacent ultrasonic vibration elements does not generate a grating lobe that is noise. And at least a distance satisfying a conditional expression that does not generate a grating lobe as noise, and the control unit includes a plurality of ultrasonic waves constituting the two-dimensional array sensor. A conditional expression that includes a use element selection circuit that selects an element to be used from among the dynamic elements, and that the inner peripheral portion is free from a grating lobe that is a distance between the gravity center positions of the adjacent ultrasonic vibration elements. The use element selection circuit sets a transmission direction during transmission of ultrasonic waves and a reception direction during reception among the ultrasonic vibration elements in the inner peripheral portion and the ultrasonic vibration elements in the outer peripheral portion. An ultrasonic vibration element that projects onto the surface of the array sensor and the distance between the gravity center positions of the adjacent ultrasonic vibration elements in the projected direction is within a distance that satisfies a conditional expression that does not generate a grating lobe that is noise is intended to select, the condition noise is a grating lobe does not occur expression distance of the center of gravity position with respect to the ultrasonic transmitting and receiving direction of the ultrasonic transducer elements adjacent 0, and θ ultrasonic transmitting and receiving angles of the transmit and receive, between the ultrasonic wavelength lambda for transmitting and receiving, L0 ≦ (λ / (1+ | a conditional expression composed of a relationship) | sin [theta.
This configuration is suitable for flaw detection of deep thick plates, as well as a possible increase in the size of the sensor opening, it increases the SN ratio.

( 2 ) In the above ( 1 ), preferably, the element selection circuit has a center of gravity position within a rectangular range in which the projected ultrasound transmission / reception direction is a long side and the diameter of the inner peripheral portion is a short side. The element to be selected is selected.
( 3 ) In the above ( 1 ), preferably, the control unit includes a delay control circuit that gives a delay time to the two-dimensional array sensor and performs a sector scan in a plane including the transmission or reception direction. is there.

( 4 ) Further, in order to achieve the above object, the present invention is used in an ultrasonic measurement apparatus that transmits ultrasonic waves and uses a reflected wave from the inside of a measurement object. An ultrasonic sensor arranged in a dimensional manner, comprising an inner peripheral portion and an outer peripheral portion having different arrangement patterns of the ultrasonic vibration elements, wherein the inner peripheral portion is a position of the center of gravity of the adjacent ultrasonic vibration element. The distance between them is within the distance that satisfies the conditional expression that does not generate a grating lobe that is noise, and the outer periphery has a grating lobe that is a distance between the center of gravity positions of the adjacent ultrasonic vibration elements. not conditional expression seen including those with a grating lobe and more than a distance that satisfies the condition expression that does not generate a noise within a distance that satisfies a condition that the grating lobes are noise-free The equation is expressed as L0 ≦ (λ / () between the distance L0 of the gravity center position in the ultrasonic transmission / reception direction of the adjacent ultrasonic vibration element, the transmission / reception angle θ of the ultrasonic wave to be transmitted / received, and the wavelength λ of the ultrasonic wave to be transmitted / received. 1+ | sin θ |) .
This configuration is suitable for flaw detection of deep thick plates, as well as a possible increase in the size of the sensor opening, it increases the SN ratio.

( 5 ) Further, in order to achieve the above object, the present invention transmits ultrasonic waves from a two-dimensional array sensor in which a plurality of ultrasonic vibration elements are two-dimensionally arranged, and reflects from the inside of a measurement object. An ultrasonic measurement method using a wave, wherein the two-dimensional array sensor includes an inner peripheral portion and an outer peripheral portion having different arrangement patterns of the ultrasonic vibration elements, and the transmission or reception direction of the ultrasonic wave is determined. The ultrasonic vibration element in the inner peripheral portion of the array pattern within the distance that satisfies the conditional expression in which the distance between the centroid positions of the ultrasonic vibration elements adjacent to the ultrasonic vibration element is set so as not to generate a grating lobe that is noise And the distance between the centroid positions of the ultrasonic transducer elements adjacent to the ultrasonic signal element is within the distance satisfying the conditional expression that does not generate a grating lobe as noise and the gray as noise. Out of the ultrasonic transducers in the outer peripheral part with different arrangement patterns including those that satisfy the conditional expression that does not cause a ringing, the transmission direction is projected on the surface of the array sensor when transmitting ultrasonic waves and the reception direction when receiving ultrasonic waves. And selecting an ultrasonic vibration element whose distance between the gravity center positions of the adjacent ultrasonic vibration elements in the projected direction is within a distance satisfying a conditional expression that does not generate a grating lobe as noise, and The ultrasonic vibration element of the selected part and the ultrasonic wave transmission or reception from the selected ultrasonic vibration element , and the conditional expression that does not generate the grating lobe as the noise is the ultrasonic transmission / reception of the adjacent ultrasonic vibration element L0 ≦ (λ / (1+ |) between the distance L0 of the center of gravity position with respect to the direction, the transmission / reception angle θ of the transmitted / received ultrasonic wave, and the wavelength λ of the transmitted / received ultrasonic wave. sin θ |) .
Such methods are suitable for flaw detection of deep thick plates, as well as a possible increase in the size of the sensor opening, it increases the SN ratio.

( 6 ) In the above ( 5 ), preferably, an element range that is used when a plurality of focal points to be connected at the time of transmission / reception of ultrasonic waves by the two-dimensional array sensor are set and ultrasonic waves are transmitted / received to / from the plurality of focal points. Are selected, and the reflection signal from the inside of the measurement target is recorded for each focus, and the obtained reflection signal from each focus is processed to form a two-dimensional image or a three-dimensional image inside the measurement target. It is a thing.
( 7 ) In the above ( 5 ), preferably, the transmission / reception gives a delay time to the ultrasonic vibration element in the inner peripheral portion and the selected ultrasonic vibration element, and within the plane including the transmission or reception direction. Sector scan.

  According to the present invention, it is suitable for flaw detection in a deep part of a thick plate material, the sensor opening can be enlarged, and the SN ratio can be improved.

It is a block diagram which shows the structure of the ultrasonic flaw detector by one Embodiment of this invention. It is a top view which shows the structure of the array sensor used for the ultrasonic flaw detector by one Embodiment of this invention. It is a schematic diagram which shows the gravity center position of the array sensor used for the ultrasonic flaw detector by one Embodiment of this invention. It is explanatory drawing of the flaw detection method by the ultrasonic flaw detector by one Embodiment of this invention. It is explanatory drawing of the array sensor used for the ultrasonic flaw detector by one Embodiment of this invention. It is explanatory drawing of the selection method of the sensor element in the ultrasonic flaw detector by one Embodiment of this invention. It is a flowchart which shows the content of the flaw detection method by the ultrasonic flaw detector by one Embodiment of this invention. It is explanatory drawing of the pattern of the use element in the ultrasonic flaw detector by one Embodiment of this invention. It is explanatory drawing of the pattern of the use element in the ultrasonic flaw detector by one Embodiment of this invention. It is a top view which shows the other structure of the array sensor used for the ultrasonic flaw detector by one Embodiment of this invention.

Hereinafter, the configuration and operation of an ultrasonic flaw detector according to an embodiment of the present invention will be described with reference to FIGS.
First, the configuration of the ultrasonic flaw detector according to the present embodiment will be described with reference to FIG.
FIG. 1 is a block diagram showing a configuration of an ultrasonic flaw detector according to an embodiment of the present invention.

  The ultrasonic measurement apparatus according to the present embodiment measures, for example, the reflection source 400A inside or on the surface of the subject 400 with a high SN ratio. The subject 400 is a thick plate material having a thickness of 200 mm to 300 mm, for example.

  The ultrasonic measurement apparatus according to this embodiment includes a flaw detection unit 401, a transmission / reception unit 402, a control unit 403, and a display unit 404. The flaw detection unit 401 includes an array sensor 401B that transmits and receives ultrasonic waves to the measurement target 400. The array sensor 401B includes a plurality of ultrasonic vibration elements 401A.

  The transmission / reception unit 402 includes a pulsar 402A that transmits an ultrasonic wave by giving a delay time to the plurality of ultrasonic transducer elements 401A of the array sensor 401B, and a receiver 402Z that converts the received ultrasonic wave from analog to digital to obtain a reception signal. And.

The control unit 403 includes a control / processing computer 403A having a storage device 403B, an element selection circuit 403C, a delay time control circuit 403D, and an addition circuit 403Z.
The used element selection circuit 403C switches and controls the ultrasonic vibration element 401A used for the ultrasonic transmission / reception element. The control circuit 403D controls the delay time during transmission / reception. The adder circuit 403Z adds a plurality of reception signals obtained from the receiver 402Z. The control / processing computer 403A controls the used element selection circuit 403C, the delay time control circuit 403D, and the addition circuit 403Z, records the received signal in the storage device 403B, and processes the received signal.

  The display unit 404 includes a setting input screen 404A that allows various settings to be displayed and input, and a display screen 404Z that displays a received signal and a measurement image.

  Next, the operation of each unit will be described.

  The control / processing computer 403A selects an ultrasonic vibration element to be used for transmission / reception of an ultrasonic wave to the element selection circuit 403C when transmitting / receiving an ultrasonic wave and recording a reflected signal from a measurement target. The transmission / reception element switching signal is transmitted, and the delay time to the ultrasonic vibration element for focusing and transmitting / receiving the ultrasonic wave is given through the delay control circuit 403D.

The transmission delay circuit 402B that has received the transmission signal and the delay time sends the transmission signal to the transmission element selection unit 402C with the given delay time. The transmission element selection unit 402C receives the transmission signal transmitted with a delay time from the transmission delay circuit 102B, selects a transmission element based on the transmission element selection signal from the used element selection circuit 403C, and transmits the transmission signal. Is transmitted to the transmission amplifier 402E.
In addition, for the ultrasonic wave transmitted in this way, the receiving side may select a signal to be received by the adder circuit 403Z, as is the information given to the used element selection circuit 403C.

Next, the configuration of the array sensor 401B used in the ultrasonic flaw detector according to the present embodiment will be described with reference to FIGS.
FIG. 2 is a plan view showing the configuration of the array sensor used in the ultrasonic flaw detector according to one embodiment of the present invention. FIG. 3 is a schematic diagram showing the barycentric position of the array sensor used in the ultrasonic flaw detector according to one embodiment of the present invention.

  As shown in FIG. 2, the array sensor 401B is circular, and a plurality of ultrasonic vibration elements are arranged. The array sensor 401B includes an inner peripheral portion 401M having different arrangement patterns and an outer peripheral portion 401N.

  The ultrasonic vibration element of the inner peripheral portion 401M has a hexagonal shape, and has a shape that can efficiently fill the plane. The size of each ultrasonic vibration element in the inner peripheral portion 401M is the same. The size of each ultrasonic vibration element in the inner peripheral portion 401M is set to a size that allows good sound directivity and improves the SN ratio of the flaw detection image.

  The ultrasonic vibration element of the outer peripheral portion 401N has a sector shape in which concentric circles are radially divided from the center of the sensor. As for the size of each ultrasonic vibration element of the outer peripheral portion 401N, the outer side is larger than the inner side.

  Here, assuming that the sensor aperture diameter considered necessary for the inspection is φ, the central ½φ region is the inner peripheral portion 401M, and the other portion is the outer peripheral portion 401N. In addition, it is preferable that the range of the inner peripheral part 401 shall be 1/4 (phi)-3/4 (phi), and the reason is later mentioned using FIG.

  Thus, the size of each ultrasonic vibration element in the inner peripheral portion 401M has good sound directivity, and the SN ratio of the flaw detection image can be improved. On the other hand, the size of each ultrasonic vibration element in the outer peripheral portion 401N is larger than the size of each ultrasonic vibration element in the inner peripheral portion 401M, and the size increases toward the outside, so the opening diameter φ is increased. Even so, the total number of elements constituting the array sensor 401B does not increase.

  Next, the gravity center position of each element constituting the array sensor 401B shown in FIG. 2 will be described using FIG. The black circle in the figure indicates the center of gravity of each element.

  In the inner peripheral portion 401M, each element has a hexagonal shape and is arranged so that the sides are in contact with each other. Therefore, the distances L1 between the gravity center positions of adjacent ultrasonic vibration elements are all equal.

  On the other hand, in the outer peripheral portion 401N, each element has a fan shape in which concentric circles are radially divided from the center of the sensor, and therefore, in the circumferential direction, compared to the distance L2 between the gravity center positions of the ultrasonic vibration elements adjacent in the radial direction. The distance L3 between the gravity center positions of the adjacent ultrasonic transducer elements is large. Further, the distance L2 between the gravity center positions of the ultrasonic vibration elements adjacent in the radial direction is equal to the distance L1 between the gravity center positions of the adjacent ultrasonic vibration elements in the inner peripheral portion 401M.

  Next, the relationship between the distance between adjacent elements and the occurrence of noise (grating lobes) will be described.

In general, in the case of an array-shaped sensor, the distance of the center of gravity position with respect to the ultrasonic transmission / reception direction of adjacent elements is L, and the transmission / reception angle θ of the ultrasonic wave to be transmitted / received,
L0 ≦ (λ / (1+ | sinθ |)
When the above relationship is satisfied, no noise (grating lobe) is generated.

  Here, λ is the wavelength of ultrasonic waves to be transmitted / received. For example, when transmitting and receiving an ultrasonic wave in the direction of ± 90 degrees, if L0 ≦ λ / 2, noise (grating lobe) is not generated. When ultrasonic waves are transmitted and received in the direction of ± 30 degrees, noise (grating lobes) does not occur if L0 ≦ λ / 1.5.

  Therefore, in each element used for the inner peripheral portion 401M of the array sensor 401B, the distance L1 between the gravity center positions of the adjacent ultrasonic vibration elements is set to a distance L0 or less at which noise (grating lobe) does not occur.

  In each element used for the outer peripheral portion 401N of the array sensor 401B, the distance L2 between the gravity center positions of the ultrasonic vibration elements adjacent in the radial direction is set to a distance L0 or less at which noise (grating lobe) does not occur. On the other hand, in each element used for the outer peripheral portion 401N of the array sensor 401B, the distance L3 between the gravity center positions of the ultrasonic vibrating elements adjacent in the circumferential direction is larger than the distance L0 where no noise (grating lobe) is generated.

  In order to improve the S / N ratio, the distance between the centroid positions of all the elements may be set to a distance L0 or less at which noise (grating lobe) does not occur. It is necessary to shorten the length in the circumferential direction. As a result, the size of one element is reduced, and even if the aperture diameter φ is increased, the total number of elements constituting the array sensor 401B is increased.

  On the other hand, the size of each ultrasonic vibration element in the outer peripheral portion 401N is larger than the size of each ultrasonic vibration element in the inner peripheral portion 401M, and the size increases toward the outer side. Is increased, the total number of elements constituting the array sensor 401B does not increase. However, in each element of the outer peripheral portion 401N, the distance L3 between the gravity center positions of the ultrasonic vibrating elements adjacent in the circumferential direction is larger than the distance L0 at which noise (grating lobe) does not occur. Noise (grating lobe) is generated.

  Therefore, in the present embodiment, the array sensor 401B shown in FIG. 2 is used, and the outer periphery of the array sensor 401B shown in FIG. For the element of the unit 401N, an element to be used is selected. In the elements of the inner peripheral portion 401M, since the distance L1 between the gravity center positions of the adjacent ultrasonic vibration elements is set to a distance L0 or less at which noise (grating lobe) does not occur, all elements in all transmission / reception directions are used. Is used. Here, the “transmission / reception direction” is not the direction in which ultrasonic waves are actually transmitted / received, but the actual ultrasonic wave transmission / reception direction is projected onto the plane of the array sensor, as will be described later with reference to FIG. It is a transmission / reception direction.

  For example, the case where transmission / reception is performed in the direction of arrow TR1 in FIG. 3 will be described. In this case, in the inner peripheral portion 401M, for example, the distance L1A between the center of gravity of the adjacent element 401M-1 and the center of gravity of the element 401M-2 in the direction of the arrow TR1 generates noise (grating lobe). Since the distance L0 = L1 or less is not used, no noise (grating lobe) is generated when the element 401M-1 and the element 401M-2 are used.

  In the outer periphery 401N, for example, the distance L2A between the center of gravity of the adjacent element 401N-1 and the center of gravity of the element 401N-2 in the direction of the arrow TR1 is a distance at which noise (grating lobe) does not occur. Since L0 = L2 or less, no noise (grating lobe) is generated when the element 401N-1 and the element 401N-2 are used.

  However, in the outer peripheral portion 401N, for example, the distance L3A between the center of gravity of the adjacent element 401N-3 and the center of gravity of the element 401N-4 in the direction of the arrow TR1 is a distance at which noise (grating lobe) does not occur. Since L0 = L2 is larger, noise (grating lobe) is generated when the element 401N-3 and the element 401N-4 are used.

  Therefore, when transmitting and receiving in the direction of the arrow TR1, the elements 401M-1 and 401M-2 and the elements 401N-1 and 401N-2 are used, but noise (grating) is prevented by not using the elements 401N-3 and 401N-4. (Lobe) can be prevented from occurring.

  In FIG. 3, for example, when transmitting and receiving in the arrow TR2 direction and TR3 direction, the center of gravity in the arrow TR2 direction and TR3 direction between them is used even if adjacent elements whose distances between the center of gravity positions are indicated by the arrow L1 are used. Since the distance between the positions is a distance L0 = L1 or less at which no noise (grating lobe) is generated, no noise (grating lobe) is generated even if these elements are used.

  As for the elements of the inner peripheral portion 401M, the distance L1 between the gravity center positions of the adjacent ultrasonic vibration elements is equal to or less than the distance L0 at which noise (grating lobe) does not occur. Even so, no noise (grating lobe) is generated.

  On the other hand, regarding the elements in the outer peripheral portion, for example, when transmitting and receiving in the direction of arrow TR4, the center of gravity in the direction of arrow TR4 between the adjacent elements whose distance between the positions of the center of gravity is indicated by arrow L2 is used. Since the distance between the positions is a distance L0 = L2 or less at which no noise (grating lobe) is generated, no noise (grating lobe) is generated even if these elements are used.

  However, with respect to the outer peripheral portion, for example, when transmitting and receiving in the arrow TR5 direction, using adjacent elements whose distance between the gravity centers is indicated by the arrow L3, the distance between the gravity positions in the arrow TR5 direction between them is Since the distance L0 = L2 at which no noise (grating lobe) is generated is larger, if these elements are used, noise (grating lobe) is generated. Therefore, when transmitting / receiving in the direction of the arrow TR5, these elements are not used. To.

  That is, the feature of the array sensor 401B of this embodiment shown in FIG. 2 is that the inner peripheral portion 401M is configured by an array pattern in which the center of gravity positions of adjacent elements are within a predetermined interval. Here, the prescribed interval is a distance L0 at which noise (grating lobe) does not occur. On the other hand, the outer peripheral portion 401N is configured by an arrangement pattern in which the centroid positions of adjacent elements are within a predetermined interval and the centroid positions of adjacent elements are greater than or equal to the predetermined interval.

  In addition to the hexagonal shape shown in FIG. 2, a triangular shape, a quadrangular shape, or a trapezoid obtained by dividing the hexagonal shape shown in FIG.

  Further, as the element arrangement pattern of the outer peripheral portion 401N, a polygonal shape can be used other than the concentric circular shape divided radially from the sensor center shown in FIG.

  As described above, by arranging the inner peripheral portion and the outer peripheral portion in an array pattern, the sensor opening is widened and deep flaw detection can be performed. And according to the transmission / reception direction of an ultrasonic wave, by selecting the element used for transmission / reception among the elements constituting the outer peripheral portion, the SN ratio can be adjusted without generating noise (grating lobe).

Next, the flaw detection method using the ultrasonic flaw detector according to the present embodiment will be described with reference to FIGS.
FIG. 4 is an explanatory diagram of a flaw detection method using an ultrasonic flaw detector according to an embodiment of the present invention. FIG. 5 is an explanatory diagram of an array sensor used in the ultrasonic flaw detector according to one embodiment of the present invention.

  In the 2D array sensor having the structure as shown in FIG. 2 and FIG. 3, when transmitting and receiving ultrasonic waves, the ultrasonic vibration element of the inner peripheral portion 401M has a center-of-gravity position interval L1 between adjacent elements within a predetermined interval. Therefore, it is possible to design so that there is no portion that becomes a noise source, and it is possible to transmit and receive ultrasonic waves using all the ultrasonic vibration elements on the inner peripheral side.

  However, the distance between the centers of gravity of the ultrasonic vibration elements in the outer peripheral portion 401N has a portion exceeding a predetermined distance as indicated by an arrow L3, which may be a very strong noise source depending on the transmission / reception direction.

  In FIG. 4, the ultrasonic array sensor 401B is installed on a plane orthogonal to the depth direction Dep. In addition, the ultrasonic array sensor 401B transmits ultrasonic waves in the ultrasonic transmission / reception direction TR and receives reflected waves. At this time, the transmission / reception direction TR projected on the plane of the ultrasonic array sensor 401B is defined as TR '.

  FIG. 5 shows a plane of the ultrasonic array sensor 401B. When the position of the center of gravity is projected on an axis along the transmission / reception direction of ultrasonic waves, transmission / reception of the projected ultrasonic waves among the ultrasonic vibration elements of the outer peripheral portion 401N. Noise (grating lobes) is generated in the intervals L3B, L3C, and L3D between the elements 401N-5, 401N-6, 401N-7, and 401N-8 arranged on the outer periphery with respect to the axis orthogonal to the direction TR ′. The ultrasonic wave which spreads more than the distance L0 not to be transmitted and strongly propagates in an undesired direction called a grating lobe is generated.

  On the other hand, the interval L2B between the elements 401N-9 and 401N-10 arranged in the transmission / reception direction TR ′ of the projected ultrasonic wave is narrower than the distance L0 where no noise (grating lobe) is generated, and a grating lobe is generated. do not do.

  Therefore, as shown in the hatched portion 2 in FIG. 5, by selecting an element in which the distance between the projected center of gravity positions does not exceed a predetermined distance, all the ultrasonic vibration elements in the inner peripheral portion and the ultrasonic wave By using a part of the ultrasonic vibration elements on the outer periphery arranged in the transmission / reception direction, flaw detection with a good SN ratio can be performed.

Next, a sensor element selection method in the ultrasonic flaw detector according to the present embodiment will be described with reference to FIG.
FIG. 6 is an explanatory diagram of a sensor element selection method in the ultrasonic flaw detector according to one embodiment of the present invention.

  As illustrated in FIG. 5, in order to use all the ultrasonic vibration elements in the inner peripheral portion and a part of the ultrasonic vibration elements in the outer peripheral portion arranged in the transmission / reception direction of ultrasonic waves, as shown in FIG. The ultrasonic vibration element to be used is selected.

  That is, for the projected ultrasonic transmission / reception direction TR ', flaw detection is performed using an element whose center of gravity exists in a range surrounded by a dotted line arranged along the transmission / reception direction. At this time, the rectangular area surrounded by the dotted line is normally set so as to include the inner circumference of the sensor. That is, the rectangular short side Ls is made equal to the diameter of the inner peripheral portion 401M of the array sensor 401B. The long side L1 of the rectangle has a length including the outer peripheral portion 401N of the array sensor 401B in the projected transmission / reception direction TR '.

  As described with reference to FIG. 2, when the cool air of the inner peripheral portion 401M is set to 1 / 2φ with respect to the sensor opening diameter φ, the ratio of the length of the short side Ls to the long side Ll is a rectangle of 1: 2. It becomes the range. Moreover, when the range of the inner peripheral part 401 is set to 1 / 4φ to 3 / 4φ, the ratio of the length of the short side Ls to the long side Ll is a rectangular range of 1: 4 to 3: 4. .

Next, the flaw detection method using the ultrasonic flaw detector according to the present embodiment will be described with reference to FIG.
FIG. 7 is a flowchart showing the contents of the flaw detection method by the ultrasonic flaw detector according to the embodiment of the present invention.

  When the setting is started, in step S101, the inspector performs element information (element size, arrangement, element position information) of ultrasonic vibration elements constituting the array sensor 401B shown in FIG. Necessary information such as the speed of sound is input using the setting input screen 404A shown in FIG.

Next, in step S102, the examiner sets a delay time and a sensor center position serving as a reference for image display for the N ultrasonic vibration elements using the setting input screen 404A. In general, the center of the ultrasonic vibration element is set as the sensor center C.
Next, in step S103, the control processing computer 403A calculates and sets the focal point F and the delay time for each ultrasonic vibration element of the array sensor 401B.

  On the other hand, in step S104, the used element selection circuit 103C uses the information given in the initial setting in step S101, and uses the ultrasonic wave used for transmission / reception without the noise elements shown in FIG. 5 and FIG. Set the vibration element group.

  In step S105, the use element selection circuit 103C selects a pattern of use elements suitable for the transmission / reception direction when transmitting / receiving ultrasonic waves to the focal point F (i) determined in step S103, and transmits / receives ultrasonic waves. To do.

Here, the pattern of the element used in the ultrasonic flaw detector according to the present embodiment will be described with reference to FIGS.
8 and 9 are explanatory diagrams of patterns of elements used in the ultrasonic flaw detector according to one embodiment of the present invention.

  FIG. 8 illustrates a pattern table of used elements. The pattern table of used elements is stored in advance in the storage device 403B of FIG. In the used element pattern table, the patterns A, B, and C, the elements used for each pattern are indicated by “1”, and the unused elements are indicated by “0”.

  For example, the pattern A selects elements to be used as shown in FIG. 9, and the pattern B selects elements to be used as shown in FIG. 9, for example. By using the pattern A, the sector scan A as shown in FIG. 9 is performed, and by using the pattern B, the sector scan B as shown in FIG. 9 is performed.

  Since the patterns A, B, and C are associated with the ultrasonic transmission / reception direction, when the transmission / reception direction is determined, a pattern necessary for transmission / reception can be selected.

  Again, in step S105 of FIG. 7, the use element selection circuit 103C selects the pattern of the use element described in FIGS. 8 and 9 when transmitting and receiving ultrasonic waves to the focal point F (i) determined in step S103. The ultrasonic wave is transmitted from the pulsar 402A.

  In step S106, the receiver 402Z records data (reflection data) for the focal point F (i).

  Next, in step S107, the control / processing computer 403A determines whether or not data recording in all directions has been completed, and if not completed (NO), the process returns to step S105 to return to the next focus. The process proceeds to F (i + 1), and transmission / reception of ultrasonic waves is performed again, and the recording of reflection data is sequentially repeated until the recording of reflection data in all measurement areas is completed.

  If it is determined in step S107 that the process has been completed (YES), in step S108, the control / processing computer 103A creates a map of pixels and pixel values, and in step S109, displays an image, and ends. To do.

  As described above, since a desired sector scan image can be obtained by selecting one pattern shown in FIG. 8, by electronically switching between the patterns A and B shown in FIG. Multiple sector scan images can be recorded, and 3D images can be obtained with high SN even in the deep part.

Next, another configuration of the array sensor used in the ultrasonic flaw detector according to the present embodiment will be described with reference to FIG.
FIG. 10 is a plan view showing another configuration of the array sensor used in the ultrasonic flaw detector according to the embodiment of the present invention.

  As shown in FIG. 10, the array sensor 401B 'is circular, and a plurality of ultrasonic vibration elements are arranged. The array sensor 401B 'includes an inner peripheral portion 401M' and an outer peripheral portion 401N 'having different arrangement patterns.

  The ultrasonic vibration element of the inner peripheral portion 401M ′, for example, does not divide the innermost circumference with respect to the concentric circles, and the outer circumference (second round) of the innermost circumference is divided into eight in the circumferential direction. (3rd round) is divided into 16 in the circumferential direction, the next outer circumference (4th round) is divided into 24 in the circumferential direction, and the next outer circumference (5th round) is divided into 32 in the circumferential direction. As the number of divisions in the circumferential direction increases. Due to the divided arrangement pattern, the size of each ultrasonic vibration element of the inner peripheral portion 401 ′ M is not the same, but is almost the same size. The size of each ultrasonic vibration element in the inner peripheral portion 401M is set to a size that allows good sound directivity and improves the SN ratio of the flaw detection image.

  As in FIG. 2, the ultrasonic vibration element of the outer peripheral portion 401N 'has a sector shape in which concentric circles are radially divided from the center of the sensor. The size of each ultrasonic vibration element in the outer peripheral portion 401N 'is larger on the outer side than on the inner side.

  As described above, the size of each ultrasonic vibration element in the inner peripheral portion 401M 'has good sound directivity, and the SN ratio of the flaw detection image can be improved. On the other hand, the size of each ultrasonic vibration element in the outer peripheral portion 401N ′ is larger than the size of each ultrasonic vibration element in the inner peripheral portion 401M ′, and the size increases toward the outer side. Is increased, the total number of elements constituting the array sensor 401B ′ does not increase.

  As described above, when ultrasonic inspection is performed on a deep portion of a thick plate material, it is necessary to increase the aperture of the sensor. However, since the number of elements is limited, it is difficult to increase the aperture with the current 2D array sensor. Met. Therefore, the use of ultrasonic sensors having different element arrangement patterns at the inner and outer peripheral parts of the sensor enables a large aperture of the sensor. Furthermore, by using only a part of the outer peripheral elements when transmitting and receiving ultrasonic waves, noise can be suppressed, and this large aperture sensor can be used to detect flaws with a high signal-to-noise ratio due to the point focusing effect on the deep part of thick plates. It becomes.

Therefore, the deep portion of the thick plate material can be three-dimensionally detected with a high SN ratio by the point focusing effect with a small number of ultrasonic vibration elements.

400 ... subject 401 ... flaw detection unit 401A ... ultrasonic transducer 401B ... array sensor 401M ... inner periphery 401N ... outer periphery 402 ... transmission / reception unit 402A ... pulser 402Z ... receiver 403 ... control unit 403A ... control / processing computer 403B ... Storage device 403C ... Used element selection circuit 403D ... Delay time control circuit 403Z ... Addition circuit 404 ... Display unit 404A ... Setting input screen 404Z ... Display screen

Claims (7)

A two-dimensional array sensor in which a plurality of ultrasonic vibration elements are two-dimensionally arranged, a transmission / reception unit that transmits ultrasonic waves from the two-dimensional array sensor, and receives a reflected wave from the inside of the measurement object, and the transmission / reception An ultrasonic measurement device having a control unit that controls transmission and reception of ultrasonic waves by the unit,
The two-dimensional array sensor includes an inner peripheral portion and an outer peripheral portion having different arrangement patterns of the ultrasonic vibration elements,
In the outer periphery of the two-dimensional array sensor, the distance between the gravity center positions of the adjacent ultrasonic vibrating elements is within a distance that satisfies the conditional expression that does not generate a grating lobe that is noise, and a grating lobe that is noise is generated. And those that exceed the distance that satisfies the conditional expression
The control unit includes a use element selection circuit that selects an element to be used among a plurality of ultrasonic vibration elements constituting the two-dimensional array sensor,
The inner peripheral portion is within a distance satisfying a conditional expression in which the distance between the gravity center positions of the adjacent ultrasonic vibration elements does not generate a grating lobe as noise,
The element selection circuit projects a transmission direction when transmitting ultrasonic waves and a reception direction when receiving ultrasonic waves onto the surface of the array sensor, among the ultrasonic vibration elements on the inner periphery and the ultrasonic vibration elements on the outer periphery. Then, the ultrasonic vibration element is selected such that the distance between the gravity center positions of the adjacent ultrasonic vibration elements in the projected direction is within a distance satisfying a conditional expression that does not generate a grating lobe as noise .
The conditional expression in which the grating lobe as noise does not occur is the distance L0 of the center of gravity position with respect to the ultrasonic transmission / reception direction of the adjacent ultrasonic vibration element, the transmission / reception angle θ of the ultrasonic wave to be transmitted / received, and the wavelength λ of the ultrasonic wave to be transmitted / received. Is an conditional expression having a relationship of L0 ≦ (λ / (1+ | sin θ |) . The ultrasonic measurement apparatus according to claim 1 ,
The use element selection circuit selects an element having a center of gravity within a rectangular range in which a transmission / reception direction of the projected ultrasonic wave is a long side and a diameter of the inner peripheral portion is a short side. measuring device. The ultrasonic measurement apparatus according to claim 1 ,
The ultrasonic measurement apparatus, wherein the control unit includes a delay control circuit that gives a delay time to the two-dimensional array sensor and performs a sector scan in a plane including the transmission or reception direction. An ultrasonic sensor that transmits ultrasonic waves and is used in an ultrasonic measurement device that uses a reflected wave from the inside of a measurement object, and in which a plurality of ultrasonic vibration elements are two-dimensionally arranged,
An inner peripheral portion and an outer peripheral portion having different arrangement patterns of the ultrasonic vibration elements,
The inner peripheral portion is within a distance satisfying a conditional expression in which the distance between the gravity center positions of the adjacent ultrasonic vibration elements does not generate a grating lobe as noise,
The outer peripheral portion satisfies a conditional expression in which the distance between the gravity center positions of the adjacent ultrasonic vibration elements is within a distance satisfying a conditional expression that does not generate a grating lobe that is noise and a conditional expression that does not generate a grating lobe that is noise. distance or more of the things seen including,
The conditional expression in which the grating lobe as noise does not occur is the distance L0 of the center of gravity position with respect to the ultrasonic transmission / reception direction of the adjacent ultrasonic vibration element, the transmission / reception angle θ of the ultrasonic wave to be transmitted / received, and the wavelength λ of the ultrasonic wave to be transmitted / received. An ultrasonic sensor characterized by a conditional expression having a relationship of L0 ≦ (λ / (1+ | sin θ |) . An ultrasonic measurement method that transmits ultrasonic waves from a two-dimensional array sensor in which a plurality of ultrasonic vibration elements are two-dimensionally arranged, and uses a reflected wave from the inside of a measurement object,
Set the transmission or reception direction of the ultrasonic wave,
The ultrasonic vibration element in the inner peripheral portion of the array pattern within a distance satisfying a conditional expression in which the distance between the centroid positions of adjacent ultrasonic vibration elements of the ultrasonic vibration element does not generate a grating lobe as noise, and The distance between the centroid positions of the adjacent ultrasonic transducer elements of the ultrasonic signal element is within the distance that satisfies the conditional expression that does not generate noise grating lobe and the distance that satisfies the conditional expression that does not generate noise grating lobe Among the ultrasonic vibrating elements in the outer peripheral portion having different arrangement patterns including those described above, the transmitting direction is projected on the surface of the array sensor when transmitting ultrasonic waves and the receiving direction is received when receiving ultrasonic waves, and adjacent in the projected direction. The distance between the positions of the center of gravity of the ultrasonic vibration element is within a distance satisfying a conditional expression that does not generate a grating lobe as noise. Select the ultrasonic vibration element,
Transmitting or receiving ultrasonic waves from the ultrasonic vibration element of the inner peripheral portion and the selected ultrasonic vibration element ;
The conditional expression in which the grating lobe as noise does not occur is the distance L0 of the center of gravity position with respect to the ultrasonic transmission / reception direction of the adjacent ultrasonic vibration element, the transmission / reception angle θ of the ultrasonic wave to be transmitted / received, and the wavelength λ of the ultrasonic wave to be transmitted / received. Is a conditional expression having a relationship of L0 ≦ (λ / (1+ | sin θ |) . The ultrasonic measurement method according to claim 5 ,
Setting a plurality of focal points to be formed when ultrasonic waves are transmitted and received by the two-dimensional array sensor;
Select each element range to be used when transmitting and receiving ultrasonic waves for the plurality of focal points,
Record the reflection signal from inside the measurement target for each focus,
An ultrasonic measurement method characterized by processing the obtained reflected signal from each focal point to form a two-dimensional image or a three-dimensional image inside the measurement object. The ultrasonic measurement method according to claim 5 ,
The transmission / reception gives a delay time to the ultrasonic vibration element in the inner periphery and the selected ultrasonic vibration element,
An ultrasonic measurement method, wherein sector scanning is performed within a plane including the transmission or reception direction.

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