JPH06138105A - Ultrasonic flaw detector - Google Patents

Abstract

PURPOSE:To prevent the erroneous judgment caused by a surface--echo by providing a surface-echo-judging-value setting circuit and a surface-echo judging circuit, and setting a defect gate and a defect judging value in response to the height and the position of the surface echo. CONSTITUTION:When the flaw of a body under test 6 is detected, defect gates 38 are set 18 on the entire range of a plate thickness. The obtained defect echo 33 is compared with a judging value 39 in a surface-echo judging circuit 16. When the surface echo is partially high and exceeds the judging value, a surface-echo judged result 36 is made ON. The defect gate 38 is set at the short value with the defect-gate setting circuit 18. When the defect echo 33 obtained with the defect gate 38 is judged with the surface-echo judging circuit 16 again, the echo 33 is smaller than the judging value 39. Therefore, the judged result 36 is made OFF, and the ' defect gate 38 is returned into the original state. Thereafter, the flaw detection is started. When the height of the surface echo is normal, the defect gate 38 does not exceed the surface echo judging value 39. Therefore, the defect gate 38 does not become short.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is intended to set a defect gate in an ultrasonic flaw detector for flaw detection inside a steel sheet, avoiding it when the height of the surface echo is large. Further, when the defect gate is set over the entire plate thickness range, the defect determination level is set according to the height of the surface echo so as to provide a flaw detection device that does not cause an erroneous determination due to the surface echo.

[0002]

2. Description of the Related Art As a conventional ultrasonic flaw detector for flaw detection of a steel sheet, for example, non-destructive inspection VOL. 29, NO. There is a steel plate digital ultrasonic flaw detector shown in P731 of 10. FIG. 4 is a diagram of, for example, an ultrasonic flaw detector for flaw detection of a conventional steel plate, in which 6 is a steel plate as a test object,
2 is a split type probe, 3 is a holding mechanism for holding the split type probe, 4 is a contact medium, 5 is a cable for transmitting a transmission pulse and a reception echo, 10 is a transmission pulse through the cable 5, Further, a transmitting / receiving circuit for receiving a reception echo from the probe 2, 14 is a defect gate circuit for extracting an echo corresponding to a defect echo of the reception echo received by the transmitting / receiving circuit 10, and 13 is the defect gate circuit. A defect echo height measuring circuit for measuring the height of the defect echo taken out by 14, a defect echo judgment value setting circuit 12 for supplying a judgment value to the defect echo judgment circuit 13, 1
Reference numeral 5 is a display circuit for displaying the result determined by the defect echo determination circuit 13.

FIG. 5 and FIG. 6 are views showing ultrasonic echoes, gates and surface echoes when a steel sheet is flaw-detected by a conventional apparatus, in which 50 is a transmission pulse and 51 is reflected from the bottom surface of the DUT. Bottom echo, 53 is a defect echo reflected from a defect inside the DUT, 52a and 52b are surface echoes reflected from the surface of the DUT and received by the transducer on the receiving side of the probe, and 34 is It is the defect determination value set by the defect echo determination value setting circuit 12.

Next, the operation will be described. In the case of flaw detection on a steel plate, the defect gate 38a is set over the entire range of the plate thickness from the position of the surface echo 52a to the position of the bottom surface echo 51 as shown in FIG. The defect echo 53 is the defect gate 3
8a is taken out and compared with the defect judgment value 34, and in this case, it is displayed that there is a defect. The height of the surface echo 52a varies greatly depending on the deterioration of the probe 2, the inclination of the holding mechanism 3 and the distance to the DUT. As shown in FIG. 6, even when there is no defect echo, the surface echo 52b is large. ,
The defect judgment value 34 is extracted by the defect gate 38a.
Is exceeded and it is determined that there is a defect. In such a case, it is necessary to avoid the surface echo 52b and set again like the defective gate 38b in FIG.

[0005]

Since the conventional ultrasonic flaw detector is constructed as described above, there are problems such as erroneous determination and resetting of the defective gate due to a defective surface echo height. .

The present invention has been made to solve the above problems, and an object of the present invention is to provide an ultrasonic flaw detection apparatus in which a defect gate is set in accordance with the height of a surface echo and erroneous determination is not made. .

[0007]

An ultrasonic flaw detector according to the present invention comprises a surface echo determination value setting circuit and a surface echo determination circuit, and a defect gate and a defect determination value are determined according to the height and position of the surface echo. Is set to eliminate erroneous determination.

[0008]

According to the present invention, since the defect gate and the defect judgment value can be set according to the height and position of the surface echo, erroneous judgment caused by the surface echo can be eliminated, and a defect of the surface echo is also displayed. Therefore, appropriate repair and maintenance can be performed.

[0009]

【Example】

[Embodiment 1] An embodiment of the present invention will be described below with reference to the drawings. In FIG. 1, 6 is a steel plate to be tested, 2 is a split-type probe, 3 is a holding mechanism for holding the split-type probe, 4 is a contact medium, and 5 is a transmission pulse and a reception echo. A cable 10 sends and receives a transmission pulse through the cable 5 and a transmission / reception circuit for receiving a reception echo from the probe 2, and 14 denotes a portion corresponding to a defective echo of the reception echo received by the transmission / reception circuit 10. Defective gate circuit for extracting echo, 18 is the defective gate circuit 14
A defective gate setting circuit for supplying a defective gate signal to the
Is a defect echo height measuring circuit for measuring the height of the defect echo extracted by the defect gate circuit 14, 12 is a defect echo judgment value setting circuit for supplying a judgment value to the defect echo judgment circuit 13, and 15 is the defect. Echo judgment circuit 13
A display circuit for displaying the result of the judgment made in step 16, a surface echo judgment circuit for judging the echo sent from the defect gate circuit 14, and a surface echo judgment circuit 19 for supplying a surface echo judgment value to the surface echo judgment circuit 16. It is a value setting circuit.

FIG. 2 is a diagram showing ultrasonic echoes, gates and surface echoes when a test object is flaw-detected by the ultrasonic flaw detector according to the present invention in a state where the height of the surface echo is large. Pulse 51, bottom echo, 52b surface echo, 38a and 38b defect gate, 39 surface echo determination value set by the surface echo determination value setting circuit 19, 33a and 33b extracted by the defect echo gate circuit 14. It is a defect echo that has been generated.

FIG. 3 is also a diagram showing the state of ultrasonic echoes, gates and surface echoes when a thin test object is flaw-detected by the ultrasonic flaw detector according to the present invention, in which 50 is a transmission pulse and 51b is a bottom surface. Echo, 52c is surface echo, 38c
Is a defect gate, 39 is the surface echo judgment value setting circuit 1
Surface echo judgment value set by 9; 34a and 3
4b is a defect echo determination value set by the defect echo determination value setting circuit 12, and 42 is a surface echo height measured by the surface echo determination circuit 16.

Next, the operation of the ultrasonic flaw detector according to the present invention will be described. As shown in FIG. 2, when the DUT 6 is flaw-detected, first, the defect gate 38a is set to the entire plate thickness range. At this time, the defect echo 33a extracted by the defect gate 38a is the surface echo by the surface echo determination circuit 16. It is compared with the judgment value 39. In the case of FIG. 2, the surface echo is large like defect 52b because it is defective, and since the defect gate 38a is set in the entire plate thickness range, the surface echo 52b exceeds the surface echo judgment value 39. . As a result, the surface echo determination result 36 is turned on, and the defective gate 38 is set to 38 in FIG. 2 by the defective gate setting circuit 18.
As indicated by b, the value is set shorter by the value of the arrow 61. In this state again, the defect echo 3 extracted by the defect gate 38b
3b is determined by the surface echo determination circuit 16 and is smaller than the surface echo determination value 39, the surface echo determination result 36 is turned off, and the defect gate remains at 38b, after which flaw detection is started. When the height of the surface echo is normal, the defect gate is not shortened because the surface echo judgment value 39 is not exceeded even when the defect gate is 38a.

Next, the operation of the ultrasonic flaw detector according to the present invention will be further described. FIG. 3 shows a case in which an object to be tested having a small plate thickness is flaw-detected in a state where surface echo is bad. At the start of flaw detection, the defect gate is set to the entire thickness range of the object-to-be-tested like 38c. The defect echo 33c extracted by the defect gate 38c is judged by the surface echo judgment circuit 16 and exceeds the surface echo judgment value 39, but since the plate thickness is thin, the defect gate is not shortened. However, as it is, the defect echo 33c is larger than the defect determination value 34a, so that an erroneous determination is made. In this case, the surface echo height 42 is measured and sent to the defect echo judgment value setting circuit 12, and the defect echo judgment value is corrected according to the surface echo height 42. As a result of the correction, the defect determination value becomes a value of 34b, and since flaw detection is performed in this state, the surface echo will not be erroneously determined as a defect. At the same time, the surface echo height determination circuit 16 sends a surface echo alarm signal 41 to the display circuit 15 to notify the abnormality of the surface echo.

[0014]

As described above, according to the present invention, the height of the surface echo of each probe and its position are measured and the defective gate is set, so that there is an effect that an erroneous determination due to the surface echo is eliminated. Also, when the plate thickness of the DUT is thin, the defect gate is not shortened to narrow the flaw detection range, but the defect judgment value is changed according to the height of the surface echo to prevent erroneous judgment and output an alarm promptly. The effect is that repairs and adjustments can be made.

[Brief description of drawings]

FIG. 1 is a diagram showing an embodiment of an ultrasonic flaw detector according to the present invention.

FIG. 2 is a diagram showing a relationship between an ultrasonic echo, a gate and a surface echo of the ultrasonic flaw detector according to the present invention.

FIG. 3 is a diagram showing a relationship between an ultrasonic echo, a gate and a surface echo of the ultrasonic flaw detector according to the present invention.

FIG. 4 is a diagram showing a configuration of a conventional ultrasonic flaw detector.

FIG. 5 is a diagram showing a relationship between ultrasonic echoes and gates and surface echoes of a conventional ultrasonic flaw detector.

FIG. 6 is a diagram showing a relationship between ultrasonic echoes and gates and surface echoes of a conventional ultrasonic flaw detector.

[Explanation of symbols]

 2 division type probe 6 device under test 10 transmission / reception circuit 12 defect echo judgment value setting circuit 13 defect echo judgment circuit 14 defect echo gate circuit 15 display circuit 16 surface echo judgment circuit 18 defect gate setting circuit 19 surface echo judgment value setting circuit

Claims (1)

[Claims] 1. An apparatus for repeatedly transmitting ultrasonic waves from the outer surface to the inside of a steel plate as a test object and receiving ultrasonic signals reflected from defects inside the steel plate, with respect to a split probe. And a transmission / reception circuit for transmitting an electric signal (reception signal) converted from an ultrasonic wave by the split-type probe, and an echo in a range to be detected among echoes output from the transmission / reception circuit. Defect echo gate circuit for taking out, defect gate setting circuit for supplying a defect gate signal to the defect echo gate circuit, defect echo judging circuit for judging the defect echo taken out by the defect echo gate circuit, and the defect echo judging circuit A defect echo judgment value setting circuit for supplying a judgment value to the display, a display circuit for displaying the judgment result of the defect echo judgment circuit, and the defect echo gate circuit The surface echo judgment circuit for judging the height of the surface echo portion of the echo taken out by, and the surface echo judgment value setting circuit for supplying the judgment value to the surface echo judgment circuit, wherein the height of the surface echo is the judgment value. The ultrasonic flaw detector is characterized in that the defect gate is set so as to avoid the surface echo when the value exceeds the limit.