JP2564558Y2 - Ultrasonic flaw detector - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to an ultrasonic flaw detector for a material to be inspected used in water immersion ultrasonic flaw detection.

(Prior Art) A conventional technique will be described using an ultrasonic flaw detection method for a steel pipe.

In a general water immersion type ultrasonic flaw detection method, as shown in FIG. 7, a steel pipe 1 to be inspected is advanced while rotating while being partially immersed in water 2. Touch 3
The entire circumference and the entire length of the flaw are inspected by the ultrasonic waves transmitted from. Alternatively, a method in which the steel tube 1 is moved straight and the probe 3 is rotated to detect a flaw is also widely used.

However, in the general oblique flaw detection, a reflected echo is generated at the end of the material to be inspected, and it is determined that the defect is a defect. To prevent this, a non-flaw detection area is provided at the end. Then, as a method of setting the undetected area, generally, a sensor is provided on the upstream side of the transport of the inspection material, and the time until the inspection material arrives at the ultrasonic probe from the transport speed is estimated, Since the measurement is performed by setting the timer, if there is an error in the speed measurement or an error in the setting of the timer, the undetected area becomes too large and the yield decreases, or the undetected area becomes In some cases, the reflected echo at the end was erroneously determined as a defect.

Therefore, as a countermeasure for this, Japanese Patent Publication No. 53-23235 proposes a method using surface echo.

(Problem to be Solved by the Invention) The method proposed in the above-mentioned Japanese Patent Publication No. 53-23235 uses a two-channel gate circuit for surface echo and a defect echo, and a signal inputted to the two-channel gate circuit is used. Is amplified and input so that the reflection signal from the standard flaw has a predetermined magnitude.

Therefore, even if the surface of the inspection material is rough and the surface echo is large even in the oblique flaw detection, the signal input to the two-channel gate circuit is large, so that the two-channel gate circuit can detect the surface echo and the defect echo. ,It is valid. Further, when the surface echo is large as in the case of the vertical flaw detection, it is effective as in the case of the oblique flaw detection.

However, in the case of a material having a good surface roughness (for example, an abrasive finishing material or a hail finishing material), in the case of oblique flaw detection, a reflection signal from the standard flaw has a predetermined magnitude because a reflection echo from the surface is small. Even when the amplification is performed as described above, the surface echo may not be detected in the two-channel gate circuit.
If the surface echo is amplified so as to be detected by the two-channel gate circuit in order to prevent this, the signal from the standard flaw is saturated, and the level cannot be set for flaw determination.

Further, in the oblique flaw detection, as shown in FIG. 8, an excessively large reflected echo is generated from the end of the test material 1 at the end, so that even if only the surface echo is detected, this erroneous detection cannot be avoided. . Further, at the rear end, when the surface echo disappears, a tube end signal has already been generated, and thus there are various problems such as erroneous detection depending on the shape.

In addition, this method requires a two-channel gate circuit in the flaw detection apparatus, and thus has a problem in terms of cost, such as the necessity of a new apparatus.

It is an object of the present invention to provide an ultrasonic inspection apparatus for inspecting a material to be inspected which can solve such a problem.

(Means for Solving the Problems) In order to achieve the above object, an ultrasonic flaw detector according to the present invention transmits an ultrasonic wave to a material to be inspected and receives a reflected signal from the material to be inspected. An ultrasonic probe, a defect determination device that determines a defect based on a received signal of the ultrasonic probe, and the same received signal, and a surface echo and an end echo are respectively determined from the received signal by predetermined values. Amplifiers that separately amplify the size, gates that extract the surface echo and edge echo of the material to be inspected from the signals separately amplified by these amplifiers, and transmit the ultrasonic beam in the same direction as the transport direction At the end, after the surface echo is inspected at the front end, an operation signal is output to the delay unit when the end echo is detected, and at the rear end, the operation signal to the delay unit is stopped when the surface echo disappears, Or, carry When transmitting an ultrasonic beam in the direction opposite to the sending direction, the front end outputs an operation signal to the delay unit after a lapse of a predetermined time from the detection of the surface echo, and the rear end delays when the end echo is detected. And a flaw detection range determination device including a logic unit that stops an operation signal to the detector and a delay unit that delays a defect signal input from the defect determination device by a predetermined time by an operation signal from the logic unit. It is.

(Operation) As described above, in the ultrasonic flaw detector according to the present invention, the flaw detection range determination device, which is a component, uses the flaw detection range based on the reception signal of the probe provided in the existing ultrasonic flaw detector. Is determined, and the defect signal output from the ultrasonic flaw detector is delayed based on the result, so that the existing flaw detector can be applied to any type.

In addition, the ultrasonic flaw detector according to the present invention separately determines a flaw detection range of a material to be inspected and a defect, and thus can flexibly set conditions in a flaw detection mode. In addition, since the output from the defect determination device is delayed for a fixed time, the echo at the front and rear ends can be eliminated,
Highly accurate pipe end control becomes possible.

(Embodiment) Hereinafter, the present invention will be described based on an embodiment shown in FIGS. 1 to 6.

FIG. 1 is a block diagram showing an embodiment of the present invention.

In FIG. 1, reference numeral 11 denotes a probe which is excited by an oscillator 12 and oscillates ultrasonic waves. Then, the probe 11 receives a reflected wave of the ultrasonic energy from the material to be inspected and converts the ultrasonic energy into electricity.

The electrical converted signal is preamplifier 13 and main amplifier 14
The gate unit 15 extracts only the necessary defect signal and outputs it to the delay unit 21 described later as an analog signal.

 The above is the defect determination apparatus B.

On the other hand, the electrical converted reception signal is also output to the flaw detection range determination device A at the same time.

The flaw detection range determination apparatus A detects, for example, an S echo amplifier 16 and a gate unit 17 which are amplified to a size suitable for detecting the surface echo S of the material to be inspected, and an end echo K of the material to be inspected. A K echo amplifier 18 and a gate unit 19 that amplify and extract to a size suitable for the detection and determine the start of flaw detection and the end of flaw detection based on the detection and non-detection of these surface echo S and end echo K, Logic unit that outputs an operation signal to control the start or stop of operation of delay unit 21
20 and a defect signal output from the gate unit 15 of the defect determination device B based on the determination result of the logic unit 20.
A delay unit 21 that delays for a fixed time is provided.

In FIG. 1, reference numeral 22 denotes an input terminal of an ultrasonic signal electrically converted by the probe 11, reference numeral 23 denotes an input terminal of an analog signal output from the gate unit 15, and reference numeral 24 denotes a D / A converter by a delay unit 21. This is the output terminal of the analog signal after being processed.

FIG. 2 shows a gate device constituting the ultrasonic flaw detector of the present invention.
It is a figure which shows the gate setting of 15, 17, and 19, (a) is a gate device 15, ie, a thing for defect detection, (b) is a gate device
Reference numeral 17 denotes a device for detecting a surface echo, and (c) denotes a gate device 19, that is, a device for detecting an edge echo. Second
As can be seen from FIGS. (A) and (C), the end point of the gate for detecting the end echo and the end point of the gate for detecting the defective echo are set to be the start points.

FIGS. 3 and 4 show timing charts for the present invention. FIG. 3 shows a case where an ultrasonic beam is transmitted in a direction opposite to the transport direction of the material to be inspected (hereinafter referred to as "T ⁺ "). FIG. 4 shows a timing chart in the case where an ultrasonic beam is transmitted in the same direction as the transport direction of the material to be inspected (hereinafter referred to as “T ⁻ ”).

When the flaw detection signal, that is, the input at the input terminal 23 is T ⁺ , as shown in FIG. 3A, only the defect echo F is present at the front end, and the end echo K and the defect echo K are present at the rear end. F is included. Furthermore, T ^- in the case of, as shown in FIG. 4 (b), the tip end echo K and defect echo F is also at the rear end portion contains only the defect echo F.

Further, the surface echo signal, that is, the output of the gate device 17 is
As shown in FIGS. 3 and 4 (b), the signal is turned on when the material to be inspected is present, and is turned off when the material to be inspected passes.

Further, the end echo signal, that is, the output of the gate device 19 is
Unlike the detection operation by the inspection direction, in the case of T ^+, as shown in FIG. 3 (c) is not detected only in the rear end side, also, T ^- in the case of, 4 (c) As shown in FIG. 7, since the detection is performed only on the distal end side, the logic unit 20 controls the gate units 17 and 19 according to the direction in which the ultrasonic beam is transmitted.
3 and FIG. 4 (d), an operation signal is output to the delay unit 21 as shown in FIG.

In this way, only the defective echo F is output from the delay unit 21 as shown in FIG. 3 and FIG.

Next, an example of a control method of the device of the present invention in the case of the shaft oblique flaw detection will be described.

First, T ^- described case.

The gate settings in the gate units 15, 17, and 19 are as described above with reference to FIG. At this time, the defect detection gate in the gate unit 15 is set to a position where 1/2 internal skips can be detected for internal standard flaws and 1 skip can be detected for external standard flaws. In addition, the delay unit 21
Then, the input from the input terminal 23 for the analog signal is output to the output terminal 24 for the analog signal with a delay of t seconds. here,
t is, for example, t = {effective beam width of the probe × (1/2)} / progression speed of the material to be inspected. In this state, when the material to be inspected is transported as shown in FIG. 5 (a), first, the gate unit 17 detects the surface echo S and the logic unit 20.
Output an ON signal.

Next, as shown in FIG. 5 (b), an echo at the inner corner of the end of the material to be inspected is emitted.
Is a gate device for detecting a defect echo, as described above.
Since the end point of the 15 gates (between 1/2 skip and 1 skip) is the start point, the echo at the end internal angle does not reach the gate of the gate unit 19 for detecting the end echo and is not detected. Therefore, the echo at the end outer angle detected at the position shown in FIG. 5 (c) is first detected by the gate unit 19 as the end echo K, and this detection signal (ON signal) is output to the logic unit 20. Is output to

Then, when this state is reached (surface echo ON, edge echo ON), the logic section 20 is set to make the output effective range.
Outputs an operation signal to the delay unit 21, and the delay unit 21 outputs a signal input from the defect determination device B based on the operation signal,
The signal is output to the output terminal 24 with a delay of t seconds. By the above operation, all the flaws detected by the defect determination device B during the flaw detection are output as defect echoes.

When the flaw detection is performed as described above and comes to the rear end of the material to be inspected, the surface echo S is not detected after the state shown in FIG. When the surface echo S is no longer detected, the output of the gate unit 17 is turned off, and the logic unit 20 is turned off.
Then, based on the OFF signal, the operation signal output to the delay unit 21 is stopped (OFF) to close the output effective range.

By the way, the end portion of the material to be inspected may be shaken during transportation due to a nose bend, and especially at the rear end, the surface echo S may be shifted in the horizontal axis direction in FIG. Even in such a case, the output from the defect determination device B is output with the effective output range being delayed for t seconds by the operation of the delay unit 21 by the above-described control. Therefore, the surface echo S detected by the bending of the nose is not output to the output terminal 24 for t seconds after the stop of the operation signal to the rear end side.

Next, the case of T ⁺ will be described. In the case of T ⁺ , only the output to the delay unit 21 at the leading end and the trailing end is different, so
Only this part will be described.

As shown in FIG. 6 (a), when the material to be inspected is conveyed, the surface echo S is detected by the gate unit 17 and the logic unit 20 is detected.
Output an ON signal. Then, in the case of T ⁺ , the logic unit 20 outputs an operation signal to the delay unit 21 T seconds after receiving the ON signal, and sets the subsequent signal to the output effective range. This T second may be the same time as the delay time t in the delay unit 21 described above, and the T second may be the same time as the delay time t in the delay unit 21 described above. Set by a timer within 20. Also,
The output defect echo within the effective range, the above-mentioned forward T ^- output as in the case with a delay t seconds to the output terminal 24.

Therefore, no signal is output for T seconds on the tip side, and there is no influence of the tip. In the front end in the case of the T ^+, the above-mentioned T ^-
As in the case of the nose bend at the rear end in the case of (1), the nose bend may cause the front end to swing during conveyance, and the surface echo S may shift in the horizontal axis direction in FIG. 3 and be detected by the defect determination device B. Even in such a case, by the above control,
Since the output effective range starts for T seconds after the detection of the surface echo S, the detected surface echo S is output to the output terminal.
Not output to 24.

On the other hand, in the case of the rear end, as shown in FIG.
When the gate unit 19 detects the end echo K, this detection signal (ON signal) is output to the logic unit 20, and the logic unit 20 operates the delay unit 21 to close the output effective range based on the ON signal. Stop the signal. At this time, the output from the defect determination device B is output with a delay of t seconds during the output effective range due to the operation of the delay unit 21. Therefore, after the logic unit 20 stops the operation signal to the delay unit 21, The end t seconds are not output, and the detected end echo K is not output to the output terminal 24.

In addition, in the case of the circumferential oblique flaw detection, the circuit for detecting the end echo is unnecessary, and only the circuit for detecting the surface echo is sufficient. However, it is necessary to control the timer T and the delay start time t to be used at the time of detecting the front and rear ends of the material to be inspected.

(Effects of the Invention) As described above, in the case of the present invention, since the end is detected by the signal of the probe itself, control can be performed without being affected by the transport speed. Therefore, this
The end undetected length can be greatly reduced. In addition, according to the present invention, the influence of the nose bend can be eliminated.

In this embodiment, the oblique flaw detection has been described, but application to other flaw detection methods is sufficiently possible.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention, FIGS. 2 (a) to 2 (c) are diagrams showing gate settings, and FIGS.
(A) to (e) of the figure show timing charts, and
FIG. 4 shows a case where an ultrasonic beam is transmitted in a direction opposite to the transport direction of the material to be inspected. FIG. 4 shows a case where an ultrasonic beam is transmitted in the same direction as the transport direction of the material to be inspected. I)~
(D) and FIGS. 6 (a) and (b) are explanatory diagrams of the control method of the device of the present invention, FIG. 7 is an explanatory diagram of a conventional water immersion ultrasonic inspection method, and FIG. It is explanatory drawing of a problem. A is a flaw detection range determination device, B is a defect determination device, 11 is a probe, 16 is an S echo amplifier, 17 and 19 are gate devices, 18 is a K echo amplifier, 20 is a logic unit, and 21 is a delay device.

Claims (1)

(57) [Scope of request for utility model registration] An ultrasonic probe for transmitting an ultrasonic wave to a material to be inspected and receiving a reflected signal from the material to be inspected, and determining a defect based on a signal received from the ultrasonic probe. A defect judging device for performing the same; an amplifier that receives the received signal, and separately amplifies the surface echo and the end echo from the received signal so as to have predetermined magnitudes, respectively; and a signal that is separately amplified by these amplifiers. Gate device that extracts the surface echo and edge echo of the material to be inspected from, and when transmitting the ultrasonic beam in the same direction as the transport direction, after detecting the surface echo at the tip,
When an end echo is detected, an operation signal is output to the delay unit, and at the rear end, the operation signal to the delay unit is stopped when the surface echo disappears, or an ultrasonic beam is transmitted in the direction opposite to the transport direction. A logic unit that outputs an operation signal to the delay unit after a predetermined time elapses from the detection of the surface echo at the front end and stops the operation signal to the delay unit when the end echo is detected at the rear end. An ultrasonic flaw detection apparatus, comprising: a flaw detection range determination apparatus including a delay unit that delays a defect signal input from the defect determination apparatus by a predetermined time according to an operation signal from the logic unit.