JP2002257799A - Flaw detection method and flaw detection device for solid shaft member - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ultrasonic flaw detection method capable of easily and precisely detecting only the echo of a flaw present in a solid shaft member. SOLUTION: This ultrasonic flaw detection method for solid shaft member comprises the step of bringing an array probe formed of a plurality of ultrasonic oscillators provided on a plane into contact with the end surface of the solid shaft member, the step of imparting a transmit-receive delay to the oscillator group formed of two or more of a prescribed number of ultrasonic oscillators among the ultrasonic oscillators constituting the array probe so that the ultrasonic beams can be transmitted and received in a preset target position to perform a flaw detection, the step of scanning the ultrasonic beams in the vicinity of the target position in the axial direction and/or circumferential direction of the solid shaft member by changing the time of the transmit-receive delay within a prescribed range, the step of subjecting a flaw detection signal in each position obtained in the scanning to moving average processing, and the step of performing a flaw judgment on the basis of the flaw detection signal after the moving average processing.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for ultrasonically detecting flaws present on a solid shaft member.
The present invention relates to an ultrasonic flaw detection method and apparatus for a solid shaft member suitable for automatically detecting a shaft member such as a railroad solid axle and accurately detecting cracks and internal defects generated on an outer peripheral surface.

[0002]

2. Description of the Related Art Conventionally, JR conventional lines, series 0 and 100
Solid axles are used for trains of the system Shinkansen and private railways. (Shinkansen trains of the 200 series and after use a boring axle with a central part of the axle hollowed out with a diameter of about 60 mm to reduce mass). Such an axle is an important part of the traveling equipment that supports the safety of railway vehicles, but it does not have a fail-safe structure, so if it breaks during traveling, it may lead to a serious accident. There is.

[0003] Therefore, ultrasonic flaw detection is always performed at a predetermined traveling distance to ensure safety. As an ultrasonic inspection method for a solid axle, for example, "Ultrasonic Testing Technology-Theory and Practice-" (Kraut Kramer, Japan Management Association) (19)
As described on pages 326 to 332 of February 25, 1980), ultrasonic waves enter the interior of the axle from an ultrasonic probe disposed on the axle end surface or the shaft peripheral surface and are reflected by the flaw. A method is employed in which the probe receives the generated ultrasonic waves.

Here, wheels, drive gears, brake discs and the like are mounted on the shaft peripheral surface by press fitting or shrink fitting. Further, since the shaft surface between the wheels is often significantly corroded, a method of detecting flaws from the axle end face is effective.
That is, flaw detection can be performed without removing the shrink-fitted wheels or the like from the axle, and the flaw detection can be performed efficiently without the need for polishing the corroded shaft surface.

[0005] In the flaw detection from the axle end face, a probe group composed of a plurality of (four) ultrasonic probes 100 as shown in FIG. 8 is usually inserted into a center punch hole located at the center of the axle end face. After inserting the punch 200 into contact with the end surface of the axle, the probe group is moved to the center punch 200.
It is performed while rotating at a predetermined speed around. Each probe 100 has a predetermined refraction angle (1 in the example shown in FIG. 9).
5 degrees, 13 degrees, 10 degrees, and 4 degrees), and each probe 100 rotates in the circumferential direction so that four target positions (A to D in FIG. 9B) are obtained. (Indicated by) is realized.

[0006] Here, the factor that hinders flaw detection in the prior art is the presence of a so-called press-in echo generated at a fitting portion between the axle and the wheel or a fitting portion between the axle and the gear portion. FIG. 11 shows an example of a press-fit echo from the axle-wheel fit, which is observed before the flaw echo. It is presumed that the press-fit echo is caused by superposition of reflected echoes from minute irregularities (voids) of the fitting portion, which are caused by surface roughness of two kinds of metal materials (the axle and the wheel in the example of FIG. 11). Unlike the flaw echo, it is a relatively wide signal (having a long duration), and most of the signals have a lower intensity than the flaw echo intensity.

However, depending on the method of superimposition, there may be a case where the intensity is locally comparable to the flaw echo. In the flaw judgment using a simple fixed threshold value, the press-fit echo is erroneously detected as a flaw. Probability is high.

As means for solving this problem, for example,
The invention described in JP-A-10-206396 is known. According to the invention described in the above-mentioned publication, a flaw detection waveform of a flawless axle is sampled by flaw detection of a large number of healthy axles, and based on the flaw detection waveform, a threshold value of a free shape as shown in FIG. It is determined in advance. When an echo exceeding the threshold value of the free shape is detected, it is determined that there is a flaw.

[0009]

However, in the prior art described in the above-mentioned Japanese Patent Application Laid-Open No. 10-206396, the threshold value of the free shape is set by detecting flaws on a large number of healthy axles. It requires a lot of man-hours. That is, it is necessary to detect a large number of healthy axles having the same material and the same shape as the axle to be inspected in advance, and when the material and shape of the axle are changed, it is needless to say that the ultrasonic probe to be used (at least When the frequency, the vibrator diameter, and the vibrator material) are changed, it is necessary to discard the flaw detection data of the healthy axle accumulated so far and collect it again.

For this reason, even if an ultrasonic probe having better flaw detection capability becomes available at a low cost, or flaw detection conditions (frequency , Transducer diameter, etc.), there is a problem that those probes and flaw detection conditions cannot be easily adopted.

The present invention has a problem of the prior art in such axle flaw detection, that is, in order to prevent erroneous detection of flaws due to press-fitting echoes, flaw detection is performed on a large number of sound axles, and a large number of man-hours are required to form a free-form. An ultrasonic flaw detection method and a flaw detection apparatus capable of easily and accurately detecting only a flaw echo existing in a solid shaft member, which is provided to solve a problem that a threshold value needs to be set. The task is to

[0012]

According to the present invention, a press-fitting echo is superimposed on a reflection echo from minute unevenness (gap) of a fitting portion caused by surface roughness of a fitting member (for example, an axle and a wheel). This is based on the presumption that it has been done.

That is, since the press-in echo is a superposition of reflection echoes from minute irregularities, if the irradiation position of the ultrasonic wave slightly changes, the reflection echoes from the individual irregularities change and are formed by superposition. The indentation echo will also change.

On the other hand, since the flaw has a certain extent in the depth direction, the circumferential direction of the solid shaft member (axle) and / or the axial direction, even if the irradiation position of the ultrasonic wave is slightly changed. The flaw echo does not change much.

FIG. 10 shows an example in which the received signal at a certain point on the axle where ultrasonic testing was performed and the received signals at three points in the vicinity are superimposed and displayed. As shown in FIG.
Although the four flaw echoes have substantially the same waveform, the press-fit echoes have different waveforms. Therefore, if an average value is obtained by adding these four signal waveforms, the intensity difference between the press-fitted echo and the echo becomes remarkable, and erroneous detection can be prevented.

The present invention has been completed on the basis of such findings, and it has been made possible to suppress only a press-in echo and detect a flaw echo with a high SN ratio by the following means.

That is, the present invention relates to an ultrasonic flaw detection method for a solid shaft member, wherein an array probe constituted by a plurality of ultrasonic transducers is brought into contact with an end face of the solid shaft member. Among the ultrasonic transducers constituting the array probe, a transmission / reception delay is set so that an ultrasonic beam can be transmitted / received to a preset target position to a transducer group including two or more predetermined number of ultrasonic transducers. Giving and flaw detection, by changing the transmission and reception delay time in a predetermined range,
Scanning the ultrasonic beam in the axial direction and / or the circumferential direction of the solid shaft member in the vicinity of the target position, and performing a moving average process on a flaw detection signal at each position obtained in the scanning And a step of making a determination based on the flaw detection signal after the moving averaging process.

According to this invention, the transmission / reception delay time is changed within a predetermined range, and the ultrasonic beam is scanned in the axial direction and / or the circumferential direction of the solid shaft member near the target position. On the other hand, while the press-in echo changes greatly, the flaw echo obtained when the flaw exists at the target position does not change much due to the minute scanning. Therefore, by applying the moving average processing to the flaw detection signal at each position obtained at the time of scanning, it is possible to suppress the press-in echo and detect only the flaw echo with high accuracy. Further, it is not necessary to accumulate flaw detection data of a large number of sound solid shaft members in advance, or to set a threshold value of a complicated free shape, so that flaw detection can be performed relatively easily. Note that the “near” indicates a range where the signal level of a flaw echo when a flaw is detected by scanning a solid shaft member, which is a flaw-detected member, with an ultrasonic beam does not change much or less. More specifically, a range from the sum of the beam size of the ultrasonic beam at the target position and the size of a flaw that can be generated to a range below this range is shown. Typically, a range of about 50 mm or less from the target position (front, rear, left and right around the target position) is shown.

Preferably, the array probe is an annular array probe composed of a plurality of fan-shaped ultrasonic transducers.

Alternatively, the array probe is a two-dimensional array probe constituted by a plurality of rectangular or square ultrasonic transducers.

Further, the present invention relates to an ultrasonic flaw detector for a solid shaft member, comprising: an array probe comprising a plurality of ultrasonic transducers; An element and a transmission / reception delay time corresponding to a preset target position are given to the transmission / reception delay element, and the transmission / reception delay time is changed within a predetermined range to thereby allow the solid shaft member to move in the axial direction near the target position. And / or a target position controller for realizing circumferential scanning, and a plurality of predetermined number of ultrasonic transducers that contribute to transmission and reception of ultrasonic waves among a plurality of ultrasonic transducers constituting the array probe. A circumferential scanner that realizes circumferential scanning of the solid shaft member at the target position by selecting and switching a group of transducers, and ultrasonic vibrations that constitute each of the selected transducer groups. Received signal obtained by child An adder that adds a predetermined reception delay after performing a predetermined reception delay, a moving average processor that performs a moving average process on the added reception signal corresponding to each of the target position and each position near the target position, and A flaw evaluator that evaluates flaws in the solid shaft member based on the intensity of a received signal that has been subjected to averaging processing.

[0022]

An embodiment of the present invention will be described below with reference to the accompanying drawings. FIG. 1 is a schematic configuration diagram showing one embodiment of an ultrasonic flaw detector according to the present invention. As shown in FIG. 1, an ultrasonic flaw detector 1 according to the present embodiment includes an array probe 10 and a transmission delay element group 20.
A delay element group 30 for reception, a target position controller 40,
Circumferential scanning controller 50, adder 60, flaw evaluator 70
, A pulsar group 80, a receiver group 90, and a moving average processor 110.

The array probe 10 of this embodiment has an inner diameter of 3
A plurality of fan-shaped ultrasonic transducers 100 (32 in this embodiment, # 1 to # 32) are arranged side by side in an annular shape having a diameter of 0 mm and an outer diameter of 90 mm. The transmission delay element group 20 includes the respective ultrasonic transducers 100 connected via the pulser group 80.
, And the reception delay element group 30 is for giving a reception delay to a reception signal input to the receiver group 90 connected to each ultrasonic transducer 100. The aim position controller 40 gives a transmission / reception delay time corresponding to a preset aim position to the transmission delay element group 20 and the reception delay element group 30, respectively. Further, the aim position controller 40 is configured to change the transmission / reception delay time within a predetermined range so as to realize axial or / and circumferential scanning near the aim position. Circumferential scanning controller 50, among a plurality of ultrasonic transducers 100 constituting array probe 10, a transducer group including two or more predetermined number of ultrasonic transducers 100 that contribute to transmission and reception of ultrasonic waves. By selecting and switching, circumferential scanning at the target position of the solid shaft member is realized. The adder 60 adds a reception signal obtained by each of the ultrasonic transducers 100 constituting each of the selected transducer groups after a predetermined reception delay. The moving average processor 110 includes a waveform memory 111 and an adder 112, and is configured to perform a moving average process on the added received signal corresponding to each of the target position and the position near the target position. The flaw evaluator 70
The flaw of the solid shaft member is evaluated based on the intensity of the received signal subjected to the moving average processing.

Hereinafter, a processing flow in the ultrasonic flaw detector 1 having the above configuration will be described with reference to a flowchart shown in FIG.

When using the ultrasonic flaw detector 1, the array probe 10 is first brought into contact with the end face of the axle to be flawed (S1 and S2 in FIG. 2).

Next, the number of transducers 100 constituting one transducer group is set (S3 in FIG. 2). Here, for example, as shown in FIG.
Out of 0 (# 1 to # 32), 11 vibrators 100 are 1
One flaw detection is performed using the vibrators 100 that are grouped and constitute one such group. This allows
Even if the area of each transducer 100 is small, that is, even if the scanning pitch in the circumferential direction is small, the area of the transducer group used for one flaw detection can be increased.

Next, the target position controller 40 determines an axial position to be flaw-detected (for example, a position at a distance A in the axial direction from the end face), and the vibrators 100 forming one group
In each of the above-described determined axial positions and the respective vibrators 10.
A transmission / reception delay time corresponding to the arrangement position in the group 0 is set (S4 in FIG. 2).

Next, a group of transducers (first group) that first contributes to transmission and reception is selected by the circumferential scanning controller 50 (S5 in FIG. 2), and each transducer 100 constituting the first group is selected. The transmission / reception delay set as above is given to perform flaw detection at a predetermined position (axial distance A, circumferential angle X). At this time, a moving average process described later is performed (S6 in FIG. 2).
Note that, in the present embodiment, as shown in FIG.
The first vibrator is set as a first group, whereby the first flaw detection is performed.

Here, when transmitting the ultrasonic beam in S6 in FIG. 2, a predetermined delay time is set by the transmission delay element group 20 with respect to each of the transducers 100 constituting the selected transducer group. Then, a transmission voltage is applied by the pulsar group 80 to transmit an ultrasonic beam inside the axle. As described above, by adjusting the setting of the delay time given to each transducer 100 constituting the selected transducer group, it is possible to focus the ultrasonic beam at an arbitrary position.

On the other hand, at the time of receiving a flaw echo or the like in S6 of FIG. 2, the signals received by the transducers 100 constituting the selected transducer group are input to the receiver group 90 and then received. Delay element group 30 (for example, an analog delay line can be used as each reception delay element)
, The same delay time as the transmitting side is given,
After being added by the adder 60 and amplified by the amplifier, it is stored in the waveform memory 111 inside the moving average processor 110.

Hereinafter, the moving average processing in S6 of FIG. 2 will be described in detail. In the moving average processing of S6, first, the above-described predetermined position (axial distance A, circumferential angle X)
(S61 in FIG. 2), and the result is stored in the waveform memory 111 (S62 in FIG. 2). Next, the ultrasonic beam is scanned in the axial direction and / or the circumferential direction of the axle near the target position by changing the transmission / reception delay time within a predetermined range by the target position controller 40 (S63 in FIG. 2). Change the flaw detection position (S6 in FIG. 2)
4). The test result at the changed test position is stored in the waveform memory 111 (S65 in FIG. 2). The above processing (S63 to S65) is repeated until scanning in a predetermined vicinity is completed (S66 in FIG. 2).

Here, in the scanning near the target position (S64 in FIG. 2), for example, first, before and after the axial direction of the axle (the traveling direction of the axial component of the transmitted ultrasonic beam is referred to as “the target position”). The transmission and reception of the ultrasonic beam are performed at two points (a total of five points including the target position) in each of the "front" and "opposite" directions. Furthermore, the left and right sides in the circumferential direction of the axial component of the transmitted ultrasonic beam are defined as “right” and the left side as “left” with respect to each of the five points. Sends and receives a sound beam. Therefore, transmission / reception of the ultrasonic beam (total 25 times) is performed toward a total of 25 (5 × 5) positions around the target position. At this time, the interval between adjacent ultrasonic beam transmitting / receiving positions can be set to, for example, 10 mm in both the axial direction and the circumferential direction. It should be noted that such scanning in the vicinity of the target position can be performed by finely adjusting the delay time given to each transducer 100 constituting one group.

FIG. 4 shows a schematic waveform example of a received signal in the above-mentioned 25 times of transmission / reception of the ultrasonic beam (FIG. 4 exemplifies four of the obtained 25 waveforms). As shown in FIG. 4, the flaw echo in the received signal waveform is 25%.
While all the received signal waveforms have substantially the same waveform, the press-in echo has a different waveform in each of the 25 received signal waveforms. Therefore, the above 25
When the received signals are added (added by the adder 112 in FIG. 1) and the average is calculated (S67 in FIG. 2), the flaw echoes are strengthened while the press-in echoes cancel each other out. The difference between the intensity and the signal intensity of the press-fit echo becomes remarkable, and erroneous detection can be prevented.

Note that the target position is not necessarily
It is not necessary to transmit and receive the ultrasonic beam to the vicinity positions in the front-back direction and the left-right direction in the circumferential direction. Only the vicinity position shifted in the axial direction or only the close position in the circumferential direction may be used. Also, in the axial direction, it is not always necessary to transmit and receive the ultrasonic waves toward the front and rear neighboring positions, and it may be only in the forward direction or only in the backward direction. Similarly,
As for the circumferential direction, only the left direction or the right direction may be used.

In performing a flaw detection at one target position, the number of positions for transmitting and receiving the ultrasonic beam (hereinafter referred to as "parameter") is determined by the number of disturbing echoes other than the flaw echo at the target position (for example, press-fit echo). ) May be set in consideration of signal strength and the like. For example, if the signal strength of the disturbing echo is large and the difference from the signal strength of the flaw echo is small, by setting a large number of parameters, when calculating the average value, the difference between the disturbing echo and the echo is calculated. Can be noticeable.
Conversely, when the signal strength of the disturbing echo is not so large, even if the parameter is small, the difference between the flaw echo and the disturbing echo is significant, so that there is little possibility of erroneous detection. Therefore,
The parameter may be set such that the intensity difference between the flaw echo and the disturbing echo such as the press-fitting echo when the received signal is averaged is sufficiently significant to prevent erroneous detection.

When detecting a plurality of portions in the axial direction of a single axle, the parameter can be changed for each portion or set to the same number.
When the parameter is changed, the parameter is increased at the time of flaw detection of a portion where the interference echo is large or expected to be large (for example, a press-fit portion of a wheel), and conversely, the interference echo is small. Alternatively, at the time of flaw detection of a portion expected to be small, the parameter may be reduced.

As described above, the moving average processing in S6 of FIG. 2 is performed. That is, the delay time given to the transmission delay element group 20 and the reception delay element group 30 is
By slightly changing the position set in step S4 of FIG.
Scan left and right. The flaw detection waveforms at each scanning position are stored in the waveform memory 111, respectively, and when a predetermined scan is completed, a moving average process is performed on the accumulated flaw detection waveforms.

Next, in S7 of FIG. 2, the waveform after the moving average processing is compared with a threshold value determined in advance by a flaw evaluator 70, and the presence or absence of flaws is evaluated.

As described above, flaw detection at a predetermined position (axial distance A, circumferential angle X) is completed.

Next, it is determined whether the flaw detection at the axial distance A has been completed for the entire circumference (S8 in FIG. 2). In this case, since it has not yet been completed for the entire circumference, # shown in FIG.
The transducers # 2 to # 12 are set as a second group (S5), and the set transmission / reception delay is given to each transducer constituting the second group, and about 11 degrees (= 360/32) in the circumferential direction.
Flaw detection is performed at the shifted position (axial direction distance A, circumferential angle X + 11 degrees) (S6 in FIG. 2), and the presence or absence of a flaw is determined (S7 in FIG. 2).

Similarly, it is determined whether or not the flaw detection at the axial distance A has been completed for the entire circumference (S8 in FIG. 2). Since the flaw detection has not been completed yet, it is determined in steps # 3 to # 13 shown in FIG. Assuming that the vibrator is a third group, the set transmission / reception delay is given to each of the vibrators constituting the third group, and a position further shifted by about 11 degrees in the circumferential direction (axial distance A, circumferential angle X + 22 degrees) 2) (S6 in FIG. 2), and the presence or absence of a flaw is determined (S7 in FIG. 2). In the same manner, the entire circumference (that is, 32 times) is sequentially repeated (S5 to S8 in FIG. 2).
Thereby, the flaw detection of the entire circumference for the axial distance A is completed.

As described above, the selected transducer group (group of 11 transducers) that contributes to the formation of the ultrasonic beam is sequentially switched at predetermined intervals and scanned.
The ultrasonic beam can be rotated and scanned in the circumferential direction, and flaw detection can be performed on the entire axle while the array probe 10 is fixed.

Next, it is determined whether or not flaw detection has been completed at all target positions (axial positions) to be flaw-detected (S9 in FIG. 2). If there are a plurality of axial positions to be inspected, the position in the axial direction to be inspected next is determined (for example, an axial distance B from the end face) since the inspection is not yet completed, and
The transmission / reception delay time corresponding to the determined axial position and the arrangement position of each transducer 100 within the group is reset for each of the transducers 100 constituting one group (S4 in FIG. 2). Thereafter, the same operation as described above is repeated (S5 to S8 in FIG. 2) until the flaw detection for the entire circumference at the position of the axial distance B is completed. After the inspection is repeated until the inspection is completed (S4 to S9 in FIG. 2), when the inspection is completed, the measurement result is output (S10 in FIG. 2), and the operation ends.

In this embodiment, even if the axial position to be inspected changes, the vibrators 10 forming one group
Although the number of 0s is the same, the number of vibrators 100 forming one group may be changed according to the distance in the axial direction. That is, in the flowchart shown in FIG. 2, if the determination in S9 is "NO", it is also possible to perform processing to return to S3 instead of S4. In such a case, as the axial distance increases, the vibrators 10 forming one group
It is preferable to increase the number of zeros to increase the area of the region contributing to the transmission and reception of the ultrasonic beam, since the beam can be easily focused.

When it is not necessary to change the number of vibrators 100 constituting one group each time, for example, when a plurality of axles having the same structure are detected, the vibration is pre-vibrated before S1 in the flowchart shown in FIG. Set the number of children, S
If the processing flow is such that S4 is performed after S2 without performing the processing of S2, the trouble of setting can be reduced, and a flaw-detecting device that is easy to use can be provided.

The total number of ultrasonic transducers 100 constituting the array probe 10 and the number of transducers in one group can be determined as appropriate in accordance with the flaw detection accuracy required for the material to be detected. . For example, if the total number of the vibrators 100 is increased, the scanning pitch in the circumferential direction can be made fine, so that it is considered that the flaw detection accuracy is improved. However, the number of required pulsers, receivers, and delay elements increases according to the total number of transducers 100, so that the device configuration becomes complicated and costs increase. Therefore, it is important to conduct an experiment in advance and set the number so that sufficient detection accuracy is obtained and the detection accuracy is not excessive. Particularly, in the case of detecting a flaw in a railway axle, when the annular array probe 10 is configured by the plurality of fan-shaped transducers 100 as in the present embodiment, the total number of transducers 100 is 25. If it is about 50, flaw detection with sufficient detection accuracy can be expected.

When the total number of the vibrators 100 is the same,
As the number of transducers forming one group increases, the area (effective area) of the transducer group that contributes to transmission and reception of ultrasonic waves increases. According to the axial distance between the transducer 100 and the flaw detection position,
Since an appropriate number of oscillators, that is, an appropriate effective area is expected to be different, it is important to calculate an appropriate number of oscillators in advance by experiments or the like.

As described above, the ultrasonic flaw detector 1 according to the present embodiment has a device configuration that realizes rotational scanning in the circumferential direction by sequentially and electronically switching the transducer group to be selected. This eliminates the need for the conventional rotating mechanism of the probe head, which simplifies the entire device,
No careful maintenance of the moving parts is required. In addition, since flaw detection capability with sufficient accuracy can be secured from the axle end face, on-axis flaw detection becomes unnecessary. Further, since a flaw having a predetermined depth can be detected by only one array probe, there is an effect that it is not necessary to prepare a probe group corresponding to the axle even in an axle having various shapes and dimensions.

The array probe 10 of the present embodiment is
The vibrator 10 is provided in a ring shape, which is preferable from the viewpoint of simplicity of arrangement / configuration and ease of control. However, the present invention is not limited to this. For example, as shown in FIG. A small rectangular or square vibrator 10 in a lattice shape
1 may be used as an array probe. That is, an array probe that can transmit and receive an ultrasonic beam to a predetermined target position by giving a predetermined delay time, and that sequentially switches a group of transducers to be selected, thereby changing the flaw detection position. Any probe that can scan in the circumferential direction can be used in any shape and arrangement.

[0050]

EXAMPLES The effects of the present invention will be further clarified by describing examples. FIG. 3 shows examples and comparative examples of flaw detection waveforms obtained as a result of flaw detection using a point where a notch-shaped artificial flaw is formed using an array probe as a target position. FIG. 3A shows an example of a flaw detection waveform in a case where the moving average processing is not performed as a comparative example, and FIG.
5 shows an example of a flaw detection waveform that has been subjected to moving average processing twice. 3 (a) and 3 (b) use the same array probe as the above-described embodiment, and in FIG. 3 (b), a predetermined target position is set as a center and a circumferential direction is set. 9 shows the result of moving the flaw detection position nine times at a pitch of 10 mm and five times at a pitch of 10 mm in the axial direction, and performing a moving average process on the flaw detection waveforms for a total of 45 times.

In the comparative example shown in FIG. 3A, that is, when the moving average processing is not performed, the press-in echo is observed so as to overlap with the flaw echo, whereas the embodiment shown in FIG. In the example, by applying the moving average processing to the flaw detection waveforms of 50 times, the press-in echo was suppressed, and only the flaw echo could be obtained with a high SN ratio. For this reason, even if the threshold value is fixed without using a free-form threshold value as in the related art, it is possible to detect a flaw echo with sufficiently high accuracy.

[0052]

As described above, according to the flaw detection method and apparatus for a solid shaft member according to the present invention, a predetermined method is performed by using an array probe that is in contact with the end surface of the solid shaft member. By scanning the ultrasonic beam in the vicinity of the set target position and performing a moving average process on the flaw detection signal at each scanning position, it is possible to suppress the press-in echo and detect only the flaw echo with high accuracy. Therefore, there is no need to accumulate flaw detection data for a large number of sound solid shaft members in advance, or to set a threshold value for a complicated free shape, so that flaw detection can be performed relatively easily. Is played.

[Brief description of the drawings]

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

FIG. 2 is a flowchart showing a processing flow in the ultrasonic flaw detector according to the present invention.

FIG. 3 is an example of a flaw detection waveform obtained as a result of flaw detection at a predetermined target position using an array probe, and FIG.
Shows a comparative example, and (b) shows an example.

FIG. 4 shows a waveform example of a received signal in transmission and reception of an ultrasonic beam by the ultrasonic flaw detector according to the present invention.

FIG. 5 is a schematic configuration diagram showing an array probe according to another embodiment of the present invention.

FIG. 6 is an explanatory diagram showing an example of selecting a transducer group in the array probe according to the present invention.

FIG. 7 is an explanatory diagram showing an example of switching of a transducer group in the array probe according to the present invention.

FIG. 8 is a perspective view schematically showing a conventional probe.

FIG. 9 is an explanatory view showing a conventional flaw detection method from the end surface of the axle, and FIG. 9 (a) shows the axial position of the axle;
(B) is an explanatory view of circumferential scanning.

FIG. 10 is an example in which a received signal at a point on the axle where ultrasonic testing was performed and a received signal at three points in the vicinity thereof are superimposed and displayed.

FIG. 11 shows an example of a press-in echo from the axle-wheel fit, observed before a 3 mm deep artificial flaw echo.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Ultrasonic flaw detector 10 ... Array probe 20 ... Delay element group for transmission 30 ... Delay element group for reception 40 ... Target position controller 50 ... Circumferential scanning control Device 60 Adder 70 Flaw Evaluator 80 Pulser Group 90 Receiver Group 100 Ultrasonic Transducer 110 Moving Average Processor

Claims (4)

[The claims] 1. An ultrasonic flaw detection method for a solid shaft member, the method comprising: contacting an array probe composed of a plurality of ultrasonic transducers with an end surface of the solid shaft member; A flaw detection is performed by giving a transmission / reception delay to a vibrator group including a predetermined number of two or more ultrasonic vibrators among the ultrasonic vibrators constituting the vibrator so that an ultrasonic beam can be transmitted / received to a preset target position. Scanning the ultrasonic beam in the axial direction and / or the circumferential direction of the solid shaft member in the vicinity of the target position by changing the transmission / reception delay time within a predetermined range; Performing a moving average process on the flaw detection signal at each position obtained at the time, and performing a determination based on the flaw detection signal after the moving average process, wherein the ultrasonic wave of the solid shaft member is provided. Flaw detection method. 2. The ultrasonic flaw detection of a solid shaft member according to claim 1, wherein the array probe is an annular array probe composed of a plurality of fan-shaped ultrasonic transducers. Method. 3. An ultrasonic flaw detector for a solid shaft member, comprising: an array probe composed of a plurality of ultrasonic transducers; a transmission / reception delay element for giving a transmission / reception delay to the ultrasonic transducer; A transmission / reception delay time corresponding to the set target position is given to the transmission / reception delay element, and the transmission / reception delay time is changed within a predetermined range, so that the axial direction and / or the circumference of the solid shaft member near the target position are changed. A target position controller that realizes directional scanning; and a transducer group including two or more predetermined number of ultrasound transducers that contribute to transmission and reception of ultrasound among a plurality of ultrasound transducers that constitute the array probe. By selecting and switching, a circumferential scanner that realizes circumferential scanning of the solid shaft member at the target position, and an ultrasonic transducer that constitutes each of the selected transducer groups are obtained. Received signal An adder that adds the delay after the delay, and a moving average processor that performs a moving average process on the added received signal corresponding to each of the target position and the position near the target position. Flaw detector for solid shaft members. 4. The solid shaft member according to claim 3, further comprising a flaw evaluator that evaluates a flaw of the solid shaft member based on the strength of the moving average-processed received signal. Flaw detection equipment.