JPH07244028A - Apparatus and method for ultrasonically detecting flaw on spherical body to be detected - Google Patents

Abstract

PURPOSE:To improve the defect detecting capacity and operability of inspection without necessity of executing a measurement with a complicated operation in the case of inspecting a defect occurred on the surface of a spherical body to be detected made of ceramics, etc. CONSTITUTION:A pair of probes 12 for simultaneously focusing ultrasonic waves to one position of the surface of a fixed spherical body 11 to be detected are disposed symmetrically to a normal O of an ultrasonic wave incident point P to the body 11 to be detected in such a manner that an ultrasonic incident beam is at a predetermined angle to be the state along the surface of the body 11 to be detected. The apparatus for ultrasonically detecting the flaw of the body to be detected comprises a driving mechanism 13 for holding and rotating the probes 12 by disposing around the normal O and angle conditions, and a controller 14 for detecting a defect position and a defect shape of the body 11 to be detected based on transmitted and received ultrasonic waveforms of the probes 12.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention inspects a spherical object such as a ceramic ball bearing for a defect and detects a minute defect and a defect position with respect to a minute defect to ensure product soundness. The present invention relates to an ultrasonic flaw detector for a spherical object and a method therefor.

[0002]

2. Description of the Related Art In a hard material such as ceramics, minute surface scratches generated during processing serve as a stress concentration source, which may cause cracks or the like to impair product soundness and reliability. Therefore, conventionally, a defect inspection by ultrasonic flaw detection has been performed for the purpose of ensuring the soundness of the object.

However, in the conventional ultrasonic flaw detection method for a spherical object such as a ceramic ball bearing, the defect detectability is generally low.

For example, as shown in FIG. 9, a spherical object 1
The vertical probe 3a with the spherical probe 1 immersed in water 2.
In the vertical flaw detection method, which is performed at a fixed position P0 on the central axis of, the flaw R0 on the surface of the spherical object 1 is limited in its flaw detection range, and it is particularly difficult to detect flaws such as cracks.
In order to perform flaw detection on the entire surface of the subject 1 under this condition, the spherical subject 1 must be rotated and the ultrasonic wave incident point P1 must be set on the entire face of the subject 1, resulting in poor reproducibility of flaw detection data. Further, it takes a lot of inspection time and there are many difficult problems.

It should be noted that the vertical probe 3a is set to a constant eccentric position P.
There is also known a method in which the ultrasonic wave is set to 1 and the ultrasonic wave is propagated on the surface of the object to be inspected, but it takes a lot of time to select the proper position P1. Since the ultrasonic wave incident point must be set on the entire surface of the subject by rotating it, the inspection time and man-hours are greatly increased.

Further, as disclosed in, for example, Japanese Patent Laid-Open No. 63-243751, there is also known a method for flaw detection of a spherical object by an oblique angle flaw detection method. That is, FIG.
As shown in 0, the incident angle γ of the bevel probe 3b is set to an angle equal to or greater than the critical angle (surface wave generation angle) and the defect R2
This is a method of flaw detection. In this method, it is necessary to increase the defect reflection area and set the defect detectability on the entire surface of the object, and there is much noise. Therefore, there is a problem in that the reproducibility of flaw detection data is difficult and the inspection time is long.

[0007]

Conventionally, when inspecting defects generated on the surface of a spherical object such as ceramic, it is necessary to set the ultrasonic wave incident point at all positions on the object surface. It is necessary to perform complicated operations such as properly rotating the subject or scanning the probe, and high precision and inspection regarding the defect shape and defect position cannot be performed,
There was also the problem of poor work efficiency.

The present invention has been made in view of the above problems, and its purpose is to detect a defect generated on the surface of a spherical object such as a ceramic, without the need to perform a measurement involving a complicated operation and to detect the defect. An object of the present invention is to provide an ultrasonic flaw detector for a spherical object and a method therefor capable of improving the performance and the workability of inspection.

[0009]

According to the present invention, for example, a pair of ring array probes in which a large number of ring-shaped transducers are concentrically arranged are used, and a method of forming the center of an object and an ultrasonic wave incident point on the object is used. Arranged on the line as a target, adjusting the excitation timing of each transducer to focus signals with high ultrasonic intensity, and transmit / receive to / from the incident point of the spherical object so that ultrasonic waves propagate on the surface of the object. Let Further, while holding such a pair of probes facing each other, ultrasonic transmission / reception is repeatedly performed while rotating around a normal line formed by the center of the subject and the ultrasonic wave incident point by a predetermined angle. .

Further, in the flaw detection on the entire surface of the spherical object, the defect echo detected in each flaw detection line is as follows:
By obtaining the measurement conditions such as the detection time and the sound velocity in the subject, the defect position can be detected with high accuracy, and the amplitude intensity data of the defect detection echo can be collated with the previously obtained distance amplitude configuration curve. Also, measure the defect size.

[0011]

According to the ultrasonic flaw detection apparatus for a spherical object and the method therefor according to the present invention, the ultrasonic wave incident angle, which is one of the flaw detection conditions, can be obtained very easily and highly accurately. Further, by performing flaw detection while rotating around a normal line formed by the center of the subject and the ultrasonic wave incident point at a predetermined angle, the entire surface of the spherical subject can be flaw-detected, and further, the defect echo detected by the flaw detection. With respect to, the defect position can be measured with high accuracy by the flaw detection line, the detection time of the defect echo, the sound velocity of the subject, and the like. Further, by comparing the amplitude intensity data of the defect echo with the previously obtained distance amplitude configuration curve, the defect size can be measured and the soundness of the product can be secured.

[0012]

Embodiments of the present invention will be described below with reference to FIGS. FIG. 1 shows the overall configuration of an ultrasonic flaw detector for a spherical object according to this embodiment, and FIGS. 2 and 3 show the measurement mechanism section in enlarged detail. 4 to 6 show the operation.

The ultrasonic flaw detector of this embodiment is basically shown in FIG.
As shown in FIG. 2 and FIG. 2, a pair of probes 12 for focusing the ultrasonic waves together on one surface of the fixed spherical object 11.
Are provided in a symmetrical arrangement with respect to the normal line O at the ultrasonic wave incident point P to the spherical subject 11, and at a constant angle such that the ultrasonic incident beam is along the surface of the spherical subject 11. A drive mechanism 13 for rotating each probe 12 around the normal O while maintaining the arrangement and the angle condition,
The spherical subject 1 based on the ultrasonic wave transmission / reception waveform of the probe 12
Control device 1 for detecting defect position and defect shape of No. 1
4 is provided.

More specifically, the probe 12 is constructed so that ultrasonic waves are transmitted and received via a contact medium 15 such as water.
At the bottom of the storage tank 16 for the couplant 14, the spherical object 11
A sheet 17 having excellent acoustic impedance characteristics is provided in order to prevent the leakage of the contact medium 15 and the deterioration of the ultrasonic wave propagation characteristics during contact with the sheet.

The distance a with respect to the normal line O of the pair of probes 12 and the distance b with respect to the subject 11 can be adjusted by mechanisms described later.

The pair of probes 12 can be sequentially and continuously rotated at a predetermined rotation angle θ on the normal line O at the ultrasonic wave incident point while the arrangement thereof is kept constant. There is.

As shown in FIG. 2, each probe 12 is installed inside a cylindrical probe scanning guide 18 whose angle can be changed and is symmetrical with respect to the normal O, and is held by a holding mechanism 19. It is held in place.

Further, a spherical incident angle setting jig 20 is arranged between both the probes 12, and a projecting portion 21 thereof is inserted into a groove portion 22 of the probe scanning guide 18 so that the incident light is set. The incident angle γ can be arbitrarily changed by the vertical movement of the drive rod 23 connected to the tool 20.

Each probe 12 is a ring array probe in which a plurality of different-diameter ring-shaped vibrators 12a are arranged concentrically.

As shown in FIG. 1, the control unit 14 controls the mechanical operation of the probe 12 by controlling the delay time of the excitation timing of each transducer of the probe 12 and the transducer 12, and controls the surface of the spherical object. A pulser group 25 as a control means for focusing the ultrasonic wave on the sound wave incident point P, a receiver group 26 for receiving ultrasonic echoes for each transducer 12a, a CPU 27 for issuing an operation command for these, and a super unit from the receiver group 26. An adding circuit 28 for summing the sound wave echoes to obtain a waveform, an A / D converter 29 for converting the added signals, a storage device 30 for storing the converted signals, and signal processing based on information from the storage device 30 and the CPU 27. It is configured to include an arithmetic processing unit 31 for performing the above and a display device 32 thereof.

Next, the operation will be described.

First, by controlling the excitation timing of the pulsar group 25 shown in FIG. 1 for the transducer 12a of each probe 12, the ultrasonic beam from each probe becomes a spherical object 11.
The light is focused on the incident point P on. Here, the incident angle γ of the ultrasonic beam is an angle α such that the surface wave propagates on the surface of the subject, which is obtained by the following equation (1).

[0023]

## EQU1 ## V1 / sin α = V2 / sin 90 ° (1) where V1 and V2 are the sonic velocities in the contact medium 15 and the spherical object 11, respectively.

With the incident angle α thus set, the probe 1
When the ultrasonic beam UB1 is made incident from one of the two, the ultrasonic beam UB1 propagates on the surface of the spherical object 11 and if there is a defect on the propagation path, the ultrasonic beam UB1 is reflected by the defect and detected as an ultrasonic echo UB2. It is received by the child 12. Further, if there is no defect on the propagation path, it is received by the other side of the probe 12 after making one round of the spherical surface. The same applies when the ultrasonic wave is incident from the other side of the probe 12, and the ultrasonic wave is received by the one side of the probe 12.

While performing such an operation, each probe 1
Reference numeral 2 indicates the same ultrasonic wave transmission / reception as described above while rotating the normal line O formed by the center of the spherical object 11 and the incident point in a state where the relative position is held by a predetermined angle.
Repeat until 60 °.

In this way, the ultrasonic waves received by each transducer 12a are converted into electric signals by the receiver group 26, delayed and added by the adding circuit 28, and then stored via the A / D converter 29. It is sent to the device 30 and stored as ultrasonic waveform data. Further, the neutron waveform data is sent to the arithmetic processing unit 31, and the arithmetic processing of the defect waveform occurrence time t1 and the amplitude value V1 is performed on all the ultrasonic waveform data at the time of flaw detection at the rotation angle θ = 0 to 360 °. Then, the equivalent defect dimension is calculated using the defect position and the evaluation curve obtained in advance. The results of these arithmetic processes and the detected total ultrasonic waveform data can be selectively displayed on the display device 32. This series of ultrasonic wave transmission / reception operations, rotation control of the probe 12, various calculation processes, display of calculation process results, etc.
Controlled by U27.

Here, a method of setting the ultrasonic wave incident angle on the spherical object 11 of the probe 12 will be described with reference to FIG. 4 which is a distribution diagram of the reception intensity with respect to the ultrasonic wave incident angle.

As described above, the probe 12 has a large number of ring-shaped vibrators 12a arranged in an array.
By controlling the excitation timing of the pulsar group 25 in accordance with the command of 7, the ultrasonic beam can be focused and the ultrasonic wave with high energy can be made incident on the incident point P on the spherical object 11. Therefore, while operating the drive rod 23 along the direction of the normal O, the ultrasonic wave transmitted from one of the probes 12 is received by the other side of the probe 12, and the ultrasonic wave reception intensity at that time is calculated. When plotted against the incident angle γ, as shown in FIG. 4, there is an angle at which the reception intensity significantly decreases. This angle is the ultrasonic critical angle, that is, the incident angle γ 0 propagating on the surface of the spherical object 11. With this method,
The incident angle γ on the spherical object 11 can be determined very easily and highly accurately without performing calculation processing.

Next, while the probes 12 are arranged opposite to each other with the normal line O interposed therebetween, the flaw detection of the spherical object 11 is performed in the same manner as above while rotating around the normal line O by a predetermined angle. I do.

FIG. 5 is a schematic diagram relating to flaw detection when the probe 12 is rotated at a predetermined angle.

As shown in the figure, the probe 12 has a spherical test object 11 as an ultrasonic wave propagation path when one of the flaw detection positions is moved by A1, A2, A3 ,. , Along the surface of the probe 12, and the other flaw detection positions of the probe 12 are set to B1, B2, B3.
, And the ultrasonic wave propagation paths when moved at predetermined rotation angles are b1, b2, b3, ... Similarly, the rotation angle θ =
By performing flaw detection in the range of 0 to 360 ° at a predetermined movement angle, it is possible to detect the entire surface of the spherical object 11.

FIGS. 6 and 7 are explanatory views relating to the defect detection of the flaw detection.

When ultrasonic waves are transmitted from the position A1 of the probe 12 and a defect R exists on the propagation path of the ultrasonic wave, a reflection echo from the defect R is detected at the position of the probe A at the time t1. At the probe position B1, ultrasonic waves do not reach and ultrasonic echoes are not detected.

When ultrasonic waves are transmitted from the position B1 of the probe 12, contrary to the above, at the probe position B1, the reflection echo from the defect R is detected at the position of time t2, and At the child position A1, ultrasonic waves do not reach and ultrasonic echoes are not detected.

The defect position detected by such a method is
It can be obtained by the following equations (2) and (3). That is,

[Equation 2]

[Equation 3]

If the distance a1 from the probe 12 to the incident point P and the sound velocity V1 of the contact medium 15 are known, the defect position can be obtained by the following equation (4).

[0037]

[Equation 4]

Further, the defect size can be obtained as an equivalent defect size by previously obtaining a distance amplitude component curve and checking the amplitude value of the detected defect echo with this curve.

According to the above embodiment, a plurality of vibrators 1
A pair of ring array probes 12 in which 2a are arranged in a ring shape are used, and they are arranged in a target with respect to a normal line O formed by the center of the spherical object 11 and its ultrasonic wave incident point P.
By electronically controlling the delay time of the excitation timing of, the signal with a large ultrasonic intensity is focused at a predetermined position, and the ultrasonic wave is transmitted / received to / from the incident point of the spherical object so that the ultrasonic wave propagates. Become. While the pair of probes 12 are held facing each other, ultrasonic waves are transmitted and received while rotating around a normal line O formed by the center of the spherical object 11 and the ultrasonic wave incident point P by a predetermined angle. By repeatedly carrying out, it is possible to detect the entire surface of the spherical object 11.

Therefore, for the defect echo detected on each flaw detection line, if the measurement conditions such as the detection time and the sound velocity of the object are known, the defect position can be detected with high accuracy.
Further, by comparing the amplitude intensity data of the defect echo with the previously obtained distance-amplitude constituent curve, the defect size can be measured and the soundness and reliability of the object product can be ensured.

In the above implementation, the probe 12 is the ring array probe, but a probe having another structure can be applied in the present invention.

For example, as shown in FIG. 8, an array probe 12 'having a plurality of transducers 12b arranged in a line is used to electronically delay the excitation timing of each transducer 12b during transmission and reception. By controlling the time, the ultrasonic wave is focused on the ultrasonic wave incident point P on the surface of the spherical object 11, and the defect and the position of the defect can be measured with high accuracy by performing the same operation as in the above embodiment. Further, it is possible to enable dimension measurement.

Here, the delay time control is set to a large value on the outside as shown in FIG. 8, so that the ultrasonic beam can be controlled to have a narrow directivity over a long distance as compared with the conventional one. To do.

That is, there is a delay time of a semicircle having a radius r1 (r1: 1/2 of the length of the array probe) centered on the transducers 12b at both ends of the array probe 12 '. The characteristics of the ultrasonic beam can be obtained by giving the method.

The array of the transducers of the array probe 12 'can be selected either in the moving direction of the pair of probes or in the direction perpendicular to the moving direction.

[0046]

As described above in detail, according to the present invention, the ultrasonic wave incident angle, which is one of the flaw detection conditions, can be determined very easily and with high accuracy, and the center of the object By performing flaw detection while rotating at a predetermined angle around the normal line formed with the ultrasonic wave incident point, the entire surface of the spherical object can be flaw-detected, and further, regarding the defect echo detected by the flaw detection, the flaw detection line, The defect position can be measured with high accuracy based on the detection time of the defect echo and the sound velocity of the object. Further, by comparing the amplitude intensity data of the defect echo with the previously obtained distance amplitude configuration curve, the defect size can be measured and the soundness of the product can be secured.

[Brief description of drawings]

FIG. 1 is an overall configuration diagram showing an embodiment of an ultrasonic flaw detector for a spherical object according to the present invention.

FIG. 2 is a detailed view showing the sensor section of FIG. 1 in an enlarged manner.

3 is an enlarged perspective view showing an X portion of FIG.

FIG. 4 is an operation explanatory view of the embodiment, showing an ultrasonic wave reception intensity distribution with respect to an ultrasonic wave incident angle.

FIG. 5 is a schematic view of flaw detection when the ultrasonic probe is rotated in the operation explanatory view of the embodiment.

FIG. 6 is an explanatory diagram relating to defect detection of ultrasonic flaw detection in the example.

7 is a diagram showing a pulse signal corresponding to FIG.

FIG. 8 shows another embodiment of the present invention, and is an explanatory diagram of a delay time given to the array probe.

FIG. 9 is an explanatory diagram showing an example of a conventional ultrasonic flaw detection method.

FIG. 10 is an explanatory view showing another example of the conventional ultrasonic flaw detection method.

[Explanation of symbols]

 1, 11 Spherical test object 2 Water 3a Vertical probe 12 Probe 12a Transducer 13 Drive mechanism 14 Control device 15 Contact medium 16 Storage tank 17 Sheet 18 Probe scanning guide 19 Holding mechanism 20 Incident angle setting jig 21 Projection part 22 Groove part 23 Drive rod 24 Controller 25 Pulsar group 26 Receiver group 27 CPU27 28 Adder circuit 29 A / D converter 30 Storage device 31 Arithmetic processing unit 32 Display device A1, A2, A3, ... A flaw detection position a1, a2, a3 , ... Ultrasonic wave propagation path B1, B2, B3, ... flaw detection position O normal line P ultrasonic wave incident point P0 fixed position on the central axis P1 eccentric position R0, R2 defect t1, t2 time UB1 ultrasonic beam UB2 ultrasonic echo V1 , V2 Sound velocity α, γ Incident angle θ Rotation angle

Claims (5)

[Claims] 1. A pair of probes for focusing ultrasonic waves together on one surface of a fixed spherical object in a target arrangement with respect to a normal line at an ultrasonic wave incident point on the spherical object. A driving mechanism for rotating the respective probes around the normal line while maintaining the arrangement and the angular conditions, the ultrasonic incidence beams being provided at a certain angle such that they are along the surface of the spherical object. And a control device for detecting a defect position and a defect shape of the subject based on an ultrasonic wave transmission / reception waveform of the probe. 2. The ultrasonic flaw detector for a spherical object according to claim 1, wherein the probe is a ring array probe provided with a plurality of ring-shaped transducers having different diameters in a concentric arrangement. 3. The ultrasonic flaw detector for a spherical object according to claim 1, wherein the probe is an array probe having a plurality of transducers arranged in parallel. 4. The spherical object according to claim 1, wherein the control device includes control means for focusing ultrasonic waves on an ultrasonic wave incident point on the surface of the spherical object by controlling the delay time of the excitation timing of each transducer. Ultrasonic flaw detector. 5. An ultrasonic flaw detection method for a spherical object using the apparatus according to claim 1, wherein one of a pair of probes is used for transmission and the other is used for reception. While moving the probes at the same time, obtain the intensity distribution of the ultrasonic wave reception waveform, set the ultrasonic wave incident angle from the angle at which the weakest intensity was obtained, and with each probe held oppositely. , The ultrasonic wave is transmitted and received sequentially while rotating around the normal line formed by the center of the spherical object and the ultrasonic wave incident point on the same object, and the entire surface of the spherical object surface is inspected and based on the inspection result. , The flaw detection line, the time of occurrence of the defect echo and the sound velocity in the subject and the subject radius are used to determine the position of the defect, and the amplitude value of the defect is further collated with the distance-amplitude constituent curve previously obtained,
An ultrasonic flaw detection method for a spherical object, which comprises measuring the size of a defect.