JP2747825B2 - Ultrasonic tomography detection method and apparatus - Google Patents

Description

The present invention relates to an ultrasonic tomographic detection method and apparatus, and more particularly, to an ultrasonic tomographic detection method and apparatus, which can be applied to nondestructive inspection of the inside of a structure and is used for determining the quality of a welding nugget. The present invention relates to a preferred ultrasonic tomographic detection method and apparatus.

[Conventional technology]

In general, means for non-destructively inspecting the inside of a structure is known, and there is an inspection device using ultrasonic waves for finding out whether or not welding strength is good, internal flaws, pinholes, and the like. For example, the strength of the spot weld is determined from the nugget, which is configured from the viewpoint that the strength of the spot weld depends on the nugget diameter. This type of method uses transmitted waves for ultrasonic pulses,
There is a method using a reflected wave. In the former case, when the diameter of the nugget is smaller than the diameter of the sensor, the transmitted wave is reduced, and the judgment is made based on the fact that the echo of the ultrasonic wave is equivalent to one sheet of two sheets or two sheets. Is determined.

However, in the former method using a transmitted wave, transmission / reception means must be arranged on both surfaces of the member to be welded,
In addition, since they must be moved synchronously, there is a problem in operability. Usually, a method using a reflected wave that can be measured on one side is often used.

By the way, by its nature, the nugget spreads substantially concentrically with respect to the center line of the electrode tip, and if welding is normal, the diameter of the formed nugget becomes equal to or larger than the diameter of the recess formed by the electrode tip. On the other hand, if the welding is poor, the nugget diameter is small,
No welding occurs at the center of the depression.

When applying the conventional ultrasonic inspection method to the strength inspection of the spot weld, the intensity of the ultrasonic pulse emitted from the probe has a maximum value at the center, and the receiving sensitivity of the probe is also high at the center, The signal at the center of the nugget was superior to other signals, making it difficult to obtain information about the periphery. For this reason, attempts have been made to transmit and receive ultrasonic pulses only to the outer peripheral portion of the nugget. These have a configuration in which an ultrasonic absorber is provided at the center in contact with the transducer at the tip of the probe, the diameter of the absorber is set slightly smaller than the reference diameter of the nugget, and a waveguide is provided around the nugget. The tip of the waveguide is annular, and the ultrasonic waves are efficiently guided to the outer periphery of the nugget.If the nugget is large enough, ultrasonic echoes are generated by the nugget, and If a welded plate is used, it vibrates at a period 2t, twice the thickness t. However, if the welding is poor, an echo is generated on the joint surface of the welding plate, and the received waveform oscillates at t. As a result, the quality of welding can be determined.

[Problems to be solved by the invention]

By the way, in the above-mentioned conventional ultrasonic inspection method, it is necessary to set the diameter of the ultrasonic absorber slightly smaller than the diameter of the nugget, and there is no problem if the nugget reference diameter is always constant. The diameter of the nugget varies depending on the type of the nugget, and there is a disadvantage that the diameter of the absorbent must be changed every time the diameter differs. Also, if the center of the nugget and the center of the ultrasonic absorbing material are not surely matched, even a nugget that meets the standard will be judged to be defective, making it extremely difficult to use it on the actual work site. There is. Furthermore, if there is a welding defect in the center of the nugget, the ultrasonic absorber will hide it,
Even if the inspection result is good, it is not possible to actually detect a failure, and there is also a problem that the inspection lacks reliability.

The present invention focuses on the conventional problems described above, and can reliably and easily determine defects and the like inside a structure such as a welding nugget, and provides an ultrasonic tomographic detection method and apparatus excellent in reliability and workability. The purpose is to provide.

[Means for solving the problem]

In order to achieve the above object, an ultrasonic tomographic detection method according to a first configuration of the present invention includes an ultrasonic sensor that irradiates a pencil beam type ultrasonic signal including a detection target portion such as a welding nugget of a detected member. Scan an arbitrary range, obtain the thickness of the detected member corresponding to the scanning position, calculate the average value of the detected member over the entire scanning range of the obtained thickness, and correspond to the scanning position. The calculated thickness is compared with the calculated average value to detect a defective portion of the detected member. An ultrasonic tomographic detecting apparatus according to a second aspect of the present invention includes an ultrasonic sensor that irradiates a member to be detected with a pencil beam type ultrasonic signal and detects a reflected wave thereof, and detects a scanning distance of the ultrasonic sensor. Based on the position detection sensor, based on the output signal of the ultrasonic sensor, an ultrasonic measurement device that determines the thickness of the detected member, based on signals from the ultrasonic measurement device and the position detection sensor, The thickness of the detected member corresponding to the scanning position is obtained and output as image information, and based on the thickness of the detected member obtained corresponding to the scanning position, a welding nugget or the like of the detected member is obtained. Control means for calculating an average value of an entire scanning range including the detection target portion, and comparing the calculated thickness corresponding to the scanning position with the calculated average value to detect a defective portion of the detected member. And having In which was formed.

[Action]

According to the above configuration, the reflected wave of the pencil-type ultrasonic signal applied to the detected member can be received by the ultrasonic sensor, and the tomographic information of the detected member in the narrowed range can be received. Then, the ultrasonic sensor is caused to scan on the surface of the detected member. On the other hand, the position detection sensor detects the scanning distance along with the scanning of the ultrasonic sensor, and outputs distance information to the control unit together with the tomographic information from the ultrasonic sensor. The control means can calculate the tomographic distance based on the detection signal from the ultrasonic sensor for each scanning unit distance based on the detection signals from both sensors, and output this as image information on a coordinate plane. The display may be performed by displaying the scanning distance on the horizontal axis of the rectangular coordinates and the tomographic distance on the vertical axis, and displaying these on two-dimensional coordinates or three-dimensional coordinates. Therefore, when this is applied to the nugget inspection of a spot weld, if the ultrasonic sensor is scanned along the diameter line of the nugget or the scanning line divided into a matrix, the fault to the boundary surface along the scanning line of the nugget surface is obtained. An image is obtained, and the welded state of the nugget can be directly visually observed.

As described above, the tomographic state of the detected member can be obtained as image information from the tomographic signal by the ultrasonic sensor that transmits and receives the pencil-type ultrasonic signal and the scanning distance signal of the ultrasonic sensor by the position detection sensor. The internal state of the member can be inspected with high reliability and simple inspection work.

〔Example〕

Hereinafter, a specific embodiment in which the ultrasonic tomographic detection method and apparatus according to the present invention is applied to a nugget inspection of a spot weld will be described in detail with reference to the drawings.

As shown in FIG. 1, the ultrasonic tomographic detection apparatus according to the embodiment includes an ultrasonic sensor 10 that scans a member to be detected, and a position detection sensor 12 that detects a scanning distance of the ultrasonic sensor 10. The detection signal from the ultrasonic sensor 10 is output to the ultrasonic measurement device 14, and the parallel interface
The data is output to a computer (control means) 18 via the controller 16. The detection signal from the position detection sensor 12 passes through a pulse output controller 20 and is also transmitted to a computer 18.
Output. Further, the ultrasonic sensor
A light emitting diode for performing signal processing, which will be described later, based on the detection signal from the position detection sensor 12 and the detection signal from the position detection sensor 12 and lighting and displaying the determination result of the inspection nugget is connected to the parallel interface 16 as a determination display unit 22. FIG. 2 shows an example of the actual configuration of the ultrasonic tomographic detector having such a main configuration. That is, this device includes a hand-held sensor 26 that scans the detection target member 24. The hand-held sensor 26 includes the ultrasonic sensor 10, the position detection sensor 12, and the pulse output controller 20, and is a handy type sensor. And The ultrasonic sensor 10 in the hand-held sensor 26 is connected to the computer 18 via the ultrasonic measuring device 14, and the position detection sensor 12 in the hand-held sensor 26 is directly connected to the computer 18. In this case, the pulse output controller 20
Upon receiving the output signal from 44, the built-in oscillator sends a pulse signal corresponding to the scanning distance to the computer 18, and the ultrasonic measuring device 14 detects the ultrasonic signal emitted from the ultrasonic sensor 10 by detecting the member 24 to be detected. The time between the echo reflected on the front surface and the echo reflected on the back surface of the detected member 24 is detected, and the thickness between the same materials is calculated based on a preset sound velocity value in the detected member 24. Is output to the computer 18 via the parallel interface 16 as a binary signal. Computer 18 receiving these signals
Is the main unit 30, image display (CRT) 32, and keyboard 3
The main body 30 is configured to calculate based on the input signal and output and display the image information on the coordinates of the scanning distance and the tomographic thickness on the image display device (CRT) 32.

Here, the specific structure of the hand-held sensor 26 is shown in FIG. 3 and FIG. The hand-held sensor 26 has a casing 36 that can be held by hand, and inside the ultrasonic sensor 10, the position detection sensor 12, the pulse output controller 20,
And a judgment display unit (LED) 22 is attached. That is, the casing 36 is a box-shaped container, and the ultrasonic sensor 10 is built in a state in which the ultrasonic sensor 10 protrudes from the lower surface of the casing so as to be able to expand and contract. The ultrasonic sensor 10 has a cylindrical shape,
A transducer for transmitting and receiving ultrasonic waves is built in the distal end side. A conical ultrasonic guide is provided on the distal end side in contact with the transducer so that the ultrasonic signal becomes a pencil beam as the ultrasonic sensor 10 having a small distal end diameter. Such an ultrasonic sensor 10 is mounted so that the columnar portion is penetrated and mounted on a bracket 38 in a casing 36, and is elastically extended and contracted via a spring 40. With this, the ultrasonic sensor
The tip of 10 can be extended and retracted from the lower surface of the casing 36 by the action of the spring 40.

Further, the casing 36 is provided with the position detection sensor 12 in line with the ultrasonic sensor 10, and this is a roller 42 that is partially protruded from the lower surface of the casing 36 and is rotatably mounted.
And an encoder 44 connected to the roller 42. For this reason, the ON / OFF signal is output from the encoder 44 for every constant rotation amount of the roller 42. This signal is attached to the upper inside position of the casing 36, and is used as an input signal to the pulse output controller 20 having a pulse oscillator. Upon receiving a signal from the encoder 44, the rotation distance of the roller 42, and thus the scanning movement of the ultrasonic sensor 10, A pulse signal corresponding to the distance is output. In this case, in the embodiment, the ultrasonic sensor 10 and the roller 42 are mounted so as to scan in parallel, but the position detection sensor 12 is connected in series with the ultrasonic sensor 10 as shown in FIG. It may be arranged, or a position detection sensor using light or sound may be used as shown in FIG. 4 (C).

The casing 36 has an ON / OFF switch 4 on its side.
6 and a judgment display section (LED) 22 are provided to switch between the start and end of measurement, and to display the judgment result by light emission. In addition, although the tip of the ultrasonic irradiation unit of the ultrasonic sensor 10 is scanned directly by directly contacting the member to be detected, it is necessary to shut off the air from the air so that the irradiation is reliably performed. As shown in the casing
A bellows tank 48 is attached to the upper end of 36, and a tube 50 leading to the tip of the ultrasonic sensor 10 is connected to this.
An ultrasonic transmission agent such as oil or water is supplied between the tip of the ultrasonic sensor 10 and the detected member while the hand-held sensor 26 is scanning. In this case, the bellows tank 48
Alternatively, an ultrasonic transmitting agent may be supplied using a dropper.

Processing of the sensor detection signal by such a hardware configuration is performed as follows.

FIG. 6 is a flowchart for the nugget pressure bonding determination, in which an initial process and a process of inputting a determination value of a pressure bonding range are performed in advance (step 100). The determination value of the crimping range may be a reference value of the nugget diameter of the target welded plate material, and the appropriateness of the nugget is determined by discriminating the magnitude from the reference value. Thereafter, it is determined whether or not the button input of the switch 46 attached to the hand-held sensor 26 (or the key switch input of the keyboard 34) has been performed (step 11).
0), if there is no input, return to step 100 (step 12
0) If the input is confirmed, it enters an infinite loop (step 1)
30). In the infinite loop, it is determined whether the button of the switch 46 of the hand-held sensor 26 has been pressed down (step 14).
0), after confirming the depression, the measured value is taken in from the hand-held sensor 26 (step 150). The reading of the measurement value is performed by associating the measurement pulse signal from the position detection sensor 12 with the ultrasonic pulse signal from the ultrasonic sensor 10 in a 1: 1 correspondence. That is, the computer 18 receives the position pulse signal output from the position detection sensor 12 and the ultrasonic measurement device.
14 takes in the thickness data of the detected member 24 obtained based on the detection signal of the ultrasonic sensor 10 and stores it in the buffer in association with the position pulse signal and the thickness data (step 16).
0), the scanning movement distance of the hand-held sensor 26 based on the data based on the position detection sensor 12, and the image display device (CR
T) An image signal is output from the main body 30 so as to be displayed as a line on 32 (straight line A in FIG. 7).
Then, dummy delay processing of the data taken into the buffer is performed (step 180),
A buffer with a small capacity is time-delayed to prevent data overflow. In this manner, the detection signal is captured during the scanning by the hand-held sensor 26. However, when the scanning by the hand-held sensor 26 is completed, the scanning operator determines that the scanning is completed and turns off the switch 46. As a result, the button OFF is detected in the determination of step 140, the infinite loop is completed, and the process proceeds to the analysis of the captured data (step 200).

The data analysis processing routine in step 200 includes:
First, the average value is calculated from all the measurement data obtained from the ultrasonic measurement device 14 (step 21).
0). This is basically based on the premise that two welded plates are spot-welded.If the nugget depth is greater than the thickness of one welded plate, it can be determined that welding has been performed. Is used as a criterion value of the welding depth. Therefore, when the detected member 24 to be inspected is not spot welding of two plate materials, in this step 210, not the average value, but the reference thickness given by design is input as the set value, and this is set as the judgment reference value. The setting process may be performed. After this processing, the thickness data is displayed as an image (step 220). In this image display, since the position data from the position detection sensor 12 and the thickness data from the ultrasonic measurement device 14 correspond to 1: 1, it can be transferred on two-dimensional coordinates, and the horizontal axis The scanning distance of the hand-held sensor 26 is set, the thickness of the detected member 24 is set on the vertical axis, and the plate thickness value at each position is graphically displayed by a computer algorithm. Then, based on the average value calculated in step 210, it is classified into the average value or more and less than the average value, and color-coded display is performed (steps 240 and 250). The result of such image display is as shown in FIG. 7, which is represented as a set of bar graphs on the two-dimensional coordinates of the scanning distance and the thickness, and the average value M from the measurement start position S to the measurement end position E.
Are displayed in red (solid hatching), and portions lower than the average value are displayed in green (dashed hatching).

After the image display processing based on the measured values in this way, a determination processing is performed as to whether or not the nugget of the detected member 24 has a reference diameter (step 260). In this process, the average value M
The calculation of the range exceeding is performed. Specifically, as shown in FIG. 7, first, the average value M
Then it became less than the mean value M from the position l ₁ that exceeded the position l ₂
The distance L to the distance is determined. That is, in the example shown in the drawing, the portions having an average value M or more are l ₁ to l ₂ and l _{3 to} l _{4. In} these ranges, the thickness is equal to or greater than the thickness of one detected member 24, and the welding is suitable. can be judged to have been performed while the measurement values in the l ₂ to l ₃ between them is smaller than the average value M, it can be determined that the weld defect portion welding is not performed. The nugget has a substantially uniform thickness from the welding start position to the end position if welding is appropriate, and the detected thickness has a value close to the thickness of one detected member 24 if there is a defective portion in the middle. Therefore, it can be said that the distance L corresponds to the actual welding range.

The operation value obtained by this operation is
Is compared with the judgment value input in step (270). The judgment value is a nugget diameter when the spot weld to be inspected has a predetermined strength, and the result is displayed as an image display as “OK” or “NG” according to the magnitude discrimination with the judgment value.
Display as In addition, a signal corresponding to the determination result is simultaneously transmitted to the determination display unit (LED) 22 provided on the hand-held sensor 26 through the parallel interface 16 and output so as to be visually displayed by the inspection operator. (Step 280). When these series of processes are completed, the process returns to the first start in step 290, and waits for the next test start.

According to the embodiment configured as described above, the ultrasonic sensor
Hand-held sensor 26 integrally including 10 and position detection sensor 12
Accordingly, the nugget portion of the detection target member 24 is scanned, and the thickness of the uniform material portion along the scanning direction can be detected by the ultrasonic sensor 10 which emits a pencil beam type ultrasonic signal. Then, by displaying these measured values on the coordinates of the scanning position and the thickness, it is possible to display an image of the tomographic state of the detected member 24. Automatically judge the suitability of the nugget state by comparing it with the judgment value corresponding to the appropriate nugget diameter while clearly displaying the color-coded distinction of the part and the crimping range along the scanning direction. Can be. Therefore, according to this embodiment, anyone can easily perform the nugget inspection simply by scanning the hand-held sensor 26 along the diametrical direction of the nugget portion, and the center of the sensor is positioned at the center of the nugget as in the conventional method. It is possible to provide an ultrasonic tomographic detection apparatus that does not require complicated operations such as positioning and does not have any difficulty in changing an ultrasonic absorber or an ultrasonic guide for each type of nugget. Moreover, even if there is a poor welding portion at the center of the nugget as shown in FIG.
Since there is no occurrence of an inspection omission that misses the center defect, the inspection accuracy can be improved.

In the above embodiment, the case where the nugget portion is scanned on a single straight line by the hand-held sensor 26 has been described. However, the nugget portion may be scanned in a matrix to display an image of the entire nugget of the detection target member 24 as an image. In this method, the measurement site is partitioned in a mesh shape (for example, 60 × 60 mesh), and the hand-held sensor 26 is scanned 60 times vertically and horizontally along each of the partition lines, and the measured value of the intersection is taken into a buffer or a memory. do it. In this case, the scanning means is a hand-held sensor
The hand-held sensor 26 may be automatically scanned by directly attaching the hand-held sensor 26 to the XY scanning device, or the detected member 24 may be moved in a line in a certain direction, and the hand-held sensor 26 may be driven in a direction orthogonal to this. It may be. Then, the latest measured value is fetched by overwriting the measured value at the same point. The data obtained in this manner may be displayed separately for each scanning line, or an elevation angle and an azimuth angle may be input to the main body 30 in a bird's-eye view and three-dimensionally displayed by a computer algorithm.

In the above embodiment, the judgment display unit (LED) 22 is provided on the hand-held sensor 26, and the judgment result is visually displayed at hand. In addition to this, a sound display such as a buzzer is performed. It is also possible. In other words, it is sufficient that the operator can understand visually and audibly when the determination result is NG.
By connecting an audio display means to the output line to the judgment display section (LED) 22, the above can be easily dealt with.

Further, in the above embodiment, an example of nugget inspection has been described, but it goes without saying that this can be applied to various nondestructive tomographic inspections performed using an ultrasonic sensor. Therefore, the present invention can be sufficiently used for application to a flaw detector, an internal inspection of a structure, and the like.

〔The invention's effect〕

As described above, according to the ultrasonic tomographic detection method and apparatus according to the present invention, a member to be detected is irradiated with a pencil beam type ultrasonic signal while scanning the same, and at the same time, a scanning distance is captured from a position detection sensor. Since tomographic data for each scanning position is obtained and displayed by coordinates for determination, the effect of simply and quickly performing high-precision tomographic measurement by simply scanning the detected member is obtained. Can be

[Brief description of the drawings]

FIG. 1 is a block diagram of a main configuration of an ultrasonic tomographic detection apparatus according to an embodiment, FIG. 2 is a perspective view of an actual configuration example, FIG. 3 is a perspective view of a hand-held sensor, and FIG. Figure, 4th
6 (B) and 6 (C) are partial cross-sectional views of another embodiment of the hand-held sensor. FIG. 5 is a cross-sectional view showing a configuration of a means for supplying an air blocking liquid to the tip of the ultrasonic sensor in the hand-held sensor. FIG. 7 is a flowchart of a measurement method, and FIG. 7 is an explanatory diagram of an image display state of a measurement example. 10 ... Ultrasonic sensor, 12 ... Position detection sensor, 14 ... Ultrasonic measuring device, 18 ... Computer (control means), 20 ...
… Pulse output controller, 22 …… Judgment display (LED),
24 ... Detected member, 26 ... Hand-held sensor.

 ──────────────────────────────────────────────────続 き Continuation of front page (72) Inventor Yoshihiro Teranishi 600, Tanakacho, Akishima-shi, Tokyo Showa Aircraft Machinery Co., Ltd. (56) References JP-A-62-293155 (JP, A) JP-A-61- 176850 (JP, A) JP-A-59-97003 (JP, A) JP-A-55-75607 (JP, A) JP-A-62-293154 (JP, A) JP-A-53-21980 (JP, A)

Claims (2)

(57) [Claims] 1. An ultrasonic sensor for irradiating a pencil beam type ultrasonic signal scans an arbitrary area including a detection target portion such as a welding nugget of a detection target member, and a thickness of the detection target member corresponding to a scanning position. The average value of the detected member over the entire scanning range of the determined thickness is calculated, and the thickness calculated corresponding to the scanning position is compared with the calculated average value to calculate the average value of the detected member. An ultrasonic tomographic detection method comprising detecting a defective portion. 2. An ultrasonic sensor for irradiating a member to be detected with a pencil beam type ultrasonic signal to detect a reflected wave thereof; a position detecting sensor for detecting a scanning distance of the ultrasonic sensor; An ultrasonic measuring device that obtains the thickness of the detected member based on the output signal; and a thickness of the detected member corresponding to a scanning position based on a signal from the ultrasonic measuring device and the position detection sensor. And output it as image information, based on the thickness of the detected member obtained corresponding to the scanning position,
Calculate the average value of the whole scanning range including the detection target portion such as the welding nugget of the detected member, compare the thickness obtained corresponding to the scanning position with the calculated average value, and calculate the detected member. Control means for detecting a defective portion of the ultrasonic tomography apparatus.