JP7757328B2 - Non-destructive testing device, method and program - Google Patents

Description

Embodiments of the present invention relate to non-destructive testing technology using ultrasonic flaw detection testing.

To reduce friction, the metal surfaces of axle sliding surfaces in power plants are coated with materials such as white metal, PEEK (polyether ether ketone), and PTFE (polytetrafluoroethylene). Abnormalities in these axle sliding surfaces are typically detected by detecting the presence or absence of abnormal noises that occur due to shaft vibration.

If an abnormality occurs in the axle sliding surface, it is only when an abnormal noise or other problem is detected that plant operations are stopped and an appropriate response is made. For this reason, in order to improve the reliability and availability of power plants, it is important to regularly inspect the coating parts and ensure their integrity.

Currently, inspections of coatings on axle sliding surfaces are limited to surface observations, and internal inspections are not generally carried out. This is because the probability of defects occurring inside the coating is considered low. However, one known technique for observing coatings is to use a scanning ultrasonic probe to predict wear at the joint surface between the boss and bush of large rotating equipment from the reflection of ultrasonic waves before an abnormal condition occurs.

Japanese Patent Application Laid-Open No. 2001-227935

Ultrasonic testing or radiographic testing could be used to inspect the entire coating on the axle sliding surface. However, due to structural constraints and the shape, it is difficult to apply radiographic testing, so the application of ultrasonic testing is being considered.

However, when applying ultrasonic flaw detection testing to coated parts, the following issues arise: (1) Because the thickness of the coated part is only a few millimeters, the influence of multiple echoes is significant. (2) When applying angle beam testing, flaw detection testing is difficult because the sound speed in resin materials is slower than that in metal materials. (3) Because the coated part is bonded to the metal surface, it has a complex structure.

The known technology using the scanning ultrasonic probe described above determines the state of separation at the joint surface between the boss and bushing from the reflected intensity of ultrasonic waves. However, this known technology only determines the state of the contact surface of the coating, making it difficult to detect internal defects.

Embodiments of the present invention have been made in consideration of these circumstances, and aim to provide a non-destructive testing technology that can easily detect internal defects in resin-coated areas using ultrasonic flaw detection testing.

A non-destructive inspection device according to an embodiment includes a transmitter that oscillates a transducer mounted on a probe to transmit an ultrasonic beam; a receiver that receives echo waveforms of the ultrasonic beam incident on a resin layer coated with a regular uneven structure; a first identifier that identifies, among the echo waveforms, those originating from the incident surface of the resin layer as first reference signals; a second identifier that identifies, among the echo waveforms, those received regularly in the surface direction at a common depth position in the resin layer as second reference signals originating from the uneven structure; and an extractor that extracts, among the echo waveforms, those received in the beam path between the first and second reference signals as defect signals.

Embodiments of the present invention provide a non-destructive testing technique that can easily detect internal defects in resin-coated areas using ultrasonic flaw detection testing.

1 is a block diagram of a non-destructive testing device that performs ultrasonic flaw detection testing on a resin layer coated with a regular uneven structure in a first embodiment of the present invention. Cross-sectional image showing the results of ultrasonic testing of a resin layer. 1 is a graph showing the echo waveform of an ultrasonic beam, with the horizontal axis representing the propagation time of the beam path and the vertical axis representing the intensity. FIG. 1 is a perspective view of a punched metal that forms a regular uneven structure on the axle sliding surface. FIG. 10 is a block diagram of a non-destructive testing device that performs ultrasonic flaw detection testing on a resin layer coated with a regular uneven structure in a second embodiment. 3 is a flowchart illustrating the steps of a nondestructive inspection method according to an embodiment and an algorithm of a nondestructive inspection program.

(First embodiment)
Embodiments of the present invention will now be described with reference to the accompanying drawings. Fig. 1 is a block diagram of a non-destructive testing device 10A (10) according to a first embodiment of the present invention, which performs ultrasonic testing on a resin layer 30 coated with a regular uneven structure 31. Fig. 2 is a cross-sectional image showing the results of ultrasonic testing on the resin layer 30. Fig. 3 is a graph showing an echo waveform 20 of an ultrasonic beam 26, with the horizontal axis representing the propagation time of the beam path 35 (A) to (I) and the vertical axis representing intensity.

As shown in FIG. 1, the nondestructive testing device 10 includes a transmitter 17 that oscillates a transducer 25 attached to a probe 27 to transmit an ultrasonic beam 26; a receiver 18 that receives an echo waveform 20 of the ultrasonic beam 26 incident on a resin layer 30 coated with a regular uneven structure 31; a first identifier 11 that identifies, as a first reference signal 21, the echo waveform 20 originating from the incident surface 32 of the resin layer 30; a second identifier 12 that identifies, as a second reference signal 22 originating from the uneven structure 31, the echo waveform 20 received at a common depth position in the resin layer 30 and regularly in the surface direction; and an extractor 13 that extracts, as a defect signal 23, the echo waveform 20 received on a beam path 28 sandwiched between the first reference signal 21 and the second reference signal 22.

Non-destructive testing using ultrasonic beams 26 is widely used to evaluate defects, voids, peeling at joints, and other conditions within structures and parts being inspected. The echo waveform 20, which is the reflection of the ultrasonic beam 26 incident on the resin layer 30 being inspected, originates from three sources: the surface (incident surface 32) of the resin layer 30, the defect 33, and the interface (uneven structure 31). Detecting the defect 33 requires processing to focus on and extract the defect signal 23 from the echo waveform 20. Then, by detecting the intensity and timing of this defect-derived defect signal 23, information such as the position and size of the defect 33 in the resin layer 30 being inspected is visualized.

The probe 27 consists of a vibrator 25 made of a piezoelectric element and a wedge-shaped shoe 29, and is placed in close contact with the surface (incident surface 32) of the resin layer 30 to be inspected, via an acoustic couplant (not shown), which is a liquid acoustic medium. The propagation speed of the ultrasonic beam 26 through the resin layer 30 is slower than that of ordinary metals. Therefore, the wedge-shaped shoe 29 is preferably made of a material in which a liquid or gel acoustic medium is enclosed in a case, or a molded resin (whether or not made of the same material as the resin layer 30).

By using a material for the wedge-shaped shoe 29 that has a sound velocity similar to that of the resin layer 30, highly accurate non-destructive testing using angle beam testing can be achieved. When using PTFE (polytetrafluoroethylene; longitudinal wave sound velocity: 1490 m/s) for the resin layer 30, it is preferable to use a gel-like acoustic medium (sound velocity: 1410 m/s) for the shoe 29. Furthermore, in the first embodiment, the probe 27 is designed to perform flaw detection over a wide area of the resin layer 30 by manually scanning the incident surface 32.

The transmitter 17 oscillates the transducer 25 provided on the probe 27 to transmit an ultrasonic beam 26. When the ultrasonic beam 26 enters the resin layer 30, the first reference signal 21 is reflected from the incident surface 32 and the second reference signal 22 is reflected from the uneven structure 31. If a defect 33 is present in the beam path 35, the beam is reflected there and detected by the transducer 25 as a defect signal 23.

The receiver 18 (Figure 1) receives the echo waveform 20 output by the transducer 25 after detecting the reflection of the ultrasonic beam 26. The echo waveform 20 output from the transducer 25 as a weak analog signal is received by the receiver 18, amplified, and then converted into a digital signal.

The first identification unit 11 identifies the echo waveform 20 that originates from the incident surface 32 of the resin layer 30 as the first reference signal 21. Specifically, after the oscillator 25 is oscillated, the first signal detected in the echo waveform 20 is identified as the first reference signal 21.

The second identification unit 12 identifies the echo waveforms 20 that are received regularly in the surface direction at the same depth position in the resin layer 30 as second reference signals 22 originating from the uneven structure 31. The second reference signal 22 observed in an uneven structure 31 such as punched metal (Figure 4) has double peaks in the echo waveform 20 as shown in the figure due to a slight time lag between reflections from the corners of the upper surface and those from the corners of the lower surface. The second reference signal 22 can also be identified based on such double peaks.

The extraction unit 13 sets the boundary of the first reference signal 21 of the echo waveform 20 to the incident surface 32 of the resin layer 30, and sets the boundary of the second reference signal 22 to the interface with the uneven structure 31. Then, it extracts the defect signal 23 detected in the region sandwiched between both ends of the boundary set in the beam path 28. This allows for highly sensitive detection of defects 33 in the resin layer 30 without being affected by noise such as reflection from the uneven structure 31.

The imaging unit 19 generates a cross-sectional image along the depth direction of the resin layer 30 or a perspective image from the incident plane 32 based on the defect signal 23. That is, it displays an echo waveform 20 (Figure 3), generally called an A-scope, a cross-sectional image of the resin layer 30, called a B-scope (Figure 2), and a planar perspective image of the resin layer 30, called a C-scope (not shown). To obtain the images of Figures 2 and 3, a scanning means (not shown) for the probe 27 and a position recognition means (not shown) for identifying the starting points of each beam path 35 (A) to (I) are required.

Figure 4 is a perspective view of a perforated metal that forms a regular uneven structure 31 on the axle sliding surface. On the axle sliding surface, perforated metal or wire is bonded onto a steel material, and then a resin layer 30 is coated on top of that. By coating this regular uneven structure 31, peeling of the resin layer 30 due to sliding is suppressed.

Note that, although punched metal is used as an example of the regular uneven structure 31 for coating the resin layer 30, this is not a limitation. As long as the surface to be bonded to the coating material has a regular uneven shape, structures such as regularly arranged wires are also applicable. Furthermore, examples of materials for the resin layer 30 include PTFE (polytetrafluoroethylene), but this is not particularly limited.

Second Embodiment
Next, a second embodiment of the present invention will be described with reference to Fig. 5. Fig. 5 is a block diagram of a non-destructive testing device 10B (10) for performing ultrasonic flaw detection testing on a resin layer 30 coated with a regular uneven structure 31 in the second embodiment.

The non-destructive testing device 10B of the second embodiment has a configuration in which at least one of an electronic scanning unit 16 and a mechanical scanning unit 14 is added to the configuration of the first embodiment described above. In the second embodiment, the probe 27 automatically performs flaw detection over a wide area of the resin layer 30 by electronically and mechanically scanning the incident surface 32. Note that in Figure 5, parts that have the same configuration or function as Figure 1 are indicated by the same reference numerals, and duplicate explanations will be omitted.

The probe 27 of the second embodiment has multiple transducers 25 arranged in a linear or matrix array. By adjusting the delay time of the oscillation timing of adjacent transducers 25, the incident direction and focal length of the ultrasonic beam 26 can be set arbitrarily. The setting unit 15 then sets the scanning conditions, such as the incident direction.

The electronic scanning unit 16 adjusts the oscillation timing to scan the ultrasonic beam 26 emitted from the array of transducers 25. The electronic scanning unit 16 also calculates the delay time for the oscillation timing of the transducers 25 based on input from the setting unit 15. The transmission unit 17 transmits a pulse signal 36 to each transducer 25 to cause it to oscillate, based on the delay time calculated by the electronic scanning unit 16.

The mechanical scanning unit 14 scans the ultrasonic beam 26 by mechanically moving the probe 27. The probe 27 is connected to a drive unit 37 that mechanically moves along the incident surface 32. The drive unit 37 scans the probe 27 on the incident surface 32 based on a drive signal 38 transmitted from the mechanical scanning unit 14. Although the probe 27 is shown moving only one-dimensionally, it can also be moved two-dimensionally.

In the second embodiment, the ultrasonic beam 26 can be scanned by mechanically moving a probe 27 equipped with a single transducer 25, rather than an array.

The steps of the non-destructive testing method according to the embodiment and the algorithm of the non-destructive testing program will be described based on the flowchart in Figure 6 (see Figures 1 and 5 as appropriate). First, the transducer 25 attached to the probe 27 in contact with the incident surface 32 is oscillated (S11), causing an ultrasonic beam 26 to be transmitted (S12). Then, the echo waveform 20 reflected by the ultrasonic beam 26 incident on the resin layer 30 is received (S13).

Next, the echo waveform 20 originating from the incident surface 32 of the resin layer 30 is recognized as a first reference signal 21 (S14). Then, the echo waveform 20 received at a common depth position in the resin layer 30 and regularly in the surface direction is recognized as a second reference signal 22 originating from the uneven structure 31 (S15). Furthermore, the echo waveform 20 received at the beam path 28 between the first reference signal 21 and the second reference signal 22 is extracted as a defect signal 23 (S16). Then, a longitudinal cross-sectional image or a planar perspective image of the resin layer 30 is generated based on the defect signal 23 (S17, END).

With at least one of the embodiments of the non-destructive testing device described above, it is possible to easily detect internal defects in resin-coated sections by recognizing echo waveforms from ultrasonic testing that are received at a common depth position and regularly in the surface direction as originating from the uneven structure of the interface.

While several embodiments of the present invention have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These embodiments may be embodied in a variety of other forms, and various omissions, substitutions, modifications, and combinations may be made without departing from the spirit of the invention. These embodiments and their variations are within the scope of the invention and its equivalents as defined in the claims, as well as the scope and spirit of the invention.

The nondestructive testing device described above includes a control device with a highly integrated processor, such as a dedicated chip, FPGA (Field Programmable Gate Array), GPU (Graphics Processing Unit), or CPU (Central Processing Unit), a storage device such as ROM (Read Only Memory) or RAM (Random Access Memory), an external storage device such as HDD (Hard Disk Drive) or SSD (Solid State Drive), a display device, an input device such as a mouse or keyboard, and a communication interface. This allows for hardware configuration using a standard computer. Therefore, the components of the nondestructive testing device can also be implemented using a computer processor and can be operated by a nondestructive testing program.

The non-destructive testing program may also be provided pre-installed in a ROM or the like. Alternatively, the program may be provided stored in an installable or executable file format on a computer-readable storage medium such as a CD-ROM, CD-R, memory card, DVD, or flexible disk (FD).

The non-destructive testing program according to this embodiment may also be stored on a computer connected to a network such as the Internet and provided by downloading it via the network. The non-destructive testing device may also be configured by combining separate modules that independently perform the functions of their components and interconnecting them via a network or dedicated lines.

10...Non-destructive testing device, 11...First qualification unit, 12...Second qualification unit, 13...Extraction unit, 14...Mechanical scanning unit, 15...Setting unit, 16...Electronic scanning unit, 17...Transmitting unit, 18...Receiving unit, 19...Imaging unit, 20...Echo waveform, 21...First reference signal, 22...Second reference signal, 23...Defect signal, 25...Transducer, 26...Ultrasonic beam, 27...Probe, 28...Beam path, 29...Shoe, 30...Resin layer, 31...Uneven structure, 32...Inciding surface, 33...Defect, 35...Beam path, 36...Pulse signal, 37...Driver, 38...Drive signal.

Claims (7)

a transmitter that oscillates a transducer provided in the probe to transmit an ultrasonic beam;
a receiving unit that receives an echo waveform of the ultrasonic beam that is incident on a resin layer coated with a regular uneven structure;
a first determination unit that determines, among the echo waveforms, a waveform originating from the incident surface of the resin layer as a first reference signal;
a second identification unit that identifies, among the echo waveforms, those that are received at a common depth position in the resin layer and are regularly received in a surface direction as second reference signals derived from the uneven structure;
an extractor that extracts, from the echo waveform, one received in a beam path between the first reference signal and the second reference signal as a defect signal. 2. The non-destructive inspection device according to claim 1,
A non-destructive testing device comprising an electronic scanning unit that scans the ultrasonic beam by adjusting the oscillation timing of each of the plurality of transducers arranged in an array. 3. The non-destructive inspection device according to claim 1 or 2,
A non-destructive testing device comprising a mechanical scanning unit that moves the probe to scan the ultrasonic beam. 4. The non-destructive inspection device according to claim 3,
A non-destructive inspection device including an imaging unit that generates a cross-sectional image along the depth direction of the resin layer or a perspective image from the incident surface based on the defect signal. a step of oscillating a transducer provided in the probe to transmit an ultrasonic beam;
receiving an echo waveform of the ultrasonic beam incident on a resin layer coated with a regular uneven structure;
identifying, among the echo waveforms, one originating from the incident surface of the resin layer as a first reference signal;
a step of identifying, among the echo waveforms, those that are received regularly in a surface direction at a common depth position in the resin layer as second reference signals derived from the concavo-convex structure;
and extracting, from the echo waveforms, those received in a beam path between the first reference signal and the second reference signal as defect signals. 6. The non-destructive inspection method according to claim 5,
A non-destructive inspection method in which the regular uneven structure is formed on the sliding surface of an axle. On the computer,
a step of oscillating a transducer provided in the probe to transmit an ultrasonic beam;
receiving an echo waveform of the ultrasonic beam incident on a resin layer coated with a regular uneven structure;
identifying, among the echo waveforms, one originating from the incident surface of the resin layer as a first reference signal;
a step of identifying, among the echo waveforms, those received regularly in a surface direction at a common depth position in the resin layer as second reference signals derived from the concavo-convex structure;
extracting, from the echo waveforms, those received in a beam path between the first reference signal and the second reference signal as defect signals.