JP3468573B2 - Defect inspection device for resin mortar composite pipe - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a resin mortar composite tube in which resin mortar is reinforced with glass fiber reinforced plastic and is continuously manufactured . the rack, etc.) to an apparatus for inspecting non-destructively. In a single material such as iron, ceramic or synthetic resin, since the composition is fine and the composition is uniform, attenuation due to reflection when ultrasonic waves pass through the inside is small. . For this reason, it is easy to receive transmitted waves and judge defect flaw detection by transmitted waves. Conventionally, this ultrasonic wave has been used as a method for inspecting internal defects of steel pipes and synthetic resin pipes that are processed products of a single material The internal flaw detection method described above has been put to practical use (see Japanese Patent Application Laid-Open No. 61-233361). On the other hand, with respect to a resin mortar composite material or the like in which a resin mortar is reinforced with glass fiber reinforced plastic, a change in the surface is visually inspected, and an inspection is performed by a manual tapping sound (tone color change). [0004] As described above, the inspection of internal defects in composite materials is still performed visually or by tapping for the following reasons. That is, in general, in a composite material, as shown in FIG. 3, attenuation due to reflection at the layer interface 71 of the composite material is large, and the composition particles 72 are rough and uneven in composition. Is also large. That is, since the composite material does not easily transmit high-frequency sound waves, internal defects cannot be found by conventional nondestructive inspection using ultrasonic waves. [0005] By the way, pipes using a resin mortar composite material composed of two types of composite materials (FRP and resin mortar) have excellent strength characteristics, and therefore are used as underground pipes for water supply / drainage pipes and power cable pipes. It is used buried in.
Therefore, since considerable pressure is applied to the pipe, if there is a small defect in the pipe wall, there is a problem that this defective portion spreads and the pipe itself is damaged. In particular, since repair work due to damage after construction requires a great deal of cost and labor, practical application of non-destructive inspection before construction is strongly desired to prevent such damage accidents. I was The present invention has been made to solve the above problems, and an object of the present invention is to provide a defect inspection apparatus for a resin mortar composite pipe for nondestructively inspecting internal defects of a composite material. [0007] [Means for Solving the Problems] to resolve the above problems
Therefore, the resin mortar composite pipe defect inspection apparatus according to the present invention is a resin mortar that is manufactured continuously and is made of glass fiber reinforced plastic.
Inspect plastic mortar composite tubes reinforced with plastic
A heating device outlet side , located near the surface of the molded resin mortar composite tube , the frequency band is 300
An ultrasonic transmitter for transmitting an ultrasonic wave in the range of 700 KHz (more preferably 400 KHz to 600 KHz) from the surface of the composite tube toward the inside, and the composite tube on the heating furnace outlet side . An ultrasonic receiver that is disposed near the surface and receives the ultrasonic waves transmitted by the ultrasonic transmitter and reflected inside the composite tube , and the reflected wave of the ultrasonic wave transmitted from the ultrasonic transmitter is A configuration is provided that includes a defect detection unit that measures a time until reception by the ultrasonic receiver and detects a portion where the time difference becomes short as a defect portion. The operation of the present invention will be described. Defects of the present invention
In the defect inspection method using the inspection device, the frequency band is 30
Ultrasonic waves in the range of 0-700 KHz are transmitted inward from the surface of the composite material. Then, by measuring a time difference from when the ultrasonic wave is transmitted to when the ultrasonic wave is internally reflected and received, a portion where the time difference becomes short is detected as a defective portion. [0009] loss of acoustic energy in the layers of the composite material as a result of experiments described later, transmission without any problem in rather diffraction of waves on the composition particle, i.e. closely related to the wavelength of the composition grain size and wave ing. Therefore,
The wavelength of the sound wave is reduced by applying the diffraction phenomenon of the sound wave to the composition particles of the composite material to eliminate the reflection (elimination of attenuation) by passing through the wave, and to easily reflect the light at a defective portion (void, poor interlayer adhesion, rack, etc.). By setting (frequency band), a defective portion can be detected. In the present invention, such a frequency band is set to 300 to 700 KHz. [0010] In the defect inspection apparatus of the present invention, the heating furnace outlet side
An ultrasonic transmitter for transmitting an ultrasonic wave having a frequency band in the range of 300 to 700 KHz from the surface of the composite tube toward the inside is disposed near the surface of the molded resin mortar composite tube . Further, an ultrasonic receiver that receives the ultrasonic waves transmitted by the ultrasonic transmitter and reflected inside the composite tube is disposed near the surface of the composite tube on the heating furnace outlet side . And
The defect detection unit measures a time until a reflected wave of the ultrasonic wave transmitted from the ultrasonic transmitter is received by the ultrasonic receiver, and detects a portion where the time difference becomes short as a defective portion. [0011] [Embodiment] Hereinafter, will be explained with reference to an embodiment of the present invention with reference to the accompanying drawings. The defect inspection method using the defect inspection apparatus for a resin mortar composite material according to the present invention has a frequency band of 40.
Ultrasonic waves in the range of 0-600 KHz are transmitted inward from the surface of the composite material. Then, by measuring a time difference from when the ultrasonic wave is transmitted to when the ultrasonic wave is internally reflected and received, a portion where the time difference becomes short is detected as a defective portion. Here, the waveform of the ultrasonic wave is an impulse waveform. [0013] Ultrasonic frequency band 400~600KHz, in the composition particle of the composite material, without being reflected by the transmission wraparound of the diffraction effect (not attenuated), defective portions (voids, interlayer adhesion failure, a rack, etc.), the diffraction This is a wavelength that does not cause wraparound due to the phenomenon. [0014] In this case, the frequency band of the ultrasonic 400-6
When setting to 00 KHz, the present inventors performed the following experiment and confirmed the effectiveness of setting to this range. [0015] Namely, the present inventors have measured the acoustic characteristics of the acoustic impedance and attenuation characteristics of the resin mortar composite materials. [0016] First, a resin mortar composite pipe of the structure shown in FIG. 4, was used as a measurement sample. That is, this resin mortar composite material tube has an outer surface (front surface) and an inner surface (back surface).
Is formed of FRP1, and the space between them is filled with a resin mortar 2 composed of unsaturated polyester resin, silica sand No. 3 and No. 7, and calcium carbonate. In the present embodiment, the composition ratio of each constituent member of the resin mortar 2 is such that the weight ratio is 1 for polyester resin, 10 for silica sand No. 3, 5 for silica sand No. 7, and 1 for calcium carbonate. [0017] Then, in order to examine the acoustic properties of FRP1 and resin mortar 2 individually conducted the following measurements. As a measurement sample, a disk-shaped FRP 1 having a diameter of 160 mm and a resin mortar 2 were prepared, and the sound velocity, the acoustic impedance, and the transmission loss were measured by a transmission method using a measurement system as shown in FIG. As the ultrasonic transmitter 81, a square piezoelectric rubber vibrator having a side of 30 mm was used, and as the ultrasonic receiver, a hydrophone having a diameter of 5 mm was used. [0019] Table 1 shows the measurement results of the acoustic velocity and acoustic impedance of FRP1 and resin mortar 2. [ Table 1] [0021] From this Table 1, FRP1 and resin mortar 2
It can be seen that both sound speeds are faster than water. Further, since these acoustic impedances are not so different from the acoustic impedance of water, FRP1, resin mortar 2,
It can be seen that a significant portion of the sound wave is transmitted at the mutual boundaries of the water. On the other hand, since the acoustic impedance of FRP1 and the resin mortar 2 and the air are greatly different, it is understood that a considerable part of the sound wave is reflected (about 90%) at the boundary between the FRP1 and the air and between the resin mortar 2 and the air. . Further, the measurement results of the transmission loss in FIG.
The thicknesses of the FRP 1 and the resin mortar 2 used for the measurement are 8 mm and 10 mm, respectively. According to the graph shown in FIG. 6, the transmission loss of air has already increased at around 100 KHz, and has a tendency to gradually increase thereafter. The transmission loss of the FRP 1 and the resin mortar 2 is relatively small between 100 KHz and 600 KHz,
In a frequency band higher than around 600 KHz, the transmission loss of the resin mortar 2 starts to increase and approaches the value of air. Further, the transmission loss of the resin mortar 2 is larger than that of the FRP 1 over the entire measurement frequency band. From the measurement results, the frequency band of the sound wave that is transmitted through the FRP 1 and the resin mortar 2 and not transmitted through the air is as follows:
It can be seen that the frequency is from 100 KHz to 600 KHz. Also,
Considering that most of the thickness of the resin mortar composite material tube is occupied by the resin mortar 2, it is considered that the transmission loss of sound waves of the resin mortar composite material tube is dominated by the effect of the resin mortar. In general, a higher measurement frequency is required to improve the measurement resolution, and a frequency of 1 MHz to 10 MHz is often used for ordinary nondestructive inspection. However, in the inspection of the resin mortar composite material tube, it is necessary to use a lower frequency if sufficient S / N is to be obtained. Next, described measurement examples of internal defects by transmission method (the relationship between the transmission frequency and internal defects). The internal defects of a resin mortar composite pipe, F
It often appears in the form of peeling at the boundary between RP1 and resin mortar 2. Therefore, as a model of the internal defect to be detected, a part of the pipe is cut out (the mortar part has a thickness of 4).
0 mm, and the overall thickness is 44 mm), near the boundary between the cut-out block FRP1 and the resin mortar 2,
Samples were prepared in which three drill holes 3 each having a diameter of 8 mm were formed (see FIGS. 7A and 7B). And using this sample,
The relationship between the transmitted wave and the internal defect was examined by applying a sound wave having a frequency of 200 kHz, 400 kHz, or 600 kHz to each sample and receiving the transmitted wave. The result is shown in FIG. [0027] As seen from the results, by using the above acoustic 400 KHz, sufficient resolution can be obtained in detecting defects of 8 mm. That is, in the case of a sound wave having a frequency of 400 KHz or more, since the wraparound phenomenon at the defect portion is small,
Since a small amount of sound waves are transmitted by the wraparound, the amount of attenuation at the defective portion increases. As a result, as shown in FIG. 8, a waveform having a sharp mountain shape at the defective portion is obtained. On the other hand, in the case of a sound wave having a frequency of 200 KHz, the sound wave that has sneak in at the defect portion is also received due to the sneak phenomenon at the defect portion, so that the attenuation amount at the defect portion does not appear so large. Therefore, FIG.
As shown in the figure, since the amount of attenuation at the defective portion is small,
It can be seen that a sound wave having a frequency of 0 KHz cannot sufficiently detect a defect. [0028] Consequently, in order to prevent the influence of waves wrapping around the defect part, as a frequency band of sound waves to be used, it can be seen that 600KHz from 400KHz are preferred. In addition, considering that the size of the defect generated in the resin mortar composite material pipe is usually about 8 mm and that the received signal becomes smaller as the frequency increases, the measurement is performed in the frequency range of 400 KHz to 600 KHz described above. It is preferred to do so. Next, the product was molded in the actual production process, it was measured similar to the above. As shown in FIG. 9, this product is a resin mortar composite material tube having an inner diameter of 150 mm and a wall thickness of 12 mm (the inner mortar portion is 10 mm), and is divided into 32 parts in the circumferential direction. The transmission loss was measured over 150 mm. The measurement frequency was 400 KHz. FIG. 10 shows an example of the measurement result at this time. In this measurement result, the divided piece 31 (addr
In es31), there is a portion 81 where the transmission loss increases at about 50 mm from the base end side in the longitudinal direction. Then, as a result of examining the presence or absence of a defect by cutting the sample at the portion where the large transmission loss occurred, poor adhesion between the FRP and the resin mortar and a crack in the resin mortar were found at such a portion. Although the present inventors also performed X-ray photography prior to the destructive inspection, these defects could hardly be confirmed from the X-ray photograph. From the above measurement results, the effectiveness of the above-described defect inspection method was confirmed. FIG . 1 shows an electrical configuration of the defect inspection apparatus of the present invention. [0034] That is, in the vicinity of the surface of the resin mortar composite material 11 which is molded together with the ultrasonic transmitter 12 for transmitting an ultrasonic wave having a frequency band of 400~600kHz is arranged, near the surface of the composite 11 An ultrasonic receiver 13 that receives the ultrasonic waves transmitted by the ultrasonic transmitter 12 and reflected inside the composite material 11 is disposed near the ultrasonic transmitter 12. Then, the output of the ultrasonic receiver 13 is guided to a time measuring unit 14 that measures a time until the reflected wave of the ultrasonic wave transmitted from the ultrasonic transmitter 12 is received by the ultrasonic receiver 13, The output of the time measurement unit 14 is guided to a defect detection unit 15 that detects a position where the measured time difference becomes short as a defect position. FIG . 2 shows a configuration in the case where the above-described defect inspection apparatus of the present invention is used in an apparatus for manufacturing a resin mortar composite material tube 20. [0036] The manufacturing apparatus so as to rotate around its axis, has a hollow mandrel 22 which is attached to the rotating mechanism 21 in a horizontal state. The mandrel 22 is in a cantilever state such that the tip is a free end that is not supported, and the tip of the mandrel 22 is located in the heating furnace 23. The mandrel 22 has an inner diameter of 1650 mm, for example.
The outer diameter is 1650 mm so as to manufacture the resin mortar composite material tube 20 of FIG. [0038] The mandrel 22, the steel belt 24 of the strip is wound helically. The steel belt 24 has an endless shape and is spirally fed while being spirally wound so as to completely cover the outer peripheral surface of the mandrel 22. And, in the heating furnace 23, it is sequentially sent out from the tip of the mandrel 22. Steel belt 24 sent out from the tip of mandrel 22
Is released into a band-like shape, inserted into the hollow mandrel 22, inserted through the mandrel 22, and returned to the base end of the mandrel 22. The steel belt 24 returned to the base end of the mandrel 22 is spirally wound around the outer peripheral surface of the mandrel 22 again. The steel belt 24 is wound around the mandrel 22 at a predetermined helical angle such that the steel belt 24 is wound around the outer peripheral surface of the mandrel 22 by a distance of 10 cm toward the tip of the mandrel 22. In addition, steel belt 24
The mandrel 22 is rotated so as to move in the axial direction at 6 m / hour. On a steel belt 24 spirally wound on the mandrel 22, a strip-shaped release film 25 is spirally wound and laminated so as to cover the entire steel belt 24. Thus, the steel belt 24 spirally wound on the mandrel 22 and the steel belt 24
A core part 29 is constituted by the release film 25 covering the whole. The reference numeral 26 in the figure denotes the thermosetting resin 2
Reference numeral 27 denotes a supply unit that supplies the resin mortar 2. In the above configuration, the resin mortar composite material tube 20 is manufactured as follows. [0043] That is, on the outer peripheral surface of the wound release film 25 in a spiral shape on the steel belt 24, the thermosetting resin 28 is supplied first from a supply 26 of the upstream side, thereafter, as a reinforcing material The glass paper 32b and the glass strand 32a are wound in this order. That is, the wound glass paper 32b and the glass strand 32
a and the thermosetting resin 28 is impregnated, and the inner peripheral side FRP layer is formed. Thereafter, the resin mortar 2 supplied from the supply device 27 is laminated on the outer peripheral surface of the glass strand 32a impregnated with the thermosetting resin 28. Then, a glass strand 33a as a reinforcing material and a glass paper 33b are wound in this order on the resin mortar layer 2 formed on the glass strand 32a, and thereafter, the thermosetting resin is supplied from the downstream supply unit 26. The resin 28 is supplied, and the thermosetting resin 28 is impregnated into the glass strands 33a and the glass paper 33b to form the outer peripheral side FRP layer. [0045] By heating in this way the resin mortar composite tube 20 formed by the heating furnace 23, so that the resin mortar composite pipe 20 from the outlet side was cured that are taken out one. In the apparatus for manufacturing the resin mortar composite material pipe 20 having such a configuration, the ultrasonic transmitter 12 and the ultrasonic receiver 13 which are the defect inspection apparatuses of the present embodiment include the heating furnace 2.
3 is located on the exit side. Then, an ultrasonic wave having a predetermined frequency is transmitted from the ultrasonic transmitter 12 to the resin mortar composite material tube 20 which is continuously formed, and the reflected wave is transmitted to the ultrasonic receiver 13.
, The internal defect is detected based on the reception level. Since the reflection type transceiver is used, the thickness of the resin mortar composite material tube 20 can be measured. The defect inspection apparatus resin mortar composite material according to the present invention is disposed in the vicinity of the surface of the molded resin mortar composite material, the ultrasonic wave frequency band is within the range of 300~700KHz An ultrasonic transmitter that transmits inward from the surface of the composite material, and is disposed near the surface of the composite material, and receives ultrasonic waves transmitted by the ultrasonic transmitter and reflected inside the composite material. By measuring the time until the reflected wave of the ultrasonic wave transmitted from the ultrasonic wave receiver and the ultrasonic wave receiver is received by the ultrasonic wave receiver, a portion where the time difference becomes short is detected as a defective portion. And a defect detection unit that performs the operation. Ultrasonic waves having a frequency band of 300 to 700 kHz detect reflected waves because the composition particles of the composite material use a diffraction phenomenon to eliminate reflection by wraparound transmission and have a wavelength that is easily reflected at a defective portion. This makes it possible to non-destructively detect a defective portion of the resin mortar composite material.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram showing an electrical configuration of a resin mortar composite material defect inspection apparatus to which a defect inspection method using the defect inspection apparatus of the present invention is applied. FIG. 2 is a schematic configuration diagram of a manufacturing apparatus for a resin mortar composite material pipe using the defect inspection apparatus of the present invention, as viewed from the front. FIG. 3 is a diagram showing a transmission state of an ultrasonic wave in a composite material. FIG. 4 is a partial longitudinal sectional view showing a structure of a composite material. FIG. 5 is a block diagram showing a measurement system for measuring sound speed, acoustic impedance, and transmission loss by a transmission method. FIG. 6 is a graph showing measurement results of transmission loss. FIG. 7 is a view showing a structure of a resin mortar composite material tube used in an experiment. FIG. 8 is a graph showing measurement results of transmission loss at each frequency. FIG. 9 is a view showing a shape of a resin mortar composite material tube formed in a manufacturing process. 10 is a graph showing the results of measuring transmission loss using a sample prepared from the resin mortar composite material tube shown in FIG. [Description of Signs] 1 FRP 2 Resin mortar 11 Resin mortar composite material 12 Ultrasonic transmitter 13 Ultrasonic receiver 14 Time measurement unit 15 Defect detection unit 20 Resin mortar composite material tube

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-4-323553 (JP, A) JP-A-5-45345 (JP, A) JP-A-3-12509 (JP, A) JP-A-61- 233361 (JP, A) JP-A-60-186755 (JP, A) JP-A-60-114741 (JP, A) JP-A-5-157740 (JP, A) JP-A-57-168555 (JP, A) (58) Field surveyed (Int. Cl. ⁷ , DB name) G01N 29/00-29/28 B29C 67/12-67/18

Claims (1)

( 1) Claims 1. An apparatus for inspecting a resin mortar composite pipe in which a resin mortar is continuously produced and reinforced with a glass fiber reinforced plastic for inspecting a defect, wherein the molding is performed at a heating furnace outlet side. An ultrasonic transmitter that is disposed near the surface of the resin mortar composite tube , and transmits an ultrasonic wave having a frequency band within a range of 300 to 700 KHz from the surface of the composite tube toward the inside, and the heating furnace outlet side. An ultrasonic receiver that is disposed near the surface of the composite pipe and receives ultrasonic waves transmitted by the ultrasonic transmitter and reflected inside the composite pipe; and reflection of the ultrasonic waves transmitted from the ultrasonic transmitter. A resin mortar composite comprising: a defect detection unit that measures a time until a wave is received by the ultrasonic receiver to detect a portion where the time difference becomes short as a defect portion. Pipe defect inspection equipment.