JP2021162383A - Resin pipe fusion joint inspection device - Google Patents

Abstract

To provide a resin pipe fusion joint inspection device which enables accurate and quick inspection of resin pipe fusion joints.SOLUTION: A resin pipe fusion joint inspection device is provided, comprising: an inspection head 3 configured to irradiate a resin pipe fusion joint connecting two fusion-bonded resin pipes with a terahertz wave and receive reflections of the terahertz wave reflecting from the resin pipe fusion joint; and a head supporting device 4 for supporting the inspection head 3, the head supporting device 4 being configured to support the inspection head 3 in such a way that the position of a resin pipe 1 can be changed in circumferential and axial directions and that the distance to the resin pipe 1 can be changed in a radial direction.SELECTED DRAWING: Figure 2

Description

The present invention relates to an inspection device for inspecting the soundness of a connected state in a resin pipe fusion portion in which resin pipes are fused and connected to each other.

For example, resin pipes made of polyethylene or the like are used for pipes for city gas and water services buried underground. As a method for connecting such resin tubes, there are a butt fusion method and an electric fusion method used for a resin tube having a relatively large diameter. The butt fusion method is a method in which the connecting ends of two resin pipes are butt-bonded while being heated and melted. The electric welding method (sometimes referred to as an EF joining method) is a method in which the ends of two resin pipes are inserted into a connecting pipe in which a coiled heating wire is embedded and welded by heating the heating wire.

In the resin pipe fusion part where the resin pipes are fused and connected in this way, when air bubbles are generated inside, or the mud adhering to the surface of the pipe remains as it is inside the resin pipe. There are cases. If there is such an abnormal part inside, there is a risk that a crack will enter from that part, the fused part will be damaged, and gas or tap water will leak out. Therefore, it is necessary to inspect such abnormal parts in a non-destructive state.

Conventionally, as an inspection device for inspecting such an abnormal portion of a fused portion, for example, there is one described in Patent Document 1. That is, the transmission unit (transmission probe) that transmits ultrasonic waves to the resin tube fusion unit and the reception unit (reception probe) that receives the ultrasonic waves reflected from the resin tube fusion unit are combined with the resin tube fusion unit. It is arranged so that it is distributed to both sides with the wearing part in between and in contact with the outer surface of the resin tube, and it is configured to inspect the inside based on the received information of the receiving part, and ultrasonic waves are efficiently transmitted. The receiving unit is supported so as to be repositionable in the axial direction of the resin tube so that it can be received (see, for example, Patent Document 1).

Japanese Unexamined Patent Publication No. 11-258215

Since the transmission speed of ultrasonic waves differs between the air and the inside of the resin, in the inspection device using ultrasonic waves as in the above conventional configuration, in order to measure accurately, the measuring parts such as the transmitting part and the receiving part are inspected. It must be inspected in contact with the surface of the target resin tube. As a result, even if the receiving unit is made as close as possible to the transmitting unit, there are places in the area of the resin tube fusion unit that are close to the transmitting unit and the receiving unit, and ultrasonic waves cannot pass through. There was a disadvantage that it was not possible to inspect all areas of the above with high accuracy.

Further, in the above-mentioned conventional configuration, the transmitting unit and the receiving unit are separately arranged on both sides of the resin tube fusion unit, and the ultrasonic waves transmitted from the transmitting unit pass through the resin tube fusion unit to the receiving unit. It is necessary to perform accurate positioning by hand with the receiving part in contact with the surface of the resin tube so that it can be reached, which has disadvantages such as requiring specialized skills and taking a long inspection time. ..

An object of the present invention is to provide an inspection device for a resin tube fused portion, which can perform an inspection of the resin tube fused portion with high accuracy and in a short time.

The characteristic configuration of the inspection device for the resin pipe fusion portion according to the present invention is that the resin pipe fusion portion connected by fusing the resin pipes to each other is irradiated with a terahertz wave, and the resin pipe fusion portion is described. An inspection head portion that receives the reflected terahertz wave reflected from the inspection head portion and a head support device that supports the inspection head portion are provided.
The head support device supports the inspection head portion so that the position can be changed in the circumferential direction and the axial direction of the resin tube and the separation distance in the radial direction from the resin tube can be changed. It is in the point that it is configured as.

According to the present invention, the resin tube fused portion is inspected using a terahertz wave. Terahertz waves are a type of electromagnetic waves located at the boundary between radio waves and light, and have the properties of radio waves that pass through resin materials, as well as light that has straightness and can be converged by a lens and reflected by a reflector. It has both the properties of.

Therefore, the inspection head portion irradiates the resin tube fusion portion with a terahertz wave, and receives the reflected wave reflected from the resin pipe fusion portion. In the received terahertz wave reception information, not only the reflection from the surface of the resin tube but also, for example, if there is an abnormal part such as air bubbles or foreign matter inside the resin tube, it is reflected from the abnormal part. Therefore, it is possible to determine whether or not an abnormal part exists inside by associating the received information with the passage of time.

As described above, the terahertz wave penetrates not only in the air but also inside the resin material like the radio wave, so that the measurement can be performed even if the transmitting part and the receiving part of the terahertz wave are separated from the resin tube. There is no need to perform measurement work while the inspection head is in contact with the resin tube, and work can be performed efficiently. Further, even if the inspection head portion is separated from the resin tube, the measurement accuracy does not deteriorate.

Since the head support device supports the inspection head so that the position can be changed in the circumferential direction and the axial direction of the resin tube, the location where the inspection head irradiates the resin tube fusion portion with the terahertz wave is arranged in the circumferential direction. Inspection can be performed while changing the position in the axial direction. As a result, it becomes possible to perform an accurate inspection over a wide area in the resin pipe fusion portion.

Further, since the head support device supports the inspection head portion in a state where the distance between the head support device and the resin tube in the radial direction can be changed, the head support device supports the inspection head portion in a wide range in the radial direction from the outer peripheral surface to the inner peripheral surface of the resin tube. , It is possible to perform inspection with high accuracy.

Therefore, it has become possible to provide an inspection device for the resin pipe fusion part, which can perform the inspection for the resin tube fusion part with high accuracy and in a short time.

In the present invention, the head support device is
A circular support that is located on the outer side in the radial direction of the resin tube, extends over the entire circumference, and can be divided into a plurality of units along the circumferential direction.
A radial position adjusting mechanism capable of adjusting the position of the inspection head portion along the radial direction with respect to the support,
In a state where the relative position of the inspection head portion can be changed and adjusted along the circumferential direction with respect to the support, and the radial separation distance between the resin tube and the support is maintained constant. , Supporting circumferential position adjustment mechanism,
The support is supported with respect to the resin tube in a state where the position can be changed and adjusted along the axis direction and the radial separation distance between the resin tube and the support is maintained constant. It is preferable to have an axial center direction position adjusting mechanism.

According to this configuration, the support is supported in a state where the radial separation distance from the resin tube is maintained constant. The inspection head portion is supported so as to be movable along the circumferential direction with respect to the support. That is, the inspection head portion can be moved along the circumferential direction while the radial separation distance from the resin tube is maintained constant.

By moving the support in the axial direction with respect to the resin tube while maintaining the position of the inspection head in the circumferential direction with respect to the support, the inspection head is moved in the circumferential direction of the resin tube. Can be moved to. Further, the position of the inspection head portion can be changed in the radial direction with respect to the support.

As a result, the inspection work can be efficiently performed while changing the positions of the inspection head portion in the circumferential direction and the axial direction, and the work of changing the radial separation distance from the resin pipe is also possible. You can do it efficiently.

In the present invention, the inspection head portion includes an irradiation portion that irradiates a detected portion of the resin tube fusion portion with a terahertz wave in a direction orthogonal to the surface of the resin tube, and the detection target portion. It is preferable that the receiving unit that receives the terahertz wave reflected from the location in the direction orthogonal to the surface of the resin tube is housed in the same housing.

According to this configuration, since the irradiation unit and the receiving unit are housed in the same housing, the entire inspection head unit can be housed in a compact shape, and the relative positions of the irradiation unit and the receiving unit are always the same. Since the state is maintained, a good state can be maintained without deteriorating the measurement accuracy.

In the present invention, it is preferable that the irradiation unit converges the terahertz wave and irradiates the detected portion with a small diameter irradiation range.

According to this configuration, since the terahertz wave is irradiated in a small diameter irradiation range, even if a small defect exists as an abnormal part inside the resin tube, the defect can be detected accurately. It becomes.

It is a front view of the inspection apparatus of a resin pipe fusion part. It is a side view of the inspection apparatus of a resin pipe fusion part. It is a side view of the inspection head part. It is a control block diagram. It is a figure which shows the received data. It is sectional drawing which shows the measurement principle. It is a figure which shows the tomographic image. It is sectional drawing of the resin tube fusion part by the electric fusion method. It is a figure which shows the received data. It is a figure which shows the tomographic image. It is a figure which shows the data of the wavelet transform. It is a figure which shows the image after conversion.

Embodiments of the present invention will be described with reference to the drawings.
1 and 2 show an inspection device for a resin pipe fusion portion according to the present invention. This inspection device is for inspecting the soundness of the resin tube fusion section 2 in which the resin tubes 1 made of a synthetic resin material such as polyethylene are fused to each other by the butt fusion method. The resin pipe fusion portion 2 is formed by abutting the rear end of one resin pipe 1 and the front end of the other resin pipe 1 and crimping them while heating and melting.

As shown in FIG. 1, this inspection device irradiates the resin tube fusion section 2 with a terahertz wave and receives the reflected wave of the terahertz wave reflected from the resin tube fusion section 2. A head portion 3 for inspection and a head support device 4 for supporting the head portion 3 for inspection are provided.

This inspection device irradiates the resin tube fusion section 2 with a terahertz wave, receives the reflected terahertz wave reflected from the resin tube fusion section 2, and uses the received terahertz wave reception information as the received information. Based on this, it is a device for evaluating the soundness of the resin tube fusion section 2.

As shown in FIG. 3, the inspection head unit 3 includes an irradiation unit 5 that irradiates a detected portion of the resin tube fusion unit 2 with a terahertz wave in a direction orthogonal to the surface of the resin tube 1. The receiving unit 6 that receives the terahertz wave reflected from the detected portion in the direction orthogonal to the surface of the resin tube 1 is housed in the same housing 3A. The irradiation unit 5 irradiates a pulsed terahertz wave (hereinafter, referred to as a terahertz pulse wave) including a frequency of 0.1 to 2.5 THz (terahertz).

Further, the inspection head unit 3 has a lens 7 that converges the terahertz wave emitted from the irradiation unit 5 and the reflected terahertz wave, and a receiver unit 6 reflects a part of the reflected terahertz wave. A beam splitter 8 for guiding is provided. The terahertz wave irradiated from the irradiation unit 5 is converged by the lens 7 so as to form a spot portion having a small diameter. The diameter of the spot portion of the terahertz wave irradiated to the detected portion is preferably about 1 mm to several mm.

The head support device 4 supports the inspection head portion 3 so that the position can be changed in the circumferential direction and the axial direction of the resin tube 1 and the separation distance in the radial direction from the resin tube 1 can be changed. It is configured as follows. That is, the head support device 4 is supported by a circular support 9 that is located on the radial outer side of the resin tube 1, extends over the entire circumference, and can be divided into a plurality of units along the circumferential direction. The position of the inspection head 3 is changed along the radial direction with respect to the body 9, and the relative position of the inspection head 3 is changed along the circumferential direction with respect to the support 9 and the radial position adjusting mechanism T3. The circumferential position adjusting mechanism T2 that supports the resin tube 1 and the support 9 with respect to the resin tube 1 are adjustable and the radial distance between the resin tube 1 and the support 9 is maintained constant. A shaft-core direction position adjusting mechanism T1 that supports the resin tube 1 and the support 9 in a state where the position can be changed and adjusted along the shaft-core direction and the radial separation distance between the resin tube 1 and the support 9 is kept constant. I have. Hereinafter, a specific configuration will be described.

The head support device 4 is provided with a circular support 9 that is located on the radial outer side of the resin tube 1, extends over the entire circumference, and can be divided into a plurality of units along the circumferential direction. .. Two supports 9 are provided so as to be separated from each other in the axial direction of the resin tube 1. The two supports 9 are integrally connected by four connecting rods 10 provided at intervals in the circumferential direction.

Each of the four connecting rods 10 is provided with two sets of rolling rollers 11 at intervals in the longitudinal direction. The rolling roller 11 is rotatably supported around the axis along the tangential direction of the outer peripheral surface of the resin pipe 1 by the support bracket 12 fixed to the connecting rod 10. The plurality of rolling rollers 11 are provided so as to be in contact with the outer peripheral surface of the resin pipe 1 and to be movable along the axis direction while rolling on the outer peripheral surface.

In this way, the support 9 is supported in a state where a plurality of rolling rollers 11 provided at intervals in the circumferential direction are in contact with the outer peripheral portion of the resin pipe 1, and therefore, between the support 9 and the resin pipe 1. The radial spacing of the is always kept constant. The rolling roller 11 of any of the plurality of rolling rollers 11 is provided with a shaft-core direction drive motor 13, and the rolling roller 11 is rotated by the shaft-core direction drive motor 13 to rotate the rolling roller 11 to make the inspection head portion 3. The entire head support device 4 including the head support device 4 is supported so as to be repositionable in the axial direction of the resin tube 1. As the axial drive motor 13, a servomotor capable of controlling the rotation speed and the rotation angle is used. The shaft-core direction position adjusting mechanism T1 is configured by the support structure of the support 9 by the plurality of rolling rollers 11 and the shaft-core direction drive motor 13.

The support 9 is configured so that it can be attached to and detached from the outer peripheral portion of the long resin tube 1. That is, it is divided into two in the circumferential direction, and at one of the divisions, it is swingably connected by a hinge 14 around the axis X parallel to the axis direction of the resin tube 1, and the other division can be connected and disconnected. It is connected by a connecting device 15.

The inspection head portion 3 is supported so that its relative position can be changed and adjusted along the circumferential direction with respect to one of the supports 9, and the position can be changed and adjusted along the radial direction with respect to the support 9. As shown in FIG. 2, a base portion 16 that is movably supported in the circumferential direction is provided with respect to the support body 9, and the inspection head portion 3 is a resin tube 1 with respect to the base portion 16. It is supported so that it can move relative to the radial direction of. A guide rail portion 17 for guiding the base portion 16 in the circumferential direction is formed on each of the outer peripheral portion and the inner peripheral portion of the support body 9.

The base portion 16 is provided with four guide wheel bodies 18 that can rotate while sandwiching the support 9 from both inside and outside, and one of them is rotationally driven to drive the base portion 16 in the circumferential direction of the resin tube 1. A circumferential drive motor 19 that can be moved along the line is provided. Each guide wheel body 18 is provided with locking collars 20 on both the left and right sides so as to be movable in the circumferential direction while preventing the guide wheels from coming off. On the outer peripheral portion of the guide wheel body 18 driven by the circumferential drive motor 19, the base portion 16 is engaged with the support body 9 while engaging with a rack gear portion (not shown) provided on the outer peripheral portion of the support body 9. A gear portion (not shown) for guiding in the circumferential direction is formed. Although not described in detail, the gear portion and the rack gear portion are gears having a fine pitch, so that the position can be adjusted in the circumferential direction with high accuracy.

As the circumferential drive motor 19, it is preferable to use a servomotor capable of controlling the rotation speed and the rotation angle. A circumferential position adjusting mechanism T2 is configured by a support structure that movably supports the base portion 16 in the circumferential direction and a circumferential drive motor 19.

Between the base portion 16 and the inspection head portion 3, for example, a slide operation mechanism 21 using a rack gear and a pinion gear, and a radial drive motor 22 for driving and operating the slide operation mechanism 21 are provided, and the radial drive motor 22 is provided. By the operation of 22, the inspection head portion 3 can be moved and operated in the radial direction with respect to the base portion 16. That is, the slide operation mechanism 21 and the radial drive motor 22 constitute the radial position adjusting mechanism T3. As the radial drive motor, it is preferable to use a servomotor capable of controlling the rotation speed and the rotation angle.

The rolling roller 11 holds the radial position of the base portion 16 with respect to the support 9 at a fixed position. The diameter of the base portion 16 with respect to the support 9 is maintained by the radial position holding structure, the support structure for supporting the inspection head portion 3 to the base portion 16 in the radial direction, and the radial drive motor 22. The directional position adjusting mechanism T3 is configured.

As shown in FIG. 4, the inspection device includes an optical pulse generating unit 23 that generates an optical pulse given to the inspection head unit 3 in order to generate a pulsed terahertz wave having a pulse width of an extremely short time. , Each drive motor of the optical pulse generation unit 23, the inspection head unit 3 and the head support device 4 is controlled, and the soundness of the resin tube fusion unit 2 is evaluated based on the received terahertz wave reception information. A control unit 24 as an evaluation processing unit is provided.

The control unit 24 processes the output signals output from the motor control unit 25 that controls the operation of the axial drive motor 13, the circumferential drive motor 19, and the radial drive motor 22 and the inspection head unit 3. A signal processing unit 26 for processing and an image display unit 27 for displaying image information obtained by signal processing are provided. Although detailed control is omitted, the motor control unit 25 scans the inspection head unit 3 along the axis direction by the axial drive motor 13 and the inspection head unit by the circumferential drive motor 19. 3 is controlled to be scanned along the circumferential direction. Further, the radial drive motor 22 is controlled to change the radial position of the inspection head portion 3.

The optical pulse generation unit 23 includes a laser transmission unit 28 having a femtosecond laser, a beam splitter 29 that divides the laser transmitted from the laser transmission unit 28 into two systems, and an optical delay unit 30 that delays the probe light. There is. The laser emitting unit 28 can repeatedly output pulsed laser light having an extremely short pulse width of ^{femtoseconds (1 × 10 -15) seconds.}

The laser light emitted from the laser transmitting unit 28 is divided into pump light and probe light by the beam splitter 29. The pump light is transmitted to the irradiation unit 5 of the inspection head unit 3 via the optical cable 31 and is used as a trigger for the irradiation timing. The probe light is transmitted to the receiving unit 6 of the inspection head unit 3 in a state of being delayed for a predetermined time via the optical delay unit 30 and the optical cable 32, and is used as a trigger for the reception timing.

After the terahertz pulse wave is irradiated by the irradiating unit 5, the light pulse is supplied from the irradiating unit 5 with a delay corresponding to the elapsed time until it is reflected and received by the receiving unit 6. The timing of irradiating the pulse wave and the timing of reflecting the terahertz pulse wave at the inspection target location are combined to determine the reception timing of the reflected wave received by the receiving unit 6 and the receiving timing of the pulse delayed by the optical delay unit 30. Matching. Terahertz time region spectroscopy, which is a well-known technique, is used to enable accurate measurement. The delay time in the optical delay unit 30 can be changed and adjusted.

The motor control unit 25 sets the inspection head unit 3 at a set position for measurement, that is, a position where the resin tube fusion unit 2 can irradiate a terahertz pulse wave, and sets the irradiation position in the circumferential direction. In addition, the axis direction drive motor 13 and the circumferential direction drive motor 19 are controlled so that the receiving unit 6 sequentially measures while scanning in the axis direction. Further, the radial drive motor 22 is controlled so that the spot portion of the terahertz wave is changed along the thickness direction (diameter direction) of the resin tube 1.

Since the signal processing unit 26 has a well-known configuration, it will not be described in detail, but signal processing can be performed based on the received information corresponding to the passage of time obtained by the receiving unit 6 of the inspection head unit 3, for example, FIG. As shown in No. 7, it is configured to obtain information on a tomographic image similar to that of a conventional ultrasonic sonar. The image display unit 27 displays a tomographic image obtained by the signal processing unit 26.

If the support 9 is connected by the hinge 14 as described above, the inspection head portion 3 cannot be moved in the circumferential direction over the entire circumference of the support 9, but for example, the inspection head portion 3 may be replaced, or two inspection head portions 3 may be provided, and it is preferable that the inspection can be performed over the entire circumference.

Next, an inspection method for evaluating the soundness of the resin pipe fusion portion 2 using the above inspection device will be described.

As shown in FIG. 3, a terahertz pulse wave is emitted from the irradiation unit 5 to the detected portion of the resin tube fusion unit 2 in the direction orthogonal to the surface of the resin tube 1, that is, in the radial direction of the resin tube 1. Irradiate toward. At this time, the terahertz pulse wave is converged by the lens 7 and irradiated to the detected portion in the resin tube fusion portion 2 in the irradiation range having a small diameter. The spot diameter of the terahertz pulse wave applied to the detected portion is set to be approximately 1 mm. Then, the terahertz pulse wave reflected from the detected portion in the direction (diameter direction) orthogonal to the surface of the resin tube 1 is received by the receiving unit 6 via the beam splitter 29. The applicant has selected a terahertz pulse wave containing a frequency of 0.1 to 2.5 THz as a frequency band as the terahertz wave emitted from the irradiation unit 5. The terahertz pulse wave is adjusted so that the number of pulses is repeatedly generated so that measurement data for about 1000 times per second can be obtained. The scanning speed of the inspection head unit 3 is set to 100 mm / sec.

Considering the wavelength corresponding to the frequency of electromagnetic waves, a terahertz wave with a frequency of 0.1 THz is suitable for inspection of an abnormal part having a size of about 3 mm, and a terahertz wave with a frequency of 1 THz has a size of about 0.3 mm. Suitable for inspection of abnormal parts. Further, a terahertz wave having a frequency of 2 THz is suitable for inspection of an abnormal portion having a size of about 0.15 mm.

5 and 6 show a measurement principle for inspecting an abnormal portion such as an internal defect of the resin tube fusion portion 2 due to the terahertz pulse wave. When the terahertz pulse wave is applied to the resin tube 1, the terahertz pulse wave passes from the surface of the resin tube 1 through the inside to the lower surface. Since the terahertz pulse wave also has the property of light, it is reflected at the boundary surface and the place where the state is different. Therefore, the resin tube 1 is strongly reflected by the outer surface 1a and the inner surface 1b (see A and B in FIG. 6). If an abnormal portion α such as a bubble or a foreign substance exists inside the resin tube 1, the terahertz pulse wave is strongly reflected at that portion α (see C in FIG. 6).

FIG. 5 shows the waveform of the received signal with the passage of time for the irradiated terahertz pulse wave. The first waveform "A" indicates the received signal reflected on the outer surface 1a, and the second waveform "B" indicates the received signal reflected on the inner surface. The third waveform “C” indicates the received signal reflected at the internal abnormal portion α.

By receiving the reflected terahertz pulse wave in the receiving unit 6 and processing the signal by the signal processing unit 26, for example, a tomographic image as shown in FIG. 7 is created and displayed on the image display unit 27. .. FIG. 7 shows the actual measurement data of the applicant, and shows a tomographic image of a portion of the resin tube fusion portion 2 irradiated with the terahertz pulse wave. In this figure, the horizontal direction corresponds to the position in the circumferential direction of the resin pipe 1, and the vertical direction corresponds to the position in the radial direction (thickness direction) of the resin pipe fusion portion 2.

In FIG. 7, it can be seen that the region on the left side has no abnormal portion inside, and the region on the right side has an arc-shaped abnormal portion α in the middle portion. In this way, it was possible to visually determine that there was an abnormality inside the resin pipe fusion portion 2. The abnormal part used in this experiment is a cavity having a diameter of 0.5 mm.

Therefore, the soundness of the resin pipe fusion unit 2 can be evaluated based on the tomographic image created by processing the signal obtained by the reception unit 6.

In order to accurately detect a small abnormal portion of about 0.5 mm, it is preferable to change the irradiation range (1 mm diameter) having a small diameter converged by the lens 7 in the radial direction with respect to the resin tube fusion portion 2. .. Therefore, it is preferable to move the inspection head portion 3 along the radial direction of the resin tube 1, for example, by 3 mm, and perform measurement while scanning at each position in the circumferential direction and the axial center direction. In this case, the delay time by the optical delay unit 30 may be changed and adjusted.

In the above-mentioned inspection method, the resin tube fusion portion 2 in which the resin tube 1 is fused by the butt fusion method is targeted, but the resin tube in which the resin tube is fused by the electric fusion method (EF joining method) is targeted. It can also be used for the fused portion 2.

FIG. 8 shows a cross section of the resin pipe fusion portion 2 by the electric fusion method. In the resin pipe fusion portion 2 by the electric fusion method, a resin connection pipe 41 in which a coil-shaped heating wire 40 is embedded is externally inserted across the ends of the two resin pipes 1 and heated by the heating wire 40. The resin pipe 1 and the connecting pipe 41 are melted and fused.

The resin pipe fusion portion 2 by the electric fusion method can be inspected by using the above-mentioned inspection device. In the inspection of the resin tube fusion portion 2 by this electric fusion method, since the fusion range is long in the axial core direction, it is necessary to take a long movable range in the axial core direction of the inspection head portion 3. Other than that, the same inspection method as the above-mentioned inspection method can be used.

9 to 12 show actual measurement data of the applicant. FIG. 9 shows a waveform of intensity that changes with the passage of time of the reflected wave reflected from the irradiated terahertz pulse wave, and FIG. 10 shows a tomographic image. In the data D that changes significantly in FIG. 9 and the tomographic image, the location β where there is an intermittently strong output on the upper side indicates the location where the heating wire 40 exists. Further, an abnormal portion γ such as a bubble is shown near the portion β of the heating wire 40. In FIG. 9, it is represented by a small variation data E. However, in the tomographic image, the ghost signal of the surface reflected wave of the terahertz wave and the reflected wave from the abnormal part overlap, and it may be difficult to determine the abnormal part from the image.

In the inspection of the resin tube fusion section 2 by bad fusion, the soundness of the resin tube fusion section 2 is evaluated based on the tomographic image created by processing the signal obtained by the reception section 6. However, in the inspection of the resin tube fusion section 2 by the electric fusion method, the image information obtained by performing wavelet transform on the tomographic image created by processing the signal obtained by the receiver 6 was obtained. Based on this, the abnormal portion in the resin pipe fusion portion 2 was determined.

Since it is a well-known technique, detailed description thereof will be omitted, but the wavelet transform is a process of performing data conversion so as to emphasize the reflected wave from an abnormal portion by extracting a specific frequency component.

For example, a process of extracting a component of a specific frequency (for example, 0.4 THz) from the output waveform shown in FIG. 9, obtaining a component of a specific frequency corresponding to the passage of time as shown in FIG. 11, and emphasizing the output is performed. Then, a new tomographic image as shown in FIG. 12 is obtained. With this tomographic image, the shadow due to the ghost signal disappears, and only the abnormal part γ is emphasized, making it easy to understand. In the drawings attached to the specification, the light and darkness of the abnormal portion γ is not clear in some cases, but it is in a state where it can be recognized by the data of the applicant.

[Another Embodiment]
(1) In the above embodiment, the head support device includes a support, a radial position adjusting mechanism, a circumferential position adjusting mechanism, and an axial centering position adjusting mechanism, but instead of this configuration. Therefore, by using a robot arm that supports the inspection head portion in a three-dimensional direction so as to be movable and reorientable, the position can be changed in the circumferential direction and the axial direction of the resin tube, and the position between the resin tube and the resin tube can be changed. The inspection head portion may be supported so that the separation distance in the radial direction can be changed.

(2) In the above embodiment, the spot diameter of the terahertz wave applied to the detected portion is approximately 1 mm, and it may be about 1 to several mm in order to inspect a small abnormal portion of 1 mm or less. However, the spot diameter of the terahertz wave may be set smaller than 1 mm or larger than several mm depending on the size of the abnormal portion to be inspected and the like.

(3) In the above embodiment, a pulsed terahertz wave including a frequency of 0.1 to 2.5 THz (terahertz) is irradiated, but the abnormality portion to be inspected is not limited to such a peripheral frequency band. Depending on the magnitude and the like, a frequency lower than 0.1 THz may be used, or a terahertz wave having a frequency higher than 2.5 THz may be used.

(4) In the above embodiment, the irradiation unit and the reception unit are housed in the same housing, terahertz waves are irradiated in a direction orthogonal to the surface of the resin tube 1, and the resin tube is irradiated from the detected portion. Although the terahertz wave reflected in the direction orthogonal to the surface of 1 is received, the terahertz wave may be configured as follows instead of such a configuration.
That is, the irradiation unit and the receiving unit are housed in separate cases, and the irradiation unit 5 is arranged on one side of the resin tube 1 in the axial direction with respect to the resin tube fusion unit 2, and the resin tube fusion unit 2 is provided. On the other hand, a receiving unit is arranged on the other side of the resin tube 1 in the axial direction, the surface of the resin tube 1 is irradiated with terahertz waves in an oblique direction, and the reflected waves reflected in the oblique direction are received. May be good.

(5) In the above embodiment, the scanning speed of the inspection head portion 3 is set to 100 mm / sec, but the scanning speed is not limited to this value, and the difference in the size of the abnormal portion to be detected and the inspection are necessary. It may be changed as appropriate according to the difference in time and the like.

The configuration disclosed in the above embodiment (including another embodiment, the same shall apply hereinafter) can be applied in combination with the configuration disclosed in other embodiments as long as there is no contradiction. , The embodiments disclosed in the present specification are examples, and the embodiments of the present invention are not limited thereto, and can be appropriately modified without departing from the object of the present invention.

INDUSTRIAL APPLICABILITY The present invention can be applied to an inspection device for inspecting the soundness of a connected state in a resin tube fusion portion in which resin tubes are fused and connected to each other.

1 Resin tube 2 Resin tube fusion part 3 Inspection head part 3A Housing 4 Head support device 5 Irradiation part 6 Receiver part 9 Support T1 Axis direction position adjustment mechanism T2 Circumferential position adjustment mechanism T3 Radial position adjustment mechanism

Claims (4)

An inspection head unit that irradiates a terahertz wave to a resin tube fusion portion connected by fusing resin tubes to each other and receives a reflected wave of the terahertz wave reflected from the resin tube fusion portion. And a head support device for supporting the inspection head portion.
The head support device supports the inspection head portion so that the position can be changed in the circumferential direction and the axial direction of the resin tube and the separation distance in the radial direction from the resin tube can be changed. An inspection device for a resin pipe fusion part configured as described above. The head support device includes a circular support that is located on the radial outer side of the resin tube, extends over the entire circumference, and can be divided into a plurality of units along the circumferential direction.
A radial position adjusting mechanism capable of adjusting the position of the inspection head portion along the radial direction with respect to the support,
In a state where the relative position of the inspection head portion can be changed and adjusted along the circumferential direction with respect to the support, and the radial separation distance between the resin tube and the support is maintained constant. , Supporting circumferential position adjustment mechanism,
The support is supported with respect to the resin tube in a state where the position can be changed and adjusted along the axis direction and the radial separation distance between the resin tube and the support is maintained constant. The inspection device for a resin pipe fusion portion according to claim 1, further comprising an axial center direction position adjusting mechanism. The inspection head portion includes an irradiation portion that irradiates a terahertz wave on a detected portion of the resin pipe fusion portion in a direction orthogonal to the surface of the resin pipe, and the resin pipe from the detected portion. The inspection device for a resin tube fusion unit according to claim 1 or 2, wherein the receiving unit that receives the terahertz wave reflected in the direction orthogonal to the surface of the same housing is housed in the same housing. The inspection device for a resin tube fusion portion according to claim 3, wherein the irradiation unit converges a terahertz wave and irradiates the detected portion with a small-diameter irradiation range.

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