JPS64561Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to an apparatus for measuring the wall thickness of thin tubes, etc. of a heat exchanger using ultrasonic waves.

Generally, in heat exchangers, the reduction in wall thickness of thin tubes over time is measured during use in order to prevent leakage due to the reduction in wall thickness. In order to measure the wall thickness of this thin tube, a probe is inserted into the thin tube and the wall thickness is measured by an eddy current method. However, this method can only be applied when the material of the capillary is a non-magnetic material. In addition, if the thin tube is made of a magnetic material such as steel, this eddy current method cannot be applied unless the thin tube is magnetically saturated, and it is difficult to magnetize the thin tube packed in the heat exchanger. Therefore, when the capillary is made of a magnetic material, it is not possible to measure the wall thickness of the capillary by the eddy current method.

For this reason, if the material of the thin tube is a magnetic material, it is conceivable to measure the wall thickness using ultrasonic waves. In this case, an ultrasonic probe is attached to the probe inserted into the thin tube, and the ultrasonic probe emits ultrasonic waves toward the inner surface of the thin tube, and the reflected waves are received. It has been difficult to reliably interpose a medium for transmitting ultrasonic waves, such as water, between the sonic probe and the inner surface of the thin tube. It is also possible to use highly viscous machine oil or the like instead of water as a medium and apply it to the inner surface of the tube, but this would require a long time to apply and clean after measurement. This causes problems that significantly reduce efficiency.

In order to eliminate such problems, an ultrasonic wall thickness measuring device as shown in FIG. 1 was developed. That is, numeral 1 in the figure is a probe, which is inserted into a thin tube 2 to be inspected. The probe 1 is equipped with an ultrasonic probe 3, which emits ultrasonic waves toward the inner surface of the thin tube 2 and receives the reflected waves. The device is configured to measure wall thickness. In addition, expansion seal bodies 4, 4 are provided on the outer periphery of the probe 1 in front and behind the ultrasound probe 3, respectively.
These inflatable seal bodies 4, 4 are inflated by high-pressure air and are configured to come into close contact with the inner circumferential surface of the thin tube 2. Further, a water spout 5 is formed by opening on the outer peripheral surface of the probe 1 between these expansion seal bodies 4, 4, and water is supplied through a water pipe (not shown) connected to the probe 1. The medium, that is, water, is configured to be ejected from these water ejection ports 5. Therefore, water is reliably filled between the outer surface of the probe 1 and the inner surface of the capillary tube 2 between the expansion seal bodies 4, 4, and accurate measurements can be made.

By the way, the above-mentioned probe 1 is small with an outer diameter of, for example, about 9.7 mm. Therefore,
It is difficult to provide a complex structure such as the inflatable seal bodies 4, 4 in such a small size. Further, such inflatable seal bodies 4, 4 are easily worn out and have a problem of low reliability.

The present invention was developed based on the above circumstances, and its purpose is to ensure that a medium is interposed between the ultrasonic probe and the inner surface of a thin tube, etc., and to have a simple and reliable structure. The objective is to provide a high quality wall thickness measuring device.

That is, the present invention is an apparatus for measuring the wall thickness of a thin tube, which includes a cylindrical body inserted into the thin tube, an inspection window opened in the central side of the body, and a portion of the body located on the rear end side of the inspection window. the formed medium discharge port; an ultrasonic probe disposed near the rear end of the inspection window that emits ultrasonic waves in the axial direction within the main body and receives the reflected waves; and the tip of the inspection window. A reflector is inserted movably in the axial direction into the main body and has a reflective surface on an end face that intersects with the axis of the main body at an angle of 45 degrees, and a medium supply pipe is connected to the rear end of the main body. This is what I did. Therefore, the medium ejected from the medium outlet is held within the inspection window, and the medium is reliably interposed between the inspection window and the inner surface of the thin tube. The ultrasonic waves emitted from the ultrasonic probe are reflected by the reflective surface of the reflector, pass through the inspection window, and reach the inner surface of the tube, and the reflected waves pass through the ultrasonic probe through the opposite path to the above. received by the tentacles. Therefore, a medium always exists in the transmission path of this ultrasonic wave, and reliable measurements can be made. Moreover, this device has a simple structure and high reliability. Furthermore, since the reflector is movable in the axial direction of the main body, the actual length of the inspection window can be adjusted by moving the reflector, thereby reliably preventing air bubbles from accumulating within the inspection window. It is something.

An embodiment of the present invention will be described below with reference to FIGS. 2 to 5. 101 in the figure is an inner probe, and this inner probe 101 is provided with an ultrasonic probe 102. Further, a pipe 103 having appropriate elasticity and flexibility is connected to the inner probe 101. This pipe 103 is connected to a water supply mechanism 104 that supplies a medium such as water. This water supply mechanism 104
is composed of a water tank 105 and a pump 106, and supplies water to the inner probe 101 via the pipe 103 described above. Then, the inner probe 101 is inserted into the thin tube 108 via the tube plate 107 of the heat exchanger by letting out the pipe 103. Note that a scale is attached to the outer periphery of the pipe 103, and the insertion position of the inner probe 101 is detected by this scale. Further, a cable 109 is connected to the ultrasonic probe 102, and this cable 109 is connected to the pipe 103.
It is led out through the inside and connected to the measuring device 110. This measuring device 110 is connected to the cable 1
The signal sent through the capillary 10
8 and displays the result on the printer 111, and displays the waveform of the reflected ultrasound wave on the oscilloscope 112, so that it can be monitored whether the ultrasound is being incident normally. It is configured.

The inner probe 101 is constructed as shown in FIGS. 3 and 4. That is, 121 is a probe body which has a hollow cylindrical shape. The aforementioned pipe 103 is connected to the proximal end of the probe body 121 and is attached by a pin 122 and a screw 123. Further, a plurality of leaf springs 124 are provided on the outer peripheries of the tip and base ends of the probe body 121, respectively.
...is provided. These leaf springs 124...
has a central portion curved outward, and only one end thereof is attached to the probe body 121 by a mounting screw 125.
. . . elastically abuts against the inner circumferential surface of the thin tube 108 to hold the probe body 121 at the center of the thin tube 108. Further, an inspection window 126 is formed in the center of the probe body 121 by cutting out a part of the peripheral wall. In addition, the probe body 121
The above-mentioned ultrasonic probe 102 is provided inside,
One end thereof is exposed on the proximal end side of the inspection window 126 and is configured to transmit ultrasonic waves in the axial direction of the probe body 121. In addition, this probe body 1
A reflector 127 is inserted into the reflector 21 from the distal end thereof so as to be movable in the axial direction. This reflector 12
A reflecting surface 128 is formed at one end of the probe body 121 at an angle of 45 degrees with respect to the axial direction of the probe body 121, and one end of this reflector 128 is exposed at the side of the distal end of the inspection window 126, so that the ultrasonic probe It faces the tentacle 102. Note that 129... are fixing screws that fix the ultrasonic probe 102 and the reflector 127.

Further, water discharge ports 130 are formed on the circumferential surface of the probe body 121 near the inspection window 126, and the medium, that is, water supplied through the pipe 103 is ejected from these water discharge ports 130. It is configured as follows.

Next, the operation of this embodiment will be explained. That is, the water spouted from the water outlet 130 flows between the outer circumference of the probe body 121 and the inner circumferential surface of the thin tube 108, flows into the inspection window 126, and enters the inspection window 1.
26 and the inner peripheral surface of the thin tube 108. Furthermore, the ultrasonic waves emitted from the ultrasonic probe 102 are reflected by the reflecting surface 128 of the reflector 127 and enter the peripheral wall of the thin tube 108 . The ultrasonic waves reflected by the inner and outer surfaces of the thin tube 108 are received by the ultrasonic probe 102 through a path opposite to that described above, thereby measuring the wall thickness of the thin tube 108. In this case, the above inspection window 126
The internal volume is relatively large, so air bubbles will not accumulate in this area. In other words, when the gap between the ultrasonic probe and the thin tube is small, as in the conventional case shown in Figure 1, once air bubbles accumulate in this gap, the holding force of the air bubbles due to surface tension acts strongly. However, these air bubbles are not easily removed by a small amount of water flow. In contrast, in the present invention, this inspection window 126
The volume of the internal space, that is, the space through which ultrasonic waves are transmitted, is large, and even if air bubbles exist within this space, the retention force of the air bubbles due to surface tension is small, so even a weak water flow can easily remove the air bubbles. can.

Further, in the present invention, since the reflector 127 is movable in the axial direction, the distance 1 between the reflector 127 and the ultrasound probe 102 can be adjusted by moving the reflector 127 in the axial direction. This can further reliably prevent air bubbles from accumulating. That is, when the device of the present invention was inserted into a transparent plastic tube simulating an actual thin tube and the state of air bubble removal was observed,
It has been found that if this distance 1 is too long, air bubbles tend to accumulate between the reflector 127 and the ultrasonic probe 102, that is, within the ultrasonic transmission path.
Therefore, it is preferable that this distance 1 is short to some extent. For example, if the inner diameter of the thin tube 108 is 10.7 mm, if 1 = 15 mm, air bubbles will not accumulate and the distance 1
= 25mm may cause air bubbles to accumulate. The limit value of distance 1 to reliably prevent this bubble accumulation is:
The inner diameter of this thin tube, water supply pressure, water supply amount, inspection window 12
The limit value of this distance 1 varies depending on various conditions such as the volume of the air bubbles inside 6, the amount of water escaping from the inspection window, etc., and there is no suitable method to numerically evaluate the ease with which air bubbles accumulate. It is currently not possible to strictly define numerically. However, in practice, it is sufficient to conduct the above-mentioned experiment and find in advance a value of distance 1 that corresponds to the actual working conditions and can reliably prevent the accumulation of air bubbles.

As described above, the present invention provides an apparatus for measuring the wall thickness of a thin tube, which includes a cylindrical body inserted into the thin tube, an inspection window opened in the central side of the body, and a rear end of the body from the inspection window. a medium discharge port formed on the side, an ultrasonic probe disposed near the rear end of the inspection window that emits ultrasonic waves in the axial direction within the main body and receives the reflected waves, and the inspection window. a reflector that is inserted movably in the axial direction into the main body near the tip of the body and has a reflective surface on an end surface that intersects with the axis of the main body at an angle of 45 degrees; and a medium supply pipe connected to the rear end of the main body. It is equipped with the following. Therefore, the medium ejected from the medium outlet is held within the inspection window, and the medium is reliably interposed between the inspection window and the inner surface of the thin tube. The ultrasonic waves emitted from the ultrasonic probe are reflected by both sides of the reflector, pass through the inspection window, and reach the inner surface of the tube, and the reflected waves pass through the ultrasonic probe through the opposite path to the above. received by the tentacles. Therefore, a medium always exists in the transmission path of this ultrasonic wave, and reliable measurements can be made. Moreover, this device has a simple structure and high reliability. In addition, since the reflector is movable in the axial direction of the main body, the actual length of the inspection window can be adjusted by moving the reflector, thereby reliably preventing air bubbles from accumulating within the inspection window. The effect is great.

[Brief explanation of the drawing]

FIG. 1 is a side view of a conventional probe. Figures 2 to 5 show an embodiment of the present invention, with Figure 2 being a schematic configuration diagram, Figure 3 being an exploded perspective view of the inner probe, and Figures 4 and 5 showing a part of the inner probe. FIG. 101... Inner probe, 102... Ultrasonic probe, 103... Pipe, 104... Water supply mechanism, 108... Thin tube, 121... Probe body,
126...Inspection window, 127...Reflector, 128...
...reflective surface.

Claims (1)

[Scope of utility model registration request] A device for measuring the wall thickness of a thin tube, which includes a cylindrical body inserted into the thin tube, an inspection window opened on the central side of the body, and a medium formed on the rear end side of the inspection window of the body. an ultrasonic probe disposed near the rear end of the inspection window that emits ultrasonic waves in the axial direction within the main body and receives the reflected waves; It is inserted so as to be movable in the axial direction, and the body axis and 45
1. A wall thickness measuring device comprising: a reflector having reflective surfaces that intersect at an angle of .degree., and a medium supply pipe connected to the rear end side of the main body.