JP2000088693A - Method and apparatus for inspection of pipe - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an inspection method, for a pipe, in which the safety of an operator can be ensured and in which the operability of inspection is superior. SOLUTION: In an inspection method, a step in which high-pressure air is supplied into a pipe in a state that the opening part at the end part of the pipe is closed is provided. In addition, a step S1 in which a sound near the coupling of the pipe is detected is provided. In addition, a step S2, a step S3, a step S4 and a step S5 in which the sound volume of the detected sound is monitored and in which whether the sound volume for a set time continued from a point of time when the sound volume at a set value or higher is detected is lowered gradually or not with the passage of time is judged are provided.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for inspecting piping and, more particularly, to a method and an apparatus for inspecting the tightness of a joint of a duct in an aircraft.

[0002]

2. Description of the Related Art For example, a duct (piping) used in an aircraft is configured by connecting a plurality of duct unit pipes. In the duct, there is a possibility that airtightness may not be maintained, particularly at a joint between duct unit pipes, and in this case, fluid in the duct may leak from the joint.

[0003]

Heretofore, the sealing test of this type of duct has been performed as follows. That is,
In a state in which a lid is attached to the opening at the end of the duct, high-pressure air is supplied into the duct, and an operator holds a hand over each joint of the duct unit pipes to check for air leakage. I was checking.

According to the above method, while supplying high-pressure air into the duct, it is necessary for an operator to approach the duct and specify an air leak location using a tentacle, soapy water, or the like. Therefore, there is a problem that the work is troublesome.

During the supply of high-pressure air, the pressure in the duct may cause the joint portion of the duct unit pipe to come off, and the detached joint portion may be scattered to impair the safety of workers. .

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a pipe inspection method and a pipe inspection apparatus which can ensure the safety of workers and have excellent workability.

[0007]

According to a method of inspecting a pipe according to the present invention, a step of supplying high-pressure air into the pipe while an opening at a pipe end is closed is provided. Detecting, and monitoring the volume of the detected sound, and determining whether or not the volume for a certain period of time continuing from the point of detecting the volume equal to or higher than the set value gradually decreases with time. Have.

[0008] Since there are various kinds of noises in the factory where the pipes are provided, the above-mentioned inspection is performed in a state where the sound around the pipes to be inspected is insulated. When air leaks from the joint portion of the pipe or the like, a sound volume that is loud or substantially the same as the surrounding noise (a volume that is not buried in the surrounding noise) is detected. The detected sound data contains loud noise in some places,
The noise is a temporary sound such as a tapping sound, and is clearly different from the sound indicating the air leaking from the pipe joint part in data. That is, the sound of the leaked air has the loudest volume at the start of the leak, and the volume gradually and substantially falls (for example, in an exponential function graph) as time passes thereafter. Therefore, not only can it be distinguished from a temporary tapping sound or the like, but even if the intermittent noise and the sound at the time of the leak overlap, it is possible to detect (identify) an air leak from a gradually descending curve or the like. it can.

The method for inspecting a pipe according to the present invention comprises the steps of: supplying high-pressure air into the pipe while closing an opening at a pipe end; detecting sound near the pipe joint; Extracting a sound of a specific frequency band from the detected sound, and monitoring the sound volume of the extracted sound, and the sound volume for a certain period of time continuing from the time when a sound volume equal to or higher than a set value is detected gradually increases with time. Determining whether the vehicle is descending.

[0010] The pipe inspection device of the present invention is provided on a pipe having an opening at an end closed and provided with an air supply source for supplying air to the pipe in a pressurized state; A microphone for detecting a nearby sound, and a detecting unit for detecting a leak of air from the pipe joint unit, wherein the detecting unit inputs data indicating the volume of the sound output from the microphone, From the input data, extract change data indicating a change in the volume of the sound that has continued for a predetermined time from the point in time when the volume of the set value or more is detected, and the volume gradually decreases with time based on the change data. It is determined whether or not the air leaks when the sound volume is gradually decreasing as a result of the determination.

An apparatus for inspecting a pipe according to the present invention is provided on a pipe whose opening at an end is closed, and an air supply source for supplying air into the pipe in a pressurized state. A plurality of microphones provided in different parts and detecting sounds near the part, and a detection part for detecting air leak from the pipe, wherein the detection part is output from each of the plurality of microphones Data indicating the sound volume of the sound is input at different timings from each other, and from the input data, change data indicating a continuous change in the sound volume of the sound for a predetermined period of time from the time when the sound volume equal to or more than the set value is detected is extracted. It is determined whether or not the sound volume is gradually decreasing with time based on the change data, and as a result of the determination, when the sound volume is gradually decreasing, it corresponds to the change data. It is determined that there is the air leakage into the serial site.

[0012] The pipe inspection apparatus of the present invention further includes a filtering section for extracting a sound in a specific frequency band from the sound near the pipe joint.

[0013]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of a piping inspection apparatus according to an embodiment of the present invention.

As shown in FIG. 3, a pipe inspection apparatus 1 of the present embodiment is an apparatus for inspecting a pipe 5 which is a duct unit pipe described above. The pipe inspection device 1 is used in a state where the opening at the end of the pipe 5 is closed with a cover 5a. The pipe inspection device 1 includes an air supply source 10 provided in the pipe 5,
A plurality of microphones 20 and a detection unit 3 connected to the microphones 20
0.

The air supply source 10 supplies air into the pipe 5 in a pressurized state. The microphones 20 are provided at all joint sites in the pipe 5 and have directivities capable of inputting sounds in a predetermined range near the sites. Since the sound of the air leak is a high frequency sound, the microphone 20
A high-frequency sound detection ability is selected.

As shown in FIG. 2, the detecting section 30 detects an air leak from the pipe 5 by the following operation. First, as shown in step S1, the detection unit 30
Data signals indicating the volume of the sound output from each of the plurality of microphones 20, 20...

Each microphone 20 inputs sounds indicating various levels of volume including silence, and outputs the data signal corresponding to the volume to the detection unit 30. In this case, the detection unit 30
Monitors whether or not the volume exceeds a preset threshold value (set value) while constantly monitoring the input data signal as shown in step S2. Step S
As shown in S3 and S4, when detecting a volume exceeding the threshold value from the data signal, the detection unit 30 extracts the data signal that has been continuous for a predetermined time from the detection point as a change data signal. I do.

The change data signal indicates a change in the volume of the sound that has continued for a predetermined time from the time when the volume exceeding the threshold is detected. As shown in step S5, the detecting unit 30 determines whether or not the volume gradually decreases with time based on the change data. In this case, as shown in FIG. 1, the drop curve of the volume is close to an exponential function curve from experience.

As shown in step S6, the detecting unit 30
Is determined based on the change data, and when it is determined that the volume is gradually decreasing, the pipe 5
It is recognized that there is an air leak from. In this case, the detection unit 30 can specify the leak location in the pipe 5 as a location corresponding to the change data.

Since there are various kinds of noises in the factory where the pipe 5 is provided, the above-mentioned inspection is performed on the pipe 5 to be inspected.
It is performed in a state where the surrounding area is sound-insulated. When air leaks from the joint portion of the pipe 5 or the like, a volume that is loud or substantially equal to that of the surrounding noise (a volume that is not buried in the surrounding noise) is detected.

As shown in FIG. 1, the detected sound data contains a large level of noise (see the broken line in FIG. 1) in some places, but the noise is a temporary sound such as a tapping sound. The sound is clearly different from the sound indicating the air leaking from the pipe 5 (see the solid line in FIG. 1). That is, the sound of the air leaking from the pipe 5 has the largest sound volume at the start of the leak, and the sound volume gradually and substantially falls (for example, in an exponential function graph) as time passes thereafter.

Therefore, not only can it be distinguished from a temporary tapping sound or the like, but even if the intermittent noise and the sound at the time of the leak overlap, an air leak is detected (identified) from a gradually descending curve or the like. can do.

As described above, the microphone 20 generates not only the sound of an air leak, but also a temporary sound such as a surrounding sound.
Input other continuous or intermittent sounds. In this case, as described above, it is possible to identify an air leak by catching, for example, a point where the sound volume of the sound for a certain period of time falls in an exponential function graph from the detection of the sound volume above the threshold value.

Furthermore, if the range of the frequency of the sound indicating the air leak can be limited (generally high frequency) in relation to the pressure of the air supplied from the air supply source 10, etc. If only the frequency components within the limited range are extracted and determined, the detection accuracy is improved. In this case, the sound indicating the air leak is not only the pressure of the air from the air supply source 10 but also
Of course, it is affected by the size of the opening area of the air leak portion of the pipe 5, but in a normal case, since the air leak portion is extremely small and its frequency can be assumed, there is no practical problem. Conceivable.

In order to input only the output data from one microphone 20 among the output data from the plurality of microphones 20, 20 to the detection unit 30 sequentially at a shifted timing, a relay means is used. Although various relays can be applied, in the present embodiment, an excitation coil and a contact type electromagnetic relay having mechanical contacts are used. This electromagnetic relay is electrically controlled, and the contacts of each circuit are sequentially controlled automatically and manually opened and closed in order to sequentially operate the circuits of another microphone 20.

As described above, in the present embodiment, the manner of change in the volume of the leaked air can be grasped, and the pipe inspection can be accurately performed regardless of the surrounding noise. On the other hand, for example, as shown in FIG. 4A, it is conceivable to use a vibration sensor 41 instead of the sound collecting microphone 20 as a pipe inspection method.

However, in the detection by vibration, first, as shown in FIG. 4 (b), vibration other than air leak of the pipe, for example, vibration accompanying work in a factory (see broken line)
There is a problem that it is difficult to distinguish the vibration from the vibration (see the solid line) when an air leak exists in the pipe. That is,
If an air leak is present, the detected "sound" falls gradually and almost smoothly (exponentially), but since the detected "vibration" is only instantaneous, the waveform in the factory It is difficult to detect the difference from the vibration caused by the above.

Secondly, as a result of actual experiments by the present inventors, the level of vibration at a site such as in a factory is detected to be much higher than the vibration due to air leak.
It is not suitable as an air leak detector.

In this embodiment, the air leak of the pipe is detected by detecting the change in the volume of the detected sound.
It is also possible to detect an air leak in the pipe by focusing on the detected frequency itself or a change in the frequency. Further, in the present embodiment, the inspection object is a pipe, but the invention can be applied to various leak tests.

[0030]

According to the pipe inspection method of the present invention, a step of supplying high-pressure air into the pipe while the opening at the pipe end is closed, and a step of detecting a sound near the pipe joint. And monitoring the volume of the detected sound,
Determining whether or not the sound volume for a certain period of time continuing from the time when the sound volume equal to or higher than the set value is detected is gradually decreasing with the elapse of time. However, the noise is a temporary sound such as a tapping sound, and is clearly different from the sound indicating the air leaked from the pipe in terms of data. Since the volume at the time is the loudest and the volume gradually decreases substantially smoothly (for example, in an exponential function graph) as time elapses thereafter, it is possible to distinguish it from a temporary tapping sound or the like. Of course, even if the intermittent noise and the sound of the leak overlap,
An air leak in the pipe can be detected from the gradually descending curve or the like.

[Brief description of the drawings]

FIG. 1 is a graph showing an example of a waveform obtained by an embodiment of a pipe inspection method according to the present invention.

FIG. 2 is a flowchart showing a flow until an air leak is detected from a pipe in the present embodiment.

FIG. 3 is a diagram illustrating a schematic configuration of the entire inspection apparatus according to the embodiment;

4A and 4B show a comparative example of the present embodiment, FIG. 4A is a diagram showing a schematic configuration of a main part thereof, and FIG. 4B is a graph showing an example of a waveform obtained by the comparative example. is there.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Pipe inspection apparatus 5 ... Pipe 10 ... Air supply source 20 ... Microphone 30 ... Detection part 41 ... Vibration sensor

Claims (5)

[Claims] A step of supplying high-pressure air into the pipe while closing an opening at a pipe end; a step of detecting a sound near the pipe joint; and monitoring a volume of the detected sound. And determining whether or not the sound volume for a certain period of time continuing from the time when the sound volume equal to or higher than the set value is detected gradually decreases as time elapses. 2. A step of supplying high-pressure air into the pipe while closing an opening at a pipe end, a step of detecting a sound near the pipe joint, and a specific frequency based on the detected sound. Extracting the sound of the band, and monitoring the volume of the extracted sound to determine whether or not the volume for a certain period of time continuing from the point of detecting the volume equal to or higher than the set value gradually decreases with time. A pipe inspection method comprising the steps of: 3. An air supply source provided in a pipe whose end opening is closed, for supplying air to the pipe in a pressurized state, and a microphone for detecting a sound near the pipe joint. And a detection unit that detects a leak of air from the pipe, wherein the detection unit inputs data indicating the volume of the sound output from the microphone, and, based on the input data, a value equal to or greater than a set value. Extraction of change data indicating a change in the volume of the sound that has been continued for a predetermined time from the point in time when the volume is detected, and based on the change data, determine whether or not the volume gradually decreases with time. As a result, the pipe inspection device determines that there is the air leak when the volume is gradually decreasing. 4. An air supply source which is provided in a pipe whose opening at an end is closed, and which supplies air in a pressurized state into the pipe, and an air supply source which is provided in different parts of the pipe. A plurality of microphones for detecting nearby sounds, and a detection unit for detecting air leak from the pipe, wherein the detection unit transmits data indicating the volume of the sound output from each of the plurality of microphones. Input with shifted timings from each other, from the input data, extract change data indicating a continuous change in the volume of the sound for a predetermined time from the point of detecting a volume equal to or greater than a set value, based on the change data It is determined whether or not the volume is gradually decreasing with the passage of time. As a result of the determination, when the volume is gradually decreasing, the air is returned to the portion corresponding to the change data. A pipe inspection device that determines that there is a leak. 5. The pipe inspection device according to claim 3, further comprising a filtering unit for extracting a sound in a specific frequency band from a sound near the pipe joint.