JPS6412335B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a hole inspection device capable of quickly inspecting a manifold for clogging.

Conventionally, to inspect the through holes of branch pipes, manifolds, etc., there are two methods: inserting an inspection rod into each hole and detecting the presence or absence of clogging from the insertion depth, or applying positive or negative pressure to the main hole side. A method was used to detect the presence or absence of a blockage based on the fluid flow generated at this time. However, the former method not only requires time and effort to insert the inspection rod into each hole, but also tends to cause detection errors due to burrs, etc., and the latter method is affected by the connection state with the pressure source, so There was a problem in that the sensitivity to clogging in areas far from the hole was low and there was a risk of false detection.

In view of these problems, the present invention irradiates the manifold to be inspected with an acoustic wave having a certain bandwidth from its outer periphery, and detects the presence or absence of a blockage based on the acoustic parameters detected through the manifold to be inspected. The purpose of the present invention is to provide a hole inspection device that is easy to handle and has high sensitivity.

Therefore, details of the present invention will be explained below based on illustrated embodiments.

FIG. 1 is a configuration diagram of an apparatus showing an embodiment of the present invention, and reference numeral 1 in the figure indicates an acoustic wave of a predetermined frequency input through a manifold pipe T to be inspected into a sound insulation chamber 2.
It is a sound conduit that transmits sound to a microphone 3 installed inside the sound insulation chamber 2, and one end extending outside the sound insulation chamber 2 is provided with a connection part 4 that airtightly holds the main section of the manifold pipe T to be tested. The microphone 3 connected to the signal processing section 5 is fixed to the other end. The signal processing unit 5 determines the quality of the manifold to be tested based on the acoustic vibrations detected through the sound pipe 1, and includes an amplifier 6 that amplifies the output from the microphone 3 to a predetermined level, and a manifold to be tested. a filter group 7 that sets an analysis frequency band according to the type of pipe;
A spectrum analyzer 8 detects the center frequency of the output from this filter group 7, and stores the center frequency when acoustic vibration is detected through the standard manifold,
It is comprised of a determination circuit 9 that compares this frequency with the center frequency detected via the manifold to be tested, indicates the deviation thereof, and at the same time determines whether the manifold to be tested is good or bad. In addition, the reference numeral 10 in the figure
is a sound source placed near the mounting position of the manifold pipe T to be inspected, to which is connected an oscillator 11 that outputs an acoustic signal with a predetermined bandwidth.

In this embodiment, when a master standard manifold pipe is inserted into the connection part 4 and the sound source 10 is operated, acoustic vibrations of a frequency determined by the position of the hole in the standard manifold, the length of the hole, etc. are transmitted to the microphone 3. The signal is input to the signal processing section 6 via the signal processing section 6. In the signal processing section 6, the spectrum analyzer 8 detects the center frequency and stores it in the determination circuit 9 as a reference frequency. After completing such preparations, when inspecting the manifold to be inspected, the signal processing section 6
Since the input frequency is biased, the quality can be easily determined based on the deviation from the reference frequency.

〔Example〕

When we used a sound source that outputs flat acoustic waves from 1000Hz to 1500Hz and captured the acoustic waves through the standard 8-way branch tube shown in Figure 2A, we obtained the spectogram shown in Figure 2B. The center frequency was 1319Hz. On the other hand, when one of the through holes was captured through a blocked branch pipe (C in the same figure), the center frequency became 1289 Hz (D in the same figure), and it was possible to detect a blockage in the branch pipe from the deviation between the two.
Furthermore, when we conducted an experiment by blocking the through hole that has the least effect on changes in the center frequency (Figure E), a downward shift of 7 Hz occurred (Figure F), indicating that the blockage could be detected even in this case. I understand.

As described above, according to the present invention, an acoustic wave having a constant bandwidth is generated, this is discarded through the manifold to be inspected, and clogging of the manifold is detected from the deviation of the center frequency. Therefore, although it is a simple device, abnormalities in the through hole can be detected easily and in a short time, and line inspection of manifold pipes can be performed.

[Brief explanation of drawings]

FIG. 1 is a block diagram of a device showing an embodiment of the present invention, and FIG. 2 is an explanatory diagram showing the detection accuracy of the device according to the present invention. T...Test manifold, 1...Sound conduit, 2...Sound isolation room, 3...Microphone, 4...Connection part, 5...
...Signal processing unit, 10...Sound source.

Claims (1)

[Claims] 1. A sounding means for irradiating the manifold to be inspected with an acoustic wave having a certain band; an acoustic-to-electric conversion means for receiving the acoustic waves from the sounding means through a hole in the manifold to be inspected; A manifold through hole inspection device comprising means for detecting a deviation between the center frequency of the pipe and the center frequency of the signal from the converting means.