JPH0894430A - Abnormal sound inspection device - Google Patents

Abstract

(57) [Summary] [Purpose] Pass / fail judgment based on the sound or vibration generated by the inspection object, which was performed by the inspector by hearing or touch, is automatically performed by frequency band analysis. [Structure] The sound or vibration generated by the inspection object 1 is converted into an electric signal by a sensor 2 such as a microphone, amplified by an amplification unit 3, and then separated into frequency components by a bandpass filter array unit 4, and each filter is separated. The rectification unit 5 connected to the column converts it into a direct current, and the AD conversion unit 6 performs sampling. The sampled data value is stored in the RAM 7, and the threshold value stored in the RAM is compared and calculated by the CPU 8 to display the pass / fail judgment on the display 9 and output to the output terminal 10.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an abnormal sound inspection apparatus used for automating a manufacturing process for inspecting a sound or vibration generated by a product or a part.

[0002]

2. Description of the Related Art Conventionally, as a device for automatically inspecting sound or vibration, a signal converted into an electric signal by a sensor is sampled directly or through a specific bandpass filter, and an FFT analyzer is used or a computer is used. In many cases, the frequency characteristic is obtained by performing the FFT operation using, and the defective product is determined.

[0003]

In the frequency analysis using the FFT arithmetic processing, since the data acquisition and the arithmetic processing are performed in order, when the low frequency component is analyzed, the processing result is obtained. However, since it is impossible to continuously process data for a long time, it is impossible to clearly detect a component of abnormal sound or vibration that occurs instantaneously at intervals.

The present invention solves the above-mentioned conventional problems, and an object of the present invention is to provide an excellent abnormal sound inspection apparatus capable of reliably detecting abnormal sound and abnormal vibration in a short time.

[0005]

In order to achieve the above object, the present invention does not use arithmetic processing for frequency analysis, but separates and rectifies frequency components by a bandpass filter array,
It is a device that performs inspection by digitizing by an analog-digital converter and determining the frequency component level. A sensor such as a microphone or an accelerometer, an amplification unit that amplifies a signal, a bandpass filter array that separates frequency bands, a rectification unit that converts the output of the filter array into DC, and a signal converted into DC for each frequency band , An analog-to-digital converter that converts
A RAM for storing the digital value, a CPU for performing a comparison operation with a set limit value and displaying the result and outputting the result to a terminal, a display for displaying the result, and an output terminal for outputting the determination result. RA here
The M, the CPU, the display device, and the output terminal may be general computer devices such as a personal computer.

[0006]

In the abnormal sound inspection apparatus of the present invention, the sound or vibration generated by the inspection object is converted into an electric signal by using a sensor such as a microphone or an acceleration pickup, and the electric signal is converted to a subsequent signal by the amplification section. Amplification is performed until a sufficient S / N ratio is obtained in each part where the treatment is performed. An electric signal corresponding to this amplified sound or vibration is put into a bandpass filter string to be separated into a plurality of frequency bands, and each output of each bandpass filter is converted into a direct current by a rectifying unit and corresponds to the amplitude of the signal. Get DC current. The DC voltage for each frequency is sequentially digitized by the analog-digital converter and stored in the RAM. By comparing the stored sound or vibration component for each frequency band with a limit value set and stored in advance by the CPU, it is possible to determine whether the inspection object is good or defective.

[0007]

Embodiments of the present invention will now be described with reference to the accompanying drawings.

FIG. 1 is a block diagram showing the configuration of the present invention. This device can judge good or bad by either sound or vibration generated by the inspection object. Generally, in the case of sound, a microphone is used as a sensor, and in the case of vibration, a vibration sensor such as an acceleration pickup. Is used to convert into an electrical signal for processing. Since the difference between the sound inspection and the vibration inspection is only in the sensor used, the following description will be made assuming that the sound inspection is performed.

FIG. 3 is an example of the original waveform of the sound generated by the inspection object, and it is assumed that FIG. 3 (A) is a normal product and FIG. 3 (B) is a sound waveform of a defective product including an abnormal sound. . In FIG. 1, the sound generated by the inspection object 1 is a sensor 2 such as a microphone.
Is converted into an electric signal. This signal is first amplified by the amplifier 3 to an amplitude that facilitates subsequent signal processing. The electric signal corresponding to the amplified sound is simultaneously given to the bandpass filter array 4. In this description,
Assume that there are 5 sets of bandpass filters. 4 and 5 show output signal waveforms of the bandpass filter array. FIG. 4 shows a non-defective product and an output in the case of the waveform of FIG.
Shows the output in the case of a defective product and the waveform of FIG. 3 (B), and FIGS. 4 and 5 (A) to (E) show the output of each bandpass filter. Comparing FIG. 4 and FIG. 5, there is a difference in the output of (E), and only the signal of the defective product has a waveform corresponding to the abnormal sound. The output waveforms of these bandpass filters are then converted into DC signals by the rectifying unit 5 shown in FIG. 6 and 7 are output waveforms of the rectification unit,
FIG. 6 shows output waveforms of the non-defective bandpass filter output of FIG. 4 and FIG. 7 shows output waveforms of the defective bandpass filter output of FIG. Each rectifier output waveform is sampled by the AD converter (analog-digital converter) 6 shown in FIG. 1 in order to perform determination processing. By performing this sampling continuously, it is possible to capture the temporal change in the signal level for each frequency band. The sampled waveform data for each frequency band is stored in the RAM, and the CPU 8 determines whether the waveform data is compared with a preset limit value. FIG. 8 is an explanatory diagram of the determination and shows an amplitude waveform of an abnormal sound peculiar to the defective product shown in FIG. In FIG. 8, assuming that a preset limit value is t, since the limit values are exceeded at three points of p, q, and r, it is possible to determine an inspection product in which this waveform appears as a defective product. This judgment result is shown in Figure 1.
The CPU 8 displays on the display 9 and outputs to the output terminal 10.

FIG. 2 shows another embodiment of the present invention.
The A / D converter, the CPU, the display, and the output terminal are replaced with an existing computer device.

[0011]

As is apparent from the above-described embodiment, the present invention can give a signal to a plurality of bandpass filters at the same time and take out an output for each frequency band, so that it is possible to make a determination in a short time. By continuing the sampling, it is possible to determine a continuous abnormal sound for a long time, and it is also possible to make a determination by capturing the continuous abnormal sound. Further, by separating the frequency band, it is possible to detect an abnormal sound component that cannot be determined only by peak determination.

[Brief description of drawings]

FIG. 1 is a block diagram of an abnormal sound inspection device according to a first embodiment of the present invention.

FIG. 2 is a block diagram of an abnormal sound inspection device according to a second embodiment of the present invention.

FIG. 3 is a sound signal waveform diagram in the first and second embodiments.

FIG. 4 is a signal waveform diagram separated into frequency bands of a sound signal in the example.

FIG. 5 is a signal waveform diagram in which the sound signal is separated into frequency bands in the same example.

FIG. 6 is a rectified waveform diagram of a signal separated into frequency bands of a sound signal in the example.

FIG. 7 is a rectified waveform diagram of signals separated into frequency bands of sound signals in the example.

FIG. 8 is a characteristic diagram showing an abnormal sound in the example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Inspection object 2 Sensor 3 Amplification section 4 Band pass filter 5 Rectification section 6 Analog-digital conversion section 7 RAM 8 CPU 9 Display 10 Output terminal 11 Computer device

Claims (2)

[Claims] 1. A bandpass filter train for decomposing an electric signal of sound or vibration into frequency components, an analog / digital conversion device for performing time-series sampling of frequency components, and a process for performing threshold determination of frequency component levels. Abnormal sound inspection device with parts. 2. A frequency component is provided by a computer device having a bandpass filter array unit for decomposing an electric signal of sound or vibration into frequency components and an analog / digital converter unit for performing time-series sampling of frequency components by a computer device. Abnormal sound inspection device that performs level threshold judgment.