JP3472711B2 - Can airtightness inspection device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a can airtightness determination device, and more particularly to a can airtightness inspection device capable of improving the reliability of determination.

[0002]

2. Description of the Related Art FIG. 6 shows, for example, JP-A-52-14528.
It is a block diagram which shows the canned goods inspection apparatus of the conventional airtightness inspection apparatus of the can shown by the 2nd publication. In the figure, 91 is a target can, 92 is a striking rod for striking the can to generate a tapping sound, 9
3 is a microphone that detects tapping sound and converts it into an electrical signal,
Reference numeral 94 is an amplifier that amplifies the electric signal detected and converted by the microphone 93. 95 is a wideband filter (Wi
deBandPassFilter (hereinafter referred to as WBPF), which is related to the internal pressure of the can 900 to 2700 Hz
The frequency component of is extracted.

Reference numeral 96 denotes a bandpass filter (BandPassf).
ilter, hereinafter referred to as BPF), has band characteristics, and separates the signal obtained from the W BPF 95 for each frequency band. A rectifier circuit 97 rectifies the signal for each frequency band obtained from the BPF 96 and converts it into a direct current.
Reference numeral 98 is an averaging circuit for averaging the DC signal obtained from the rectifying circuit 97. It should be noted that a plurality of BPFs 96 are provided, and the ratio of the center frequencies of the respective pass bands is constant. Further, the rectifying circuit 97 and the averaging circuit 98
Also, a plurality is provided corresponding to the plurality of BPFs 96.

Reference numeral 99 denotes a frequency calculation circuit, which receives the signal obtained from each averaging circuit 98 and calculates the frequency having the maximum peak of the sound pressure signal of the tap sound. A frequency gauge pressure conversion circuit 100 converts the frequency obtained from the frequency calculation circuit 98 into a gauge pressure signal. Reference numeral 101 denotes a pass / fail determination circuit, which determines pass / fail based on the gauge pressure obtained from the frequency gauge pressure conversion circuit 100.

Next, the operation will be described. First, the striking rod 92 strikes the can 91 that is the object. The tapping sound generated at this time is detected by the microphone 93 and converted into an electric signal, and the electric signal obtains an appropriate gain through the amplifier 94 and a frequency band of 900 to 2700 Hz related to the internal pressure of the can is obtained through the WBPF 95. Extracted, B
It is input to the PF 96.

Next, a plurality of BPFs 96 having band characteristics extract signals for each frequency band, and a rectifying circuit 97 converts the signal into a direct current and an averaging circuit 98 performs averaging to obtain a temporal average level for each frequency band. . From these average levels, the frequency calculation circuit 99 calculates the frequency at which the average level becomes the maximum level, and the frequency gauge pressure conversion circuit 100
Calculates the gauge pressure inside the can 91 from the obtained frequency. The pass / fail judgment circuit 101 judges whether the gauge pressure thus obtained is within the specified pressure range, and outputs an alarm if it is outside the range.

[0007]

As described above, in the hitting sound inspection device as the hitting sound determination device of the related art shown in FIG. 6, the predetermined time for each frequency band in the sound pressure signal generated by hitting. Since only the frequency with the maximum average level in the, i.e., the frequency that is the main component, is obtained, if an abnormal characteristic appears in frequencies other than the main component in the tap sound inspection that features the composite frequency, The abnormality could not be detected accurately.

Further, since the average level within a predetermined time for each frequency band is targeted for evaluation, it is not possible to evaluate the magnitude of the instantaneous sound pressure at a plurality of frequencies generated immediately after striking, which is a characteristic of the striking sound. greatly generated sound pressure and lingering there has been a problem that it is impossible to distinguish between long levels of low sound pressure. This is a problem that similarly occurs in a tapping sound determination device that uses Fourier transform as one of the processes for averaging levels. Also, if the impact strength varies, the generated sound
The pressure level also changes and frequency changes depending on the magnitude of the applied external force.
For complex structures where the distribution of several components changes
In some cases, the reliability of detection was low.

The present invention has been made to solve the above problems, and an object thereof is to obtain an air tightness inspection device for a can as follows. a. The reliability of determination can be improved by comparing the state of vibration generated by impact with the reference state. b. Inexpensive and high-speed processing is possible. c. Alternatively, it can be miniaturized and can flexibly respond to changes in conditions. d. Operability can be improved. e. It is possible to prevent the influence of variations in external force applied to the object. f. It is possible to prevent noise from the surroundings and the influence of noise.

[0010]

According to a first aspect of the present invention , there is provided an airtightness inspection apparatus for a can, which comprises a striking means for applying an external force to the can.
External force that detects the magnitude of applied external force as an external force signal
Signal detecting means, external force signal for amplifying the detected external force signal
Maximum value of external force signal output from amplifier, external force signal amplifier
External force signal maximum value calculator for calculating, external force signal reference value in advance
Set the maximum value of the external force signal in the reference value setting mode.
External force signal reference value setter to set and store, in inspection mode
Detected and amplified external force signal maximum value and external force
External force with a ratio calculator that calculates the ratio with the signal reference value
Is it a can due to the correction means and the external force applied by the striking means?
Vibration signal detection that detects the sound wave generated from it as a vibration signal
Means for amplifying the detected vibration signal to a predetermined frequency
Multiple converters that convert time series signals for several bands respectively
Stage, and for each frequency band based on the conversion result by the conversion means
Extract each maximum value and store the extracted maximum value
A plurality of extraction means consisting of a vibration signal maximum value calculator,
For each frequency band of the vibration signal in the reference value setting mode
Multiple vibration signals that set and store each vibration reference value
No. reference value setter and ratio calculated by external force correction means
Multiply the maximum value for each frequency band of the above vibration signal by
With multiple vibration signal compensators that compensate by
Maximum value of the corrected vibration signal for each frequency band and the above vibration
Vibration reference for each frequency band set in the signal reference value setter
Outputs the comparison result and the comparison method that compares each value
And an output means for outputting.

Strike as a reference in the reference value setting mode
Set the external force signal reference value to
Since the correction is made according to the magnitude of the force,
It is possible to prevent the influence of rattling. Also the frequency
Adding different corrections according to the external force for each band
The distribution of frequency components should change according to the external force obtained.
Reliable comparison even for objects with complex structures
it can.

An airtightness inspection device for a can according to claim 2 of the present invention.
The device uses the vibration signal detected by the converting means of claim 1 as a way.
Wavelet transform means for bullet transform
The stage is based on the conversion result by the wavelet conversion means.
The maximum value for each frequency band is extracted by
Improve the characteristics when separating into time series signals for each frequency.
Therefore, the reliability of the determination is improved.

[0013] A can airtightness inspection device according to claim 3 of the present invention.
The conversion means of claim 1 detects the vibration signal in a short time.
Short-time fast Fourier transform means for performing fast Fourier transform between
However, the extraction means uses a short-time fast Fourier transform
Configuration for extracting the maximum value for each frequency band based on the conversion result
If the short-time Fourier means is used, the frequency resolution is improved.

An airtightness inspection device for a can according to claim 4 of the present invention.
Location is the structure of claims 1 to 3, the trigger detector that outputs an operation start command when the magnitude of the detected external force signal by an external force signal detection hand stage exceeds a preset operation start value provided Since the extraction means is operated by the operation start command of the trigger detector and the operation is not started until a command is issued, ambient noise, vibration, noise, etc. when there is no command is used as a vibration signal. There is no risk of erroneous processing, and the reliability of inspection is improved.

An apparatus for inspecting air tightness of a can according to claim 5 of the present invention
As for the arrangement, the maximum value and the peak of the external force signal are added to the configurations of claims 1 to 4.
Providing a ratio determiner that determines the ratio of the reference value
It is configured to output whether it is within the range of
The ratio of the external force to the external force reference value is within the specified range.
No, that is, the external force applied to the object, that is, the excitation force, is small
If it is out of this range, it is judged whether it is too big or too big.
It was found that an inappropriate external force such as
When the frequency characteristics of the vibration signal of the emitted sound wave are different, etc.
Moreover, erroneous determination can be prevented. If you give an inappropriate external force
If you understand, you can apply external force again, so that God
It can be operated without using the sutra and the operability is improved.

An airtightness inspection device for a can according to claim 6 of the present invention.
The position is detected by an external force signal detecting means according to the structure of claims 1 to 5.
Where the maximum value of the external force signal that has been output and amplified is preset
When an external force signal is detected that exceeds the fixed value
Detected by the over-over detector and vibration signal detection means.
Where the amplified vibration signal maximum value is preset
Vibration signal level that detects when the value exceeds a certain value
It has a configuration with a failover sensor.
Signal amplification means and vibration signal amplification means are saturated
It can detect that a signal has been input, and
Inspection can be eliminated.

[0017] A can airtightness inspection device according to claim 7 of the present invention.
In the configuration of claims 1 to 6, the output of the external force signal calculator is
The amplification factor of the external force signal amplifier is automatically adjusted to the proper value.
External force signal amplification rate automatic setting means to set and vibration signal performance
Amplification of the vibration signal amplifier so that the output of the calculator becomes an appropriate value
Equipped with external force signal amplification rate automatic setting means to automatically set the rate
It has the same configuration as above, but it does not include amplified external force signal or amplified vibration signal.
The gain can be easily set so that the signal has an appropriate output range.
And the operability is improved. Also, low S / N ratio
The lowering can be prevented and the reliability of the judgment is improved.

An airtightness inspection device for a can according to claim 8 of the present invention.
The rotating means rotates the striking means having the structure according to any one of claims 1 to 7 at an intermediate portion.
A ball that is freely supported and has an elastic body at one end
Of the attached arm and the support of the arm and the ball
A stopper that stops rotation at the intermediate position is provided, and the arm
Is attached with a spring that pulls in the direction in which the
Drive machine that pushes the other end of the arm downward to open it.
Configuration all SANYO where the structure provided with the external force is stabilized to give the can, the variation in the determination of the airtight state of the can is reduced.

[0019]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiment 1. Hereinafter, the first embodiment of the present invention will be described with reference to FIG. 1 is a can of an object, 2 is a hammer as a striking means for striking the can 1 to generate a hammering sound, and 11 is an external force signal.
Attached to a hammer 2 for detecting as a signal, an exciting force sensor for converting an exciting force into an electric signal, and 12 an exciting force sensor 1
An external force signal amplifier for amplifying the external force signal detected by 1; 13
Is a rectifier that converts the signal amplified by the external force signal amplifier 12 into direct current.

Reference numeral 14 denotes an external force signal maximum value calculator for calculating the maximum peak value of the DC signal output from the rectifier 13 , and 15
Is a ratio calculator for obtaining the ratio between the output of the external force signal maximum value calculator 14 and the external force reference value stored in the external force signal reference value setting device 16, and 17 is a trigger detection for detecting a trigger from the DC signal output from the rectifier 13. It is a vessel.

Reference numeral 19 is a ratio determiner for determining the ratio obtained by the ratio calculator 15, and 20 is an automatic amplification factor of the external force signal amplifier 12 based on the peak value output from the peak hold 7 or the external force signal maximum value calculator 14. It is a range automatic setting device that sets manually. 21 is an external force signal maximum value calculator 1
Detects range over from the peak value output from 4
It is an external force signal range over detector.

Reference numeral 3 is a vibration signal detecting hand which is attached to the hammer 2 and detects a tapping sound of the can that is hit and converts it into a vibration signal.
Stage microphones 4 vibration is converted by the microphone 3
A vibration signal amplifier 5 for amplifying the motion signal is an analog bandpass filter (hereinafter referred to as an analog BPF) as a conversion means for separating the signal obtained from the vibration signal amplifier 4 for each frequency band. The analog BPF 5 covers 9 octaves of 31.25 Hz to 16 kHz so as to substantially cover the human audible range of 20 Hz to 20 kHz, and provides a total of 28 bands for giving a resolution of 1/3 octave.

Reference numeral 6 denotes a rectifier for rectifying a signal for each frequency band obtained from the analog BPF 5 and converting it into a direct current. Reference numeral 7 denotes an oscillator for calculating and holding the maximum peak value of the output from the rectifier 6.
A motion signal maximum value calculator , 8 is a vibration signal corrector for correcting the peak value output from the vibration signal maximum value calculator 7 from the ratio obtained from the ratio calculator 15, and 9 is an output of the vibration signal corrector 8 and vibration. comparator for comparing the value stored in the signal reference value setter 10, 18 outputs an alarm to come and determines as abnormal makes a determination of the total based on the comparison result from the comparator 9 outputs It is an alarm device.

Reference numeral 31 is a rectifier that does not pass the analog BPF,
32 is a vibration signal maximum value calculator that calculates and holds the maximum peak value of the output from the rectifier 31, and 33 is a vibration signal maximum value.
A range automatic setting device for automatically setting the amplification factor of the vibration signal amplifier 4 based on the peak value output from the computing unit , 34
Is a range over detector that detects a range over from the peak value output from the vibration signal maximum value calculator 32.

Next, by using a reference object as an operation
The reference value setting mode for setting the external force signal reference value and the vibration signal reference value will be described. First, the vibration signal amplifier 4
And the amplification factor of the external force signal amplifier 12 is minimized. In this state, the can 1, which is the object, is struck by the hammer 2, the generated struck sound is converted into an electric signal by the microphone 3, and the rectifier 31 and the peak hold 3 that do not pass the analog NBPF.
The maximum value of the impact sound signal is obtained by 2.

This maximum value is input to the automatic range setting device 33, and the gain of the vibration signal amplifier 4 is set so as to obtain an appropriate measurement range. Similarly, after the vibration generated in the hammer by the impact is converted into an electric signal by the excitation force sensor 11, the external force signal is transmitted.
No. amplifier 12, rectifier 13, external force signal maximum value calculator 14
The maximum value of the vibration signal is obtained by inputting this maximum value to the automatic range setting device 20 so that an appropriate measurement range is obtained.
The gain of the external signal amplifier 12 is set.

The appropriate measurement range is, for example, the correction based on the difference in external force as in the first embodiment. If the range is 1/2 to 2 times, the maximum value is 2 times as large as the reference value. Since it is necessary to receive input, the signal level input in this reference value setting mode is 50
Set the gain to be%. In this way, both the vibration and the sound pressure amplification factors are set by the first first impact in the reference value setting mode.

Next, the can 1 which is a reference object is hit with the hammer 2. At this time, the vibration generated in the hammer 2 is converted into an external force signal by the excitation force sensor 11, and the external force signal amplifier 12 gives the gain set by the first first impact in the reference value setting mode. The amplified signal is converted into direct current by the rectifier 13. The trigger detector 17 compares the DC signal from the rectifier 13 with a preset reference value, and outputs a trigger when the DC signal exceeds this reference value.

The external force signal maximum value calculator 14 is a rectifier 13
Record the maximum value of the DC signal input from. At this time, the operation of the external force signal maximum value calculator 14 is started by the trigger signal from the trigger detector 17.

The recording of the maximum value is performed for a certain period of time until the sound pressure generated by the object is attenuated to some extent, and then the output from the external force signal maximum value calculator 14 is changed to the external force.
It is stored in the signal reference value setting device 16.

Similarly, the sound wave generated by striking is converted into an electric signal by the microphone 3, and the amplifier 4 gives the gain set by the first striking in the first reference value setting mode. A plurality of the amplified sound pressure signals are provided and input to the analog BPF 5 that is set to pass different frequency bands, and separated into time series signals for each frequency band.

The time-series signal separated by the analog BPF 5 for each frequency band is converted into a DC signal by the rectifier 6 and vibrated.
It is input to the signal maximum value calculator 7. Vibration signal maximum value calculation
The maximum value recording operation of the DC signal from the rectifier 6 that receives the output of the device 7 is started by the trigger signal from the trigger detector 17, and the sound pressure attenuation of the object is performed in the same manner as the external force signal maximum value calculator 14. It is held for a certain period of time. In this way, the instantaneous maximum value for each frequency band is recorded. After a fixed time until the sound pressure is attenuated, the maximum value recorded by the vibration signal maximum value calculator 7 is stored in the vibration signal reference value setting device 10.

By the operation of the reference value setting mode as described above, the external force signal reference value setting device 16 stores information indicating the strength of impact, and the vibration signal reference value setting device 10 stores the tapping sound in each frequency band. Information indicating the instantaneous maximum sound pressure is stored.

Next, the inspection mode for inspecting the object will be described. First, a can 1 which is an object with a hammer 2.
Hit. At this time, as in the reference value setting mode,
The vibration generated in the hammer 2 is converted into an electric signal by the excitation force sensor 11, amplified by the external force signal amplifier 12, and converted into direct current by the rectifier 13. Similarly, the trigger detector 17 also performs trigger output from the DC signal from the rectifier 13,
The external force signal maximum value calculator 14 records the maximum value of the DC signal for a fixed time from the trigger output to the sound pressure attenuation.

In the case of the test mode, enter after a certain time has expired until the sound pressure attenuation, the maximum value recorded in the external force signal maximum value calculator 14 to the ratio calculator 15, the ratio calculation unit 15, an external force
The ratio between the maximum value from the signal maximum value calculator 14 and the reference value stored in the external force signal reference value setting device 16 is calculated and output.

Similarly to the reference value setting mode, the sound wave generated by the impact is converted into a vibration signal by the microphone 3 and is amplified by the vibration signal amplifier 4, and the analog BPF 5 is used.
Are separated into time series signals for each frequency band, converted into DC signals by the rectifier 6, and input to the vibration signal maximum value calculator 7. The vibration signal maximum value calculator 7 records the maximum value of the DC signal for a fixed time from the trigger output to the sound pressure attenuation.

In the case of the test mode, enter after a certain time has expired until the sound pressure attenuation, the maximum value recorded by the vibration signal maximum value calculator 7 to the vibration signal corrector 8, the vibration signal corrector 8 ratio calculator An appropriate correction value is calculated from the ratio obtained from 15, corrected to the maximum value obtained from the vibration signal maximum value calculator 7, and output.

At this time, for example, if the correction of the vibration level and the sound pressure is performed in proportion, when the ratio twice the reference value is obtained by calculation, the maximum value recorded in the vibration signal maximum value calculator 7 is calculated. Divide the value by 2. In other words, if the excitation force in the inspection mode is doubled with respect to the excitation force in the reference value setting mode, the generated sound pressure for each frequency is also doubled, and the maximum value is obtained. Is divided by 2 so as to be converted into the excitation force in the reference value setting mode.

The maximum value corrected in this way is compared with the reference value stored in the vibration signal reference value setting device 10 by the comparator 9, and an alarm is issued when a predetermined relationship set in advance is exceeded. Output to the container 18.

The predetermined relationship at this time is, for example, in a band, the corrected maximum value is set to be normal within the range of 80% to 120% with respect to the vibration reference value of the band and abnormal outside the range. Keep it. In addition, in another certain band, for example, 70 to 1 is applied to the vibration reference value of the band.
It is set so that the range within 10% is judged as normal and the range outside is judged as abnormal.

Further, when the vibration reference value is smaller than the overall sound pressure, a judgment signal is prevented from being erroneously issued in a frequency band which is not the main component by taking measures such as canceling the comparison on the lower limit side.

The alarm device 18 inputs the judgment signal from the comparator 9 of the frequency band, and when the number of judgment signals exceeds a preset number, for example, two, it outputs an alarm to the outside as an abnormality.

The ratio determiner 19 outputs an out-of-correction alarm when the ratio calculated by the ratio calculator 15 exceeds a predetermined relationship. The predetermined relationship at this time is set to, for example, 1/2 to 2 times. Then, when there is an input less than 1/2 or more than twice, an out-of-correction range alarm is output.

By thus setting the range limitation on the correction by the exciting force, it is possible to surely inspect the object whose frequency characteristic of the hitting sound generated when the exciting force changes extremely. It becomes possible.

Further, when the magnitude of the vibration exceeds a predetermined value in the trigger detector 17, the maximum value of the vibration signal of the extracting means is calculated.
Since the instruction means for instructing the start of the operation of the container 14 is provided,
It is possible to reduce the influence of noise from the surroundings and improve the reliability of the determination.

A predetermined magnitude of vibration is detected by the trigger detector 17.
When the value is exceeded, a vibration signal amplifier, conversion means or ratio
The operation may be started for any of the comparison means.
Yes.

Further, by starting the operation of the can airtightness inspection device by the trigger signal from the trigger detector 17, it is possible to prevent the noise from the surroundings and the influence of the noise and improve the reliability of the judgment. The trigger detector 1
Although the trigger signal of 7 is given to the peak hold 14 and 7, the excitation force sensor 11 and the external force signal amplifier 1 are shown.
2, analog BPF 5, rectifier 6, vibration signal corrector 8,
The same effect can be obtained even if it is given to the comparator 9 or the like to start the storage operation of the maximum value or the comparison operation.

In each of the reference value setting mode and the inspection mode, the external force signal range over detector 21 inputs the peak value obtained from the external force signal maximum value calculator 14 for the vibration signal, and the peak values have a predetermined relationship. Outputs a range over alarm when exceeding. Range over detector 34
Inputs the peak value obtained from the vibration signal maximum value calculator 7 for the sound signal, and outputs a range over alarm when the measurement signal exceeds a predetermined relationship.

The predetermined relationship at this time is set, for example, as 99% of the measurement range. In this case, when a signal exceeding 99% is input, a range over alarm is output.

Further, by setting an appropriate measurement range in the first first impact in the reference value setting mode, the trouble of manually setting the measurement range is eliminated and the operability is improved. Furthermore, when setting manually, if the range is not appropriate, the S / N ratio will decrease and the reliability of the inspection will decrease, but this will not occur because the range is automatically set. Therefore, it is possible to obtain a can airtightness inspection device with improved inspection reliability.

By outputting the range over alarm just before the input of each signal is saturated, erroneous determination due to saturation of the amplifier can be prevented, and a can air tightness inspection device with improved inspection reliability can be obtained. It will be possible. Note that the inspection can be performed at high speed by using the analog BPF.

Embodiment 2. Although the analog BPF is used to obtain the maximum value for each frequency in the first embodiment, a digital BPF may be used. In the second embodiment, a case where a digital BPF is used will be described with reference to FIG. In FIG. 2, reference numeral 51 is an A / D converter that converts an analog signal from the rectifier 13 into a digital signal, and 52 is an A / D converter that converts an analog signal from the vibration signal amplifier 4 into a digital signal. 5
Reference numeral 3 is an external force signal maximum value calculator as an extracting means for extracting the maximum value from the digital signal from the A / D converter 51.

Reference numeral 61 is a digital BPF as a conversion means for converting a digital signal into a time series signal for each frequency band. The digital BPF 61 has a frequency range of 31.25 to 16,000 Hz so as to substantially cover the human audible range of 20 to 20,000 Hz as in the embodiment of FIG.
A total of 28 bands are provided by targeting the octave and providing resolution for each 1/3 octave. Reference numeral 62 is a rectifier for rectifying the AC signal from the digital BPF, and 63 is a vibration signal maximum value calculator as an extracting means for extracting the maximum value from the rectified digital signal.

Reference numeral 64 denotes a corrector, which corrects the peak value output from the vibration signal maximum value calculator 63 by the ratio obtained from the ratio calculator 15 and outputs the corrected value. Reference numeral 65 is a comparator as a comparison means, and the output of the vibration signal corrector 64
The reference value stored in the vibration signal reference value setting unit 66 is compared. In addition, the rectifier 62, the vibration signal maximum value calculator 63,
The vibration signal corrector 64, the comparator 65, and the vibration signal reference value setting device 66 are digital BPFs 61 provided for all 28 bands.
28 are provided corresponding to each.

Reference numeral 41 denotes a vibration signal maximum value calculator, which extracts the maximum value from the digital signal from the A / D converter 52 rectified by the rectifier 31. Since other configurations are the same as those shown in FIG. 1, corresponding components are designated by the same reference numerals and description thereof will be omitted.

Next, the operation will be described. First, a reference value setting mode for setting each reference value using a reference object will be described. The A / D converter 51 converts the analog DC signal from the rectifier 13 into a digital signal. At this time, the A / D converter 51 receives the trigger signal from the trigger detector 17 and starts its operation, and continues to operate for a certain period of time until the sound pressure generated by the impact is reduced to a predetermined value or less. Be seen. The external force signal maximum value calculator 53 extracts the maximum value of the digital signal and stores it in the external force signal reference value setting device 16 as a peak reference value.

Similarly, the sound wave generated by striking is detected by the microphone 3 and converted into a vibration signal, and the vibration signal is vibrated.
After being given an appropriate gain by the signal amplifier 4, it is converted into a digital signal by the A / D converter 52. At this time, A / D
The converter 52 starts its operation in response to the trigger signal from the trigger detector 17, and operates for a certain period of time until the sound pressure generated by the impact of the object attenuates below a predetermined value. The converted digital signal includes 28 digital BPFs 61 that are set to pass different frequency bands.
And is separated into time series signals for each frequency band.

The time series signals separated for each frequency band by the digital BPF 61 are converted into DC signals by the rectifier 62,
It is input to the vibration signal maximum value calculator 63. Vibration signal maximum value calculator 63 extracts the maximum value of the DC signal, the vibration
It is stored in the signal reference value setting unit 66. In this way, the instantaneous maximum value for each frequency band is extracted and stored in the vibration signal reference value setting unit 66. By the operation in the reference value setting mode, the external force signal reference value setting unit 16 stores information indicating the strength of impact, and the vibration signal reference value setting unit 66 instantaneously in each frequency band of the tapping sound. Information indicating the maximum sound pressure is stored.

Next, a judgment mode for judging an object will be described. First, the hammer 2 hits the can 1, which is the object. At this time, as in the reference value setting mode, the vibration generated in the hammer 2 is converted into an electric signal by the excitation force sensor 11, amplified by the external force signal amplifier 12, and the rectifier 13 is used.
Convert to DC with. Similarly, the trigger detector 17 also has a rectifier 1
A trigger signal is output from the DC signal from the A / D converter 3, and the A / D converter 51 converts the DC signal into a digital signal for a fixed time from the trigger output to the sound pressure attenuation. External signal maximum value calculator
53 extracts and outputs the maximum value of the digital signal.

In the judgment mode, the external force signal maximum value calculator
The maximum value extracted by 53 is input to the ratio calculator 15, which calculates and outputs the ratio between the maximum value and the peak reference value stored in the external force signal reference value setting device 16.

Similarly to the reference value setting mode, the sound wave generated by striking is detected by the microphone 3, converted into a vibration signal, amplified by the vibration signal amplifier 4, and converted into a digital signal by the A / D converter 52. To be done. At this time A
The operation of the / D converter 52 is started by the trigger signal from the trigger detector 17, and is performed for a fixed time until the sound pressure is attenuated. The digital signal is separated into a time series signal for each frequency band by the digital BPF 61, converted into a DC signal by the rectifier 62, and input to the vibration signal maximum value calculator 63. Shaking
The motion signal maximum value calculator 63 extracts and outputs the maximum value of the DC signal.

[0062] When the determination mode, the maximum value extracted by the vibration signal maximum value calculator 63 is input to the vibration signal corrector 64, the vibration signal corrector 64 is appropriate correction based on the ratio obtained from the ratio calculator 15 The value is calculated, and the maximum value obtained from the vibration signal maximum value calculator 63 is corrected and output. The corrected maximum value is output by the comparator 65 to the vibration signal reference value setter 6
6 is compared with the reference value stored in 6, and when a predetermined relationship set in advance is exceeded, it is output to the alarm device 18 as an alarm. As for the predetermined relationship to be set, for example, as in the embodiment shown in FIG. 1, the range of 80 to 120% with respect to the reference value is normal, and the case of deviation from this range is abnormal, and a determination signal is output. To set. In addition, in another certain band, a determination signal is set to be normal within the range of 70 to 110% with respect to the vibration reference value of the band and abnormal outside the range. When the number of input determination signals exceeds a preset number, for example, two, the alarm device 18 sounds a buzzer as a notification message and blinks a lamp to give an alarm.

As described above, by using the digital BPF 61 as a method for obtaining a time-series signal for each frequency, the apparatus can be downsized, and since the processing is performed by software (S / W), the filter characteristic is changed and the frequency band for diagnosis is changed. It is possible to deal flexibly with additions.

Third Embodiment FIG. 3 is a block diagram of an airtightness inspection device for a can according to the third embodiment. Although the digital BPF is used to obtain the maximum value for each frequency in the second embodiment, a wavelet transform may be used. In the third embodiment, the case of using the wavelet transform will be described with reference to FIG.

In the third embodiment, a wavelet transformer 71 is provided to obtain a time series signal for each frequency band, and other operations are the same as those in the second embodiment. Since the effective value of the wavelet transform is calculated by the analytical calculation, it is not necessary to provide a rectifying means.

In the figure, reference numeral 71 is a wavelet transform as a transforming means.
The digital sound pressure signal is separated into time series signals for each frequency band by enlarging or reducing the basis function (mother wavelet). The wavelet-transformed signals are provided in 28 sets of vibration signal maximum value calculators 6
3, the vibration signal corrector 64 and the comparator 65 are input. The comparator 65 vibrates similarly to that shown in FIGS. 1 and 12.
Is compared with the reference value stored in the signal reference value setter 66,
A judgment signal is output to the alarm device 18 when a predetermined relationship set in advance is met.

At this time, by selecting an appropriate basis function in accordance with the measured waveform and the phenomenon to be observed, the frequency separation characteristic is improved and the reliability of judgment can be improved. Further, the apparatus can be downsized by using the wavelet transform.

Fourth Embodiment FIG. 4 is a configuration diagram of an airtightness inspection device for a can according to the fourth embodiment. Although the digital BPF is used to obtain the maximum value for each frequency band in the second embodiment, a short-time FFT may be used. In the fourth embodiment, the case of using the short-time FFT will be described with reference to FIG. In the fourth embodiment, a short-time FFT calculator 81 is provided to obtain a time series signal for each frequency band, and other operations are the same as those in the second embodiment. Since the FFT conversion calculates the effective value by the analytical calculation, it is not necessary to provide a rectifying means. In the figure, 81 is a short-time FFT (STFT: Short-TimeF) as a conversion means.
This is an operator-transform) arithmetic unit, which is adapted to obtain a time-series signal for each frequency band.

Thus, the short time F which is the Fourier transformer
The frequency resolution can be improved by providing the FT calculator 81 and determining the time series signal for each frequency band.

Therefore, by utilizing the excellent resolution of the short-time FFT, the reliability of diagnosis can be improved in the case where the characteristics of the change in frequency appear due to the structure of the test object. Further, the device can be downsized by using the short-time FFT conversion.

Fifth Embodiment Embodiment 5 is an embodiment of hitting means for hitting a can. In the first to fourth embodiments, the inspector hits the can with a hammer, but the size of the hit varies depending on the individual and may change depending on the fatigue of the inspector and mood, and there is a large variation in the determination. Expected to become. In the fifth embodiment, an impact device as shown below is used to inspect the impact so that the impact is always constant.

The structure of the striking device is shown in FIG. In the figure, 110 is an arm made of an elastic body, 111 is a ball made of an elastic body, 112 is a rotating shaft that rotatably supports the arm 110, 113 is a stopper that regulates the rotating position of the arm 110, Reference numeral 114 is a spring that applies a rotational force to the arm, 115 is a drive mechanism that pushes down and opens the other end of the arm, and 116 is a pedestal.

The ball 111 is made of an elastic material so that noise is not generated in the hitting sound when hitting the can, and the arm 11
Reference numeral 0 indicates a state in which the ball 111 is attached to one end of the ball 0, and is formed to have appropriate elasticity. Drive mechanism 11
5 rotates once with a miniature motor or the like to push down the other end side 110a of the arm 110 to open it,
When the arm 110 is released, it is returned by the pulling force of the spring 114, and the ball 11 hits the can at the moment when the arm contacts the stopper 113.

By setting the drive mechanism 115 as a motor, remote control is possible, and a constant impact can be automatically applied to the can. By driving the can airtightness inspection device using this striking device, the can airtightness determination accuracy can be improved.

Further, in each of the above-mentioned embodiments, a hammer is used to apply an external force, but an external force may be applied by other means, or an electromagnetic force, a cylinder or the like may be used.

[0076]

The airtightness inspection device for a can according to claim 1 of the present invention has the maximum external force signal of the external force signal of the external force applied to the can.
It is configured to detect the value, and the external power
No. reference value is set and added in the inspection mode.
The ratio between the maximum value of the external force signal and the external force signal reference value
Calculate and multiply this ratio by the vibration signal at the time of inspection
Force correction means is provided, and it is added by striking means.
The sound wave generated from the can by the external force is detected as a vibration signal.
And convert each to a time-series signal for each predetermined frequency band.
The maximum value for each frequency band is extracted and extracted.
Extractor consisting of vibration signal maximum value calculator that stores the maximum value
And the frequency of the vibration signal in the reference value setting mode in advance.
Set multiple vibration reference values for each band and store them.
Equipped with a vibration signal reference value setter, extraction in inspection mode
External force correction means to the maximum value for each frequency band of the generated vibration signal
Corrected by multiplying each by the ratio calculated by
Value of vibration signal for each frequency band and vibration signal reference value
The vibration reference value for each frequency band set in the setting device
It is configured to inspect by comparing each
Is outside the standard impact strength in the reference value setting mode.
Set the reference value of the force signal and set the external force in the inspection mode.
Since the correction is made according to the
Can be prevented from being affected. Also, for each frequency band
Added by making different corrections according to external force
Complexity such that the distribution of frequency components changes according to external force
Highly reliable comparisons can be made even for structural objects.

A can airtightness inspection device according to claim 2 of the present invention.
The position of the vibration signal detected by the conversion means having the structure of claim 1
As wavelet transform means for wavelet transform,
The extraction means is the conversion result of the wavelet conversion means.
The maximum value for each frequency band is extracted based on
Therefore, the characteristics when separating into time series signals for each frequency
Can be improved, and the reliability of judgment can be improved.

Airtightness inspection apparatus for cans according to claim 3 of the present invention
Is a vibration signal detected by the conversion means having the structure of claim 1.
Short-time Fast Fourier Transform to Short-time Fast Fourier Transform
And the extraction means is a short-time fast Fourier transform means.
The maximum value for each frequency band is extracted based on the conversion result by
It is configured to use short-time Fourier means
And the frequency resolution is improved.

A can airtightness inspection device according to claim 4 of the present invention.
According to the structure of claims 1 to 3,
Detected external force signal magnitude starts preset operation
A trigger detector for outputting an operation start command when it exceeds the value provided by the operation start command of the trigger detector, which has a structure for operating the extraction means, does not start operating until the command is issued Therefore, there is no possibility that the ambient noise, vibration, noise, etc., when there is no command is erroneously processed as a vibration signal, and the reliability of the inspection is improved.

An apparatus for inspecting air tightness of a can according to claim 5 of the present invention
As for the arrangement, the maximum value and the peak of the external force signal are added to the configurations of claims 1 to 4.
Providing a ratio determiner that determines the ratio of the reference value
It is configured to output whether it is within the range of
The ratio of the external force to the external force reference value is within the specified range.
No, that is, the external force applied to the object, that is, the excitation force, is small
If it is out of this range, it is judged whether it is too big or too big.
It was found that an inappropriate external force such as
When the frequency characteristics of the vibration signal of the emitted sound wave are different, etc.
Moreover, erroneous determination can be prevented. If you give an inappropriate external force
If you understand, you can apply external force again, so that God
It can be operated without using the sutra and the operability is improved.

The airtightness inspection device for a can according to claim 6 of the present invention.
The position is detected by an external force signal detecting means according to the structure of claims 1 to 5.
Where the maximum value of the external force signal that has been output and amplified is preset
When an external force signal is detected that exceeds the fixed value
Detected by the over-over detector and vibration signal detection means.
Where the amplified vibration signal maximum value is preset
Vibration signal level that detects when the value exceeds a certain value
It has a configuration with a failover sensor.
Signal amplification means and vibration signal amplification means are saturated
It can detect that a signal has been input, and
Inspection can be eliminated.

An airtightness inspection device for a can according to claim 7 of the present invention .
In the configuration of claims 1 to 6, the output of the external force signal calculator is
The amplification factor of the external force signal amplifier is automatically adjusted to the proper value.
External force signal amplification rate automatic setting means to set and vibration signal performance
Amplification of the vibration signal amplifier so that the output of the calculator becomes an appropriate value
Equipped with external force signal amplification rate automatic setting means to automatically set the rate
It has the same configuration as above, but it does not include amplified external force signal or amplified vibration signal.
The gain can be easily set so that the signal has an appropriate output range.
And the operability is improved. Also, low S / N ratio
The lowering can be prevented and the reliability of the judgment is improved.

An apparatus for inspecting air tightness of a can according to claim 8 of the present invention.
The rotating means rotates the striking means having the structure according to any one of claims 1 to 7 at an intermediate portion.
A ball that is freely supported and has an elastic body at one end
Of the attached arm and the support of the arm and the ball
A stopper that stops rotation at the intermediate position is provided, and the arm
Is attached with a spring that pulls in the direction in which the
Drive machine that pushes the other end of the arm downward to open it.
The structure is equipped with a structure, and the external force applied to the can is low.
Therefore, the variation in the determination of the airtight state of the can is reduced.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a can airtightness inspection device according to a first embodiment of the present invention.

FIG. 2 is a configuration diagram of a can airtightness inspection device according to a second embodiment of the present invention.

FIG. 3 is a configuration diagram of an airtightness inspection device for a can according to Embodiment 3 of the present invention.

FIG. 4 is a configuration diagram of an airtightness inspection device for a can according to Embodiment 4 of the present invention.

FIG. 5 is a configuration diagram of a striking device of an airtightness inspection device for a can.

FIG. 6 is a block diagram of a conventional can airtightness inspection device.

[Explanation of symbols]

1 object (can), 2 hammer, 3 microphone, 4
External signal amplifier, 5 analog BPF, 6 rectifier,
7 vibration signal maximum value calculator , 8 vibration signal corrector, 9
Comparator, 10 vibration signal reference value setting device, 11 excitation force sensor, 12 external force signal amplifier, 13 rectifier, 14 outside
Force signal maximum value calculator , 15 ratio calculator, 16 external force signal
No. reference value setting device, 17 trigger detector, 18 alarm device,
19 ratio determiner, 20 range automatic setting device, outside 21
Force signal range over detector, 31 rectifier, 32 vibration
Signal maximum value calculator , 33 range automatic setting device, 34 vibration
Dynamic signal range over detector, 41 Vibration signal maximum value calculator, 51, 52 A / D converter, 53 External force signal maximum value calculator, 61 Digital BPF, 62 Rectifier, 63
Vibration signal maximum value calculator, 64 vibration signal corrector, 65
Comparator, 66 vibration signal reference value setting device, 71 wavelet converter, 81 short time FFT calculator, 110 arm, 111 ball, 112 rotating shaft, 113 stopper, 114 spring, 115 drive mechanism, 116 mount.

─────────────────────────────────────────────────── ─── Continuation of front page (58) Fields surveyed (Int.Cl. ⁷ , DB name) G01M 3/24 G01L 11/00

Claims (8)

(57) [Claims] 1. A striking means for applying an external force to a can,
External force signal detection that detects the magnitude of external force as an external force signal
Means, an external force signal amplifier for amplifying the detected external force signal,
Calculate the maximum value of the external force signal output from the external force signal amplifier
External force signal maximum value calculator, preset external force signal reference value
Set the maximum value of the external force signal in the reference value setting mode.
Stored in the external force signal reference value setter, in the inspection mode
The maximum value of the detected and amplified external force signal and the external force signal
Of external force with a ratio calculator that calculates the ratio with the signal reference value
The can by the positive means and the external force applied by the striking means.
Vibration signal detection that detects sound waves generated from
The output means and the detected vibration signal are amplified to a predetermined frequency.
Multiple conversions that convert to time series signals for each wave number band
Means and a frequency band based on the conversion result by the conversion means
Extracts the maximum value for each and stores the extracted maximum value
A plurality of extracting means consisting of a vibration signal maximum value calculator,
In advance in the reference value setting mode, the frequency band of the vibration signal
Set multiple vibration reference values for each region and store them.
Calculated by the dynamic signal reference value setting device and the external force correction means.
To the maximum value for each frequency band of the vibration signal.
A plurality of vibration signal compensators that multiply and correct each, and the above vibration
For each frequency band of the vibration signal corrected by the signal corrector
Maximum value and frequency set in the vibration signal reference value setting device
Comparing means for respectively comparing the vibration reference value for each band,
And an output means for outputting the comparison result.
Airtight inspection device for cans. 2. The conversion means outputs the detected vibration signal.
Wavelet transform means for wavelet transform
The output means is the conversion result by the wavelet conversion means.
The airtightness inspection device for a can according to claim 1, wherein the maximum value for each frequency band is extracted based on the above. 3. The converting means shortens the detected vibration signal.
Short-time fast Fourier transform means for time fast Fourier transform
The extraction means is the short-time fast Fourier transform means
The maximum value for each frequency band is extracted based on the conversion result by
Airtightness inspection apparatus can of claim 1, wherein the that. 4. Detected by the external force signal detecting means
The magnitude of the external force signal exceeds the preset operation start value.
When a trigger detector that outputs an operation start command is provided,
The above extraction means is activated by the operation start command of the trigger detector.
Any one of claims 1 to 3 characterized in that
The can airtightness inspection device described in Crab. 5. The maximum value of the external force signal and the peak reference value
Equipped with a ratio determiner for determining the ratio of
Claim that is characterized by outputting whether it is within the range
The airtightness inspection device for a can according to any one of claims 1 to 4. 6. The external force signal detection means detects,
The amplified external force signal maximum value is a preset value
When an external force signal range is detected that exceeds
Detected by the probe detector and the vibration signal detecting means.
Where the amplified vibration signal maximum value is preset
Vibration signal level that detects when the value exceeds a certain value
6. A dead-over detector is provided.
The airtightness inspection device for a can according to any one of 1. 7. The output of the external force signal calculator is set to an appropriate value.
To automatically set the amplification factor of the external signal amplifier
External force signal amplification factor automatic setting means and the above vibration signal calculation
Increase the vibration signal amplifier so that the output of the
External force signal amplification factor automatic setting means for automatically setting the width ratio
7. The method according to claim 1, further comprising:
Air tightness inspection device for cans. 8. The striking means for applying an external force to the can is an intermediate portion.
A bow that is rotatably supported and has an elastic body at one end
The arm to which
A stopper that stops rotation at an intermediate position with the ball is provided.
And pull it in the direction in which the arm contacts the stopper.
The spring is attached and pushes the other end of the arm downward.
Characterized by having a drive mechanism that lowers and opens
Airtightness of the can according to any one of claims 1 to 7.
Inspection device.