JP2000131291A - Material inspection device of casting - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a material inspection device of a casting product, capable of inspecting precisely the quality of material of the casting product by hammering. SOLUTION: An exciting force, applied for hammering a casting product 1 by a hammer 2 is detected by an exciting force sensor 11, and the ratio thereof to an exciting reference value is determined by a ratio computing unit 15. And the hammering sound generated on the hammer bolt 2 is detected by a microphone 3, and separated into time series signals in each frequency zone by an analog BPF 5, and the time series signals are rectified and instantaneous maximum values in each frequency zone are extracted by a peak hold 7. The maximum values are corrected based on the ratio calculated by the ratio computing unit 15, and compared with a vibration reference value corresponding to the quality of material set up beforehand by a comparator 9, to thereby execute determination of 'normal or abnormal', and in case of an abnormal result, it is displayed on an alarm unit.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a casting material inspection apparatus for inspecting the quality of a casting product.

[0002]

2. Description of the Related Art An object having a predetermined shape vibrates when it is hit or the like to generate a sound wave. The frequency of the generated sound wave varies depending on the shape, material, and the like. When the shape is constant, the frequency changes depending on the material. Utilizing this fact, Japanese Patent Application Laid-Open No. S59-48655 discloses an example of an inspection apparatus for measuring a vibration frequency by hitting a casting having a predetermined shape and estimating a material. FIG. 6 shows the configuration. In the figure, reference numeral 91 denotes a casting product of an object, and 92 denotes a casting product 91.
, A hammer that generates vibration by hitting the microphone, 93 is a microphone that converts a tapping sound into an electric signal, 94 is an amplifier that amplifies the electric signal converted by the microphone, 95 is a low-pass filter, 96 is a high-pass filter, and 97 is an A / A. A D converter 98 is a microprocessor, and 99 is a display for displaying the output of the microprocessor 98.

A method of inspecting the quality of a cast product in the configuration shown in FIG. 6 will be described. First, when the casting 91 is hit with the hammer 92, the casting 91 vibrates and generates sound waves. The generated sound wave is converted into an electric signal by a microphone 93 and input to an amplifier 94, and is amplified by the amplifier 94, and is amplified by a low-pass filter 95 and a high-pass filter 9.
6, unnecessary frequency components are removed, and the A / D converter 9
7, the digital signal is converted into a digital signal, and is input to the microprocessor 98 as waveform data.
In, the relationship between the material of the casting product to be inspected and the natural frequency is stored in advance, the natural frequency is obtained by calculating the frequency spectrum based on the measured vibration data of the casting product, and stored in advance. The material of the casting is inspected from the relationship between the material and the natural frequency, and the inspection result is displayed on the display 99.

[0004]

As described above, in the conventional inspection apparatus for estimating the material of a cast product shown in FIG. 6, since the judgment is made only based on the natural frequency of the vibration signal generated by the impact, when the impact is applied, In the case where the vibration has a complex frequency, if the characteristic other than the main frequency component shows an abnormal characteristic, there is a problem that the material cannot be inspected accurately.

The present invention has been made to solve the above problems, and has as its object to obtain the following casting material inspection apparatus. a. The reliability of the determination can be improved by comparing the state of the vibration generated by the impact with the reference state. b. Inexpensive and high-speed processing is possible. c. Alternatively, it can be downsized and can flexibly respond to changes in conditions. d. Operability can be improved. e. The influence of the variation of the external force applied to the object can be prevented. f. Noise from the surroundings and the effects of noise can be prevented.

[0006]

In a casting material inspection apparatus according to the present invention, a signal detecting means for detecting a vibration generated from an object to which an external force is applied as a vibration signal;
A converting unit that converts the vibration signal into a time-series signal for each of a plurality of predetermined frequency bands; an extracting unit that extracts a maximum value of the time-series signal for each frequency band; and a maximum value for each predetermined frequency band. A comparison means for comparing the vibration reference value with each other is provided.

[0007] Since the vibration signal is converted into a time-series signal for each of a plurality of frequency bands, and the maximum value of each of the time-series signals is extracted, the frequency resolution of the vibration signal is improved, and the sensitivity from the time-series signal is improved. The maximum value can be extracted well. Therefore, it is possible to accurately grasp the characteristics of the loud sound or vibration immediately after the occurrence, which is also the characteristic of the striking sound, and make a comparison.

The converting means is a plurality of band filters for passing a frequency component of a predetermined frequency band of the vibration signal. The extracting means rectifies the frequency components passing through each band filter, and converts the rectified frequency components. The maximum value among the peak values is extracted as the maximum value.

If the converting means is a bandpass filter, the processing can be performed at a high speed, and the apparatus is simple and inexpensive. In particular, if an analog bandpass filter is used, the processing can be speeded up. If a digital bandpass filter is used, the size can be reduced, and the condition can be flexibly changed. In addition, since the extraction means extracts the maximum value from the rectified frequency components, it can be detected even if the maximum value is present in the negative sign portion of the vibration signal, and can be accurately compared even in the case of an object where the vibration signal rapidly attenuates. .

The converting means is a wavelet converting means for performing a wavelet conversion of the vibration signal, and the extracting means is for extracting the maximum value of the time series signal for each frequency band based on the result of the conversion by the wavelet converting means.
If the wavelet transform means is used, the characteristics at the time of separation into a time-series signal of a frequency band can be improved, and the reliability of determination can be improved.

The converting means is a short-time fast Fourier transform means for short-time fast Fourier transform of the vibration signal,
The extracting means extracts the maximum value of the time-series signal for each frequency band based on the conversion result by the short-time fast Fourier transform means. The use of the short-time Fourier means improves the frequency resolution.

Further, an external force detecting means for detecting the magnitude of the applied external force is provided, and at least one of a vibration signal, a time-series signal, a maximum value, and a vibration reference value is corrected according to the magnitude of the external force. A correction means is provided.

The correction is made according to the magnitude of the external force to prevent the comparison means from being affected by the variation in the magnitude of the external force. Also, for example, by performing different corrections according to the external force for each frequency band, it is possible to compare with high reliability even an object with a complicated structure in which the distribution of frequency components changes according to the applied external force. it can.

Further, an external force detecting means for detecting the magnitude of the applied external force is provided, and at least one of a signal detecting means, a converting means, an extracting means, and a comparing means when the magnitude of the external force exceeds a predetermined value. Command means for commanding the start of operation is provided.

Since the operation is not started until a command is issued, there is no possibility that noise, vibration, noise, etc. in the surroundings when there is no command are erroneously processed as a vibration signal. Therefore, the influence of these can be prevented, and the reliability of comparison is improved.

Further, there is provided external force detecting means for detecting the magnitude of the applied external force as an external force signal, and a ratio calculating means for obtaining a ratio obtained by dividing the external force signal by a preset external force reference value. Correction means for correcting the relationship between the maximum value and the vibration reference value in the comparison means by correcting at least one of the vibration signal, the time-series signal, the maximum value and the vibration reference value based on the ratio; And a ratio determining means for determining whether the value is within the range.

The ratio calculating means determines whether the ratio between the external force and the external force reference value is within a predetermined range, that is, whether the external force applied to the object, that is, the exciting force is not too small or too large. It is made clear that an inappropriate external force that is out of this range is applied. If the excitation force is too small or too large, erroneous determination can be prevented, for example, when the frequency characteristics of the vibration generated by the object are different. If it is known that an inappropriate external force has been applied, the external force may be applied again, so that the operation can be performed without using much nerves, and the operability is improved.

Further, there are provided external force signal amplifying means for amplifying the external force signal and outputting it as an amplified external force signal, and vibration signal amplifying means for amplifying the vibration signal and outputting it as an amplified vibration signal. It shall be used as an external force signal, the converting means shall use the amplified vibration signal as a vibration signal, and a range over detecting means for detecting that at least one of the peak values of the amplified external force signal and the amplified vibration signal has exceeded a predetermined value. It is characterized by having been provided.

In order to ensure the reliability of the measurement, the fact that the amplified external force signal or the amplified vibration signal exceeds a predetermined value, that is, that a large signal that saturates the external force signal amplifying means or the vibration signal amplifying means is input. To detect.

Further, the present invention is characterized in that amplification factor automatic setting means for automatically setting the amplification factor of at least one of the external force signal amplification means and the vibration signal amplification means is provided.

The amplification factor can be easily set so that the amplified external force signal and the amplified vibration signal have an appropriate output range.
Operability is improved. Further, a decrease in the S / N ratio can be prevented, and the reliability of the determination is improved.

Further, a hitting means for applying an external force to the casting product is rotatably supported at an intermediate portion, and has an arm having a ball attached to one end thereof, and stops rotating at an intermediate position between the arm support portion and the ball. A stopper is provided, and a spring that pulls in the direction in which the arm contacts the stopper is mounted.
It is characterized in that it is provided with a drive mechanism that pushes the other end of the arm downward and opens it. By using this impact device, the external force applied to the casting is stabilized, and the variation in the determination of the material of the casting is reduced.

[0023]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiment 1 Hereinafter, Embodiment 1 of the present invention will be described with reference to FIG. 1 is a cast product as an object, 2 is a hammer that strikes the cast product 1 and generates a sound, 11 is a vibrating force sensor attached to the hammer 2 and converts a vibrating force into an electric signal, and 12 is a vibrating force sensor An amplifier for amplifying the electric signal converted by 11;
Is a rectifier that converts the signal amplified by the DC into DC.

Reference numeral 14 denotes a peak hold for holding the maximum peak value of the DC signal output from the rectifier. Reference numeral 15 denotes a ratio calculator for calculating the ratio between the output of the peak hold 14 and the external force reference value stored in the reference value setting device 16. , 17 is a rectifier 13
Is a trigger detector that detects a trigger from the DC signal output from the trigger signal.

Reference numeral 19 denotes a ratio determiner for determining the ratio obtained by the ratio calculator 15, and reference numeral 20 denotes an automatic range setting device for automatically setting the amplification factor of the amplifier 12 from the peak value output from the peak hold 14. . Reference numeral 21 denotes a range over detector which detects an over range from the peak value output from the peak hold 14.

Reference numeral 3 denotes a microphone which is attached to the hammer 2 and converts an impact sound of the cast product into an electric signal. Reference numeral 4 denotes an amplifier which amplifies the electric signal converted by the microphone 3. Reference numeral 5 denotes a signal obtained from the amplifier 4. An analog bandpass filter (hereinafter, referred to as an analog BPF) as a conversion unit for separating each frequency band. This analog BPF
5 is, for example, a human audible range of 20 Hz to 20 kHz.
9 from 31.25 Hz to 16 kHz to cover almost all
For 28 octaves, a total of 28 bands are provided with a resolution of 1/3 octave.

6 is a rectifier for rectifying a time-series signal for each frequency band obtained from the analog BPF 5 and converting it to a direct current.
7 is a peak hold that holds the maximum peak value of the output from the rectifier 6, 8 is a corrector that corrects the peak value output from the peak hold 7 based on the ratio obtained from the ratio calculator 15, and 9 is the output of the corrector 8. And a comparator 18 for comparing the value stored in the reference value setting device 10 with the value stored in the reference value setting device 10. It is.

31 is a rectifier that does not pass through the analog BPF,
32 is a peak hold for holding the maximum peak value of the output from the rectifier 31; 33 is an automatic range setting device for automatically setting the amplification factor of the amplifier 4 from the peak value output from the peak hold 32; Is an over-range detector that detects over-range from the peak value output from.

Next, a reference value setting mode for setting each reference value using an object serving as a reference will be described. First, the amplification factors of the amplifiers 4 and 12 are minimized. In this state, the casting product 1 as an object is hit by the hammer 2, the generated tapping sound is converted into an electric signal by the microphone 3, and the maximum value of the hitting sound signal is converted by the rectifier 31 and the peak hold 32 that do not pass through the analog BPF. Ask.

The maximum value is input to the automatic range setting unit 33, and the gain of the amplifier 4 is set so as to have an appropriate measurement range. Similarly, the vibration generated in the hammer 2 by the impact is converted into an electric signal by the excitation force sensor 11, and then the maximum value of the vibration signal is obtained by the amplifier 12, the rectifier 13, and the peak hold 14. 20 and sets the gain of the amplifier 12 so as to have an appropriate measurement range.

The appropriate measurement range is, for example, corrected by the difference in the excitation force as in the first embodiment. If the range is 1/2 to 2 times, the range is at most 2 times larger than the reference value. Since it is necessary to accept twice the input, the signal level input in this reference value setting mode is 5 times the measurement range.
The gain is set to be 0%. In this way, the amplification rate of both the vibration and the sound pressure is set by the first hit in the reference value setting mode.

Next, the cast product 1 as a reference is hit by the hammer 2 as an object. At this time, the vibration generated in the hammer 2 is converted into an electric signal by the excitation force sensor 11, and the amplifier 12 gives the gain set by the first hit in the reference value setting mode. The amplified signal is converted into a direct current by the rectifier 13. Trigger detector 17 is rectifier 13
Is compared with a preset reference value, and when the DC signal exceeds this reference value, a trigger is output.

The peak hold 14 records the maximum value of the DC signal input from the rectifier 13. At this time, the operation of the peak hold 14 is started by a trigger signal from the trigger detector 17.

The recording of such a maximum value is performed for a certain period of time until the vibration of the object caused by the impact is attenuated to some extent, and thereafter the output from the peak hold 14 is stored in the reference value setting unit 16.

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

The time series signal separated for each frequency band by the analog BPF 5 is converted into a DC signal by the rectifier 6 and input to the peak hold 7. The maximum value recording operation of the DC signal from the rectifier 6 of the peak hold 7 is performed by the trigger detector 1.
7 and is carried out for a fixed time until the sound pressure of the object is attenuated, similarly to the peak hold 14 for vibration. In this way, the instantaneous maximum value for each frequency band is recorded. After a certain period of time until the sound pressure decay, the maximum value recorded by the peak hold 7 is stored in the reference setting device 10.

By the operation in the reference value setting mode, the reference value setting device 16 stores the information indicating the strength of the hitting, and the reference value setting device 10 stores the instantaneous maximum value for each frequency band of the hitting sound. Information indicating the sound pressure is stored.

Next, an inspection mode for inspecting an object will be described. First, the cast product 1 as an object is hit with the hammer 2. At this time, similarly to the case of 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 amplifier 12, and
Is converted to DC. The trigger detector 17 similarly outputs a trigger from the DC signal from the rectifier 13, and the peak hold 14 records the maximum value of the DC signal for a fixed time from the trigger output to the sound pressure decay.

In the case of the inspection mode, the maximum value recorded in the peak hold 14 is input to the ratio calculator 15 after a fixed time until the sound pressure decay, and the ratio calculator 15 determines the maximum value from the peak hold 14 as the maximum value. The ratio with respect to the reference value stored in the 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 an electric signal by the microphone 3 and amplified by the amplifier 4, separated into a time series signal for each frequency band by the analog BPF 5, and The signal is converted into a signal and input to the peak hold 7. The peak hold 7 records the maximum value of the DC signal for a fixed time from the trigger output to the sound pressure decay.

In the case of the inspection mode, the maximum value recorded by the peak hold 7 is input to the compensator 8 after a certain period of time until the sound pressure decay, and the corrector 8 determines an appropriate value from the ratio obtained from the ratio calculator 15. The correction value is calculated, corrected to the maximum value obtained from the peak hold 7, and output.

At this time, for example, assuming that the correction of the vibration level and the sound pressure is performed in proportion, when the ratio twice as large as the reference value is obtained by calculation, the maximum value recorded in the peak hold 7 is set to 2 Divide. That is, if the exciting force in the inspection mode is twice as large as the exciting force in the reference value setting mode,
The maximum value obtained assuming that the sound pressure for each generated frequency band is also doubled is divided by 2 in order to convert it 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 reference value setting device 10 by the comparator 9, and when a predetermined relationship is exceeded, an alarm 18 is issued. Is output to

At this time, the predetermined relationship is, for example, that in a band, the corrected maximum value is set as normal within a range of 80% to 120% of the sound pressure reference value of the band and abnormal outside the range. Keep it. In some other band, for example, 70 to 1 with respect to the sound pressure reference value of the band.
It is set so that the determination is made as normal within the range of 10% and abnormal outside the range.

Further, when the sound pressure reference value is smaller than the entire sound pressure signal, a judgment signal is prevented from being erroneously output in a frequency band other than the main component by taking measures such as canceling the comparison on the lower limit side. .

The alarm 18 receives the judgment result from the comparator 9 in each frequency band, and outputs an alarm to the outside as an abnormality when the number of judgment signals exceeds a predetermined number, for example, two.

The ratio judging unit 19 outputs an out-of-correction range 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, if there is an input less than や or more than twice, an out-of-correction-range alarm is output.

By thus limiting the range of the correction by the excitation force, it is possible to reliably inspect even an object whose frequency characteristic of a tapping sound generated when the excitation force changes extremely is changed. It becomes possible.

Also, command means is provided for instructing the trigger detector 17 to start at least one of signal detecting means, converting means, extracting means and comparing means when the magnitude of vibration exceeds a predetermined value. Therefore, the influence of noise or the like from the surroundings can be reduced, and the reliability of determination can be improved.

Furthermore, by starting the operation of the casting material inspection apparatus with a trigger signal from the trigger detector 17, it is possible to prevent noise from surroundings and the influence of the noise, thereby improving the reliability of the judgment. Although the trigger signal of the trigger detector 17 is given to the peak hold 14 and the peak hold 7, the maximum value is given to the vibration detector 11, the amplifier 12, the analog BPF 5, the rectifier 6, the compensator 8, the comparator 9, and the like. The same effect can be obtained by starting the storage operation or the comparison operation.

In each of the reference value setting mode and the inspection mode, the range over detector 21 inputs the peak value obtained from the peak hold 14 for the vibration signal,
An overrange alarm is output when the peak value exceeds a predetermined relationship. The range over detector 34 inputs the peak value obtained from the peak hold 7 for the sound signal,
An overrange alarm is output when the measurement signal exceeds a predetermined relationship.

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

Further, by setting an appropriate measurement range in the first hit in the reference value setting mode, the trouble of manually setting the measurement range is eliminated, and the operability is improved. Further, when the range is not appropriate when setting manually, the S / N ratio is lowered and the reliability of the inspection is lowered. However, such a problem does not occur because the range is automatically set to an appropriate value. In addition, it is possible to obtain a casting product material inspection apparatus with improved inspection reliability.

Further, by outputting a range over alarm immediately before the input of each signal is saturated, an erroneous determination due to saturation of the amplifier is prevented, and a material inspection apparatus for a cast product with improved inspection reliability is obtained. Becomes possible. Note that analog B
Inspection can be performed at high speed by using the PF.

Embodiment 2 In the first embodiment, the analog BP is used to determine the maximum value of the time-series signal for each frequency band.
Although F is used, the second embodiment is an embodiment using a digital BPF, and will be described with reference to FIG. 2, reference numeral 51 denotes an A / D converter for converting an analog signal from the rectifier 13 into a digital signal, and reference numeral 52 denotes an A / D converter for converting an analog signal from the amplifier 4 into a digital signal. Numeral 53 denotes a 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 denotes a digital BPF as conversion means for converting a digital signal into a time series signal for each frequency band. The digital BPF 61 is, for example, the first embodiment shown in FIG.
In the same way as above, 9 to 31.25 to 16,000 Hz is used to cover almost 20 to 20,000 Hz which is the human audible range.
For 28 octaves, a total of 28 bands are provided with a resolution of 1/3 octave. Reference numeral 62 denotes a rectifier for rectifying an AC signal from the digital BPF, and reference numeral 63 denotes a maximum value calculator as extraction means for extracting a maximum value from the rectified digital signal.

Reference numeral 64 denotes a corrector which corrects the peak value output from the maximum value calculator 63 based on the ratio obtained from the ratio calculator 15 and outputs a correction value. Reference numeral 65 denotes a comparator as a comparing means, which outputs the output of the compensator 64 and the reference value setting device 66
Is compared with the reference value stored in. The rectifier 62,
The peak hold circuit 63, the compensator 64, the comparator 65, and the reference value setting unit 66 are digital B provided for all 28 bands.
28 are provided corresponding to the PFs 61, respectively.

A maximum value calculator 41 extracts the maximum value from the digital signal from the A / D converter 52 rectified by the rectifier 31. Other configurations are the same as those shown in FIG. 1, and the corresponding components are denoted by the same reference numerals and description thereof is omitted.

Next, the operation will be described. First, a reference value setting mode for setting each reference value using a reference target object will be described. The A / D converter 51 converts an analog DC signal from the rectifier 13 into a digital signal. At this time, the A / D converter 51 starts operating in response to the trigger signal from the trigger detector 17, and is continuously performed for a certain period of time until the vibration generated by the impact on the target object attenuates to a predetermined value or less. . The maximum value calculator 53 extracts the maximum value of the digital signal and stores it in the reference value setting device 16 as a peak reference value.

Similarly, the sound wave generated by the impact is converted into an electric signal by the microphone 3, given an appropriate gain by the amplifier 4, and then converted into a digital signal by the A / D converter 52. At this time, the A / D converter 52 starts operating in response to a trigger signal from the trigger detector 17 and operates for a certain period of time until the sound pressure generated by the impact on the target object attenuates below a predetermined value. This converted digital signal is
The signals are input to 28 digital BPFs 61 set so as to pass through different frequency bands, and are separated into time-series signals for each frequency band.

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

Next, a judgment mode for judging an object will be described. First, the cast product 1 as an object is hit with the hammer 2. At this time, similarly to the case of 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 amplifier 12, and
To convert to DC. Similarly, the trigger detector 17 is connected to the rectifier 1.
The A / D converter 51 converts the DC signal into a digital signal for a certain period of time from the trigger output to the vibration damping. The maximum value calculator 21 extracts and outputs the maximum value of the digital signal.

In the judgment mode, the maximum value extracted by the maximum value calculator 21 is input to the ratio calculator 15, and the ratio calculator 15 calculates the maximum value and the peak reference value stored in the reference value setter 16. Calculates and outputs the ratio.

Similarly to the reference value setting mode, the sound wave generated by the impact is converted into an electric signal by the microphone 3, amplified by the amplifier 4, and converted into a digital signal by the A / D converter 52. At this time, the operation of the A / D converter 52 is started by a trigger signal from the trigger detector 17, and is performed for a certain period of time until sound pressure decay. The digital signal is separated into a time series signal for each frequency band by a digital BPF 61, converted into a DC signal by a rectifier 62,
3 is input. The maximum value calculator 63 extracts and outputs the maximum value of the DC signal.

In the judgment mode, the maximum value extracted by the maximum value calculator 63 is input to the corrector 64,
Reference numeral 4 calculates an appropriate correction value based on the ratio obtained from the ratio calculator 15, corrects the maximum value obtained from the maximum value calculator 63, and outputs the corrected value. The corrected maximum value is compared with the reference value stored in the reference value setting device 66 by the comparator 65, and is output to the alarm device 18 as an alarm when the value exceeds a predetermined relationship set in advance. The predetermined relationship to be set is, for example, 80 to 80 with respect to the reference value as in the first embodiment shown in FIG.
A setting is made so that a judgment signal is output with a normal value within a range of 120% and an abnormal condition when the value is out of the range. Further, in another certain band, a determination signal is output as normal within a range of 70 to 110% of the sound pressure 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 and flashes a lamp as a notification need 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 band, the size of the apparatus can be reduced. It is possible to flexibly respond to additions and the like.

Embodiment 3 FIG. 3 is a configuration diagram of a casting product material inspection apparatus according to the third embodiment. In the second embodiment, a digital BPF is used to determine the maximum value for each frequency band.
Wavelet transform (Wavelet Transform)
May be used. In the third embodiment, a case where a wavelet transform is used will be described with reference to FIG.

In the third embodiment, a wavelet transform calculator 71 is provided to obtain a time-series signal for each frequency band. The other operations are the same as those in the second embodiment. The wavelet transform is
Since the effective value is calculated by the analysis operation, there is no need to provide a rectifier.

In the figure, reference numeral 71 denotes a wavelet transform (Wavelet Transform) operation unit as a conversion means, which converts a digital sound pressure signal into a time-series signal for each frequency band by expanding or reducing a basis function (mother wavelet). To separate. The wavelet-transformed signal is
28 sets of maximum value calculator 63, corrector 64, and comparator 65 are input. The comparator 65 is compared with the reference value stored in the reference value setting device 66 in the same manner as that shown in FIGS. 1 and 12, and outputs a determination signal when a predetermined relationship is established. 18 is output.

At this time, by selecting an appropriate basis function in accordance with the measured waveform and the phenomenon to be observed, the frequency separation characteristics can be improved, and the reliability of determination can be improved. Further, the size of the device can be reduced by using the wavelet transform.

Embodiment 4 FIG. 4 is a configuration diagram of a casting product material inspection apparatus according to the fourth embodiment. In the second embodiment, the digital BPF is used to determine the maximum value of the time-series signal for each frequency band, but a short-time FFT may be used. Embodiment 4 is a case where short-time FFT is used,
A description will be given based on FIG. In the fourth embodiment, a short-time FFT calculator 81 is provided to obtain a time-series signal for each frequency band. Other operations are the same as those in the second embodiment. In the short-time FFT conversion, an effective value is calculated by the analysis operation, and therefore, there is no need to provide a rectifier. In the figure, reference numeral 81 denotes a short-time FFT (STFT: Short-Time Fourier-Tr)
ansform) arithmetic unit, which obtains a time-series signal for each frequency band.

As described above, the short-time F which is a Fourier transformer
By providing the FT calculator 81 and obtaining the maximum value of the time-series signal for each frequency band, the frequency resolution can be improved.

Therefore, the reliability of diagnosis can be improved in the case where a characteristic appears in a change in frequency due to the structure of a casting product by utilizing the excellent resolution of the short-time FFT. Further, the size of the apparatus can be reduced by using the conversion by the short-time FFT.

Embodiment 5 Embodiment 5 is an embodiment of a hitting means for hitting a casting product. Embodiment 1
In No. 4, the cast product was hit with a hammer, but the magnitude of the hit may vary depending on the individual, and may vary depending on the degree of fatigue and the mood of the inspector, so that it is expected that the judgment will vary widely. In the fifth embodiment, an inspection is performed by a hitting device as described below so that the hitting is always constant.

FIG. 5 shows the structure of the striking device. 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, 114 is a spring for applying a rotational force to the arm, 115 is a drive mechanism for pushing down and opening the other end of the arm, and 116 is a gantry.

The ball 111 is formed of an elastic body so as to prevent noise from being produced in the sound of a blow when the casting product is hit. The arm 110 has a suitable elasticity with the ball 111 attached to one end. Is formed. When the drive mechanism 115 makes one rotation with a miniature motor or the like, the other end 110a of the arm 110 is pushed down and opened. When the arm 110 is opened, it is returned by the pulling force of the spring 114 and the arm comes into contact with the stopper 113. It is configured so that the ball 11 hits the casting at an instant.

By using a motor as the drive mechanism 115, remote control is possible, and a constant impact can be automatically applied to the casting 1. Driving a casting product material inspection device using this impact device can improve the accuracy of determining the material of the casting product.

Further, in each of the above-described embodiments, an example in which an external force is applied by a hammer has been described. However, an example in which an external force is applied by other means, or an apparatus in which an external force is applied by an electromagnetic coil or a cylinder may be used.

[0079]

Since the present invention is configured as described above, it has the following effects.

Signal detecting means for detecting a vibration generated from a casting product to which an external force is applied as a vibration signal; converting means for converting the vibration signal into a plurality of time-series signals for a plurality of predetermined frequency bands; Extraction means for extracting the maximum value for each frequency band, and comparison means for comparing each maximum value with a vibration reference value for each preset frequency band are provided. The frequency distribution of sound pressure can be accurately grasped, and the reliability of comparison can be improved.

Further, the converting means is a plurality of band filters for passing the frequency components of a predetermined frequency band of the vibration signal, and the extracting means rectifies the frequency components passing through each band filter, and converts each of the rectified frequency components. Since the maximum value among the peak values is extracted as the maximum value, if the converting means is a band-pass filter, the processing can be performed at high speed, and the apparatus is simple and inexpensive.
Further, since the extracting means extracts the maximum value from the rectified frequency components, it is possible to detect even when the maximum value is present in the negative sign part of the vibration signal, and to accurately compare even when the vibration signal is rapidly attenuated.

Further, the transforming means is a wavelet transforming means for wavelet transforming the vibration signal, and the extracting means extracts the maximum value of the time series signal for each frequency band based on the result of the conversion by the wavelet transforming means. Therefore, it is possible to improve characteristics when separating the signals into time-series signals for each frequency, and it is possible to improve the reliability of comparison and determination.

Since the converting means is a short-time fast Fourier transforming means, and the extracting means extracts the maximum value of the time-series signal for each frequency band based on the result of the conversion by the short-time fast Fourier transforming means. Resolution can be improved.

Further, an external force detecting means for detecting the magnitude of the applied external force is provided, and at least one of a vibration signal, a time-series signal, a maximum value, and a vibration reference value is corrected according to the magnitude of the external force. Since it is characterized by the provision of a correction means, by correcting according to the magnitude of the external force,
In the comparison by the comparison means, the influence of the variation in the magnitude of the external force can be prevented, and the reliability of the comparison is improved.

An external force detecting means for detecting the magnitude of the applied external force is provided, and at least one of a signal detecting means, a converting means, an extracting means and a comparing means when the magnitude of the external force exceeds a predetermined value. A command means for commanding the start of operation is provided. Since the operation is not started until a command is issued, the surrounding noise, vibration, noise, etc. when there is no command may be erroneously processed as a vibration signal. There is no. Therefore, the influence of these can be prevented, and the reliability of the determination is improved.

Further, there is provided external force detecting means for detecting the magnitude of the applied external force as an external force signal, and a ratio calculating means for calculating a ratio obtained by dividing the external force signal by a preset external force reference value; Correction means for correcting the relationship between the maximum value and the vibration reference value in the comparison means by correcting at least one of the vibration signal, the time-series signal, the maximum value and the vibration reference value based on the ratio; It is characterized in that it is provided with a ratio determining means for determining whether or not it is within the range. it can.

Further, external force signal amplifying means for amplifying the external force signal and outputting it as an amplified external force signal and vibration signal amplifying means for amplifying the vibration signal and outputting it as an amplified vibration signal are provided. A range over detecting means for detecting that the peak value of at least one of the amplified external force signal and the amplified vibration signal has exceeded a predetermined value is assumed to be used as an external force signal, and the converting means is to use the amplified vibration signal as a vibration signal. Since it is characterized in that it has been provided, it is detected that the amplified external force signal or the amplified vibration signal exceeds a predetermined value, that is, it is detected that a large signal is input such that the external force signal amplifying means or the vibration signal amplifying means is saturated. As a result, the reliability of the measurement can be ensured.

[0088] Further, since amplification factor automatic setting means for automatically setting the amplification factor of at least one of the external force signal amplifying means and the vibration signal amplifying means is provided, the amplified external force signal and the amplified vibration signal are output. The amplification factor can be easily set so as to be in an appropriate output range, and operability is improved.
Further, a decrease in the S / N ratio can be prevented, and the reliability of the determination is improved.

Further, the striking means for applying an external force to the casting product is rotatably supported at an intermediate portion, and has an arm having a ball formed of an elastic body at one end thereof, and an arm between the arm supporting portion and the ball. A hitting device provided with a stopper that stops rotation at an intermediate position, a spring that pulls the arm in a direction in which the arm contacts the stopper, and a drive mechanism that pushes the other end of the arm downward to open it. And By using this impact device, the external force applied to the casting is stabilized, and the variation in the determination of the material of the casting is reduced.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a casting product material inspection apparatus according to Embodiment 1 of the present invention.

FIG. 2 is a configuration diagram of a casting product material inspection apparatus according to Embodiment 2 of the present invention.

FIG. 3 is a configuration diagram of a casting product material inspection apparatus according to Embodiment 3 of the present invention.

FIG. 4 is a configuration diagram of a casting product material inspection apparatus according to Embodiment 4 of the present invention.

FIG. 5 is a configuration diagram of a striking device of the casting product material inspection device.

FIG. 6 is a configuration diagram of a conventional casting product material inspection apparatus.

[Explanation of symbols]

1. Casting product of the object, 2. Hammer, 3. Microphone, 4. Amplifier, 5. Analog BPF, 6. Rectifier, 7.
Peak hold, 8 compensator, 9 comparator, 10 reference value setting device, 11 excitation force sensor, 12 amplifier, 13
Rectifier, 14 peak hold, 15 ratio calculator,
16 Reference value setting device, 17 Trigger detector, 18 Alarm device, 19 Ratio judgment device, 20 Range automatic setting device, 21
Range over detector, 31 rectifier, 32 peak hold, 33 range automatic setting device, 34 range over detector, 41 maximum value calculator, 51, 52 A / D converter, 61 digital BPF, 62 rectifier, 53, 63
Maximum value calculator, 64 compensator, 65 comparator, 66
Reference value setter, 71 Wavelet transform calculator, 81
Short-time FFT calculator, 110 arm, 111 ball, 112 rotation axis, 113 stopper, 114 spring, 115 drive mechanism, 116 mount.

Claims (10)

[Claims] 1. A signal detecting means for detecting a vibration generated from a casting product to which an external force is applied as a vibration signal; a converting means for converting the vibration signal into a time series signal for each of a plurality of predetermined frequency bands; Extraction means for extracting the maximum value of the time series signal for each of the frequency bands, and a material inspection apparatus for a casting, comprising: comparison means for comparing each of the maximum values with a preset vibration reference value for each of the frequency bands. . 2. The converting means is a plurality of bandpass filters for passing a frequency component of a predetermined frequency band of the vibration signal,
2. The method according to claim 1, wherein the extracting means rectifies the frequency components passing through the band-pass filters, and extracts a maximum value among peak values of the rectified frequency components as maximum values. Material inspection device for the castings described. 3. The converting means is a wavelet converting means for performing a wavelet transform on the detection signal, and the extracting means extracts a maximum value of a time-series signal for each frequency band based on a result of the conversion by the wavelet converting means. The casting material inspection apparatus according to claim 1, wherein: 4. A short-time fast Fourier transform means for performing a short-time fast Fourier transform on a detection signal, and the extracting means comprises a maximum of a time-series signal for each frequency band based on a result of the conversion by the short-time fast Fourier transform means. The casting material inspection apparatus according to claim 1, wherein the apparatus extracts a value. 5. An external force detecting means for detecting the magnitude of the applied external force, and correcting at least one of a vibration signal, a time-series signal, a maximum value, and a vibration reference value according to the magnitude of the external force. The casting material inspection apparatus according to claim 1, further comprising a correction unit. 6. An external force detecting means for detecting the magnitude of the applied external force, and at least one of a signal detecting means, a converting means, an extracting means, and a comparing means when the magnitude of the external force exceeds a predetermined value. 2. The casting material inspection apparatus according to claim 1, further comprising command means for commanding the start of the operation. 7. An external force detecting means for detecting the magnitude of the applied external force as an external force signal, and a ratio calculating means for calculating a ratio obtained by dividing the external force signal by a preset external force reference value; The vibration signal, a time-series signal, a maximum value, and a correction means for correcting at least one of the vibration reference values based on the correction means for changing a relationship between the maximum value and the vibration reference value in the comparison means. The casting material inspection apparatus according to claim 1, further comprising a ratio determination unit configured to determine whether the ratio is within a predetermined range. 8. An external force signal amplifying means for amplifying an external force signal and outputting it as an amplified external force signal, and a vibration signal amplifying means for amplifying a vibration signal and outputting the amplified vibration signal as an amplified vibration signal, wherein the ratio calculating means comprises the amplified external force signal. Is used as an external force signal, the converting means uses the amplified external force signal as a vibration signal, and a range for detecting that the peak value of at least one of the amplified external force signal and the amplified vibration signal exceeds a predetermined value. The casting material inspection apparatus according to claim 7, further comprising an over-detection means. 9. A casting material inspection apparatus according to claim 7, further comprising an automatic amplification factor setting device for automatically setting the amplification factor of at least one of the external force signal amplifying device and the vibration signal amplifying device. . 10. A striking means for applying an external force to a casting product,
An arm to which a ball formed of an elastic body is attached at one end and is rotatably supported at an intermediate portion, and a stopper which stops rotation at an intermediate position between the support portion of the arm and the ball is provided; 10. A structure according to claim 1, further comprising a drive mechanism for attaching a spring for pulling the arm in a direction in which the arm comes into contact with the stopper, and having a drive mechanism for pushing down the other end of the arm to open it. A device for inspecting the quality of castings described in Crab.