JP4949568B2 - Blow inspection device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an impact inspection apparatus for discriminating an inspection object, and more particularly to an impact inspection apparatus for inspecting defects such as fuel cells and concrete test pieces.
[0002]
[Prior art]
Conventionally, a hit inspection has been performed in order to inspect an inspection object such as a fuel cell. The fuel cell is a multilayer structure in which a copper plate and a rimple material are laminated by adhesion, and it is necessary to inspect defects such as adhesion failure of each layer. In the conventional batting inspection, a fuel cell as an inspection object is placed on a work table, an inspector strikes the fuel cell with a hammer, and the quality of the fuel cell is determined by listening to the hitting sound.
[0003]
On the other hand, in Japanese Patent Laid-Open No. 61-23966, an inspection sample such as a casting is hit, and a sound generated by the hit is picked up by a microphone and passed through a band pass filter. Based on output data from the band pass filter. An automatic sensitive inspection device that discriminates the good / bad rank of a sample is described.
Japanese Patent Laid-Open No. 6-34430 discloses a sound quality in which a sound to be evaluated generated from an automobile part or the like is detected by a microphone, and the detected sound is evaluated based on a membership function obtained in advance by a sensitivity test. An evaluation device is described.
[0004]
[Problems to be solved by the invention]
In the conventional batting inspection in which an inspector hits a fuel cell and the like and judges the hitting sound, the judgment of defect determination depends on personal experience, sensitivity, etc., so the evaluation is not quantitative and results vary. There are problems such as.
In addition, in the inspection apparatuses described in Japanese Patent Application Laid-Open Nos. 61-23966 and 6-34430, the impact sound is detected by a microphone, so that the determination is made based on the influence of ambient noise such as background noise. There is a problem that the accuracy of the result is lowered.
[0005]
An object of the present invention is to provide a batting inspection apparatus capable of obtaining a uniform inspection result without depending on the experience and sensitivity of the inspector.
It is another object of the present invention to provide a batting inspection apparatus that can perform an inspection with high accuracy even in an environment with large ambient noise.
[0006]
[Means for Solving the Problems]
In order to achieve this object, the present invention is a impact inspection device for a portable inspection object, which is a non-contact displacement meter that detects vibrations at a plurality of locations excited by the inspection object. Or a plurality of sensors that are non-contact type vibrometers, a plurality of recesses for providing these sensors, and an object to be inspected on the entire surface excluding the portions that are perforated to form these recesses In addition, an elastic part that supports the object to be inspected from below and separated from the plurality of sensors is provided above the plurality of sensors, and a base member to which the plurality of sensors are attached and signals detected by the plurality of sensors. And a signal processing device for inspecting an inspection object.
[0007]
In this configuration, the inspection object is supported from below by the base member to which the sensor is attached. When vibration is excited in the inspection object by exciting the inspection object, the sensor detects the vibration, and the inspection object is inspected based on the measurement data detected by the sensor.
With this configuration, it is possible to obtain a uniform inspection result without depending on the experience and sensibility of the inspector, and not to detect the hit sound of the inspection object with a microphone, but to detect vibration of the inspection object itself. Therefore, the inspection can be performed with high accuracy even in an environment with a large ambient noise.
[0008]
Further, in the impact inspection apparatus according to the present invention, the signal processing device has a frequency analysis unit for obtaining a frequency spectrum of the signal measured by the sensor, and a sound frequency of the frequency spectrum obtained by the frequency analysis unit. And a discriminator for discriminating the inspection object by comparing with the dominant frequency of the inspection object.
In this configuration, measurement data detected by the sensor is sent to the frequency analysis unit of the signal processing device. The frequency analysis unit calculates the frequency spectrum of the measurement data based on the measurement data, and obtains the dominant frequency. The obtained superior frequency is compared with the preferential frequency of a healthy object to be inspected in advance, and the object to be inspected is determined based on the comparison result.
[0009]
Further, the impact inspection apparatus of the present invention is configured such that the sensor is an accelerometer, the base member has an elastic portion, and the inspection object is supported from below by an accelerometer attached to the elastic portion of the base member. May be.
Alternatively, the sensor may be a load meter, and the inspection object may be supported from below by a load meter attached to the base member.
Further, the sensor is a non-contact displacement meter or a non-contact vibration meter, and the base member to which the sensor is attached has an elastic portion, and the elastic portion provided on the base member is above the sensor. You may comprise the impact inspection apparatus of this invention so that it may space apart from a sensor and to support a test object.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
Next, an embodiment of the present invention will be described with reference to the drawings, taking a fuel cell as an inspection object as an example. First, a first embodiment of the present invention will be described with reference to FIGS.
FIG. 1 is a perspective view of a batting inspection apparatus 1 according to the first embodiment of the present invention. The impact inspection apparatus 1 is detected by a base member 2, an elastic portion 4 provided on the base member 2, five accelerometers 6a to 6e that are sensors attached to the four corners and the center of the elastic portion 4, and an accelerometer. And a signal processing device 8 for processing the processed signals. The elastic portion 4 provided on the base member 2 is formed of any appropriate elastic member such as a rubber plate or a sponge. The material, thickness, etc. of the elastic member are appropriately selected according to the inspection object. The five accelerometers 6a to 6e are attached to the elastic part 4 so that the test object can be supported on them. The arrangement and number of accelerometers can be arbitrarily changed according to application. Further, the entire base member 2 may be made of an elastic member by omitting the portions other than the elastic portion 4 of the base member 2.
[0011]
The outputs of the accelerometers 6a to 6e are connected to the signal processing device 8. The signal processing device 8 includes a frequency analysis unit 12 for frequency analysis of the output signals of the accelerometers 6a to 6e, a determination unit 14 that determines the presence / absence of a defect in the inspection object based on the analysis result of the frequency analysis unit 12, and And a display unit 10 for displaying the discrimination result of the discrimination unit 14.
[0012]
Next, with reference to FIG. 2 thru | or FIG. 4, the effect | action of the impact inspection apparatus 1 by 1st Embodiment of this invention is demonstrated. FIG. 2 is a schematic diagram illustrating a state of a batting test by the batting inspection device 1 according to the first embodiment. First, the impact inspection apparatus 1 is installed on the work desk D, and the fuel cell T that is an inspection object is placed on each accelerometer 6 attached to the elastic portion 4 of the impact inspection apparatus 1. When the inspection object is supported on each accelerometer 6, the elastic portion 4 to which the accelerometer 6 is attached is deformed by a certain amount due to the weight of the inspection object, and the inspection object is supported at that position. Next, the inspector strikes a predetermined position of the fuel cell T with the hammer H and vibrates the fuel cell T. The position where the inspection object is struck is set to an appropriate position such as the corner or the center of the inspection object according to the application so that the dominant frequency described later can be clearly detected.
[0013]
The fuel cell T excited by the vibration is deformed and vibrated on each accelerometer 6. For example, when a portion of the fuel cell T supported by the accelerometer 6a vibrates downward, the accelerometer 6a is pressed downward by the fuel cell T, and the elastic portion 4 is deformed by the force, and the accelerometer 6a is moved downward. Moved. On the contrary, when the fuel cell T vibrates upward, the elastic part 4 deformed downward by the dead weight of the fuel cell T is restored to its original shape, so that the accelerometer 6a is pressed against the fuel cell T by the elastic part 4. It is done. Preferably, the material and thickness of the elastic portion 4 are selected so that the accelerometer 6 is in contact with the inspection object over the entire period of vibration of the inspection object. In this way, each accelerometer 6 vibrates up and down while being in contact with the fuel cell T according to deformation and vibration of the fuel cell T. The output signal of each accelerometer 6 is sent to the signal processing device 8.
[0014]
Next, signal processing performed by the signal processing device 8 will be described with reference to FIGS. 3 and 4. FIG. 3A is a flowchart of signal processing for obtaining sound reference data of an object to be inspected before an actual impact test is performed, and FIG. 3B is a signal when performing an actual impact test. It is a flowchart of a process.
[0015]
When the reference data is acquired, the fuel cell T that has been confirmed to be free of defects by a conventional impact inspection method or the like is placed on the impact inspection device, and the impact is performed. The other points are the same as the actual hammering test procedure. That is, the vibration is excited by hitting a healthy fuel cell T, and the five accelerometers 6a to 6e detect the time history waveform of the vibration. In step S <b> 1, the frequency analysis unit 12 built in the signal processing device 8 acquires these time history waveforms. Next, in step S2, the frequency analysis unit 12 calculates the frequency spectrum of each time history waveform. For calculation of the frequency spectrum, FFT calculation (fast Fourier calculation) or the like well known to those skilled in the art can be used. In step S3, a dominant frequency that is a frequency at which each frequency spectrum shows a peak is extracted. 4A to 4E are frequency spectra of time history waveforms acquired by the accelerometers 6a to 6e, respectively. The frequency spectrum at the four corners of the fuel cell T shown in FIGS. 4A to 4D has a dominant frequency at about 1750 Hz, and the frequency spectrum at the center of the fuel cell T shown in FIG. Has a dominant frequency. In step S4, these dominant frequencies are stored as reference data in the determination unit 14 incorporated in the signal processing device 8, and the reference data acquisition process is terminated.
[0016]
Preferably, the elastic portion is such that the natural frequency defined by the mass of the object to be inspected and the spring characteristics of the elastic portion 4 (the natural frequency of the rigid body mode) is sufficiently lower than the dominant frequency to be measured. 4 is selected and the impact inspection apparatus is configured.
[0017]
Next, a data processing procedure in an actual impact test will be described with reference to FIG. In an actual impact test, first, the fuel cell T to be inspected is placed on the impact inspection device 1 and impacted with a hammer H. Since the processing from the acquisition of the striking waveform data in step S11 in FIG. 3B to the determination of the dominant frequency in step S13 is the same as steps S1 to S3 in FIG. Next, in step S14, the dominant frequency of the reference data stored in the determiner 14 in step S4 of FIG. 3A and the dominant frequency of the fuel cell T to be inspected extracted in step S13 are determined by the determiner. 14 is compared. If the dominant frequencies of the frequency spectra match, the process proceeds to step S15, and the display unit 10 displays that the fuel cell T is not defective. If any one of the dominant frequencies does not match the reference data, the process proceeds to step S16, and the fact that the fuel cell T is defective is displayed. As an example, in the fuel cell T having defects such as adhesion failure, the dominant frequency existing at 1750 Hz is reduced to about 1500 Hz, and the dominant frequency existing at 3000 Hz is reduced to about 2300 Hz. In the present embodiment, it is determined that there is a defect when the dominant frequency of 1750 Hz drops to 1550 Hz or lower, or when the dominant frequency of 3000 Hz drops to 2350 Hz or lower. However, the determination method and the threshold frequency can be arbitrarily determined according to the application.
[0018]
According to the batting inspection apparatus of the present embodiment, a uniform inspection result can be obtained without depending on the experience and sensitivity of the inspector, and the inspection can be performed with high accuracy even in an environment with a large ambient noise. be able to. Furthermore, since the vibration of the inspection object is measured by a plurality of accelerometers, local defects in the inspection object can also be detected. In addition, according to the present embodiment, it is not necessary to attach an accelerometer to an object to be inspected, as in a vibration test that is generally performed using an accelerometer, and the inspection can be performed quickly.
[0019]
Next, with reference to FIG. 5, the impact inspection apparatus 20 by 2nd Embodiment of this invention is demonstrated. The impact inspection apparatus 20 according to the second embodiment is different from the first embodiment in that a load meter is used as a sensor instead of the accelerometer, and the base member does not have an elastic portion. Constituent elements similar to those in the first embodiment are denoted by the same reference numerals, and descriptions of configurations, operations, and effects similar to those in the first embodiment are omitted.
[0020]
The impact inspection device 20 according to the second embodiment of the present invention includes a base member 22, five load meters 24 attached to the four corners and the center of the base member 22, and a signal processing device 8 connected to each load meter 24. Have
[0021]
Next, the operation of the second embodiment will be described. First, as in the first embodiment, a fuel cell T as an inspection object is placed on each load meter 24, and a predetermined position is hit with a hammer. When the test object is vibrated by the impact, and a part of the fuel cell T vibrates and deforms downward, the force acting on the load meter supporting the part increases. On the other hand, when a part of the fuel cell T vibrates and deforms upward, the force acting on the load cell supporting the part decreases and may become zero at the minimum. In this way, the time history waveform corresponding to the vibration of the inspection object is detected by the load meter. At this time, the position at which each load meter 24 supports the object to be inspected moves only by the amount of deformation of the load meter 24 and the base member 22, so the amount of movement is very small. Therefore, the vibration amplitude of the inspection object is generally smaller than that in the first embodiment. Since the processing of the signals detected by each load cell 24 is the same as that in the first embodiment, description thereof is omitted.
[0022]
In this embodiment, since the dominant frequency is grasped by the load change, it is not necessary to float the inspection object with an elastic body such as rubber or sponge, and it can be applied to an inspection object with a large weight.
[0023]
Next, with reference to FIG. 6 (a) and (b), the impact inspection apparatus 30 by 3rd Embodiment of this invention is demonstrated. The impact inspection apparatus 30 according to the third embodiment supports an inspection object by placing it on an elastic part 34 provided on the base member 32, and the vibration of the inspection object is detected in a non-contact manner by a sensor. Different from one embodiment. Constituent elements similar to those in the first embodiment are denoted by the same reference numerals, and descriptions of configurations, operations, and effects similar to those in the first or second embodiment are omitted.
[0024]
Fig.6 (a) shows the perspective view of the impact inspection apparatus 30 by 3rd Embodiment, FIG.6 (b) shows the bb cross section of Fig.6 (a). The impact inspection device 30 includes a base member 32 provided with five recesses 38 for mounting sensors, an elastic portion 34 provided in the base member 32, and a non-contact sensor 36 attached in each recess 38. And a signal processing device 8 connected to each non-contact type sensor. As the non-contact sensor 36, a laser displacement meter, a laser vibration meter, a capacitance displacement meter, an eddy current displacement meter, or the like can be used depending on the application. The elastic portion 34 provided on the upper portion of the base member 32 is made of sponge or flexible rubber, and is a fuel cell that is an object to be inspected on the entire surface except for a portion that is perforated to form the recess 38. It is comprised so that T may be supported. Further, the thickness and material of the elastic portion 34 are selected so that a predetermined gap is formed between the non-contact sensor and the inspection object when the inspection object is placed on the elastic portion.
[0025]
Next, the operation of the third embodiment will be described. First, the fuel cell T to be inspected is placed on the elastic portion 34 of the base member 32. At this time, the fuel cell T is supported in a state where the elastic portion 34 is deformed by a predetermined amount due to the weight of the fuel cell T. Next, when the fuel cell T is hit, the fuel cell T deforms and vibrates on the elastic portion 34. Due to this vibration, the distance between the fuel cell T and the non-contact type sensor 36 changes, and a signal corresponding to this change is detected by each non-contact type sensor 36. Since the signal processing procedure by the signal processing device 8 is the same as that of the first embodiment, description thereof is omitted.
[0026]
In the present embodiment, since the sensor and the inspection object are not in contact, the influence of the weight of the sensor and the influence due to the contact of the sensor can be eliminated, and the determination can be performed with high accuracy. Further, in this embodiment, since almost the entire surface of the inspection object is supported by the elastic portion, the pressure acting on the inspection object is small and the inspection object is not damaged.
[0027]
Although the preferred embodiments of the present invention have been described above, various modifications can be made to the disclosed embodiments within the scope of the technical matters described in the claims without departing from the scope or spirit of the present invention. be able to. In particular, the impact inspection apparatus of the present invention can inspect any portable inspection object other than the fuel cell exemplified in the present embodiment. Further, the purpose of the inspection does not necessarily need to be to find a defect, and the impact inspection apparatus of the present invention can be used for ranking and sorting products. Further, the vibration does not necessarily need to be impact vibration using a hammer, and any vibration method such as impact vibration using an electrodynamic vibrator or random vibration can be employed.
[0028]
【Effect of the invention】
According to the impact inspection apparatus of the present invention, it is possible to obtain a uniform inspection result without depending on the experience and sensitivity of the inspector, and to perform inspection accurately even in an environment with a large ambient noise. Can do.
[Brief description of the drawings]
FIG. 1 is a perspective view of an impact inspection apparatus according to a first embodiment of the present invention.
FIG. 2 is a schematic view showing a state of a batting inspection by the batting inspection apparatus according to the first embodiment of the present invention.
FIG. 3 is a flowchart showing a data processing procedure of the batting inspection apparatus according to the first embodiment of the present invention.
FIG. 4 is a diagram showing an example of a frequency spectrum measured by the impact inspection apparatus according to the first embodiment of the present invention.
FIG. 5 is a perspective view of a hit inspection device according to a second embodiment of the present invention.
FIG. 6 is a perspective view of a hit inspection device according to a third embodiment of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Impact test | inspection apparatus 2 of 1st Embodiment Base member 4 Elastic part 6 Accelerometer 8 Signal processing apparatus 10 Display part 12 Frequency analysis part 14 Discriminating part 20 Impact test apparatus 22 of 2nd Embodiment Base member 24 Load meter 30 3rd Blow Inspection Device 32 of Embodiment Base Member 34 Elastic Part 36 Non-Contact Sensor 38 Recess

Claims (2)

A batting inspection device for a portable inspection object,
A non-contact displacement meter that detects vibrations at a plurality of locations excited by the impact on the inspection object , or a plurality of sensors that are non-contact vibration meters ,
A plurality of recesses for providing these sensors, and an object to be inspected are supported on the entire surface excluding a portion that is perforated to form these recesses, and above the plurality of sensors, from the plurality of sensors A base member that includes an elastic portion that is spaced apart and supports an object to be inspected from below, and to which the plurality of sensors are attached;
A batting inspection apparatus comprising: a signal processing device for inspecting an inspection object based on signals detected by the plurality of sensors. A frequency analysis unit for obtaining a frequency spectrum of the signal measured by the sensor;
2. A discrimination unit for discriminating an inspection object by comparing a dominant frequency of the frequency spectrum obtained by the frequency analysis unit with a dominant frequency of a healthy inspection object. The batting inspection device described.

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