JP3908379B2 - Vibration detector and vibration inspection device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a vibration detection device and method for vibrations generated by various devices, and in particular, eliminates irregularly generated dark vibrations during vibration inspection performed in the final inspection process of a production assembly line in a manufacturing factory. The present invention relates to a vibration detection apparatus and method for accurately detecting vibration and determining an abnormal state.
[0002]
[Prior art]
Usually, in a final inspection process of a manufacturing assembly line in a manufacturing factory, vibrations of various devices assembled as inspection objects are detected and compared with appropriate values to inspect whether there is an abnormality in the internal state.
[0003]
However, in general, dark vibrations (line vibrations) exist because various devices are operating in the production assembly line. Therefore, when inspecting, vibrations are usually detected after they are not affected by dark vibrations by using a vibration detection device with a vibration isolation structure under the object to be inspected and the vibration detection part. An abnormality is being judged. The outline of the vibration inspection apparatus used for these is as follows.
[0004]
FIG. 5 is a block diagram showing the overall configuration of the vibration detection apparatus. The vibration detection unit 21 is composed of a vibration detector 22 that detects vibration by contacting the object 7 and a charge amplifier 23 that amplifies the output from the vibration detector 22. ing. An abnormality determination unit 24 that determines an abnormality based on an output from the charge amplifier 23 is connected.
[0005]
FIG. 5 is a block diagram showing the configuration of the vibration detector. In the vibration detector 22, a vibration sensor 15 is fixed to the tip of a drive arm 25 of a vibration detector (not shown) via a vibration isolator 26, and the tip of the vibration detector 15 is covered. A chip 27 that comes into contact with the inspection body 7 is provided.
[0006]
In addition, as a technique somewhat related to these, there is a technique disclosed in Japanese Patent No. 2562708. This is a technology related to noise cancellation. Noise from the outside in a closed space is detected by a microphone, and the detected external noise signal is corrected with a pre-stored sound insulation characteristic, and then a pseudo signal obtained by phase inversion is applied to the audio signal line. It is supplied and output from the speaker, so that sound can be heard well from the speaker even under high noise.
[0007]
[Problems to be solved by the invention]
Even if the vibration generated from the object to be measured in the factory inspection process is detected by a precise vibration measuring device, the production line in the factory usually causes irregularities such as falling or crashing of objects. It is difficult to avoid the influence of the dark vibrations that occur. For this reason, the vibration detection apparatus often results in erroneous determination.
[0008]
Further, the technology described in Japanese Patent No. 2562708 is completely different in purpose and technical problem, and no method for detecting vibration as in the present invention is disclosed.
[0009]
[Means for Solving the Problems]
According to the means of the first aspect of the invention, the vibration detecting device detects the vibration of the object to be inspected by contacting the object to be inspected by the vibration detecting unit, and determines the abnormality of the vibration by the abnormality determining unit based on the detection result. In
The vibration detection unit is held by a drive mechanism, a tip having a predetermined curvature is provided at a tip for contacting the object to be inspected, and is fixed to a vibration isolating material, and an output thereof is connected to an adder. The first vibration inspection unit is fixed to a symmetrical position on the opposite surface of the antivibration material in a posture opposite to that of the first vibration inspection unit, and a tip similar to the chip is provided at the tip and its output is A second vibration inspection unit connected to the adder via a digital filter,
In addition, the abnormality determination unit is in a vibration detection device that determines an abnormality of vibration based on an output from the adder.
[0010]
According to the means of the invention of claim 2, the vibration isolator is a vibration detection device that performs vibration isolation from the outside.
[0011]
According to the means of the invention of claim 3, the predetermined curvature of the tip provided at the tip of the first vibration detection unit is a curvature that makes point contact with the object to be inspected. In the device.
[0012]
According to the means of the invention of claim 4, the second vibration detection unit and the tip provided at the tip thereof, and the first lead detection unit and the tip provided at the tip thereof have a mass thereof. And the spring constant are equal to each other.
[0013]
According to the means of the invention of claim 5, the digital filter is such that the transfer function of the damping characteristic is equal to the transfer function from the second vibration tester to the first vibration detector including the vibration isolator. The vibration detecting apparatus is characterized in that a coefficient is set in advance.
[0014]
According to the means of the invention of claim 6, the step of detecting the vibration of the object to be inspected by the first vibration detecting unit contacting the object to be inspected;
Detecting vibrations by a second vibration detection unit provided at a symmetrical position between the first vibration detection unit and the vibration isolator;
An addition step of adding the detection output from the first vibration detection unit and the detection output from the second vibration detection unit via the digital filter;
The vibration detection method includes an abnormality determination step of determining an abnormality based on a result of the addition step.
[0015]
According to the means of the invention of claim 7, the digital filter has a damping function whose transfer function is equal to the transfer function from the second vibration tester to the first vibration detector including the vibration isolator. According to the vibration detecting method, the coefficient is set in advance, and the external vibration is canceled by the adder to which the output is input.
[0016]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0017]
FIG. 1 is a schematic diagram showing an outline of the vibration detection device of the present invention, FIG. 2 is an explanatory diagram showing the overall configuration of the vibration detection device of the present invention, and FIG. It is a side view which shows a structure.
[0018]
The overall structure of the vibration detection device 1 is roughly divided into a measurement structure unit 2, a vibration detection unit 3, a digital filter 4, an adder 5, and an abnormality determination unit 6.
[0019]
In the measurement structure section 2, a measurement column 9 is erected at an end of a measurement table 8 having a horizontal surface on which an object to be measured is placed. A cylinder 10 is attached to the upper end of the measurement column 9, and a structure in which the drive arm 11 is lowered from the cylinder 10 by a drive mechanism (not shown) toward the measurement table 8 is formed. A vibration measuring device 12 is fixed to the tip of the drive arm 11.
[0020]
As shown in FIG. 2, the vibration detector includes a first vibration detector 13 and a second vibration detector 14. As shown in FIG. 3, both the vibration detection units have a vibration sensor 15 and a chip 16 provided at the tip of the vibration sensor 15, and are arranged via a vibration isolating material 17.
[0021]
The vibration sensor 15 is a generally used piezoelectric element type vibration sensor (piezoelectric accelerometer), and the converted voltage is amplified by the charge amplifier 18. The output amplified by the charge amplifier 18 is input to the adder 5 in the case of the first vibration detection unit 13 and input to the adder 5 via the digital filter 4 in the case of the second vibration detection unit 14. .
[0022]
Structurally, the vibration detector is structured such that the first vibration detection unit 13 and the second vibration detection unit 14 are opposite to each other in a symmetrical position on the opposing surface of a cylindrical vibration isolation material 17 such as an anti-vibration rubber. It is fixed and provided. As a result, the output signals of the two vibration detectors are signals whose phases are different from each other by 180 degrees.
[0023]
Further, since the second vibration detection unit 14 is fixed to the drive arm 11 of the vibration detection device 1, the vibration detector moves in the vertical direction as the drive arm 11 moves.
[0024]
Further, the chip 16 provided at the tip of the vibration sensor 15 of the first vibration detector 13 is formed in a curved surface such that the tip contacts the object to be inspected. On the other hand, the tip 16 provided at the tip of the second vibration detection unit 14 and the vibration sensor 15 is set to the same mass as the tip 16 provided at the tip of the first vibration detection unit 13 and the vibration sensor 15. ing.
[0025]
The digital filter 4 vibrates the vibration detector from the outside as its attenuation characteristic to obtain a transfer characteristic from the second vibration detection unit 14 to the first vibration detection unit 3 including the vibration isolating material 17. Equivalent coefficients are set. FIG. 4 is a graph showing an example of vibration damping characteristics of the vibration isolator 17.
[0026]
The adder 5 is composed of a commonly used adder circuit.
[0027]
The abnormality determination processing unit includes a circuit (not shown) that performs FET frequency analysis processing, a combination of dedicated filters, envelope processing, and the like.
[0028]
A vibration measuring method using these configurations will be described below.
[0029]
When the measured object 7 is placed and fixed on the measuring table 8 via the vibration isolator 17a, and the vibration measuring instrument 12 is fixed from the upper side of the measured object 7 to the tip, the drive arm 11 is gradually lowered. The chip 16 of the first vibration measuring unit 13 of the vibration measuring instrument 12 is in point contact with the upper surface of the measured object 7. In this state, vibration detection is started.
[0030]
That is, the first vibration detection unit 3 starts detecting vibration transmitted from the object to be inspected that is in contact via the tip 16 at the tip.
[0031]
On the other hand, sudden vibrations generated for various reasons outside the measured object 7 are first detected by the second vibration detection unit 14 when propagating to the measured object 7 from the outside. As a result, the phase of the signal detected by the first vibration detection unit 13 is 180 degrees that is equal to that transmitted to the first vibration detection unit 13 via the vibration isolator 17 by the digital filter 4. A signal is obtained. The output from the first vibration detector 3 is amplified by the charge amplifier 18 and then input to the adder 5.
[0032]
On the other hand, the second vibration detector 14 is similarly amplified by the charge amplifier 18 and then input to the adder 5 through the digital filter 4.
[0033]
In the digital filter 4, the damping characteristic is determined in advance by externally vibrating the vibration detection unit 3 to obtain a transfer characteristic from the second vibration detection unit 14 to the first vibration detection unit 3. Since it is set, it is equal to that detected by the second vibration detection unit 14 and propagated to the first vibration detection unit 13 via the vibration isolator 17 by the digital filter 4 and the first vibration detection. A signal that is 180 degrees different from the phase of the signal detected by the unit 13 is obtained.
[0034]
The signal obtained in this way and the signal detected by the first vibration detection unit 3 are canceled by adding by the adder 5, and the vibration from the outside can be canceled.
[0035]
At this time, the vibration of the object to be inspected is first detected by the first vibration detector 3 and amplified by the charge amplifier 18, and the second vibration detector 14 is attenuated by the vibration isolator 17. After the vibration is detected and amplified by the charge amplifier 18, it is further attenuated by the digital filter 4, so that the output signal of the digital filter 4 is very small.
[0036]
Therefore, the signal after the addition by the adder 5 is almost equal to the signal obtained by the charge amplifier 18 from the first vibration detector 3 and can accurately detect the vibration of the object to be inspected.
[0037]
The output signal of the adder thus obtained is input to the abnormality determination processing unit, and abnormal characteristics are extracted inside the abnormality determination processing unit by FET frequency analysis processing, a combination of dedicated filters, envelope processing, or the like. Based on the result, abnormality determination processing is performed.
[0038]
The digital filter 4 and the adder 5 can perform both processes by using, for example, a DSP (Digital Signal Processor).
[0039]
Further, if the signal is delayed after the digital filter 4, the phase of the signal from the first vibration detection unit 13 can be more accurately matched, so that the cancellation effect can be increased. .
[0040]
【The invention's effect】
As described above, the present invention detects two vibrations so that the vibration detectors of the vibration detection device sandwich the vibration isolator 17 so that the opposite positions of the antivibration material 17 are opposite to each other. Since part 3 is provided, even if vibration of the object to be inspected is detected in the production line of the factory, impacts caused by collisions of parts existing in automated lines, dropping of parts and tools, carts, caulking machines, presses, etc. Since the natural dark vibration can be canceled without affecting the vibration measurement of the object to be inspected, accurate vibration detection can always be performed.
[Brief description of the drawings]
FIG. 1 is a schematic diagram showing an outline of a vibration detection apparatus of the present invention.
FIG. 2 is a configuration diagram showing the overall configuration of the vibration detection apparatus of the present invention.
FIG. 3 is a side view showing the structure of the main part of the vibration detector of the vibration detecting apparatus of the present invention.
FIG. 4 is a graph showing an example of vibration damping characteristics of a vibration-proof material.
FIG. 5 is a configuration diagram showing the overall configuration of a conventional vibration detection apparatus.
FIG. 6 is a side view showing a structure of a main part of a vibration detector of a conventional vibration detection device.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Vibration detection apparatus, 2 ... Measuring instrument rear part, 3, 21 ... Vibration detection part, 4 ... Digital filter, 5 ... Adder, 6, 24 ... Abnormality determination part, 7 ... Measuring object, 8 ... Measuring stand, 9 ... measurement column, 10 ... cylinder, 11, 25 ... drive arm, 12, 22 ... vibration measuring device, 13 ... first vibration detection unit, 14 ... second vibration detection unit, 15, 28 ... vibration sensor, 16, 27 ... Chip, 17, 26 ... Vibration isolator, 18, 23 ... Charge amplifier

Claims (7)

In the vibration detection device that detects the vibration of the object to be inspected by contacting the object to be inspected by the vibration detection unit, and performs the abnormality determination of the vibration by the abnormality determination unit based on the detection result.
The vibration detection unit is held by a drive mechanism, a tip having a predetermined curvature is provided at a tip for contacting the object to be inspected, and is fixed to a vibration isolating material, and an output thereof is connected to an adder. The first vibration inspection unit is fixed to a symmetrical position on the opposite surface of the antivibration material in a posture opposite to that of the first vibration inspection unit, and a tip similar to the chip is provided at the tip and its output is A second vibration inspection unit connected to the adder via a digital filter,
And the said abnormality determination part determines the abnormality of a vibration by the output from the said adder, The vibration detection apparatus characterized by the above-mentioned. The vibration detection device according to claim 1, wherein the vibration-proof material is used for vibration isolation from the outside. The vibration detection apparatus according to claim 1, wherein the predetermined curvature of the tip provided at the tip of the first vibration detection unit is a curvature that makes point contact with the object to be inspected. The second vibration detector and the tip provided at the tip thereof, and the first lead detector and the tip provided at the tip thereof have the same mass and spring constant. The vibration detection apparatus according to claim 1. The digital filter has a coefficient set in advance so that the transfer function of the damping characteristic is equal to the transfer function from the second vibration tester to the first vibration detection unit including the vibration isolator. The vibration detection apparatus according to claim 1. A step in which the first vibration detection unit is in contact with the object to be inspected and detects the vibration of the object to be inspected;
Detecting vibrations by a second vibration detection unit provided at a symmetrical position between the first vibration detection unit and the vibration isolator;
An addition step of adding the detection output from the first vibration detection unit and the detection output from the second vibration detection unit via the digital filter;
And an abnormality determination step of determining an abnormality based on the result of the addition step. The digital filter has a coefficient set in advance so that the transfer function of the damping characteristic is equal to the transfer function from the second vibration tester to the first vibration detection unit including the vibration isolator. The vibration detection method according to claim 6, wherein an external vibration is canceled by the adder to which an output is input.

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