JP2009115619A - State monitoring method, monitoring system, computer program and recording medium for periodical moving object - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve a problem wherein a moment of four degree of a probability density function of a vibration signal becomes complicated, even though it has been calculated conventionally, after being normalized. <P>SOLUTION: The present invention provides a method of monitoring a state of a periodical moving object and a method of determining it by graphical display, by detecting a peak waveform of a vibration amplitude, out of one side derived impact wave generated at an abnormal time in the periodical moving object, by forming a statistical normalized moment Q of six degree into a continuous time system, by finding finally (1) the moment and the normalized moment of six degree using N data, when the impact wave is not generated, and (2) the moment and the normalized moment of six degree, when the impact wave is generated, respectively; and by using a numerical value calculated by a certain formula, and provides a device applied therewith. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a method for monitoring the state of a periodic moving body, when a shock wave is generated and a system abnormality progresses, pay attention to a wave in a time traveling direction of a triangular wave on one side rather than a derivative shock wave before and after the shock wave. The present invention relates to a good index with good sensitivity for cases such as damage to the outer race, and relates to a method, system, computer program, and recording medium for calculating an index as an absolute index and monitoring the state of a periodic moving body.

In the steel industry, etc., which have large facilities, if the line is shut down due to a sudden equipment failure, the capacity utilization rate of the equipment will be reduced, the supply of materials to the lower process will be insufficient, and the delivery date will be delayed for orders that are imminent. , Suffers a lot of impact and leads to a lot of damage.
Equipment abnormality detection plays an important role in preventing these problems. Conventionally, time-based maintenance (TBM) has been the mainstream, but in recent years there has been a significant shift to condition-based maintenance (CBM) due to the enhancement of equipment monitoring hardware and software. This is because this leads to a reduction in parts cost, maintenance cost, and failure rate. When maintenance is performed, the probability of an initial failure after maintenance increases. Something that wasn't necessary for maintenance is maintained by regular maintenance, so an initial failure may occur. There are also places where this is called "smashing" in the field. When moving to CBM, capturing the signs of anomalies as soon as possible is highlighted. Various methods are being studied for this purpose. Since the index varies depending on the field, the present invention performs the abnormality detection of the rotating body, which is the most universal theme as abnormality detection of the mechanical system.

Conventionally, Kurtosis, Bicoherence, impact deterioration factor (Impact Deterioration Factor: ID Factor), etc. have been studied as sensitive indicators.
As a conventional sensitive index, Kurtosis (Kurtosis: Kurtosis) as in Patent Document 1 (Japanese Patent Laid-Open No. 2006-153760), Normalized sixth moment use as in Patent Document 2 (Japanese Patent Laid-Open No. 2004-46654), Examination of Bicoherence (bicoherence: frequency component ratio), impact degradation factor (Impact Deterioration Factor: ID Factor) such as Patent Document 3 (Japanese Patent Publication No. 62-60011) and Patent Document 4 (Japanese Patent Publication No. 64-4611) It has been.

Non-patent document 1 (in the “one-triangle-derived shock wave model” that represents the absolute index value ^- Zn (bar Zn)) with higher accuracy using the Kurtosis (kurtosis: kurtosis) to aim for absolute index "Simple calculation method and absolute indexization of Kurtosis" (Kazuhiro Takeyasu, Yuki Higuchi, 51st System Control Information Society Conference Presentation (May 16-18, 2007)).

Furthermore, by using a sixth-order normalized moment, to that examined the absolute indexed from both sides shockwave, Non-Patent Document 2 ( "Simplified Machine Diagnosis Techniques by Impact Vibration Using Absolute Deterioration Factor of 6 th Nomalized Moment " Kazuhiro Takeyasu Yuki Higuchi's "Economic Research" (Osaka Prefectural University) Sept. 20, 2007, distribution September 21, 2007).

JP 2006-153760 A JP 2004-46654 A Japanese Examined Patent Publication No. 62-60011 Japanese Patent Publication No. 64-4611 "Simple calculation method and absolute indexing of Kurtosis in one-triangle-derived shock wave model" (Kazuhiro Takeyasu, Yuki Higuchi, 51st Annual Conference of the Institute of Systems, Control and Information Engineers (May 16-18, 2007)) "Simplified Machine Diagnosis Techniques by Impact Vibration Using Absolute Deterioration Factor of 6th Normalized Moment" by Kazuhiro Takeyasu Yuki Higuchi "Economic Research" (Osaka Prefecture University) Sept. 20, 2007, distributed on September 21, 2007)

  Although the fourth moment of the probability density function of the vibration signal was normalized and calculated, there is a need for precise diagnosis in the field, but there are places where precise diagnosis technology cannot be incorporated due to hardware, software, and cost. In addition, there may be a case where an immediate response is required while monitoring the signal waveform on site. Therefore, in the present invention, when a shock wave is generated and an abnormality of the system progresses, the sixth normalization moment when the calculation is performed including the derivative shock wave before and after the shock wave, and further when the periodic moving body is abnormal, is generated. Introducing a simple calculation method that detects the peak waveform of vibration amplitude among unilateral derived shock waves and uses the statistical sixth-order normalized moment Q as a continuous-time system for the waveform generated in the direction of time travel. There is to make it.

であり、離散時間系で記述すると

となり、
（１）衝撃波が発生しない場合のN個のデータを用いたモーメント、6次正規化モーメントをそれぞれ

とし、衝撃波が発生した場合についてはそれぞれ

と表記することにする場合、

を得、ここで、

とすると、

となり、
ここで、

であるとき、
（式中：ｐはピーク波形の大きさ、ｍは異常振動の発生回数、ｑはサンプリング回数を示す。）
系が正常の時、Ｑは常に15.0であることから、

として、

である。
傷が拡大するにつれて、^-Q_Nの値も増大する場合

として、絶対指標値とし、バーＷ_Nが、回転運動体の正常時は１になり、異常が進行するにつれて値は０に近づくことを以って異常を判定する工程を備えることを特徴とする周期運動体の状態監視方法を提供する。 According to a first aspect of the present invention, a peak waveform of vibration amplitude is detected from one-side derived shock waves generated when a periodic moving body is abnormal, and the waveform generated in the time progress direction is detected as a statistical sixth-order normalized moment. Let Q be a continuous time system and

And in discrete time system

And
(1) Moment using N data and 6th normalized moment when no shock wave is generated

And when shock waves are generated,

If you decide to write

Where

Then,

And
here,

When
(In the formula, p is the size of the peak waveform, m is the number of occurrences of abnormal vibration, and q is the number of samplings.)
Since Q is always 15.0 when the system is normal,

As

It is.
As scratches expand, ^- if the value of Q _N also increases

As an absolute index value, the bar W _N is set to 1 when the rotating moving body is normal, and the value approaches 0 as the abnormality progresses, and includes a step of determining abnormality. A method for monitoring the state of a periodic moving body is provided.

として、
絶対指標値とし、^-Ｕ_N（バーＵ_N）が、回転運動体の正常時は１になり、異常が進行するにつれて値は０に近づくことを以って異常を判定する工程を備えることを特徴とする周期運動体の状態監視方法を提供する。 In the first solving means, ^- using a Q _N (bars Q _N),

As
The absolute index value, ^- U _N (Bar U _N) is comprised in a normal rotational movement body 1, further comprising a step of determining abnormality drives out that the value is closer to 0 as the abnormality progresses Provided is a method for monitoring a state of a periodic moving body.

Second aspect of the present invention provide a condition monitoring system of the periodic motion body, characterized in that to monitor the status of the absolute indicator bar W _N or by notation bar U _N in the graph periodic motion body.

Furthermore, to provide a state monitoring computer program absolute indicator bar W _N or bar U _N, characterized in that it comprises a simplified manner the procedure for calculating the periodic movement thereof.
Furthermore, the present invention provides a computer-readable recording medium in which the above program is recorded.

  In a rotating body such as a bearing and a gear, vibration increases as deterioration progresses. Further, it is generally well known that vibration is increased even when installation is inappropriate. Various kinds of deterioration indexes are described in detail in the patent document 1 of the inventors.

であり、離散時間系で記述すると

となる。
衝撃波が発生しない場合のN個のデータを用いたモーメント、6次正規化モーメントをそれぞれ

とし、衝撃波が発生した場合についてはそれぞれ

と表記することにする。
衝撃波発生時の分散は

となる。

を用いて、

を得る。
ここで、

である。
よって、

となる。
ここで、

である。
系が正常の時、Ｑは常に15.0である。
そこで、

とすると、

である。
傷が拡大するにつれて、^-Ｑ_Nの値も増大する。
同様に、^-Ｑ_Nの絶対指標は以下の式で求められる。

また、^-Ｑ_Nの絶対指標は以下の式でも求められる。

Describes a simple calculation method for sixth-order normalization moments.
6th order normalized moment Q is described in continuous time system.

And in discrete time system

It becomes.
Moment using N data and 6th normalized moment when no shock wave is generated

And when shock waves are generated,

Will be written.
Dispersion at the time of shock wave generation

It becomes.

Using,

Get.
here,

It is.
Therefore,

It becomes.
here,

It is.
When the system is normal, Q is always 15.0.
Therefore,

Then,

It is.
As the wound is enlarged, ^- the value of Q _N is also increased.
Similarly ^: -The absolute index of Q _N is obtained by the following formula.

Further, ^- the absolute index of Q _N is calculated in the following equation.

In describing the detailed description of the implementation of the present invention,
When the rotating body is damaged, a peak waveform is generated for each rotation cycle. In particular, in the case of an initial abnormality, it is assumed that this peak appears clearly as long as the single damage of the rotating body or rolling element does not propagate to other rotating bodies or rolling elements. In many cases, when the body or rolling element is damaged, the contact surface is damaged, and the damage to other rotating bodies or rolling elements is spread over time). As the wound expands and propagates, a shock wave with a lower peak level around the shock wave occurs in the shape of Mt. Fuji.

In the present invention, when a shock wave is generated and an abnormality progresses, a simple calculation method of a sixth-order normalized moment when a derivative shock wave is generated only on one side in the time axis direction following the shock wave is converted into an absolute index. The behavior of the 6th normalization moment was analyzed by modeling the above case. FIG. 1 is a schematic diagram showing a one-side derived shock wave of a vibration signal of a normal rotating body for explaining one embodiment of the present invention. In particular, when there is an abnormality in the bearing outer race, such a one-triangular abnormality signal is generated.
In FIG. 1, it is assumed that a signal having a normal p-fold peak appears every m rotations of sampled data. As for the method of determining the sampling interval, a determination method based on the sampling theorem is well known, but the determination method is not described in the present invention. For the derived shock wave, if the sampling count is d for convenience,
When d = 1, normal p-fold peak level When d = i, normal [p− (i−1) (p−1) / q] times (peak level (i = 1, 2,..., q)),
When d = q + 1, it is modeled as a triangular attenuation pattern that returns to the normal peak level.

In the present invention, a sixth-order normalization moment is used as an index and used for determination in the form of numerical values and diagrams. That is, the present invention is characterized in that a calculation is performed using a moment using N pieces of data when a shock wave is not generated and a sixth normalized moment, and an abnormality is monitored and an abnormal state is detected based on the numerical value.
FIG. 2 is a schematic diagram of a double-sided shock wave shown for comparison.

FIG. 3 is a block diagram showing the configuration of a specific periodic motion body monitoring system. A rotating body, which is a periodic moving body in a factory, is provided with a sensor 31 that detects vibration, is connected to a data acquisition device 32, and inputs measurement data to the device. The data acquisition device 32 has a function of sampling measurement data at a predetermined cycle, creating a signal sequence composed of a plurality of signals, and acquiring various data from the created signal sequence. Further, it is connected to a communication network NW in the factory and transmits to the system monitoring apparatus main body 10.
The data acquisition device 32 is connected to the system monitoring device main body 10 in parallel with the NW 33.
The system monitoring device main body 10 also has a function as a sixth-order normalization moment calculation device of the present invention, and is configured using a computer. The apparatus main body 10 includes a CPU 11 that performs calculations, a RAM 12 that stores temporary information generated along with the calculations, an external storage device 13 such as a CD-ROM drive, and an internal storage device 14 such as a hard disk. The computer program 21 of the present invention is read by the external storage device 13 from the state monitoring system 20 of the present invention such as a CD-ROM, the read computer program 21 is stored in the internal storage device 14, and the computer program 21 is loaded into the RAM 12. The CPU 11 executes processing necessary for the state monitoring device 10 based on the computer program 21. The state monitoring device 10 includes an input unit 15 (accepting unit) connected to the communication network NW33 in the factory, and receives data from the data acquisition device 32 via the communication network NW33. Furthermore, the state monitoring device 10 includes an output unit 16 that outputs information to the outside. The output unit 16 is connected to the alarm device 34, and the state monitoring device 10 sends information indicating an abnormality of the facility from the output unit 16 to the alarm device. 34. The alarm device 34 includes a buzzer, a lamp, or a display unit that displays the content of the alarm, and notifies the abnormality of the facility according to the information received from the state monitoring device 1.

  The state monitoring device 10 may be in a form in which the computer program 21 according to the present invention is downloaded from an external server device (not shown) connected to the communication network NW 33 and the process is executed by the CPU 11.

The internal storage device 14 has a standard signal sequence composed of N signals acquired by the data acquisition device 32 when the equipment to be monitored is normal, and a standard sixth-order normalized moment Q _N calculated from the standard signal sequence. remembered that, ^- comprising the step of calculating a Q _N.

  FIG. 4 is a flowchart showing operations performed by the state monitoring system of the present invention. The sensor 31 measures data such as vibration as shown in FIG. 1 generated with the operation of the equipment, and the data acquisition device 32 is input from the sensor 31 at a predetermined cycle such as a cycle that substantially matches the vibration of the equipment. The measurement data is sampled (S101), and a signal sequence including a plurality of signals having an average value of 0 is acquired. The data acquisition device 32 determines whether or not q acquired signals are accumulated as a result of sampling (S102). If q signals are not accumulated (S102: NO), the process returns to step S101. Sampling is continued and q signals are accumulated (S102: YES), a predetermined value such as a predetermined multiple of the average of the absolute values of the signals in the first signal sequence composed of the accumulated q signals is used. It is determined whether or not a large signal having a larger absolute value is included in the first signal sequence (S103). When the large signal is included in the first signal sequence (S103: YES), the data acquisition device 32 uses the first signal sequence to multiply the absolute value p of the large signal with respect to the absolute value of the other signal p, The shock wave count number q and the signal interval number m between large signals are measured (S104), and the magnification p, the shock wave count number q, the interval number m, and the first signal sequence are sent to the state monitoring device 10 via the communication network NW33. Transmit (S105).

The state monitoring device 10 receives the first signal sequence from the data acquisition device 32 such as the magnification p, the shock wave count number q, and the signal interval number m (S106), reads Q _N stored in the internal storage device 14, On the other hand, p, q, the kurtosis calculation formula from m ^- calculate the Q _N (S107), further ^- W a _N value is calculated (S108), determines in comparison with a predetermined value (S109). The method of determination, ^- to W _N value may be one based on the result of larger than a predetermined value, it may be a representation of a table or graph. If the equipment is normal, since the standard signal sequence is believed to follow a substantially normal distribution, ^- the value of W _N is calculated as 1.0.
If the determination shows a value smaller than a predetermined value, an alarm signal is transmitted as abnormality information (S110), and if there is no abnormality, the measurement state is returned to normal. If there is an abnormality, it is displayed with a buzzer, a lamp, etc., and the equipment is stopped based on the manual.

  FIG. 5 is a conceptual diagram of a state monitoring method showing an embodiment of the present invention. This shows a simple determination calculation device such as a calculator. A data display device 51 such as an oscilloscope is connected to the sensor 31 provided in the facility, and the sensor 31 measures the data display device 51. The data can be displayed as shown in FIG. Also, the operator of the facility can input predetermined data from the data display device to the calculator, calculate it with a judgment formula set in the calculator, and use it for checking during operation of the facility.

The pitching flaw small level generally indicates a state such as p = 2. Similarly, the flaw level p = 4 corresponds to the flaw large level p = 6.
From these, ^- W _N can be said to be a good indicator of sensitivity to degradation diagnosis. In addition, this method is easy to incorporate into a microcomputer chip and can be effectively used for facility diagnosis in the field such as a factory.

ｐが増大すると、^-Ｑ_Nの値は増大する。一方、ｐの値が同じ場合ｑの値が大きくなるに従って、^-Ｑ_Nの値は下がってくる。傷が拡大したり伝播していくとピークレベルは大きくなり、派生衝撃波も拡大してゆく。
衝撃波による影響の状態は、イメージ的には表の左上から右下へとシフトしてゆくことが考えられる。
例えば、表２をとると、

と推移してゆくことが窺える。 Now, assuming m = 12, and considering the cases of p = 1, 2,..., 6 and q = 1, 2, 3, 4, Table 1 shows the results of transition of the value of equation (8). .

If p is increased, ^- the value of Q _N is increased. On the other hand, according to the value of p is a value of the same if q is increased, ^- the value of Q _N will come down. As the wound expands and propagates, the peak level increases and the derived shock wave also expands.
It is conceivable that the state of influence by the shock wave shifts from the upper left to the lower right of the table.
For example, taking Table 2,

It can be seen that it will change.

表3，4から、^-Ｗ_Nおよび^-Ｕ_Nをの値は、

と推移してゆくことが窺える。 Similarly, ^- W _N and ^- calculating the U _N, the results of Tables 3 and 4 is obtained.

Table 3, 4, ^- W _N and ^- the value of the U _N is

It can be seen that it will change.

これと今回の計算結果とを比較してみると、今回の結果の方がより敏感な反応を示していることがわかる。
例えば

The result of the same experiment (see Non-Patent Document 2) in the simplified model (FIG. 2) when the double-sided shock wave generated by the inventors is compared will be compared. The previous calculation results are shown in the table below.

Comparing this with the results of this calculation shows that the results of this time show a more sensitive reaction.
For example

From these results, when the shock wave level is the same, the simple calculated value of the sixth moment shows a more sensitive behavior in the case of the one-side derived shock wave than in the case of the two-side derived shock wave. In addition, ^- W _N and ^- when it comes to U _N, ^- W, but is more sensitive is better of _N, it would say to react sensitively even a little scratch. For example, ^- W _N is taking the 0.03 following values when p = 2. In contrast ^- U _N is decreasing slowly, is believed to be suitable for practical use.

It is the typical figure showing the unilateral derivative shock wave of the vibration signal of the normal rotating body for describing one embodiment of the present invention. It is a schematic diagram of the both-side shock wave of the vibration signal of the normal rotating body, shown for comparison with the present invention. It is a block diagram which shows the structure of the monitoring system of the specific periodic motion body of this invention. It is a flowchart which shows the operation | movement which the state monitoring system of this invention performs. It is a conceptual diagram of the state monitoring method which showed one Embodiment of this invention. In the present invention ^- showing the transition of values used to W _N. In the present invention ^- showing the transition of values used the U _N.

Explanation of symbols

1 Peak of Shock Wave 2 Derived Shock Wave 10 Condition Monitoring Device 11 CPU
12 RAM
DESCRIPTION OF SYMBOLS 13 External storage device 14 Internal storage device 15 Input part 16 Output part 20 State monitoring determination system 21 Computer program 31 Sensor 32 Data acquisition device 34 Alarm device

Claims (8)

Detects the peak waveform of vibration amplitude among unilateral shock waves generated when the periodic moving body is abnormal, and uses the statistical sixth-order normalized moment Q as a continuous-time system for the waveform generated in the time progression direction. To describe

And in discrete time system

And
(1) Moment using N data and 6th normalized moment when no shock wave is generated

And when shock waves are generated,

If you decide to write

Where

Then,

And
here,

When
(In the formula, p is the size of the peak waveform, m is the number of occurrences of abnormal vibration, and q is the number of samplings.)
Since Q is always 15.0 when the system is normal,

As

Because
As scratches expand, ^- if the value of Q _N also increases

As an absolute index value, the bar W _N is set to 1 when the rotating moving body is normal, and the value approaches 0 as the abnormality progresses, and includes a step of determining abnormality. A method for monitoring the state of a periodic moving body. According to claim 1, ^- with Q _N (bars Q _N),

As
The absolute index value, ^- U _N (Bar U _N) is comprised in a normal rotational movement body 1, further comprising a step of determining abnormality drives out that the value is closer to 0 as the abnormality progresses A method for monitoring the state of a periodic moving body. A state monitoring system for a periodic motion body, wherein the absolute indicator bar W _N based on claim 1 is represented on a graph to monitor the state of the periodic motion body. Condition monitoring system of the periodic motion body said value by notation graphed absolute indicator bar U _N based on claim 2 as an absolute index index value and judging as abnormal if less than a predetermined value. A computer program for monitoring a state of a periodic moving body, comprising a procedure for easily calculating the absolute indicator bar W _{N according} to claim 1. Periodic motion body state monitoring computer program characterized in that it comprises the steps that the absolute indicator bar U _N of claim 2 is simply calculated.   A computer-readable recording medium on which the program according to claim 5 is recorded.   A computer-readable recording medium on which the program according to claim 6 is recorded.

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