JP7528035B2 - Vibration monitoring device for machinery and equipment - Google Patents

Description

The present invention relates to a vibration monitoring device for machinery and equipment used in machinery and equipment with rotating parts.

Conventionally, in machinery and equipment with rotating parts, the vibration of the machinery and equipment caused by the operation of the rotating parts may be monitored to detect mechanical abnormalities. A vibration monitoring device that performs such vibration monitoring processes and analyzes the output signal of a vibration sensor installed near the rotating part to determine the presence or absence of abnormal vibration. Examples of such a vibration monitoring device are disclosed in, for example, Patent Documents 1 and 2.

Patent No. 5293300 Patent No. 6283591

Conventional vibration monitoring devices such as those described in Patent Documents 1 and 2 are dedicated machines for vibration monitoring, and so do not essentially have the functionality to control external devices. Therefore, when it is determined that there is an abnormality in the vibration, if one wishes to operate external devices such as a buzzer, warning lamp, or computer to notify of the abnormality, it is necessary to create a separate control device that controls the external devices based on the vibration diagnosis, which incurs development costs.

On the other hand, there is a PLC (Programmable Logic Controller) as a general-purpose machine that controls external devices. For example, if a program for vibration diagnosis is set in the PLC and a vibration sensor is connected as an input device and an alarm device such as a buzzer or warning lamp is connected as an output device, the PLC will perform vibration diagnosis based on the signal from the vibration sensor and activate the alarm device based on the diagnosis result.
However, in vibration diagnosis using only a general-purpose PLC, if the PLC input signal contains high frequencies that are more than half the sampling frequency, aliasing (folding back phenomenon) occurs, in which the signal appears as a lower frequency signal than the actual signal, and so there is a problem that it is not possible to perform a diagnosis with the same high accuracy as with the dedicated machine mentioned above.

The present invention has been made to solve these problems, and aims to provide a vibration monitoring device for mechanical equipment that can perform vibration diagnosis with high accuracy at low cost and control external devices such as alarm devices based on the results of the vibration diagnosis.

The inventors came up with the idea that if vibration diagnosis using a PLC could achieve the same diagnostic accuracy as a dedicated machine, it would be possible to utilize the functions of the PLC to link it with other equipment.
The present invention is based on this idea, and specifically comprises the following configuration.

(1) The vibration monitoring device for mechanical equipment according to the present invention determines whether or not there is an abnormality in the vibration based on a vibration waveform acquired from a vibration sensor that detects the vibration of the mechanical equipment, and controls an alarm device that issues an alarm based on the determination result, and is characterized in that it includes a vibration input unit that receives an analog vibration waveform output from the vibration sensor and performs noise removal, and a PLC that receives the analog vibration waveform from which noise has been removed by the vibration input unit, converts it into a digital vibration waveform, removes noise from the converted vibration waveform, determines whether or not there is an abnormality based on the noise-removed vibration waveform, and controls the alarm device based on the determination result.

(2) Also, in the above (1), the vibration input unit is characterized by including an analog circuit that adjusts the gain.

The vibration monitoring device for mechanical equipment according to the present invention includes a vibration input unit that receives an analog vibration waveform output from a vibration sensor and performs noise removal, and a PLC that receives the analog vibration waveform from which noise has been removed by the vibration input unit, converts it into a digital vibration waveform, removes noise from the converted vibration waveform, determines whether or not there is an abnormality based on the noise-removed vibration waveform, and controls an alarm device based on the determination result. This allows for low development costs, high accuracy in vibration diagnosis, and easy integration with external devices such as alarm devices.

1 is an explanatory diagram of a vibration monitoring device for mechanical equipment according to an embodiment of the present invention;

A vibration monitoring device 1 for mechanical equipment according to one embodiment of the present invention (hereinafter simply referred to as "vibration monitoring device 1") determines the presence or absence of an abnormality in vibration based on an analog vibration waveform output from a vibration sensor 3, and controls an alarm device 7 based on the determination result, and as shown in Figure 1, is equipped with a vibration input unit 5 which receives as input the analog vibration waveform output from the vibration sensor 3 and performs noise removal, and a PLC 9 which receives as input the analog vibration waveform from which noise has been removed by the vibration input unit 5, determines the presence or absence of an abnormality, and controls the alarm device 7 based on the determination result. Noise removal as described here refers to extracting necessary frequencies.
A detailed description will now be given of each component of the vibration monitoring device 1. In the following, an example will be described in which an acceleration sensor that outputs an analog waveform of vibration acceleration is used as the vibration sensor 3.

<Vibration input unit>
The vibration input unit 5 performs analog signal processing such as noise removal on the analog vibration acceleration waveform output from the vibration sensor 3, and inputs the processed vibration acceleration waveform to the PLC 9. The vibration input unit 5 can also supply power to the vibration sensor 3.

Analog signal processing of the vibration acceleration waveform is performed by a vibration waveform processing section 11 of the vibration input unit 5 .
The vibration waveform processing unit 11 is composed of an analog circuit, and performs processing such as AC coupling (HPF: high pass filter) and aliasing filter (LPF: low pass filter) on the vibration acceleration waveform to remove noise components.
By performing noise removal on the vibration acceleration waveform of the analog signal in this manner, it is possible to remove noise components that cannot be removed by the noise removal using the digital processing of the PLC 9 .

Furthermore, the vibration waveform processing unit 11 includes an analog circuit that adjusts the gain (amplifies according to the amplitude of the vibration waveform). By adjusting the gain of the analog vibration acceleration waveform in the vibration input unit 5, it is possible to utilize the full-scale resolution of the A/D conversion by the PLC 9, which is preferable.

<PLC>
The PLC (programmable logic controller) 9 inputs the analog vibration waveform (vibration acceleration waveform in this example) from which noise has been removed by the vibration input unit 5, converts it into a digital vibration waveform, removes noise from the converted vibration waveform, determines whether or not there is an abnormality based on the noise-removed vibration waveform, and controls the alarm device 7 based on the determination result, and is equipped with an A/D conversion processing unit 13, an integration processing unit 15, a digital filter processing unit 17, an analysis/calculation processing unit 19, a memory unit 21, a control unit 23, and a communication unit 25.
Each component will be described in detail below.

<A/D conversion processing section>
The A/D conversion processing section 13 converts the analog vibration acceleration waveform output from the vibration input unit 5 into a digital vibration acceleration waveform. As described above, in this embodiment, the vibration input unit 5 adjusts (amplifies) the gain of the vibration acceleration waveform, so that the resolution of the A/D conversion processing section 13 can be utilized at full scale, improving the accuracy of calculations in the analysis and calculation processing section 19 (described in detail later).

<Integration processing section>
The integration processing section 15 performs integration processing on the vibration acceleration waveform generated by the A/D conversion processing section 13 to generate a vibration velocity waveform.
By generating a vibration velocity waveform from the vibration acceleration waveform, the vibration state can be analyzed from the viewpoints of both vibration acceleration and vibration velocity. This is preferable because it allows simultaneous judgment of abnormal vibrations that exhibit different behaviors, such as shock vibrations caused by damage to rotating parts and poor lubrication (preferably judged by acceleration waveforms) and dynamic vibrations caused by backlash and imbalance in mechanical equipment (preferably judged by velocity waveforms).

<Digital filter processing section>
The digital filter processing unit 17 performs digital filter processing on the vibration acceleration waveform generated by the A/D conversion processing unit 13 and the vibration velocity waveform generated by the integration processing unit 15 to remove noise components, and has a function of completing the digital filter processing time within 0.25 times the vibration measurement time (as a specific example of 0.25 times, the digital filter processing time is 0.25 seconds for a vibration measurement time of 1.0 second per point), and this function is realized by executing a specified program.

<Analysis and calculation processing section>
The analysis/calculation processing section 19 performs calculations required for vibration diagnosis on the vibration acceleration waveform and vibration velocity waveform from which noise has been removed by the digital filter processing section 17, and judges the presence or absence of an abnormality. The vibration acceleration waveform and vibration velocity waveform subjected to the vibration diagnosis by the analysis/calculation processing section 19 are stored in the memory section 21.

The method for determining whether or not there is an abnormality is not limited, but for example, the maximum value, effective value, crest factor (hereinafter also referred to as "level value"), etc. of the normal vibration waveform (vibration acceleration waveform and vibration velocity waveform) can be stored in advance in the memory unit 21 as vibration analysis parameters, and the presence or absence of an abnormality can be determined based on the vibration analysis parameters and the level value of the diagnosis target.

In this embodiment, the analog vibration acceleration waveform output from the vibration sensor 3 is subjected to noise removal by an analog circuit before being input to the PLC 9. Therefore, compared to the conventional case in which noise is removed only by the digital filter processing of the PLC 9, the accuracy is improved by the amount of noise components contained due to aliasing that are removed.
In addition, by adjusting the gain (amplification) of the vibration input unit 5, the resolution of the A/D conversion processing unit 13 is utilized at full scale, making it possible to perform highly accurate calculations, for example, with absolute accuracy (not the A/D conversion resolution, but the error accuracy of the entire monitoring device) in units of 0.05 [m/ ^s2 ] or less for vibration acceleration (measurement frequency range: 1000 to 15000 Hz) and in units of 0.5 [mm/s] or less for vibration velocity (measurement frequency range: 10 to 1000 Hz).
Therefore, it is possible to perform vibration diagnosis with higher reliability than vibration diagnosis using a conventional PLC.

<Memory section>
The memory unit 21 stores various types of data, such as the vibration analysis parameters described above, each vibration waveform of the monitored object (vibration acceleration waveform, vibration velocity waveform), past level values of the monitored object, and historical data of abnormal vibrations that have triggered an alarm.

<Control Unit>
The control unit 23 controls the alarm device 7 based on the determination result of the analysis and calculation processing unit 19 .
The warning device 7 may be, for example, a buzzer or a rotating lamp.
When the analysis and calculation processing unit 19 determines that there is an abnormality in the vibration, the control unit 23 operates the alarm device 7 to issue an alarm.
The control by the control unit 23 can also be performed by an operator via an operation screen 27 (such as a touch panel) which is an external device of the PLC 9 .

Communications Department
The communication unit 25 transmits and receives data to and from other devices 29 via a network. The other devices 29 can access the data stored in the storage unit 21 of the PLC 9 via the network and the communication unit 25.
This makes it possible to monitor each vibration waveform in real time from a computer on the network.Furthermore, since it is possible to obtain information from multiple PLCs with one computer, it becomes possible to simultaneously monitor operational information other than vibration, enabling efficient monitoring of equipment status.
In addition, other equipment 29 (such as a personal computer or another PLC) can acquire the vibration waveform from the storage unit 21 and perform more detailed vibration analysis (such as frequency analysis).

As described above, according to this embodiment, the analog vibration waveform output from the vibration sensor 3 is input to the PLC 9 via the vibration input unit 5, which removes noise components that cannot be handled by the digital signal processing of the PLC 9, and the A/D conversion resolution of the PLC 9 can be utilized at full scale, improving the accuracy of vibration diagnosis by the PLC 9.

In addition, by utilizing the control functions and communication functions of external devices that the general-purpose PLC 9 has, it is possible to control the alarm device 7 and link with other devices 29 via a network at low cost.

As described above, in this embodiment, an acceleration sensor is used as the vibration sensor 3, but the present invention is not limited to this, and other types of vibration sensors can be used. For example, a velocity sensor that outputs an analog waveform of the vibration velocity can be used as the vibration sensor 3. In this case, digital vibration velocity waveform data can be generated by the A/D conversion processing unit 13, and then the data can be differentiated to generate vibration acceleration waveform data.

1 Vibration monitoring device 3 Vibration sensor 5 Vibration input unit 7 Alarm device 9 PLC
REFERENCE SIGNS LIST 11 vibration waveform processing section 13 A/D conversion processing section 15 integration processing section 17 digital filter processing section 19 analysis/calculation processing section 21 storage section 23 control section 25 communication section 27 operation screen 29 other devices

Claims (2)

A vibration monitoring device for a mechanical equipment, the device determining whether or not there is an abnormality in vibration based on a vibration waveform acquired from a vibration sensor that detects vibration of the mechanical equipment, and controlling an alarm device that issues an alarm based on the determination result,
a vibration input unit that receives an analog vibration waveform output from the vibration sensor and performs noise removal processing including aliasing filtering;
a PLC that inputs a vibration waveform from the vibration input unit and controls an alarm device,
The PLC is configured with a program for vibration diagnosis, and has the functions of inputting an analog vibration waveform from which noise has been removed by the vibration input unit, converting it into a digital vibration waveform, removing noise from the converted vibration waveform, determining whether or not there is an abnormality based on the noise-removed vibration waveform, and controlling the alarm device based on the determination result. The vibration monitoring device for mechanical equipment according to claim 1, characterized in that the vibration input unit includes an analog circuit for gain adjustment.

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