JPH01274019A - Monitoring of vibration for rotary machine - Google Patents

Abstract

PURPOSE:To achieve a higher accuracy in multi-point online monitoring of vibration of a rotary construction, by storing a vibration waveform and revolution data into a storage device while a Cambel chart is prepared by performing a frequency analysis of a display channel set. CONSTITUTION:When a rotary machine 1 is rotated, vibrations of blades 3a-3c are detected with strain gauges 5-7 to be sent with telemeter oscillators 8-10 to a transmitter 11. An output of the receiver 11 is inputted into a CPU 22 as vibration waveform through a channel controller 21 of a data processor 200. Likewise, a revolutions signal detected with a rotation pulse pickup 12 is converted into a digital signal synchronizing rotation with a tracking analyzer 13 to be inputted into the CPU 22. Data of the vibration waveform and revolutions inputted into the CPU 22 are stored 23 while undergoing a frequency analysis with a microprocessor 24. Then, based on the results, a Cambel chart of a measuring channel is prepared again with the CPU 22 to be displaced on a monitor CRT 26.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to vibration monitoring of rotating machines, and particularly to a method suitable for monitoring vibrations of rotating machines and structures.

[Conventional technology]

Conventionally, the vibration monitoring method for rotating structures such as blades was disclosed in Japanese Patent Application Laid-Open No. 1986.
As described in Publication No. 151075, the acceleration of the bearing that supports the rotating machine is detected, the acceleration component corresponding to the vibration frequency of the blade is separated from this, and the rotor blade is determined based on the magnitude of the blade vibration component of this bearing acceleration. Although this method has the advantage of being easy to measure, the problem is that it is not always sufficient to improve measurement accuracy because the blade vibration is measured indirectly using acceleration. was there.

[Problem to be solved by the invention]

On the other hand, a commonly used method is to directly measure the vibrations of blades, etc., and display the vibration waveform and frequency on a cathode ray tube for monitoring. This alone is not enough.

By the way, in order to monitor the presence or absence of excessive vibration due to resonance with the natural frequency of a rotating structure, it is ideal to use a diagram called a Campbell diagram as shown in FIG. FIG. 5 shows the change in the natural frequency depending on the rotational speed, and this curve is obtained by connecting points with large amplitudes where the excitation frequency and the natural frequency match. The size of the circle indicates the vibration amplitude level, which is monitored to see if it is excessive. In the past, online monitoring using Campbell diagrams was difficult because it took time to analyze the vibration and display the diagram, but it is now possible to some extent due to faster measurement systems. One of the problems in this case is how to obtain a clear Campbell diagram for vibration levels that are difficult to predict, and how to improve the efficiency and economy of multi-point measurements.

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for improving the accuracy and efficiency of multi-point online vibration monitoring of rotating structures using clear Campbell diagrams.

[Means to solve the problem]

The above purpose is to measure the vibration of a rotating structure at multiple points at each predetermined rotation speed, store this vibration waveform and rotation speed data in a storage device, and at the same time perform frequency analysis of the set display channel to create a Campbell diagram. However, this can be achieved by displaying this on a display device online, and also by making it possible to freely change the display level of the Campbell diagram, change the display channel, and temporarily suspend data collection online.

[Effect]

The main effects of the vibration monitoring method of the present invention will be described.

Changing the display level of a Campbell diagram involves changing the size of the mark (for example, a circle) that indicates the size of its vibration amplitude and the threshold level for displaying the size of many frequency spectra that are the results of frequency analysis. By appropriately changing this level while looking at the displayed Campbell diagram, the optimum display level can be obtained for the vibration level to be monitored. Changing the display channel has the effect of changing the measurement channel for frequency analysis to the display channel displayed on the display device, and making it possible to monitor the changed display channel from the time of change. Further, the temporary suspension of data acquisition has the effect of eliminating unnecessary data acquisition when the rotational speed is constant, for example.

〔Example〕

Hereinafter, the details of the present invention will be explained with reference to examples.

FIG. 1 shows an embodiment of the vibration monitoring method for a rotating machine according to the present invention, and FIG. 2 shows the hardware configuration thereof. To explain Fig. 1 and Fig. 2 in correspondence, first, Fig. 1 shows step 1 of setting display channels etc. prior to measurement, multi-channel vibration waveform, and step 2 of acquiring rotation speed. A step 3 of storing in a storage device, a step 4 of performing frequency analysis of the set channel, a step 5 of creating a Campbell diagram from the analysis result and displaying it on a display device, and a step 6 of changing the display level of the displayed Campbell diagram. It has at least ten steps: a step 7 of changing the display channel, a step 8 of instructing to copy the display screen, a step 9 of copying the display screen based on the change, and a step 10 of instructing the end of the measurement.

In FIG. 2, 3a, 3b, and 3c are blades to be subjected to vibration monitoring, and these are embedded in the chassis 4a, 4b, and 4c to form a blade wheel, which is a component of the rotating machine 1. There is. 2a
, 2b are support bearings of the rotating machine 1. When rotating machine 1, g3a.

The vibrations at 3b and 3c are detected by strain gauges 5.6 and 7, respectively, and sent to receiver 11 by telemeter oscillators 8, 9 and 10. The output of the receiver 11 is sent to C through the channel controller 21 of the data processing device 200.
The vibration waveform is taken into the PU 22 as a vibration waveform. Similarly, the rotational speed signal detected by the rotational pulse pickup 12 is converted into a digital signal synchronized with the rotation by the tracking analyzer 13, and is taken into the CPU 22.

In this case, the vibration waveform is captured at constant rotational frequency intervals, and this rotational frequency interval is determined by the amount of captured data and the storage capacity. The step of importing this vibration waveform and rotational speed signal into the CPU is step 2 in FIG. The procedure in Figure 1 is CP
It is provided as software in the memory of U22, and is configured so that necessary messages are output on monitor CRT 26 by input from keyboard 25. In FIG. 1, prior to step 2, step 1 includes inputting measurement channels and display level conditions to be displayed on the CRT 26 from the keyboard 25.

The vibration waveform and rotation speed data taken into the CPU 22 in FIG. 2 are stored in the external storage device 23, and at the same time
Frequency analysis is performed by the microprocessor 24 using the fast Fourier transform (FFT) method for the display channels set in . This step corresponds to steps 3 and 4 in FIG. Next, based on this result, CP
A Campbell diagram of the measurement channel is created by U22 and displayed on the monitor CRT26. This corresponds to step 5 in FIG. In this case, the process from data acquisition in step 2 to displaying the Campbell diagram in step 5 is executed almost in real time, so the vibration waveform is analyzed every time the rotation speed of rotating machine 1 changes and reaches the measured rotation speed. The data is displayed online on the monitor CRT 26 as a Campbell diagram.

This state continues until there is an instruction to end the measurement.

If the display level of the Campbell diagram displayed on the monitor CRT 26 is not appropriate, a predetermined character (for example, L) is input from the keyboard 25 to stop setting the display level in step 1.

This process is repeated until an appropriate display state is obtained while observing changes in the Campbell diagram as the rotational speed changes. This corresponds to step 6 in FIG. Specifically, resetting the display level in step 6 involves changing the reference value that determines the size of the mark (circle in this case) that displays the threshold and amplitude of the frequency spectrum of the frequency analysis result. In other words, lowering the frequency spectrum threshold increases the number of points representing the spectrum displayed on the Campbell diagram, while increasing or lowering the amplitude reference value changes the size of the circle of the displayed points. do. Therefore, if the threshold value is too low, the number of displayed points will be too large and the characteristics of the natural frequency shown in Figure 5 will not be clear. Normally, it is difficult to know in advance the vibration level that corresponds to an appropriate display level, so being able to change the display level online makes it possible to optimize the display level and clarify the Campbell diagram. Encourage improvement of vibration monitoring accuracy.

Also, if you want to change the display channel of the Campbell diagram, you can also use the keyboard 25 to select a character (for example, C).
Enter to reset the display channel in step 1 to the desired channel. Then, steps 4 to 5 are performed for the changed display channel, and the monitor CRT 26 displays the Campbell diagram of the changed channel after the time of the change. Similarly, changes to other display channels can be made as appropriate, so multi-channel vibration monitoring can be performed efficiently. As a result, even when changing the display channel, Step 2
and step 3 are performed for all measurement channels including the display change channel.

Next, if it is desired to copy the display screen of the monitor CRT 26, steps 8 and 9 in FIG. 1 are executed. That is,
Characters specified by the keyboard 25 (for example, copy
) is input to the monitor CRT using the hard copy device 27.
Copy the display screen of 26.

Changing the display level in step 6, changing the display channel in step 7, and copying the display screen in step 8 can each be executed online at any time required, and the order of each can be changed. . However, step 6. Step 7. While the process 8 and 9 are being executed, the data acquisition in process 2 is interrupted, but this is only for a short time and does not pose any problem in terms of monitoring.

The process from step 1 to step 9 is step 10 in FIG.
) runs online continuously until However, this execution can also be performed automatically under certain conditions.

FIG. 3 shows the procedure of a second embodiment of the vibration monitoring method for a rotating machine according to the present invention, and is a modification of FIG. 1.

In FIG. 3, a step 11 for interrupting data acquisition is provided after step 6 in FIG. 1. Referring to FIG. 2, this step 11 starts by inputting a predetermined character (for example, dan) from the keyboard 25 to start the interruption, and includes inputting from the keyboard again to end the interruption (for example, dan again). While this step 11 is being executed, the data acquisition in step 2 and the data storage in step 83 are interrupted, and the display screen in step 5 before step 11 is continued as it is. In FIG. 3, step 11 is the next step after step 6, but this is step 7. It may be the next step after step 9, or step 6. Step 11. The order of steps 7 and 8 may be changed from one another as needed.

Step 11 is executed when the rotational speed is constant or when there is no need to capture vibration data, resulting in savings in the storage capacity of the storage device 23 in FIG. 2 and an increase in the efficiency of vibration monitoring.

FIG. 4 shows the procedure of a third embodiment of the vibration monitoring method for a rotating machine according to the present invention, and is a modification of FIGS. 1 and 3. Fourth
In the figure, after step 7 in FIG. 3, there is a step 12 for instructing a change in the rotational speed direction, that is, a change in the rotational speed from increasing to decreasing or vice versa, and then data after the rotational speed direction change. The method newly includes a step 13 of collecting the data and a step 14 of reading the stored data before the change in speed direction, and after step 12, either step 13 or step 14 can be selected. Post-process 1 of process 12
When 3 is selected, data acquisition after the rotational speed direction has changed is started in step 2, and after passing through steps 3 and 4, the Campbell diagram after the rotational speed direction has been changed is displayed in step 5. Process 1
When the post-process 14 of 2 is selected, the process 14 sets the display channel according to the process 1 and the process 3 in order to display the Campbell diagram of an arbitrary measurement channel before changing the rotational speed direction.
read out the stored data. Thereafter, through steps 4 and 5, a Campbell diagram of the newly selected display channel before the rotation speed direction change is displayed. Process 1
If these processes from 2 onwards correspond to Figure 2, process 1
2 is a predetermined character (for example, M) from the keyboard 25.
) is done by inputting the first monitor CRT
26 displays whether to select step 13 or step 14, and according to the instruction, characters indicating step 13 or step 14 are input again from the keyboard 25.

When step 13 is input, the data after the change in the rotational speed direction is input into the CPU 22 in step 2, and the Campbell diagram after the change in the rotational speed direction is displayed on the monitor CRT 26 according to the normal process. On the other hand, when step 14 is selected, the display channel is subsequently input from the keyboard 25, and as a result, reading of the display channel data from the storage device 23 is started, and after frequency analysis by the microprocessor 25, the Campbell diagram is is created and displayed on the monitor CRT 26.

In FIG. 4, step 12 is the next step after step 7, but this is step 6. Step 11. They may be performed at any point after step 9, and their order may be changed from one another as desired. Step 12 makes it possible to monitor before and after a change in the rotational speed direction, thereby increasing the efficiency of vibration monitoring.

〔Effect of the invention〕

According to the present invention, the reliability of vibration monitoring can be improved by increasing the clarity of the Campbell diagram according to the vibration level, and the efficiency of vibration monitoring can be increased.

[Brief explanation of the drawing]

Fig. 1 is a flowchart of an embodiment of the present invention, Fig. 2 is a block diagram of the embodiment of Fig. 1, Fig. 3 is a flowchart of a second embodiment of the invention, and Fig. 4 is a flowchart of the embodiment of the invention. The flowchart of the third embodiment, FIG. 5, is an explanatory diagram using a Campbell diagram. DESCRIPTION OF SYMBOLS 1... Rotating machine, 38-3c... Blade, 5-7... Strain gauge, 8-1o... Transmitter, 11... Receiver, 12... Rotating pulse pickup, 13. ... Trunking synthesizer, 21... Channel controller, 22... CPU, 23... Storage device, 24
... Microprocessor, 25 ... Keyboard, 2
6...Monitor CRT, 27...Hard copy device,
200...Data processing device. Figure 1 Figure 2 Figure 3 Figure 4

Claims (1)

[Claims] 1. A method for online monitoring of vibrations of a rotating machine, which comprises: a first step of setting a display channel and a display level among multiple measurement channels; and a rotating member of the rotating machine. a second step of measuring vibrations at multiple points at predetermined rotation speed intervals; a third step of storing measured vibration waveforms and rotation speed data for all measurement points in a storage device; a fourth step of frequency-analyzing the vibration waveform of one set display channel; a fifth step of creating a Campbell diagram from the frequency analysis result and displaying the Campbell diagram on a display device; a sixth step of changing the display level when the display level of the Campbell diagram is not appropriate; a seventh step of changing the display channel to view vibrations of other measurement channels; and a hard copy of the display screen. The eighth step of giving instructions;
A vibration monitoring method for a rotating machine, comprising: a ninth step of making a hard copy of the display screen; and a tenth step of instructing the end of measurement. 2. A patent claim that provides an eleventh step for temporarily suspending and canceling the second step after any one of the sixth step, the seventh step, and the ninth step. Range 1
Vibration monitoring method for rotating machines as described in . 3. After any one of the sixth step, the seventh step, the ninth step, and the eleventh step, a twelfth step of instructing a change in the rotational speed direction, and further thereafter, rotation. The vibration monitoring method for a rotating machine according to claim 1 or 2, further comprising a thirteenth step of collecting data after the speed has changed, and for monitoring vibration after the rotation speed has changed. 4. After any of the sixth step, seventh step, ninth step, and eleventh step, the twelfth step, and then the third step. A fourteenth step is provided to read data of an arbitrary measurement channel before the rotation speed change from the result, and after the rotation speed direction change, vibration monitoring of the arbitrary measurement channel before the change is performed. The vibration monitoring method for a rotating machine according to item 2 or 3. 5. A patent in which the order of the sixth step, the seventh step, the eighth step, the eleventh step, and the twelfth step can be changed arbitrarily as necessary. A vibration monitoring method for a rotating machine according to claim 1, 2, 3, or 4.