JPH08261818A - Vibration detecting method and apparatus for rotor - Google Patents

Abstract

PURPOSE: To provide a vibration detecting method and apparatus of a rotor which can simplify a structure to detect vibration generated in the rotor during grinding or the like. CONSTITUTION: An acoustic emission generated from a grinding stone G as rotor is detected by an AE sensor 1. A signal detected undergoes an envelope detection with a rectifier circuit and the signal after the envelope detection is subjected to a frequency analysis to detect vibration generated in the grinding stone G.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for detecting vibration of a rotating body suitable for detecting vibration of the rotating body in a machine tool or the like, and an apparatus used therefor.

[0002]

2. Description of the Related Art As means for detecting a vibration generated in a rotating body in a machine tool or the like, for example, FIGS.
There is something like that shown in

FIG. 10 is an explanatory diagram showing how vibration and contact detection of a rotating body is performed in a grinding apparatus. The grinding apparatus 51 is built in a grindstone head 53 arranged in a column 52. The grinding wheel G is rotated by the driving device to grind the workpiece W placed on the table 54. FIG. 11 is an explanatory diagram showing the configuration of the signal processing device 58 shown in FIG. Is.

The vibration of the grinding wheel G, which is a rotating body, while it is rotating is detected by an acceleration sensor 56 attached to the grinding wheel head 53 near the grinding wheel G. Further, the origin detection sensor 55 detects the origin position signal of the grindstone shaft used for calculating the rotation speed and the phase of the grinding grindstone G.

On the other hand, the AE (acoustic emission) sensor 57 is used to detect the contact between the grinding wheel G and the work W, not the vibration.

As shown in FIG. 11, the acceleration signal from the acceleration sensor 56 is input to the central processing unit (CPU) 63 via the bandpass filter 59, and
An output signal from the AE sensor 57 is input to a central processing unit (CPU) 63 via a preamplifier 60 for amplification, a high-pass filter 61 for removing low frequency components, and a rectifier circuit 62 for envelope detection. To be done.

The signal detected by each sensor is CP
U63 performs arithmetic processing. The balance state of the grinding wheel G and the magnitude of vibration are calculated from the origin position signal from the origin detection sensor 55 and the acceleration signal from the acceleration sensor 56, and the grinding wheel G is calculated from the output signal from the AE sensor 7.
And the information regarding the presence or absence of contact between the workpiece W and the workpiece W are calculated and displayed on the display unit 64.

[0008]

However, in such a conventional vibration detecting means, the acceleration sensor 56 is used for the vibration of the grinding wheel G, and at the same time, the grinding wheel G and the workpiece are simultaneously used. Since the AE sensor 57 is used for detecting the contact with W, each sensor must be arranged in the vicinity of the grinding wheel G and the workpiece W, which complicates the structure and increases the cost. There was a problem, and the task was to solve this problem.

[0009]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned conventional problems, and provides a rotary body having a simple structure for detecting vibrations generated in the rotary body during grinding or the like. An object of the present invention is to provide a vibration detection method and device.

[0010]

According to a first aspect of the present invention, there is provided a vibration detecting method for a rotating body, wherein an acoustic emission generated from a rotating body such as a grinding wheel or a workpiece in grinding or turning. Detected by the AE sensor, the detected signal is envelope-detected by the rectifier circuit, and the vibration of the rotating body is detected from the envelope-detected signal. The frequency analysis is performed, and the balance state of the rotating body is determined from the amplitude of the vibration frequency component corresponding to the rotation speed of the rotating body in the result of the frequency analysis. The acoustic emission generated near the point is detected by the AE sensor, and the vibration frequency and vibration level of the abnormal vibration generated by the contact between the processing tool and the workpiece are detected. It is configured to be out. Also,
A vibration detecting device for a rotating body according to claim 4 of the present invention is a device used for detecting the vibration of the rotating body by the method according to any one of claims 1 to 3, and is an acoustic emission emitted from the rotating body. An AE sensor for detecting
A configuration is provided that includes a rectifier circuit that performs envelope detection of a signal from the AE sensor and a determination unit that determines the vibration of the rotating body based on the output from the rectifier circuit. As a means.

[0011]

According to the method of detecting vibration of a rotating body according to the first aspect of the present invention, acoustic emission generated from a rotating body such as a grinding wheel or a workpiece in grinding or turning is detected by an AE sensor. Then, the detected signal is envelope-detected by the rectifier circuit, and the vibration of the rotating body is detected from the envelope-detected signal, whereby the vibration generated in the rotating body is detected by the AE sensor. Therefore, it is not necessary to use an acceleration sensor to detect vibration, and since the AE sensor used to detect contact of the rotating body is also used to detect vibration at the same time, the vibration generated in the rotating body is eliminated. The structure for detecting is simple.

A method for detecting vibration of a rotating body according to a second aspect of the present invention is configured as described above. For example, when the amount of unbalance of rotation of the grinding wheel, which is the rotating body, is large, the result of the frequency analysis indicates that grinding is performed. A peak appears in the frequency component corresponding to the rotational speed of the grindstone, and the magnitude of the peak (amplitude) determines the magnitude of the unbalance amount.

The method for detecting vibration of a rotating body according to a third aspect of the present invention is configured as described above. For example, in addition to the forced vibration generated by the imbalance of the grinding wheel, the workpiece is ground by the grinding wheel. Vibrations such as self-excited vibrations and chattering vibrations that occur during operation are also detected, and the life of the grinding wheel is judged based on the frequency and amplitude of the detected vibrations.

A vibration detecting device for a rotating body according to a fourth aspect of the present invention is configured as described above, and is suitable for carrying out the methods according to the first to third aspects.

[0015]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is an explanatory view showing an embodiment of the present invention, in which a cover 20 for preventing the scattering of the coolant.
The workpiece W installed on the table 21 is ground by a grinding wheel G that is a rotating body provided inside, and an AE sensor 1 is provided on the upper surface of the table 21.

When the coolant C is being supplied from the coolant supply nozzle 2 toward the gap between the grinding wheel G and the workpiece W, and vibration of the grinding wheel G alone is detected, that is, the grinding wheel. When G and the work W are not in contact with each other, the acoustic emission generated in the grinding wheel G propagates to the work W via the coolant C and is detected by the AE sensor 1.

At this time, the smaller the gap between the grinding wheel G and the work W, and the larger the flow rate of the coolant C supplied, the larger the amount of acoustic emission emitted.

On the other hand, during the grinding process, the grinding wheel G
Acoustic emission generated at the contact point between the workpiece W and the work W is detected by the AE sensor 1.

FIG. 2 shows a signal processing procedure in the signal processing device 3 of the acoustic emission signal detected by the AE sensor 1.

In FIG. 2, the acoustic emission signal detected by the AE sensor 1 is the preamplifier 11
After being amplified by, the low-frequency noise component is removed through the high-pass filter 12, and the rectifier circuit 13 performs envelope detection processing.

Then, the signal subjected to the envelope detection processing is inputted to the frequency analyzer 14 which is a judging means for judging the vibration of the grinding wheel G which is the rotating body, and is subjected to the Fourier transform processing to output and display the frequency spectrum.

An example of the frequency spectrum of the acoustic emission signal subjected to the envelope detection processing is shown in FIGS. 3 and 4.

FIG. 3 shows the frequency spectrum when the unbalance amount of the grinding wheel G is small, and FIG. 4 shows
The frequency spectrum when the unbalance amount of the grinding wheel G is large is shown.

When the unbalance amount of the grinding wheel G, which is a rotating body, is small, there are no noticeable frequency components,
When the amount of unbalance is large, the peak of the frequency component corresponding to the rotation speed of the grinding wheel G is conspicuous, and from this, it is possible to confirm the existence of vibration caused by the unbalance of the rotation of the grinding wheel G.

Next, FIG. 5 shows a flow chart of the imbalance detection of the grinding wheel G, in which the grinding wheel G is rotated (S1) and the frequency spectrum of the AE signal during the rotation of the grinding wheel G is monitored. If the frequency component corresponding to the rotation speed of the grinding wheel G does not exceed the set value (S2), the machining is started (S3), and the frequency component corresponding to the rotation speed of the grinding wheel G exceeds the set value. If so, the balance is corrected (S4). By doing so, processing can be started in a good balance state.

Incidentally, vibrations in the grinding process include not only forced vibrations caused by the imbalance of the grindstone G but also self-excited vibrations that do not vibrate during non-machining but only during machining. There is a great need to detect in-process the processing state by detecting whether or not various vibrations are occurring.

As described above, since the acoustic emission generated at the contact point between the grinding wheel G and the work W is detected by the AE sensor 1, it is possible to detect the vibration during processing, and the vibration frequency can be detected from the frequency spectrum. It can also be specified.

Further, for example, in the case of self-excited vibration due to the gradual wear of the grinding wheel G, it is possible to detect the growth of vibration and determine the life of the grinding wheel G.

Next, FIG. 6 is a flowchart for determining the life of the grinding wheel G due to chatter vibration.

As shown in FIG. 6, the frequency spectrum of the AE signal during the grinding process is monitored (S5), and when the specific frequency component exceeds the set value, it is judged that the grinding wheel G has reached the end of its life (S6). The grinding wheel G called truing is corrected (S7). By doing so, it is possible to know the life time of the grinding wheel G, and it is possible to always perform the grinding process with the grinding wheel G in a good state.

As described above, according to the present invention, the AE sensor 1 can detect the vibration of the grinding wheel G, which is a rotating body, and can also be used for detecting the contact between the grinding wheel G and the work W as in the conventional case. Therefore, it is possible to monitor a plurality of phenomena with one AE sensor 1, and it is possible to simplify the structure for detecting the vibration generated in the grinding wheel G that is the rotating body.

FIGS. 7 and 8 are explanatory views showing another embodiment of the present invention, and FIG. 7 shows a state in which vibration detection and contact detection of a rotating body in a grinding apparatus are performed. The processing device is the grindstone head 3 arranged in the column 31.
The grinding wheel G is rotated by a driving device incorporated in the No. 2 to grind the workpiece W placed on the table 21, and FIG. 8 shows the signal processing device 3 shown in FIG. It is explanatory drawing which shows a structure.

Here, the origin detection sensor 5 attached to the end of the grindstone head 32 detects the origin position signal of the grindstone shaft used for calculating the rotational speed and the phase of the grinding grindstone G.

On the other hand, the AE sensor 1 detects not only vibration but also contact between the grinding wheel G and the work W.

The acoustic emission signal detected by the AE sensor 1 passes through the preamplifier 11, the high-pass filter 12, the rectifier circuit 13 and the band-pass filter 15 in order and is input to the CPU 16 and also detected by the origin detection sensor 5. Signal is also input to the CPU 16 at the same time.

In the CPU 16, the origin detection sensor 5
The rotational frequency of the grinding wheel G is determined by measuring the pulse cycle of the origin position signal from the control signal to the band pass filter 15 so that only the band of the center frequency corresponding to the rotational frequency is passed. Output.

Further, the AE signal subjected to the envelope detection processing is input to the CPU 16 via the band pass filter 15, and the magnitude of the vibration of the grinding wheel G is determined from the detection signal, and the origin detection sensor 5 detects the vibration. The phase position at which the vibration is maximized is determined by comparing with the origin position signal of. That is, the CPU 16 functions as a determination unit that determines the vibration of the grinding wheel G that is a rotating body.

As a result, the magnitude of the vibration and the position of the imbalance are displayed on the display unit 17, and the balance state of the grinding wheel G can be known.

FIG. 9 is an explanatory view showing still another embodiment of the present invention. In this embodiment, the vibration in the turning process is detected.

In FIG. 9, the acoustic emission emitted at the processing point is detected by the AE sensor 1 mounted on the side of the tool rest 10 during the turning of the workpiece W rotated by the tip T mounted on the tool rest 10. To be done.

By finally processing the acoustic emission detected by the AE sensor 1 by the signal processing device 3 in the same manner as in the procedure shown in FIG. 2, a frequency spectrum is finally obtained.

If chatter vibration occurs during turning, a remarkable peak appears in this frequency spectrum, and the vibration can be determined by this.

[0044]

As described above, according to the vibration detecting method for a rotating body according to the first aspect of the present invention, the rotating body such as the grinding wheel or the workpiece in the machining such as the grinding or the turning is processed. The acoustic emission generated is detected by the AE sensor, the detected signal is envelope-detected by the rectifier circuit, and the vibration of the rotating body is detected from the envelope-detected signal. Since the vibration generated in the body is detected, it is not necessary to use the acceleration sensor for detecting the vibration, and the AE sensor used for detecting the contact of the rotating body is also used for the vibration detection at the same time. Therefore, there is an excellent effect that the structure for detecting the vibration generated in the rotating body can be simplified.

According to the second aspect of the present invention,
For example, when the amount of unbalance of rotation of the grinding wheel, which is a rotating body, is large, a peak appears in the frequency component corresponding to the number of revolutions of the grinding wheel in the frequency analysis result, and the peak (amplitude) causes an unbalance. The effect is that the size of the quantity can be determined.

According to the third aspect of the present invention,
For example, in addition to the forced vibration generated due to the unbalance of the grinding wheel, it is possible to detect vibrations such as self-excited vibration and chatter vibration that occur while grinding the work piece with the grinding wheel. The life of the grinding wheel can be judged based on the detected vibration frequency and vibration level vibration amplitude.

According to the vibration detecting device for a rotating body of claim 4 of the present invention, by virtue of the above structure,
The effect that it becomes suitable for implementing the method of ~ 3 is brought about.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing an embodiment of the present invention.

FIG. 2 is an explanatory diagram showing a configuration of a signal processing device in FIG.

FIG. 3 is an explanatory diagram showing an example of a result of frequency analysis of an AE signal.

FIG. 4 is an explanatory diagram showing another example of the result of frequency analysis of the AE signal.

FIG. 5 is an explanatory diagram showing a flowchart of the present invention.

FIG. 6 is an explanatory diagram showing a flowchart of the present invention.

FIG. 7 is an explanatory diagram showing another embodiment of the present invention.

8 is an explanatory diagram showing a configuration of a signal processing device in FIG.

FIG. 9 is an explanatory diagram showing still another embodiment of the present invention.

FIG. 10 is an explanatory diagram showing an example of conventional vibration detection of a rotating body.

11 is an explanatory diagram showing a configuration of a signal processing device in FIG.

[Explanation of symbols]

 1 AE sensor 2 Coolant supply nozzle 3 Signal processing device 5 Origin detection sensor 10 Turret 11 Preamplifier 12 High-pass filter 13 Rectifier circuit 14 Frequency analyzer 15 Band-pass filter 16 CPU 17 Display 20 Cover 21 Table 31 Column 32 Grindstone G Grinding Whetstone W Work C Coolant T Tip

Claims (4)

[Claims] 1. An acoustic emission generated from a rotating body such as a grinding wheel or a workpiece in machining such as grinding or turning is detected by an AE sensor, and the detected signal is envelope-detected by a rectifier circuit, A vibration detecting method for a rotating body, which comprises detecting the vibration of the rotating body from the signal subjected to the envelope detection. 2. A balance state of the rotor is determined by frequency-analyzing the signal after the envelope detection, and determining the balance state of the rotor from the amplitude of the vibration frequency component corresponding to the rotation speed of the rotor in the frequency analysis result. Item 1. A vibration detection method for a rotating body according to item 1. 3. An acoustic emission generated in the vicinity of a contact point between a machining tool and a workpiece during machining is detected by an AE sensor, and a vibration frequency and a vibration level of abnormal vibration generated by the contact between the machining tool and the workpiece are detected. The method for detecting vibration of a rotating body according to claim 1, wherein. 4. An apparatus used for detecting vibration of a rotating body by the method according to claim 1, comprising an AE sensor for detecting acoustic emission generated from the rotating body, and the AE sensor. A vibration detecting device for a rotating body, comprising: a rectifying circuit that envelope-detects the signal of 1. and a determining unit that determines the vibration of the rotating body based on an output from the rectifying circuit.