JPH0911084A - Chatter detecting method for roll grinder - Google Patents

Abstract

PURPOSE: To reduce a roll mark caused by a chattering mark of a rolling roll by determining the occurrence of a chatter when the level of a component of a specified frequency band exceeds a threshold value. CONSTITUTION: The vibration level of every subdivided frequency band is computed by a frequency analyzing computing unit 7. The values of the vibration levels of the plural frequency bands are sent to a secondary converter 8 to extract the vibration level of the frequency band concerning a chatter previously set in the secondary converter 8 by a frequency setting device 9. The value of the vibration level is sent to a chatter determining device 10 to be compared with a threshold previously set by a threshold setting device 11. When the vibration level exceeds the threshold, the occurrence of a chatter is determined, and the signal of the determination result is sent to a warning buzzer 12 to give a warning.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a chattering of a roll grinder for detecting occurrence of chattering marks on the surface of a rolling roll when a rolling roll for rolling a metal material such as steel is ground by the roll grinder. Regarding detection method.

[0002]

2. Description of the Related Art When a high-precision ultra-thin steel material is rolled by a rolling roll, a roll mark sometimes affecting the quality of the product may be attached to the surface of the steel material. This roll mark does not become a flaw to the extent that it affects the quality of the product when rolling a relatively thick steel material that has been conventionally rolled, and in particular measures to prevent its occurrence are implemented. It didn't come.

However, in a high-precision ultra-thin steel material, such a roll mark becomes a serious surface defect in terms of quality. Therefore, it is desired to establish a method for preventing the roll mark from occurring.

The above-mentioned roll mark is a fine chatter mark formed on the surface of the rolling roll and transferred to the surface of the rolled steel material. If the roll mark is prevented from occurring, the roll mark is also formed. It is thought to disappear.

The chatter mark generated on the surface of the rolling roll is considered to have been formed during the grinding of the rolling roll. Therefore, if it is possible to detect under what kind of grinding conditions the chatter mark occurs, the chatter mark will naturally occur. It can be prevented.

As a conventional technique for detecting a grinding (cutting) abnormality such as the occurrence of chatter marks, Japanese Patent Laid-Open No. 63-188 is known.
There is a technique disclosed in Japanese Patent No. 735. In this technique, when a cylindrical sample for component analysis is sampled online from a cast piece by a cutting method, when chattering occurs in the cutting portion, the cutting condition is changed and the sample is continuously cut. The method is to measure and analyze the vibration of the cutting device system during cutting in advance, obtain the causal relationship between the sample ring cutting conditions and the vibration, and always detect the vibration of the cutting device system with a vibration sensor to obtain the obtained vibration. The sample ring cutting condition is dynamically controlled according to the above.

[0007]

However, the chattering detection method during cutting disclosed in the above-mentioned Japanese Patent Laid-Open No. 63-188735 has the following problems. That is, in this method, the average value of the vibration level over a wide frequency band is constantly grasped, and when the average value of the vibration level becomes a certain value or more, chatter is generated, and the cutting condition If the amount of chattering is extremely large, it is possible to detect the occurrence of chattering by such a method. There is a problem in that mild chattering that causes roll marks, which is a problem during rolling of thin steel materials, cannot be detected.

The present invention has been made in order to solve the above-mentioned problems of the prior art, and has a low level of chattering which causes a problematic roll mark during rolling of high precision ultra-thin steel material. It is an object of the present invention to provide a chattering detection method for a roll grinder that can detect it.

[0009]

According to a first aspect of the present invention, there is provided a roll grinder chattering detection method, wherein a level of a component of a specific frequency band in a vibration signal of a roll bearing of a roll grinder exceeds a threshold value. It is characterized in that it is determined that chattering has occurred. It should be noted that the specific frequency band may be one or a plurality, and when a plurality is provided, when the level of the component of any one of the specific frequency bands exceeds a threshold value, or all of them are threshold. When the value is exceeded, it is determined that chattering has occurred. When a plurality of specific frequency bands are provided, the threshold value may be provided for each specific frequency band. As a more specific form of the invention, a vibration signal from a vibration sensor attached to a roll bearing portion of a roll grinder is input to a frequency analyzer, the vibration level of each frequency band is analyzed by the frequency analyzer, and the vibration A method of inputting the vibration level of a specific vibration band to the chattering determiner and comparing it with a threshold value set in advance to this chattering determiner and determining that chattering has occurred when the vibration level exceeds the threshold value is a method. Conceivable.

A roll grinder chattering detection method according to a second aspect of the present invention is the roll grinder chattering detection method, wherein vibration is generated when chattering is intentionally generated in the roll grinder in setting a specific frequency band and a threshold value. The frequency distribution is compared with the vibration frequency distribution when no chattering occurs, and the frequency band where the vibration level changes by a certain value or more is set as the specific frequency band, and the vibration level when chattering occurs in that frequency band. The threshold value is set based on

[0011]

In the roll grinder chattering detection method according to the present invention, the reason for paying attention to the vibration level in the specific frequency band from the vibration signals of the roll bearing portion of the roll grinder is as follows. That is, by making a cut above the standard in the roll being ground with a roll grinder, a vibration signal from a vibration sensor provided in the roll bearing portion obtained when chatter is intentionally generated,
When comparing the vibration signal obtained when the chattering is not intentionally generated with the average vibration level of a wide frequency band as in the conventional case, the average vibration level hardly changes. It has proved impossible to detect the cause of chattering.

However, when the vibration frequency waveform is analyzed by the frequency analyzer, the vibration level for each constant frequency band is grasped, and the vibration levels are compared for each same frequency band, it is found that in a specific frequency band, It was found that the vibration level after chattering was significantly higher than the vibration level when chattering did not occur.

That is, comparing the vibration frequency waveform in the case where chattering is not generated as shown in FIG. 2A and the vibration frequency waveform in which chattering is generated as shown in FIG. It can be seen that there is no significant change in the vibration level, but in the frequency band near 175 Hz, it changes enough to be discriminated.

Therefore, if it is always detected in this frequency band whether or not the vibration level reaches the level indicated by the square marks in FIGS. 2 (a) and 2 (b), for example,
It is possible to reliably know that chattering has occurred.

On the contrary, like the vibration frequency waveform shown in FIG. 2 (c), the vibration level in the frequency band unrelated to the occurrence of chattering becomes high, and compared with the vibration frequency waveform of FIG. 2 (a). In some cases, the overall vibration level becomes high, but as is clear from this example, it cannot be determined that chattering has occurred even if the overall vibration level becomes high.

That is, in order to grasp the occurrence of chattering that causes the roll mark, which is the object of the present invention,
It is necessary to detect the vibration level in a specific frequency band.

As a method of setting the allowable vibration level in a specific frequency band relating to chattering, chattering is intentionally generated by changing the degree of chattering, and the vibration level at that time and the degree of chatter mark on the roll surface generated. It may be determined from the relationship with.

It is considered that the specific frequency band relating to chattering is determined by the natural vibration of the grinding machine system including the rolls.
The frequency bands are the same, and the specific frequency band is not set every time grinding is performed.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A chattering detection method for a roll grinder according to an embodiment of the present invention will be described with reference to FIG. FIG. 1 is a block diagram showing a procedure for implementing this chattering detection method.

In this chattering detection method, vibration is detected by the charge type acceleration sensor 4 attached to the bearing portion 3 of the roll 2 of the roll grinder 1, and the vibration signal obtained by converting the vibration into electric charge by the charge type acceleration sensor 4 is used. ,
The vibration signal converted into the voltage through the charge-voltage converter 5 is converted into the vibration signal, which is amplified by the amplifier 6 and then input to the frequency analysis calculator 7.

Then, the frequency analysis calculator 7 calculates the vibration level for each subdivided frequency band. The vibration level values in the plurality of frequency bands are sent to the secondary converter 8, and the vibration level in the frequency band relating to chattering which is preset in the secondary converter 8 by the frequency setting unit 9 is extracted.

Then, the value of this vibration level is sent to the chattering judging device 10 and compared with the threshold value set in advance by the threshold value setting device 11. When the vibration level exceeds the threshold value, it is determined that chattering has occurred, and a signal is sent to the alarm buzzer 12 to issue an alarm. Therefore, it is possible to change the cutting conditions based on this alarm and eliminate chattering.

Further, based on this signal, the waveform output device 1
By 3, the vibration frequency waveform at that time can be plotted by a plotter.

Further, based on the same signal, the waveform display 1
4, the vibration frequency waveform at that time can be displayed on the CRT.

Further, the waveform output device 13 and the waveform display device 1
4 can output or display the vibration waveform analyzed by the frequency analysis calculator 7 regardless of occurrence of chattering. Therefore, an appropriate threshold value for chattering can be set based on the information on chattering artificially generated by the waveform output device 13 and the waveform display device 14 and the information at the normal time.

The width of the specific frequency band relating to chattering is ± 2 to 3 Hz from the result of the investigation, and it is possible to clearly distinguish it from the vibration caused by factors other than chattering.

FIG. 2 is a graph showing the vibration waveform of the roll grinder. FIG. 2A shows a vibration waveform when chattering does not occur.

FIG. 2B shows a vibration waveform when chattering occurs. The roll grinding conditions at this time are as follows: the diameter of the grindstone of the roll grinder is 600 mm and the rotational speed of the grindstone is 580 rp.
m, the diameter of the work roll to be ground is 70 mm, the rotation number is 35 to 40 rpm for rough grinding, 45 rpm for intermediate finishing, and 50 to 55 rpm for finishing. 2B shows the vibration level of the entire frequency band, the vibration level of 175 Hz in FIG. 2A is as large as 1.5 V, and 175 Hz is the frequency due to chattering. Can be recognized. Then, this frequency substantially matches the natural frequency of the roll to be ground.

Therefore, the setting of the specific frequency band and the threshold for chattering in the present invention can be easily determined by looking at the spectrum display in all frequency bands. It is also possible to calculate the natural frequency of the roll to be ground and hit it.

FIG. 2C shows the case where chattering does not occur and the overall vibration level rises. In this case, there is no change in the vibration level at 175 Hz, and the whole frequency band is simply changed. It can be seen that it is impossible to detect the occurrence of chattering due to the fluctuation of the average vibration level of.

[0031]

According to the present invention, chattering generated during grinding of a rolling roll can be accurately detected, and chattering can be eliminated by changing grinding conditions. It is possible to reduce the roll mark caused by the chatter mark of the rolling roll.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an implementation procedure of a roll grinder chattering detection method according to an embodiment of the present invention.

FIG. 2 is a graph showing a vibration waveform of a roll grinder, where (a) shows the case where chattering does not occur, (b) shows the case where chattering occurs, and (c) shows the case where there is no chattering and the overall vibration level. Shows the case where is increased.

[Explanation of symbols]

 1 roll grinder 2 roll 3 bearing part 4 charge type acceleration sensor 5 charge-voltage converter 6 amplification amplifier 7 frequency analysis calculator 8 secondary converter 9 frequency setting device 10 chatter judgment device 11 threshold setting device 12 alarm buzzer 13 Waveform output device 14 Waveform display device

Claims (2)

[Claims] 1. A roll grinder chattering detection is characterized in that when a level of a component in a specific frequency band of a vibration signal of a roll bearing portion of the roll grinder exceeds a threshold value, chattering is determined to have occurred. Method. 2. The chattering detection method for a roll grinder according to claim 1, wherein when setting a specific frequency band and a threshold value, a chattering is generated in a vibration frequency distribution when chattering is intentionally generated in the roll grinder. Compared with the vibration frequency distribution when not being set, set the frequency band where the vibration level changes by a certain value or more as a specific frequency band, and set the threshold value based on the vibration level when chattering occurs in that frequency band. A roll grinder chattering detection method characterized by setting.