KR19980053189A - How to detect hot rolling mill chatter - Google Patents

Abstract

The present invention is a method for detecting hot rolling mill chatter (Chatter) generation, the vibration frequency (f _fn ) generated in the work roll (1) of hot rolling mill hot rolling mill with a vibration acceleration sensor (1 ') installed in the stand frame (3) ) the detection and vibration frequency with respect to a frequency (f _on) calculating a driving speed of the rotation frequency (f _fn) for analysis _{(f fn / f on) /} n chattering of the mill when in the 0.8 to 1.2 range Since it is determined that the occurrence of chatter is notified to the operator by an alarm on the monitor, there is an advantage to improve the chatter prevention measures, stabilization of operation, thickness quality and error rate.

Description

How to detect hot rolling mill chatter

The present invention relates to a method for detecting a chatter (Chatter) generated in the finishing mill, and in particular, whether the chattering occurs in the rolling mill by detecting and analyzing the vibration generated in the work roll of the finishing mill of the hot rolling mill in the stand frame (Stand Frame) The present invention relates to a method for detecting a hot mapping mill chatter (Chatter) occurrence, which checks and alerts the operator of a chatter occurrence by a monitor alarm.

As shown in FIG. 1, the finishing rolling process of the hot rolling mill produces a final hot rolled coil (COIL) through a mill (MILL) of multiple stages (usually 6 to 7 stages). In consideration of the quality and productivity of the final product, the rolling amount to be rolled down between each stand is decided. Usually, the rolling pressure is reduced from F1 (FINISHING MILL NO1) to F3, and from F4 to F6, Work with a small reduction in temperature considering the temperature. At this time, there is a case where a certain interval of band appears in rolling direction at right angle on the strip that is being rolled at the end of F2 or F3 that has a large amount of rolling down. This is called Chatter Mark, and this band is due to the thickness variation of the rolled plate. It is the cause of poor quality in the final product. In addition, roughness bands are formed at regular intervals on the circumferential surface of the work roll in which the chatter occurs during work, which shortens the service life of the work roll. Due to the shortening of the service life of the work roll, it is inevitable to perform frequent roll change work, which causes a decrease in productivity. The generated vibration is transmitted to the stand housing, which causes various electrical appliances or mechanical parts installed on the stand, which can directly shorten the life of the equipment and cause equipment failure. In the long run, spindle gear teeth, roll drive systems, wear out and roll bearings deteriorate, leading to excessive maintenance costs and adversely affecting equipment life. Vibration acceleration sensor (2) in the work roll support bearing portion supporting the work roll (1) of the rolling mill as shown in Figure 2 to monitor and analyze the vibration phenomenon that appears when the chatter (CHATTER) occurs in the finishing mill Has been temporarily fixed and simple diagnostic equipment has been used to make measurements. In particular, the finishing mill replaces the work roll (1) for 10 to 15 minutes at intervals of 3 to 5 hours every time. The new work roll after removing the acceleration sensor (2) temporarily fixed to the work roll support bearing part (1) The work was cumbersome because it had to be reattached to the support bearing. In addition, since the mounting position of the acceleration sensor 2 is the support bearing part of the work roll 1, it is in direct contact with the cooling water used in the rolling mill, which makes it difficult to protect the sensor. In addition, since the vibration of the chatter that is to be measured and monitored does not occur at all times, it is difficult to match the vibration generation conditions to be measured and monitored, which leads to a lot of unnecessary waiting time and the lack of accurate chatter judgment. No prediction of outbreak was possible.

The present invention has been invented to solve the problems of the conventional hot rolling mill chatter generation detection method in view of the above-described setting, and the characteristics of the rolling mill vibration such as driving system vibration, rolling mechanism vibration, etc. generated in the work roll during driving of the hot rolling mill in the hot factory Hot rolling mill that can contribute to the improvement of equipment life by preventing the product quality defect and predicting the failure deterioration of the drive system by predicting the occurrence of chattering in advance by detecting and analyzing it in the stand frame. Its purpose is to provide a chatter generation detection method.

1 is a configuration of the finishing mill system,

2 is an installation position of the vibration sensor,

3 is a vibration generating principle in the rolling mill,

(A) shows the load, vibration and frictional force during rolling,

(B) shows the ORBIT of the upper work roll,

(C) is an explanatory diagram of vibration noise generation form.

4 is an explanatory diagram of a chatter occurrence phenomenon;

5 is a correlation analysis graph of the work roll support bearing part vibration and the stand vibration,

(A) is the result of stand vibration acceleration frequency analysis,

(B) is a graph showing the stand vibration acceleration according to the work roll vibration acceleration,

(D) is the result of vibration analysis of work roll vibration acceleration frequency.

6 and 7 are flowcharts illustrating the chatter generation detection method of the present invention.

* Description of the symbols for the main parts of the drawings *

1: work roll 2, 2 ': vibration acceleration sensor

3: stand frame (roller housing) 4: backup roll

The hot mapping mill chatter generation monitoring method of the present invention for achieving the above object is a vibration acceleration sensor (1 ') installed in the stand frame (3) vibration frequency generated in the work roll (1) of the hot rolling mill hot rolling mill ( detecting the f _fn), and the rolling mill when the operation speed by rotating analyze the oscillation frequency (f _fn) for a frequency (f _on) calculated at the frequency _{(f fn / f on) /} n is in the 0.8 to 1.2 range It is characterized by determining that the chattering occurs by alerting the operator to the monitor.

Hereinafter, the hot mapping mill chatter generation detection method of the present invention will be described in detail with reference to the accompanying drawings.

As shown in FIG. 1, the hot finishing mill stands are comprised of 6-7 pieces. Among them, the stand that vibrates badly is Stand No. 2 (F2 Stand) and Stand No. 3 (F3 Stand), and chattering (Cattering) is the vibration phenomenon between the roll and the material during the work in the rolling mill. Say. Typically, the frequency generated is a lot of generation during continuous continuous rolling of the museum from tens of Hz to several hundred Hz. In general, it is proportional to the rolling speed, rolling amount, and rolling force, and there are differences depending on the emulsification characteristics, lubricity, and material of the roll used during rolling. As shown in FIGS. 3 and 4, when the chattering occurs, the rotation of the rolling roll is irregular and a temporary stop occurs due to the spindle elastic deformation caused by excessive rolling torque. A temperature drop occurs to form a band. When the chattering occurs, a large noise is generated by the rolling friction characteristics, and it is accompanied by vibration characteristics peculiar to the rolling mill.

If there is a vibration generating factor mechanically or by rolling conditions in the rolling mill, as shown in FIG. As the vibration gradually increases, a band-shaped mark is generated in the coil in operation, and when this phenomenon is continuously repeated, a mark is generated in the work roll. When the vibration occurs, the vibration generated from the work roll is transmitted in the order of work roll → work roll support bearing → work roll fixing device → stand frame (STAND FRAME) and monitors chatter vibration by finding the characteristics of the transmitted vibration.

Frequency analysis of the vibration measured by installing the vibration acceleration sensor at the center of the work roll support bearing part and the stand frame cab side up and down direction, but the size of the vibration component was reduced as shown in FIG. The intrinsic vibration component generated at the time of occurrence is measured on the stand to determine the chatter vibration occurrence, and it can be seen that the vibration magnitude is proportional to the vibration analysis result of the roll support bearing portion of FIG. 5 and the stand. The measurement site was selected as the part where vibration transmission of the stand was large, not the work roll support bearing.

The vibration of the work roll 1 is transmitted to the stand housing 3 via the roll supporting bearing. The vibration sensor 2 'is installed at the center of the housing 3 where roll vibration is best transmitted and connected to a monitor capable of collecting vibration data. Measure the vibration when the data acquisition condition signal occurs In general, since the rolling time of one coil is at least one minute, five or more measurements are performed per coil, and the largest value among them is the vibration data of the coil. Vibration value display shows signal of about 1㎑ at 2Hz as vibration acceleration single amplitude. If the vibration acceleration deviation amplitude is over the set level (LEVEL), frequency analysis is automatically performed, and an alarm is generated when a chatter is anticipated. Frequency when the mill unique vibration frequency of the analyzed data as in Figure 5 occurs by chattering (CHATTERING) indication to establish a countermeasure, and chattering (CHATTERING) signs frequency {32f _o ~ 40f _o, as judged by a) _n (F _o : roll rotation frequency, n: 1,2,3, ...).

Conventionally, the vibration acceleration sensor 2 is installed in the bearing portion of the work roll 1, whereas in the present invention, the vibration acceleration sensor 2 '(ACCELEROMETER) is installed in the housing 3; As shown, the vibration acceleration signal is amplified and measured at the LOCAL STATION according to the instruction sent from the MONITORING computer based on the load cell signal indicating the rolling force of the mill stand. Create (DATA) and send the result to the monitoring computer. When the vibration value exceeds the specified level (LEVEL) during the measurement of the vibration signal in the local station, the frequency analysis is automatically performed and the result is transmitted to the MONITORING computer.

In this way, the vibration frequency f _fn generated in the work roll 1 is detected, and the vibration frequency f _fn is analyzed with respect to the frequency f _on which the operation speed is calculated as the rotation frequency (f _fn / f). _{When on} ) / n is in the range of 0.8 ~ 1.2, it is judged as a vibration phenomenon, that is, chattering phenomenon, and it is recognized by MONITORING computer and the driver of the finishing mill is notified of the chatter vibration phenomenon.

As described above, according to the present invention, it is possible to establish an optimal operation pattern (PATTERN) by realizing the quantification of the vibration generation size for each operating condition, thereby improving the establishment of chatter prevention measures, stabilization of operation, thickness quality and error rate.

Claims (1)

The vibration frequency f _fn generated by the work roll 1 of the hot rolling mill of the hot rolling mill is detected by the vibration acceleration sensor 1 'installed on the stand frame 3, and the operating speed is calculated as the rotation frequency ( By analyzing the vibration frequency (f _fn ) with respect to f _on ), when (f _fn / f _on ) / n is in the range of 0.8 ~ 1.2, it is judged as chattering of rolling mill and the chatter occurrence is alerted to the operator on the monitor. The hot mapping mill chatter (Chatter) generation detection method characterized in that the notification.