JPH08164403A - Method for detecting defective supply of lubricant in single cross mill - Google Patents

Abstract

PURPOSE: To prevent excessive thrust force from occurring at the time of the defective supply of lubricating oil which is supplied between a work roll and a back-up roll by attaching detaching sensors and detecting the vibration level of a rolling mill. CONSTITUTION: The housing 1 of a rolling stand is provided with an acceleration sensor 9, an AE (elastic wave) sensor and a sensor for detecting the level of velocity change, variation of velocity at the time of changing the cross angle of the work rolls 2, 6 from 0 deg. to 1 deg. is measured and it is verified that the velocity variation is in a linear relationship to the thrust force. Then, by setting a threshold value in the vibration level and monitoring the value, the excessive thrust force generated due to the defective supply of the lubricating oil is detected. By monitoring the frequency band where the output on a strong level is generated as detecting method by frequency, the defective supply of the lubricating oil is detected.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a roll-cross type hot rolling mill capable of meeting the needs of various sheet crown materials, and more particularly, upper and lower backup rolls are kept in parallel and the work roll axis line is a backup roll. The present invention relates to a method for detecting a supply failure of a lubricant supplied between a work roll and a backup roll in a single cross mill of a type that crosses the axis line.

[0002]

2. Description of the Related Art As a roll-cross type rolling mill that has been put to practical use in hot rolling, Mitsubishi Heavy Industries Vol.
21, No. 6 (1984), pp. 61-67, the roll set of the pair of upper work roll and upper backup roll and the roll set of the pair of lower work roll and lower backup roll are integrated respectively, and A pair-cross type rolling machine is known in which pair rolls are crossed with each other. According to this rolling mill, the work rolls and the backup rolls that make up the pair of upper and lower roll sets do not cross each other, so relative slippage does not occur between the two rolls, and a large thrust force does not occur, but the pair members do not Since they are crossed, the center of the metal chock of the backup roll that directly receives the rolling load deviates from the center of the screw down screw, which causes a moment, which hinders smooth operation of down rolling. In order to deal with this problem, a structure in which a beam with high rigidity is provided to balance the beam is adopted, but it is inevitable that the rolling mill becomes large or complicated.

As a roll-cross type rolling mill, a single-cross type rolling mill has also been proposed, in which the upper and lower backup rolls are kept in parallel and the work roll axis line crosses the backup roll axis line. The single cross type rolling mill has the advantages that the above problems do not occur, the structure is simplified, and the rolling mill can be downsized, and the thrust force generated between the work roll and the backup roll is It can be reduced relatively easily by supplying the lubricant to the.

[0004]

In a single cross mill in which only work rolls are crossed, a stable supply of lubricant is the most important factor in reducing thrust force. When crossed, although depending on the cross angle, a thrust force reaching about 30% of the rolling load is generated, and there is a sufficient risk of equipment damage and operation stoppage.

As a method of reducing the thrust force generated when the lubricant supply fails, the thrust force of the backup roll is detected by the load cell provided in the backup roll chock, and the detected thrust force exceeds the set threshold value. At this time, attempts have been made to make the cross angle between the work roll and the backup roll 0 °. However, if the load cell fails, the load cell cannot be repaired unless the backup roll is removed, which is a maintenance problem.

The present invention does not cause the problems as in the above method, allows the detector to be easily replaced without stopping the entire mill even when the detector fails, and facilitates maintenance of the detector. It is an object of the present invention to provide a method for detecting a lubricant supply failure.

[0007]

Therefore, in the first invention, a detection sensor is attached to a rolling mill in a single cross mill including a pair of vertically parallel backup rolls and a pair of work rolls whose axes cross the backup rolls. , The excessive thrust force generated when the lubricant supplied between the work roll and the backup roll is improperly supplied,
It is intended to detect the vibration of the rolling mill.
The invention of claim 1 is intended to detect the supply failure of the lubricant by monitoring the frequency generated due to the supply failure of the lubricant with the detection sensor attached to the rolling mill.
That is, the supply failure of the lubricant is detected by the level of the vibration caused by the thrust force generation in the first invention, and the thrust force is not managed in the second invention, but the lubricant generation is performed by the generated frequency. It is intended to detect the supply failure state itself. The rolling mill referred to in the present invention includes a rolling stand, rolls, chocks and the like. The detection sensor used in the present invention is required to be a sensor capable of performing the above-mentioned detection in a hot and humid environment such as in hot rolling. The sensor for detecting the vibration level of the first invention is a sensor for detecting acceleration, velocity, displacement and AE (Accoustic Emission), and the sensor for detecting the frequency of the second invention is an acceleration sensor. To be done. The verification of the method of detecting the supply failure of the lubricant using these sensors was performed. The results are detailed below.

[0008]

The work side of the rolling stand (hereinafter referred to as "W
"S") near the backup roll keeper plate (hereinafter referred to as the housing keeper), WS mill top, drive side (hereinafter "D")
"S") and the WS backup roll chock are each equipped with an acceleration sensor, and the work roll of the cross mill has a cross angle of 0 ° to 1
The magnitude of acceleration when shaken was measured. Then, the thrust force of the WS backup roll at that time was measured by the load cell provided in the chock, and both measured values were compared. As shown in FIG. 2, there is a linear relationship between the two fixed values. Found.

Further, sensors for detecting the speed change level are attached to the vicinity of the WS housing keeper of the rolling stand and the WS backup roll chock, respectively, and the work roll of the single cross mill is cross angle 0 ° to 1 ° in the same manner as described above. The change in speed when shaken was measured and compared with the measured value of the load cell. As a result, they found that the two measured values have a linear relationship.

Furthermore, the housing of the rolling stand has an A
The E sensor was attached and AE (elastic wave) measurement was performed.
As a result, as shown in FIG. 3, it was found that there is a linear relationship with the load cell measurement value. As described above, it was verified that the vibration acceleration, velocity, and AE level have a linear relationship with the thrust force, instead of the load cell measurement. Therefore, by setting a threshold value for the vibration level and monitoring the threshold value, it becomes possible to detect the excessive thrust force generated due to the insufficient supply of the lubricant. On the other hand, with regard to the latter frequency detection method, the frequency that occurs due to poor supply of lubricant is found, so periodic repair is underway (because it is difficult to operate without supplying lubricant in the actual machine).
In the kiss roll state, that is, when the backup roll and the work roll are crossed and the rolling is applied, the vibration of the rolling mill when the lubricant is not supplied and when it is supplied is collected by the acceleration sensor installed near the housing keeper. , And the generated frequencies were compared.
As a result, it was found that a strong level of output was generated in a specific frequency band when the lubricant was not supplied, and it was verified that the lubricant supply failure can be detected by monitoring this frequency band. Detection of a lubricant supply failure by monitoring a specific frequency band can be performed by using a device as shown in FIG. According to this device,
After the vibration of the rolling mill collected by the acceleration sensor is amplified by the amplifier, it is passed through the bandpass filter (BPF) that passes only the frequency in the specified range and exceeds the threshold set in the process computer (PC). It is designed to output the output.

BEST MODE FOR CARRYING OUT THE INVENTION W of the quadruple hot rolling mill shown in FIG.
Accelerometers 9 are installed in the vicinity 5 and 5'of the S housing keeper and the backup roll chock 10 of the WS
Was adhered, and the cross angle of the work roll was swung from 0 ° to 1 °, and the acceleration in each part was measured. The results are shown in Figure 2. FIG. 3 shows the results of AE measurement by attaching the AE sensor to the housing of the rolling stand and swinging the work roll angle from 0 ° to 1 °. Next, the cross angle of the work roll was set to 1 ° in the kiss roll state during regular repair, and the vibration frequency obtained from the acceleration sensor 9 was detected for each of the case where the lubricant was supplied and the case where the lubricant was not supplied. 4 and 5 show the results,
Comparing the two, it was found that the frequency band of 55 to 75 Hz was strongly generated when the lubricant of FIG. 5 was not supplied. The frequency generated due to the insufficient supply of the lubricant is 55 to 75 Hz in the above-mentioned example, but it is considered that it varies depending on the size and shape of the rolling mill. Figure 6
Shows the result of frequency analysis of the mill vibration when the supply failure of the lubricant occurs in the single cross mill in the actual machine operation in which the cross angle of the work roll is set to 1 °, and can be seen from the same figure. As described above, it was found that the frequency band of 55 to 75 Hz found in the kiss roll state of FIG. FIG. 8 shows the output obtained through the BPF that passes only the frequency band of 55 to 75 Hz using the device shown in FIG. 7 for the above-mentioned mill vibration. Lubrication by monitoring the output level of the BPF from the same figure. It was confirmed that defective supply of the agent could be detected.

[0012]

As described above, the detection method of the present invention monitors the supply failure of the lubricant supplied between the work roll and the backup roll in the single cross mill and the level of vibration caused by the thrust force generation. By doing
Alternatively, the detection is performed by monitoring the frequency generated due to the defective supply of the lubricant, and it is possible to prevent the excessive thrust force generated due to the defective supply of the lubricant from occurring. Further, unlike the load cell provided in the roll chock, maintenance of the detection sensor is easy.

[Brief description of drawings]

FIG. 1 is a diagram showing a mounting position of an acceleration sensor of a single cross mill.

[Fig. 2] Crossing angle from 0 ° to 1 ° in a poor lubrication state
→ The figure which shows the transition of acceleration and thrust force when changing to 0 °.

FIG. 3 is a diagram showing AE waves detected by an AE sensor.

FIG. 4 is a diagram showing frequencies generated when a lubricant is not supplied in a kiss roll test.

FIG. 5 is a diagram showing frequencies generated when a lubricant is supplied in a kiss roll test.

FIG. 6 is a view showing a result of frequency analysis of mill vibration when a lubricant supply failure occurs during operation.

FIG. 7 is a block diagram of a detection system.

FIG. 8: BP when lubricant supply failure occurs during operation
The figure which shows F output.

[Explanation of symbols]

1 ・ ・ Housing 2 ・ ・ Upper work roll 3 ・ ・ Upper backup roll 4 ・ ・ Backup keeper plate 5, 5 ', 8, 8' ・ Near housing keeper 6 ・ ・ Lower work roll ． 7 ... Lower backup roll 9 ... Accelerometer 10 ... Backup roll chock

Claims (7)

[Claims] 1. A single cross mill comprising a pair of up and down backup rolls and a pair of work rolls whose axes intersect the backup rolls,
A lubricant supply failure characterized by mounting a detection sensor on the rolling mill and detecting excessive thrust force generated when the lubricant supplied between the work roll and the backup roll is not supplied properly based on the vibration level of the rolling mill. Detection method. 2. The supply failure of the lubricant is detected by monitoring a frequency generated due to the supply failure by a detection sensor attached to the rolling mill.
A method for detecting a lubricant supply failure as described. 3. A state in which a backup roll and a work roll are crossed and a rolling force is applied to rotate the roll,
The method for detecting a defective supply of lubricating oil according to claim 2, wherein the frequency generated due to the defective supply of the lubricant is found by comparing the generated frequencies depending on the presence or absence of the lubricant. 4. A method for monitoring a frequency generated due to a defective lubricant, comprising using a bandpass filter that allows only a frequency within a designated range to be monitored, and monitoring the output level of the bandpass filter. Item 3. A method for detecting defective lubricant supply according to Item 2. 5. The method for detecting defective lubricant supply according to claim 1, wherein the detection sensor is an acceleration sensor. 6. The method for detecting defective lubricant supply according to claim 1, wherein the detection sensor is a speed sensor. 7. The method of detecting a lubricant supply failure according to claim 1, wherein the detection sensor is an AE sensor.