JPH0938707A - Method for correcting oil film thickness of roll bearing of rolling mill - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the precision of a plate thickness at the outlet side of a rolling mill and to improve the quality of a product by correcting an oil film thickness under consideration of an upper and a lower backup roll diameter, the number of revolutions of the backup rolls measured just after rolling and the temporary variation of the oil film thickness at the time of starting acceleration and deceleration. SOLUTION: In the correction of the oil film of a bearing in the backup roll for estimating the plate thickness with the rolling mill until the temp. of lubricant for the bearing just after rolling is lowered, the oil film thickness of the bearing for the backup roll is measured as function of an average number of the revolutions and a loading obtd. from the average value of the upper and the lower backup roll diameter. Further, the number of revolutions is obtd. from the average of repeating from the low speed to the high speed and from the high speed to the low speed. Then, the precision of the plate thickness at the outlet side of the rolling mill becomes extremely good by correcting the calculated plate thickness based on the measured value of both cases, and the quality of the product can be improved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rolling bearing oil film thickness correction method for a rolling mill.

[0002]

2. Description of the Related Art Conventionally, when the oil film thickness of a backup roll oil film bearing in a rolling mill changes, it affects the plate thickness accuracy on the delivery side of the rolling mill. Therefore, various studies have been made to correct the oil film thickness change. However, as a means thereof, for example, as disclosed in Japanese Patent Laid-Open No. 58-212806, the oil film thickness correction is considered as a method for controlling the plate thickness of a rolling mill using a gauge meter type. That is, the strip thickness is set to the target strip thickness ha in the rolling mill.
Based on the predicted rolling load Fo when the target plate thickness ha is rolled down, the elastic constant M of the rolling mill, the oil film thickness correction term δo, and the gauge meter type correction term E,
It is a strip thickness control method for a rolling mill, which is calculated by So = ha- (Fo / M + δo + E). So is calculated from the roll speed and rolling load, and Fo / M is the elongation of the rolling mill, which is generally corrected by the strip width. As described above, it has been conventionally known to correct the oil film thickness in the plate thickness estimation.

Further, in Japanese Patent Publication No. 63-33924, a load function generator for selecting a load coefficient corresponding to a rolling load detected by a load detector and a roll peripheral speed detected by a speed detector are supported. The oil film thickness function generator that selects the oil film thickness when the roll peripheral speed is constant under the standard rolling load, and the oil film thickness and function generator selected by this oil film thickness function generator In a multiplier for obtaining an oil film thickness to be corrected by multiplying the load coefficient, and an oil film thickness correction device for a rolling mill roll bearing equipped with a roll gap adjusting device operated by a signal from this multiplier, A comparison calculator provided between the oil film thickness function generator and the multiplier, and an oil when the roll peripheral speed is constant at a reference rolling load, which corresponds to the roll peripheral speed during roll acceleration or deceleration. Determine the oil film thickness deviation with respect to thickness,
A device provided with a hysteresis correction function generator that gives this deviation to a comparison calculator is disclosed. That is, it is described that the oil film thickness is corrected in consideration of the hysteresis amount during acceleration / deceleration in the relationship between the roll peripheral speed and the oil film thickness, and the relationship between the rolling load and the load coefficient.

[0004]

However, Japanese Patent Laid-Open No. 58-212806 only shows that the oil film thickness is taken into consideration as a correction term in the plate thickness estimation.
Further, JP-B-63-33924 discloses only that the oil film thickness is corrected in consideration of the hysteresis during acceleration / deceleration in the relationship between the roll peripheral speed and the oil film thickness, and the relationship between the rolling load and the load coefficient. However, the actual oil film thickness occurs between the sleeve and the bushing, which affects the diameter of the upper and lower backup rolls, the number of revolutions of the backup roll, and temporary fluctuations in the oil film thickness at the start of acceleration / deceleration. Therefore, there is a problem that the oil film thickness at the time of normal rolling cannot be correctly corrected unless these large fluctuations are taken into consideration.

[0005]

DISCLOSURE OF THE INVENTION The present invention has solved the above-mentioned problems, and the diameter of the upper and lower backup rolls and the number of revolutions of the backup roll and the temporary start of acceleration / deceleration by measuring immediately after rolling. An object of the present invention is to provide a rolling bearing oil film thickness correction method for a rolling mill in which the oil film thickness correction is performed in consideration of the oil film thickness variation. The gist of the invention is as follows. (1) In the backup roll bearing oil film thickness correction for plate thickness estimation of the rolling mill, the oil film thickness of the backup roll bearing is adjusted to the upper and lower sides before the temperature of the bearing lubricating oil immediately after rolling falls. Measured as a function of the average number of revolutions and load obtained by the average value of the backup roll diameter, and when measuring the oil film thickness, the speed was determined by the average value of the reciprocation from low speed to high speed and from high speed to low speed, and these measured values A rolling bearing oil film thickness correction method for a rolling mill, comprising: (2) A roll bearing oil film thickness correction method for a rolling mill characterized by correcting a temporary change in the oil film thickness at the start of acceleration / deceleration in the actual rolling described in (1).

[0006]

Hereinafter, the present invention will be described in detail with reference to the drawings. FIG. 1 is a view showing the relationship between the backup roll rotation speed and the oil film thickness. As a method of measuring the oil film thickness, the roll gap is set to a certain load and the backup roll rotation speed is changed from a low rotation speed to a high rotation speed range. Conversely, the high speed is changed to the low speed range. Further, the load is changed and the measurement is performed in the same manner as above. In this case, it has been found that the oil film is generated between the sleeve and the brushing, and is related to the rotation speed of the roll, not the peripheral speed of the roll. That is, the oil film thickness _{△ h oil = {P (V} ) -P (V O)}
/ M where P (V): load at a certain speed P (V _O ): load at a standard speed M: mill rigidity When measured by this method, even with the same backup roll,
It was found that there were large variations depending on the timing of the measurement.

That is, FIG. 1 shows an example of a certain stand, and it can be seen that there are large variations even in the same backup roll chock. This means that even with the same backup roll, there are large variations depending on the measurement timing. That is, since the conditions at the time of measurement have a great influence, in order to correct the oil film thickness during rolling correctly, the bearing lubricating oil temperature immediately after rolling,
For example, since it usually has 38 to 39 ° C., it was found that it is necessary to measure at an oil temperature of at least 30 ° C. or higher. It was also found that it is appropriate to obtain the average value during acceleration and deceleration, rather than saying that the oil film thickness is not the same during acceleration and deceleration, but it has hysteresis. Furthermore, the upper backup roll diameter and the lower backup roll diameter are not always the same, and therefore it is necessary to use the relationship between the rotational speed and the oil film obtained from this average value.

FIG. 2 is a plate thickness chart showing the relationship between time and plate thickness deviation. As shown in FIG. 2, although the plate thickness deviation is once 0 according to the actual result of the plate thickness deviation on the output side, the deviation occurs on the negative side. Moreover, the points A and B almost coincide with the acceleration start point or the deceleration start point. This means that the oil film thickness compensation is insufficient. Therefore, the oil film thickness temporarily fluctuates only at the start of acceleration or deceleration, and there is a phenomenon that affects the plate thickness. Therefore, it was found that this temporary change should be corrected.

FIG. 3 is a chart showing the actual speed results of time and mill speed. That is, FIG. 3 shows the actual speed at the final stand, and it can be seen that the mill speed greatly fluctuates at points A and B as in FIG. This variation point almost coincides with the acceleration start point or the deceleration start point, which means that the plate thickness varies greatly when the acceleration / deceleration changes. Therefore, it is necessary to correct the temporary fluctuation of the oil film thickness only at the start of acceleration or the start of deceleration. FIG. 4 is a diagram showing the relationship between the acceleration / deceleration change rate and the correction value. As shown in FIG. 4, the correction value increases according to the magnitude of the acceleration / deceleration change rate, and it is necessary to give an appropriate correction according to the change rate.

As described above, before the temperature of the bearing lubricating oil immediately after rolling is lowered, the oil film thickness of the backup roll bearing is changed to
Measured as a function of the average number of rotations and the weight obtained by the average value of the upper and lower backup roll diameters, and furthermore, the number of rotations was obtained as the average value of the reciprocation from low speed to high speed and from high speed to low speed, and the measured value of both Based on the above, by correcting the calculated plate thickness, the accuracy of the plate thickness on the delivery side of the rolling mill became extremely good, and the product quality could be improved.

[0011]

As described above, by performing the oil film thickness correction in consideration of the upper and lower backup roll diameters and the backup roll rotational speeds measured immediately after rolling according to the present invention, and the temporary oil film thickness fluctuation at the start of acceleration / deceleration. The oil film thickness can be accurately corrected according to the operating state, and therefore the accuracy of the rolling mill delivery side plate thickness becomes extremely good, and various effects such as the improvement of product quality can be achieved. .

[Brief description of drawings]

FIG. 1 is a diagram showing a relationship between a backup roll rotation speed and an oil film thickness,

FIG. 2 is a plate thickness chart showing the relationship between time and plate thickness deviation,

FIG. 3 is a chart showing the actual speed of time and mill speed;

FIG. 4 is a diagram showing a relationship between an acceleration / deceleration change rate and a correction value.

Claims (2)

[Claims] 1. In the backup roll bearing oil film thickness correction for estimating the plate thickness of a rolling mill, the oil film thickness of the backup roll bearing is adjusted before the bearing lubricating oil temperature immediately after rolling falls.
Measure as a function of the average number of rotations and load obtained by the average value of the upper and lower backup roll diameters, and when measuring the oil film thickness, obtain the speed by the average value of the reciprocation from low speed to high speed and from high speed to low speed, and measure these. A method for correcting a roll bearing oil film thickness of a rolling mill, which comprises correcting the calculated plate thickness based on the calculated value. 2. In the actual rolling according to claim 1,
A roll bearing oil film thickness correction method for a rolling mill, which comprises correcting a temporary change in the oil film thickness at the start of acceleration / deceleration.