JP3240599B2 - Roll opening setting method for hydraulic rolling mill - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for setting a roll opening of a rolling mill, which suppresses fluctuations in sheet thickness due to sinking of an oil column at the time of biting in plate rolling by a hydraulic rolling mill.

[0002]

2. Description of the Related Art In a rolling mill equipped with a hydraulic pressure reduction device, when rolling a steel sheet, an impact load is generated when the steel sheet is engaged, and oil in a hydraulic cylinder constituting the hydraulic pressure reduction device is instantaneously compressed. A so-called oil column sink occurs in which the cylinder position is opened from the target position.

There is a system that performs fixed position control in order to keep the cylinder position at a target position, but the hydraulic cylinder cannot completely follow the instantaneous change at the time of biting. For this reason, before the rolled position corresponding to the desired plate thickness is reached, the rolling of the leading end of the steel plate proceeds, which causes a disadvantage that the leading end of the steel plate becomes thick as shown in FIG.

[0004] In order to solve such inconvenience,
Heretofore, a correction means for setting the position of the hydraulic cylinder to a small value in advance only when the plate is engaged has been adopted. This is done by first-order approximation from the actual rolling data, experimentally obtaining the peak load and oil column compression during biting as shown in FIG. 2, and then calculating the biting load from the rolling load calculated by a process computer or the like. Predict the peak load at the time of intrusion. From FIG. 1, a method is adopted in which the roll opening is set to be smaller by the amount of oil column compression, and the correction amount is released Δt seconds after detecting the plate biting into the rolling mill by a load meter or the like. (See JP-A-59-183915).

[0005]

However, in the conventional correction at the time of plate biting, in which the position of the hydraulic cylinder is set small beforehand only at the time of plate biting, the oil column sinking amount at the time of biting is reduced. Prediction accuracy was a problem.

That is, in plate rolling, the shape of the plate tip changes in various ways, and the shape of the plate tip greatly changes the load fluctuation and the oil column sinking amount during biting.

FIG. 3 shows actual data on the relationship between the peak load at the time of biting and the amount of oil column sinking. The reason for the large variation in the relationship between the two is that the amount of submersion in the oil column differs depending on the inclination of the load rise even at the same peak load. That is, FIG.
As shown in (A), for example, crop length (crop length)
If the length measured in the hand direction is short and the inclination of the load rise at the time of biting is large, the amount of oil column sinking becomes large, while the crop length is long, as shown in FIG. If the slope of the load rise is small, the oil column subsidence amount will be small.

[0008] Crop shape in sheet rolling (in the sheet width direction)
FIG. 5 shows the relationship between the crop length distribution) and the load at the time of biting. The load at the time of biting changes greatly depending on the shape of the crop. As shown in FIG. 5 (B), when the crop length is long, the unsteady state at the time of biting becomes longer, so that the slope of the load rise becomes smaller. As shown in FIG. 5 (A), when the crop length is short, the slope of the load rise becomes large.

In the conventional prediction of the peak load at the time of biting based on the prediction of the rolling load of the next pass, it was not possible to predict the load variation at the time of biting due to this crop shape. For this reason, it is difficult to accurately predict the amount of oil column sinking during biting only from the rolling load predicted by a process computer, etc., and it is not possible to optimally correct the roll opening during plate biting. Did not.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned conventional problems. In plate rolling by a hydraulic rolling mill, correction of the roll opening degree at the time of biting is performed with high accuracy, and the plate at the tip end of the plate is formed. An object of the present invention is to provide a roll opening degree setting method capable of suppressing thickness fluctuation.

[0011]

SUMMARY OF THE INVENTION The present invention relates to a method for correcting a roll opening degree at the time of biting in a sheet rolling by a hydraulic rolling mill, wherein a crop shape at the time of biting through a previous pass (a front stand at the time of tandem rolling) is removed. Measure, or, based on the crop shape model, predict the crop shape of the next pass, using the measured or predicted crop shape and rolling load ,
Predict the amount of oil column sinking during the next pass (the next stand for tandem rolling) from the oil column sinking model, and correct the roll opening during biting to reduce the oil column sinking during biting. The above object has been achieved by suppressing the thickness variation due to the above.

[0012]

According to the present invention, in sheet rolling, the next pass is measured by actually measuring the crop shape at the time of the previous pass (the front stand in the case of tandem rolling) or by estimating the crop shape using a crop shape model. (The next stand in the case of tandem rolling.) The amount of oil column sinking during biting can be accurately predicted. As a result, it is possible to accurately correct the roll opening degree at the time of the sheet biting, and the sheet thickness accuracy of the leading end portion in the sheet rolling is improved.

[0013]

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

FIG. 6 is an explanatory view showing a first embodiment of the present invention, wherein 10 is a CCD camera, 12 is an image processing device,
4 is a process computer, 16 is a hydraulic pressure reduction control device,
18 is a hydraulic cylinder, 20A and 20B are work rolls,
22A and 22B are backup rolls, and 24 is a rolled material.

In the sheet rolling, first, a CCD camera 10 captures an image of a crop shape when a material to be rolled is caught in a previous pass (a front stand in the case of tandem rolling).
Performs image processing. The process computer 14
Based on the measured data of the crop shape and the predicted load of the next pass (the next stand in the case of tandem rolling), the oil column subsidence model at the time of biting in the next pass (the next stand in the case of tandem rolling) The amount is predicted, and the roll opening correction value at the time of biting is calculated from the amount.

The oil column subduction model is as follows. That is, as shown in FIG. 3, the oil column sinking amount has a large correlation with the rolling load. Further, as can be seen from FIGS. 4 and 5, the influence of the crop shape is large. That is, the oil column sinking amount ΔS is defined by the following equation, where F is the rolling load and L is the crop length.

[0017]

(Equation 1)

As described above, the oil column sinking amount ΔS is represented by a function of the rolling load F and the crop length L.

The outline of the oil column subduction model is shown in the graph of FIG. That is, if the crop length L is long and the unsteady state during biting is long, the oil column sinking amount ΔS is small even with the same load, and if the crop length L is short, the oil column sinking amount ΔS is large.

The roll opening correction value at the time of engagement determined by the process computer 14 is applied to the hydraulic pressure reduction control device 16.
The hydraulic pressure reduction controller 16 corrects the cylinder position of the hydraulic cylinder 18 at the time of biting, and sets the roll opening of the work rolls 20A and 20B.

As described above, by measuring the crop shape at the time of biting through the previous pass (the front stand at the time of tandem rolling), the amount of oil column sinking at the time of biting at the next pass (the next stand at the time of tandem rolling) is measured. Can be accurately predicted.

In the present embodiment, since the crop shape is actually measured using a CCD camera, a particularly high-precision correction is possible.

FIG. 8 is an explanatory view showing a second embodiment of the present invention.

In FIG. 8, reference numeral 26 denotes a process computer provided with a crop shape model which is a feature of the present invention. The crop shape model is obtained by calculating the crop length in the sheet width direction (1/2 crop, 1/4 crop, 1/8 crop) from the extension width ratio (total ratio / width extension ratio in plate rolling).
It is a method of predicting.

The outline of the crop shape model is shown in FIG. 9 and the following equation.

[0026]

(Equation 2)

The process computer 26 obtains the sheet width and the sheet length in the current pass from the rolling schedule calculation, and determines the slab width and the extension ratio LHP (total ratio / width ratio in thick plate rolling) from the slab width and the slab length. . This extension width ratio L
HP is given to the crop shape model, and the crop length (１ ／ crop, ４ crop, １ ／ crop) at each point (１ ／ width, １ ／ width, １ ／ width) in the plate width direction. Predict).

Further, the process computer 26 predicts the amount of oil column sinking at the time of the next pass bite using an oil column sink model from the predicted crop shape and the predicted load of the next pass. Find the opening correction value.

The roll opening correction value obtained by the process computer 26 is sent to the hydraulic pressure reduction control device 16,
The hydraulic pressure reduction controller 16 corrects the cylinder position of the hydraulic cylinder 18 at the time of biting, and sets the roll opening of the work rolls 20A and 20B.

In this embodiment, since the crop shape is predicted by the model, the hardware configuration is simple.

FIG. 10 shows a slab size of 210 × 1560 ×
It shows the thickness variation at the tip of the plate when a thick steel plate of 12 m × 3500 mm × l is rolled from 2200 mm. In the first and second embodiments of the present invention, the occurrence of excessive thickness is reduced by appropriately correcting the roll opening degree.

[0032]

As described above, according to the present invention, the oil is measured by actually measuring the crop shape at the time of the previous pass (the front stand at the time of tandem rolling) or by estimating the crop shape using a crop shape model. By accurately predicting the amount of oil column sinking during the next pass (the next stand in the case of dandem rolling) from the column sinking model, the oil column sinking amount is more accurate than the conventional prediction of peak load during biting Now you can predict. As a result, the roll opening can be accurately corrected at the time of the sheet biting, and there is an effect that the thickness accuracy of the leading end portion in the sheet rolling is improved.

[Brief description of the drawings]

FIG. 1 is a diagram showing a state in which a thick portion is formed at a tip portion of a plate when the plate is bitten.

FIG. 2 is a diagram qualitatively showing a relationship between a peak load at the time of biting and a compression amount of an oil column.

FIG. 3 is a correlation diagram based on actually measured values of a relationship between a peak load at the time of biting and a compression amount of an oil column.

FIG. 4 is a diagram showing a relationship between a crop shape, a load rise, and an oil column sinking amount.

FIG. 5 is a diagram showing a relationship between a crop shape and a load at the time of biting;

FIG. 6 is a block diagram including a partial cross-sectional view showing the first embodiment of the present invention.

FIG. 7 is a diagram showing an outline of an oil column subduction model used in an embodiment of the present invention.

FIG. 8 is a block diagram including a partial cross-sectional view showing a second embodiment of the present invention.

FIG. 9 is a diagram showing an outline of a crop shape model used in the second embodiment.

FIG. 10 is a diagram showing a comparison between examples of the actual plate thickness variation between the conventional method and the embodiment.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 10 ... CCD camera 12 ... Image processing apparatus 14 ... Process computer 16 ... Hydraulic pressure reduction control device 18 ... Hydraulic cylinder 20A, 20B ... Work roll 24 ... Material to be rolled 26 ... Process computer provided with a crop shape model

Continuation of the front page (56) References JP-A-63-119921 (JP, A) JP-A-6-182419 (JP, A) JP-A-61-292716 (JP, A) JP-A-60-223607 (JP, A) JP-A-57-142707 (JP, A) JP-A-63-235010 (JP, A) JP-A-59-183915 (JP, A) JP-A-5-115909 (JP, A) (58) Field surveyed (Int. Cl. ⁷ , DB name) B21B 37/18

Claims (2)

(57) [Claims] In a roll opening correction at the time of biting in a sheet rolling by a hydraulic rolling mill, a crop shape at the time of a previous pass or a front stand biting is actually measured, and the actually measured crop shape and rolling load are used. Then, by predicting the amount of oil column sinking in the next pass or the next stand from the oil column sinking model, and correcting the roll opening during biting, the thickness variation due to the oil column sinking during the biting A roll opening setting method for a hydraulic rolling mill, characterized in that the roll opening degree is reduced. 2. A roll opening correction when biting of the plate rolling by the hydraulic pressure rolling mill, on the basis of the crop shape model, to predict the crop shape follows the path or the next stand, and the predicted cropped shape Using the rolling load , predict the amount of oil column sinking in the next pass or next stand from the oil column sinking model, and correct the roll opening at the time of biting to reduce the oil column sinking at the time of biting. A roll opening setting method for a hydraulic rolling mill characterized by suppressing plate thickness fluctuation due to pressure.