JP3132333B2 - Camber reduction method in metal sheet rolling - 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 reducing the bent shape of a rolled material called a camber generated in a vertical rolling mill-horizontal rolling mill arrangement such as a rolling process of a metal plate, particularly a rough rolling process of hot rolling. .

[0002]

2. Description of the Related Art In a rough rolling step of hot rolling or a thick plate rolling, bending of a sheet material called a camber has become a problem. The occurrence of camber leads to a decrease in yield due to a deterioration in width accuracy, and in an extreme case, it is impossible to pass the next rolled sheet. Causes of camber include uneven thickness distribution, hardness distribution, and temperature distribution in the width direction of the rolled material, poor leveling of the rolls, off-center of the rolled material to the center of the rolling mill, rolled material to the roll bite It is generally known that the direction is skew. Due to these factors, a nonuniform rolling load distribution occurs in the sheet width direction, and a camber is generated due to a difference in roll gap opening between the left and right rolling mills.

Conventionally, as a method for preventing the off-center and skew of a rolled material, which is one of the causes of camber, a side guide opening on the entrance side of a horizontal rolling mill is set to be about 50 mm wider than the width of the rolled material and the rolling is performed. A method of guiding a material to a center of a horizontal rolling mill is widely used. However, in order to prevent scratches due to strong contact of the rolled material to the side guides, poor sheet passing, and the like, the side guide opening is set to be wider than the rolled material sheet width as described above, so that a large bent shape can be prevented. However, at present, satisfactory effects have not been obtained.

[0004] Most of the camber correction methods performed at the manufacturing site are based on a leveling operation of a horizontal rolling mill according to the camber amount. In order to detect the camber amount, the wedge amount and camber amount are estimated from the rolling load difference normally detected by the left and right load cells of the horizontal rolling mill, and the level difference between the left and right rolls to correct these is calculated. I do. However, by adjusting the roll gap, the change in load due to the leveling operation is superimposed on the difference between the left and right rolling loads due to the cross-sectional shape of the rolled material itself, the temperature deviation in the sheet width direction, etc. It is difficult to detect the amount and camber amount, and at present, sufficient effects have not been obtained.

[0005] As described above, asymmetrical rolling in a horizontal rolling mill has been mainly used for the camber shape over the entire length of the rolled material. It is known that, in addition to factors such as chock fluctuation at the time of biting and trailing off due to backlash of a horizontal rolling mill, especially in the hot rolling roughening step, it occurs during width rolling in a vertical rolling mill. This occurs because the rolled material is off-centered, which is offset from the center of the vertical rolling mill, or when the rolled material bites obliquely with respect to the rolling direction and the width rolling becomes asymmetrical in width. Normally, a side guide device for centering the rolled material is arranged in front of the vertical rolling mill. However, as described above, conventionally, a flaw caused by strong contact of the rolled material with the side guide, and a poor sheet passing due to a clogged guide. In order to prevent the like, the side guide opening on the entrance side of the vertical rolling mill is set to be about 50 mm wider than the width of the rolled material in the same manner as in the case of the horizontal rolling mill, and only the extremely off-centered rolled material is vertical. The method of guiding to the center of a rolling mill is widely used. Therefore, the guiding effect in this case was not sufficient, and in particular, it had little effect in preventing the occurrence of a nose bend.

As a method for correcting such front and rear end local bending, there is a method described in JP-A-6-226318. FIG. 6 is a diagram showing an example of the prior art by such a method. In FIG. 6, 1 is a rolled material, 2a and 2b are vertical rolling rolls, 4 is a horizontal rolling roll, 21 is a side guide, 22 and 23 are load detectors, 24 is a control device, and 25 is a rolling device. The rolled material 1 is guided by the side guide 21, and the load due to the change in the attitude of the end of the rolled material 1 is detected by the load detectors 22 and 23 provided on the side guide 21. Output a signal to adjust the left and right roll gaps. As a result, the roll gap on the side where the load is detected by the side guide 21 is reduced to reduce the drawing speed, and the drawing speed on the opposite side is increased to cause a change in the posture of the rolled material end on the horizontal mill entry side. To prevent local bending of the ends.

[0007]

However, the prior art as described in the above-mentioned Japanese Patent Application Laid-Open No. 6-226318 has the following problems.

This method is effective when the thickness profile of the rolled material after rolling by the vertical rolling mill is the same along the width of the plate. However, when the rolled material is in the form of a wedge along the width direction of the plate, or in particular, after the width rolling by the actual vertical rolling mill, a bulge called a dog bone occurs at the left and right plate ends at the left and right of the rolled material. When the nose is bent due to asymmetric biting, the left and right dog bone shapes are asymmetric. Therefore, in this case, the width spreading behavior and the strain distribution in the rolling direction in the subsequent horizontal rolling are different between the left and right. As a result, the width and the rolling direction distortion at the end of the plate with the higher dog bone height (in this case, the end opposite to the off-center) are increased, and as a result, the rolled material moves in the same direction as the off-center. This causes the nose bend generated by asymmetric width rolling to be enlarged. In other words, even if the right and left side guide reaction forces between the vertical rolling mill and the horizontal rolling mill are the same, if the rolled material thickness profile including the dog bone shape is asymmetric, the rolled material bending in horizontal rolling is prevented. There is a problem that cannot be done.

An object of the present invention is to provide a method for reducing a camber generated in a rolling step for producing a metal sheet, particularly in a rough rolling step of hot rolling, and ensuring the sheet passing property of a rolled material and improving the width yield. Aim.

[0010]

The above object is achieved by the following means.

In a method for reducing camber in a metal sheet rolling line in which a vertical rolling mill and a horizontal rolling mill are arranged,
The thickness distribution in the sheet width direction of the rolled material and the positions of both ends in the sheet width direction of the rolled material are measured by a shape measuring device provided between the vertical rolling mill and the horizontal rolling mill, and the tip of the rolled material is determined from the measurement results. Calculate the deformed shape of both ends in the sheet width direction near the roll and the off-center amount from the center of the rolled material center line from the line center, and calculate the amount of change in the left and right roll gap spacing of the horizontal rolling mill required for camber reduction from the obtained results And adjusting the roll gap interval.

[0012]

In the structure of the present invention, when the rolled material is disengaged from the pass center and bites into the vertical rolling mill in an off-center state, the rolled material corner on the off-center side first contacts the roll on the off-center side. , And is pushed by the roll without being deformed, and the incident angle is inclined. Then, when biting into the vertical roll, the tip opposite to the off-center is subjected to high pressure, so that the off-center side is bent. At this time, the thickened shape called the dog bone on the side where the high pressure is applied (on the side opposite to the off center) becomes large, and the rolled material tip becomes a dog bone shape that is asymmetrical in the sheet width direction. Here, when such a rolled material having such asymmetrical dogbone shape is horizontally rolled as it is, the longitudinal expansion at the end on the side where the dogbone shape is large becomes large, so that the off-center side is bent, and the vertical roll is generated. The bent nose is further promoted and enlarged.

Therefore, in the present invention, the thickness distribution of the rolled material in the sheet width direction is measured by a shape measuring device provided between the vertical rolling mill and the horizontal rolling mill, and based on the measured thickness distribution at the leading end of the rolled material. Then, a dog bone shape at both ends in the width direction of the board is obtained. Next, the amount of change in the left and right roll gap intervals of the horizontal rolling mill required for camber reduction is calculated from the obtained left-right asymmetric dog bone shape.

On the other hand, when the rolled material comes off the pass center and bites into the vertical rolling mill in an off-center state, the asymmetric width rolling by the vertical rolling mill is performed in parallel with the generation of the dogbone shape described above. The rolled material has a bent shape.
Therefore, in the present invention, the position of both ends in the sheet width direction of the rolled material is measured by a shape measuring device provided between the vertical rolling mill and the horizontal rolling mill, and the rolled material is measured from the measured positions of both ends of the rolled material. The position of the center line is determined, and the off-center amount from the center of the rolled material center line is determined from this. Next, the curvature of the bent shape of the rolled material is calculated from the result of the obtained off-center amount,
Based on this, the amount of change in the gap between the left and right roll gaps of the horizontal rolling mill required for camber reduction is calculated.

The left and right roll gap spacing variations of the horizontal rolling mill required for the respective camber reductions obtained by the above calculations are added, and the left and right roll gap spacings of the horizontal rolling mill are adjusted based on this value. As a result, in the horizontal rolling mill, since the rolling is performed so that the longitudinal extension at the small off-center side end of the dog bone shape becomes large, the dog bone shape generated by the vertical roll is rolled by the horizontal rolling mill. This can prevent camber from occurring. Further, in the horizontal rolling mill, the rolling is performed so as to correct the bending generated in the vertical rolling mill, so that the bending generated in the vertical roll is corrected, and the occurrence of camber can be prevented.

[0016]

An embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is a view showing the configuration of an embodiment of the present invention, in which the present invention is applied to a rough rolling step of a hot rolling line configured by a vertical rolling mill and a horizontal rolling mill. is there.
In the following drawings, the same portions as those in FIG. 6 are denoted by the same reference numerals, and description thereof will be omitted. In FIG. 1, 3 is a shape measuring device, 5 is an off-center amount / dog bone shape detecting unit, 6
Denotes a roll gap adjustment amount calculation unit. Here, as the shape measuring instrument, for example, a plurality of thickness gauges using an X-ray thickness gauge, a γ-ray thickness gauge, or a laser distance meter may be arranged.

When the rolled material 1 is disengaged from the pass center and bites in the vertical rolling rolls 2a and 2b in an off-center state,
The rolled material corner on the off-center side first comes into contact with the vertical rolling roll 2a, and is pressed by the roll without being deformed, so that the incident angle is inclined. Then, when biting into the vertical rolling rolls, the tip is reduced under high pressure by the vertical rolling rolls 2b on the opposite side of the off-center, so that the off-center side bends. At this time, the dogbone on the side where the high pressure is applied (on the side opposite to the off-center) becomes large at the forefront of the rolled material, resulting in an asymmetric dogbone shape. FIG. 2 is a diagram showing a dog bone shape after such vertical rolling.

Here, the shape measuring device 3 measures the thickness distribution in the strip width direction at the tip end of the rolled material 1 and the position of both ends in the strip width direction, and detects the off-center amount / dog bone shape detection signal. Send to Part 5. The off-center amount / dog bone shape detection unit 5 calculates a numerical value related to a simplified dog bone shape from the obtained thickness distribution, and calculates the off-center amount of the rolled material with respect to the pass center from the center position of the rolled material. Is calculated. The result is sent to the roll gap adjustment amount calculation unit 6, where the left and right roll gap adjustment amounts of the horizontal rolling rolls required for camber reduction are calculated based on the calculation formula. By the control from the roll gap adjustment amount calculation unit 6, the required amount of the left and right roll gaps of the horizontal rolling roll is adjusted based on the calculation result, and the bending of the rolled material generated by the vertical rolling roll is corrected, and the horizontal rolling is performed. Later camber is prevented from occurring.

An example of the operation method will be described below. FIG.
FIG. 3 is a view showing a shape of a rolled material in a case where a dog bone shape is simplified according to the present invention. In FIG. 3, H ₁ is the maximum height of the dog bone on the side opposite to the off center, W ₁ is the distance from the edge of the dog bone at the maximum height of the dog bone on the side opposite to the off center, and L ₁ is the side opposite to the off center. distance dog bone height from the plate end of 0 a position, the distance from the H ₂ is the maximum height of the dog bone off-center side, W ₂ is plate end of the dogbone maximum height position of the off-center side , L ₂
Is the distance from the plate edge at a position where the dog bone height on the off-center side is 0, and h is the average plate thickness at the center of the rolled material.

From the sheet thickness distribution in the sheet width direction obtained by the shape measuring instrument of the present invention, H ₁ , W ₁ , L ₁ ,
H ₂ , W ₂ , L ₂ , and h are obtained by the controller, and a function dS representing the left-right asymmetry of the dog bone is obtained from the following equation. S ₁ = L ₁ × (H ₁ -h) / 2 S ₂ = L ₂ × (H ₂ -h) / 2 dS = (1−W ₁ / L ₁ ) × S ₁ − (1−W ₂ / L ₂ ) × S ₂ (1) where (1−W ₁ / L ₁ ) and (1−W ₂ / L ₂ ) indicate the positions of the vertices of the dog bone, and the vertices of the dog bone are near the plate edge. The larger the value of dS, the greater the influence on the camber.

From the dS obtained by the equation (1), the left and right roll gap adjustment amounts Δy ₁ of the horizontal roll for correcting the bending generated when the asymmetric dog bone shape is horizontally rolled are obtained by the following equation. Δy ₁ = h × (1-r) × C × dS (2) Here, the meanings of the symbols are as follows. Δy ₁ : roll gap interval change amount for correcting the bending generated when the asymmetrical end shape is horizontally rolled h: average sheet thickness at the center of the rolled material r: reduction ratio in horizontal rolling C: shape conversion coefficient C is a shape conversion coefficient for converting a dog bone shape obtained from an experimental regression equation into a wedge shape, and C × d
S is a value representing the left-right asymmetry after conversion to the wedge shape.

In addition to the above-described calculation of Δy ₁ , the left and right roll gap adjustment amounts Δy _{2 of the} horizontal roll required to correct the bent shape of the rolled material caused by the asymmetric width rolling in the vertical rolling mill.
Is determined by the following equation. Δy ₂ = h × (1-r) × κ ₂ × λ ² × b / (1-α) (3) Here, the meanings of the symbols are as follows. κ ₂ : Rolled material curvature after horizontal rolling λ: Elongation during horizontal rolling b: Rolled material sheet width α: Lateral flow rate Here, from the measurement result of the shape measuring instrument, the amount of lateral deflection of the rolled material center line is calculated. The calculation is performed on the assumption that the rolled material bending shape is an arc passing through the center lines of the left and right vertical rolls. Further, it is assumed that this arc-shaped rolled material has an arc shape at each moment during rolling, and the rolled material curvature after horizontal rolling at the moment is κ.
Calculated as ₂ .

In equation (3), the term κ ₂ × λ ² × b is a value obtained from the relationship between the curvature and the amount of change in the wedge rate, and the lateral flow rate α represents the lateral flow of the material obtained from the experimental regression equation. This is a coefficient, and the value of Δy ₂ increases as the cross flow increases.

By adding the roll gap adjustment amounts obtained from the expressions (2) and (3), the final roll gap adjustment amount ΔY is obtained by the following expression. ΔY = Δy ₁ + Δy ₂ (4) By controlling the left and right roll gap adjustment amounts of the horizontal rolling roll according to the expression (4), the bending of the rolled material generated by the vertical rolling roll is corrected, and The occurrence of camber can be prevented.

FIG. 4 is a flowchart showing a control method according to the present invention when the roll gap of horizontal rolling is adjusted by the above equation (4).

FIG. 5 is a graph showing the relationship between the off-center amount of the rolled material before rolling and the amount of lateral deflection of the tip of the rolled material after rolling. In the case of only width rolling without control according to the present invention (indicated by ●), the off-center amount increases and
In the case of width rolling + horizontal rolling (indicated by a circle) where the control is not performed according to the present invention, the amount of lateral deflection of the tip is increased due to the asymmetrical dog bone shape compared to the case of width rolling alone. It can be seen that is further increased. On the other hand, when the left and right roll gaps of the horizontal rolling roll according to the present invention were adjusted (marked by “x”), the lateral run-out amount at the leading end of the rolled material did not increase with the off-center amount. Is stable around 0, which indicates that the camber reduction effect of the present invention is enormous.

[0028]

As described above, according to the present invention, it is possible to reduce the camber generated in the rolling step for producing a metal sheet, particularly in the rough rolling step of hot rolling or in the thick plate rolling, and to improve the sheet passing property of the rolled material. As a result, the yield and width yield can be improved, and the productivity and economic effects are very large.

[Brief description of the drawings]

FIG. 1 is a diagram showing an embodiment of the present invention.

FIG. 2 is a view showing a dog bone shape after vertical rolling.

FIG. 3 is a diagram showing a shape of a rolled material when a dog bone shape according to the present invention is simplified.

FIG. 4 is a flowchart showing a control method when adjusting a roll gap in horizontal rolling according to the present invention.

FIG. 5 is a diagram showing the relationship between the off-center amount of a rolled material before rolling and the amount of lateral deflection of the tip of the rolled material after rolling.

FIG. 6 is a diagram showing an example of the related art.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Rolled material 2a, 2b Vertical rolling roll 3 Shape measuring device 4 Horizontal rolling roll 5 Off-center amount / dog bone detection unit 6 Roll gap adjustment amount calculation unit

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) B21B 37/00-37/78

Claims (1)

(57) [Claims] In a method for reducing camber in a metal plate rolling line in which a vertical rolling mill and a horizontal rolling mill are arranged, a shape measuring device provided between the vertical rolling mill and the horizontal rolling mill is used to measure the width direction of the rolled material. The thickness distribution and the position of both ends of the rolled material in the width direction of the rolled material are measured, and the deformed shape of the both ends in the width direction of the roll near the tip end of the rolled material and the off-center from the line center of the rolled material center line are obtained from the measurement results. A camber reduction method comprising: calculating the amount of the roll gap; calculating the amount of change in the left and right roll gap intervals of the horizontal rolling mill required for reducing the camber from the obtained result; and adjusting the roll gap interval.