JPH0261847B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for controlling the camber of a rolled material in thick plate rolling.

[Conventional technology]

During rolling of steel plates, etc., during rolling,
If there is a difference in the hardness of the left and right sides of the rolled material or a difference in the left and right rigidity (mill constant) of the rolling mill, a meandering phenomenon in which the biting position of the rolled material in the rolling mill shifts in the width direction, or camber, may occur. There is. Particularly, when the camber occurs, and if it is large, the material to be rolled may damage the rolling rolls and guides, and in extreme cases, lead to breakage, causing great damage in terms of time and property. On the other hand, even if this camber is small, as shown in FIG. 2, it becomes impossible to obtain the predetermined dimensions of the plate 2 as indicated by the broken line, and the yield of the product decreases. Therefore, in order to suppress such camber, it is important to measure the center line profile of the material to be rolled 1 and quickly control the rolling according to the amount of camber.

By the way, in conventional camber control, a method is generally used in which the difference in opening between the left and right rolls is manipulated (leveling operation) so that a plate wedge corresponding to the amount of camber is obtained. In this conventional method, leveling is controlled according to the amount of meandering (off-center) that occurs during rolling, using a target value of the exit side wedge amount determined in advance from the entrance side camber amount and wedge amount as a control variable. It is.

[Problem to be solved by the invention]

In general, work rolls have roll crowns such as initial crowns, worn crowns, and heat crowns, as well as roll deflections, so when meandering occurs, the thickness distribution in the width direction becomes asymmetrical, causing wedges. and the relationship between camber changes. Therefore, since the conventional camber control method described above is mainly a method of controlling only the wedge amount set before rolling, if there is a roll crown as described above, this will cause an error in sheet wedge control. However, there was a problem in that the predetermined camber correction could not be carried out, and uncorrected camber remained.

That is, the reason why uncorrected camber remains in the conventional method can be explained from FIGS. 3 to 6 below.

FIG. 3 shows the deformation of the rolled material 1 and the deflection shape of the work rolls 3, 3' when the rolled material is not meandering. By rolling down the rolled material 1 on one side, a wedge and a plate crown are formed in the rolled material 1. The amount of deflection of the work rolls 3, 3' is almost symmetrical, and the plate crown is symmetrical on the left and right sides of the plate when the wedge (the shape is indicated by the broken line A in the figure) is used as a reference. Assuming that the difference in elongation in the width direction due to the wedges is all caused by bending and no internal stress is generated, the internal stress caused by the difference in elongation in the width direction due to the plate crown will be symmetrical in the width direction,
Balance left and right.

FIG. 4 shows a case where the work rolls 3, 3' have crowns, but the rolled material 1 does not have meandering, similar to FIG. 3. In this case as well, the plate crown based on the wedge is symmetrical, and if the rolled material has no meandering, the bending of the plate can be corrected only by changing the wedge amount.

On the other hand, FIG. 6 shows a case where the rolled material has meandering and no roll crown, and FIG. 5 shows a case with a roll crown.

As is clear from FIGS. 5 and 6,
In either case, the plate crown amount based on the wedge becomes asymmetrical, and the internal stress distribution of the plate also becomes asymmetrical, so the plate bends so that the internal moment due to this internal stress is balanced.
The bending of the board cannot be corrected simply by using wedges alone. Furthermore, the roll opening degree is zero-adjusted prior to rolling, but at this time an error may occur in the left and right roll opening degrees, and this deviation in the left and right roll opening degrees has a subtle effect on the camber.
This was especially a problem with thin thick plates. Conventionally, this difference in the left and right roll opening degrees was not considered at all.

An object of the present invention is to solve the drawbacks and problems of the conventional method, that is, the problems of the method that attempts to correct the exit camber only based on the relationship between the camber and the wedge amount in the previous pass. An object of the present invention is to provide a camber control method for rolled material.

[Means to solve the problem]

To achieve the above-mentioned purpose, the present invention provides a camber control method for a rolled material in thick plate rolling, that is, information on the left and right roll opening difference and the left and right roll load difference during rolling before the current pass, and the resulting wedging. From this relationship, we estimated the amount of left-right deviation of the roll opening during zero adjustment and the amount of deviation caused by the asymmetry of the roll profile, and decided to reflect this amount of deviation in the camber control of the next pass rolling.

That is, the gist of the present invention is to estimate the camber in the control path based on the camber amount and wedge amount of the material to be rolled, and to perform the horizontal leveling operation of the rolling rolls so that the exit camber in this control path becomes zero. In the camber control method for rolled material in thick plate rolling, we actually measure the difference in opening between the left and right sides of the rolling rolls, the difference in load between the left and right sides, and the wedge amount of the plate in the immediately preceding pass rolling, and also combine these measured values with the rolls in the current pass. The method is characterized in that the amount of deviation from the initial setting value of the opening degree is determined, and the next pass rolling is performed while sequentially correcting the set value of the roll opening degree during the leveling operation according to the amount of deviation of the opening degree of the rolls. be.

[Effect]

When rolling a plate to a predetermined size using a reverse rolling mill, as in the case of rolling a thick plate, the rolling conditions change sequentially as the passes progress. However, if it is a continuous path, the difference is small. In particular, regarding the amount of left-right deviation in the roll opening during zero adjustment, and the amount of deviation due to left-right asymmetry of the roll profile,
There is almost no change between consecutive passes before and after, and they can be considered to be the same.

Therefore, in the case of plate rolling in which multiple passes are performed in the same rolling mill, a predetermined plate wedge can be controlled by performing a leveling operation based on the rolled shape of the previous pass.

Such control of the plate wedge amount can be calculated geometrically using the following equation (1) with reference to the schematic diagrams of the plate profile before and after the control shown in FIGS. 7A and 7B.

ρ _i = α ₁ 1/b Δφ _i + α ₂ ρ _0i where ρ _i : Output camber curvature ρ _0i : Inlet camber curvature b : Plate width Δφ _i : Wedge ratio change (= hdf _i /h _i −Hdf _i /H _i ) Hdf _i : Input side wedge amount hdf _i : Output side wedge amount H _i : Inlet side plate thickness h _i : Output side plate thickness α ₁ , α ₂ : Coefficient determined from deformation characteristics Subscript i: Plate length direction From equation (1), the exit target wedge amount hdf _i ^* with the exit camber curvature ρ _i =0 is obtained, and the leveling operation is performed so that Hdf _i ^* is obtained.

In addition, the plate wedge amount Pdf _i obtained by the leveling operation, the left and right roll opening difference Sdf _i , and the left and right load difference
The relationship of Pdf _i is shown as the following equation (2).

hdf _i = β ₁・Pdf _i +β ₂・2df _i +β ₃ ………(2) Here, β ₁ , β ₂ , and β ₃ are real terms shown below, and are determined by the rolling conditions. .

β ₁ = f ₁ (b, q _p , C _w ,…) β ₂ = f ₂ (b, q _p , C _w ,…) β ₃ = f ₃ (b, q _p , C _w ,…) However, b: Plate width, q _p : Rolling pressure, C _w : Roll crown The roll opening difference Sdf _i can be recognized from the feedback signal of the hydraulic rolling device, etc., but this includes the aforementioned left and right roll opening deviation amount. ΔSdf is not reflected. Therefore, taking this into account, formula (2)
If you rewrite it, it becomes the following equation (3).

hdf _i = β ₁ · Pdf _i + β ₂ (Sdf _i + ΔSdf) + β ₃ ...... (3) The amount of deviation ΔSdf is the difference in left and right roll opening degree Sdf ₀ one pass before the pass to be controlled, the plate wedge amount Hdf ₀ , It is obtained from the left and right load difference Pdf ₀ using the following equation (3)'.

ΔSdf=(Hdf ₀ −β′ ₁ Pdf _i −β′ ₂ SdF ₀ −β′ ₃ )/β′ ₂ ………(3)′ However, β′ ₁ , β′ ₂ in equation (3)′, β′ ₃ is defined by the rolling conditions of one pass before.

These functions may be based on data at one point during rolling one pass before, or may be based on average values in the length direction of the plate, but generally there are variations in measurement data, so It is more accurate to use each average value.

Note that, in equation (1), the inlet wedge amount Hdf _i is an actual value measured by a plate thickness measuring device such as a γ-ray thickness meter installed near the rolling mill.

However, when using the actual measured value of the entry side wedge amount as a standard for calculating the sheet wedge amount to be controlled, variations in the sheet thickness measuring device directly appear as variations in the control amount. There is a problem in that the control amount fluctuates in steps and the control accuracy is restricted by the response characteristics of a plate thickness control device such as a hydraulic reduction device.

Therefore, from equation (1), the exit standard wedge amount hdf _i ^* is
By calculating from the following equation (4) from the rolling conditions of the previous pass, it is possible to eliminate fluctuations in the control amount due to wedge amount measurement errors.

Hdf _i = β' ₁ Pdf _0i + β' ₂ (Sdf _0i + ΔSdf) + β' ₃ ......(4) In this case, the calculated value of the plate wedge also has no large difference in rolling conditions between successive passes, so its relative error is It's also small.

An example of control logic based on the above concept will be explained using the control logic block diagram shown in FIG.

1 is a rolled material, 3, 3' is a work roll, 4,
4' is a back-up roll, 5, 5' is a load cell that detects the rolling load, 6, 6' is a hydraulic lowering device,
7 is a hydraulic pressure reduction control panel.

8 is the target wedge amount on the exit side from the board profile
This is a computer for calculating hdf _i ^* , and also calculates the constants β ₁ to β ₂ and the deviation ΔSdf between the left and right roll opening degrees.

9 is the left and right load difference Pdf _i and the left and right roll opening difference
Sdf _i is an arithmetic unit for calculating the wedge feedback value hdf^ _i from the deviation ΔSdf between the left and right roll openings, and 10 is a calculator for calculating the deviation ΔSdf _i ^* of the left and right roll openings from the wedge deviation Δdf _i . , and 11 is the PI gain.

Next, the present invention will be explained with reference to examples.

Example 8 shows an example of the results of camber control performed using the control logic block diagram shown in FIG.
As shown in the figure. According to the invention, rolling dimensions thickness 10 mm,
To achieve a width of 4,000 mm and a length of 40,000 mm, we were able to reduce the thickness of the plate from 11.8 mm and camber amount of 60 mm before one pass to 20 mm of camber after control. In this example, a value actually measured using a γ-ray thickness meter was used for the inlet wedge amount Hdf _i in equation (1).

The deviation ΔSdf between the average wedge amount before control, 32 μm, the left and right roll opening difference, and the left and right roll opening difference data, which was determined from the left and right load difference data, was 0.142 mm.

Further, FIG. 9 shows the results of control according to the present invention in comparison with the results of a normal control method (when ΔSdf=0 in FIG. 1). Figure 9a is the formula
When the inlet wedge amount Hdf _i in (1) is actually measured, the figure b
is a diagram showing the relationship between the plate length and the camber amount when estimated using model formula (4).

As is clear from the figure, in the present invention, the left and right roll opening difference deviation amount ΔSdf is estimated from the rolling conditions of the previous pass, and this is used to sequentially correct the roll opening difference set value for the next pass rolling. According to the method of performing dynamic control, there is less variation in control accuracy compared to the conventional method, and a rolled material with a good planar shape can be obtained. On the other hand, according to the conventional method, not only the variation in control accuracy was large, but also the camber was sometimes increased.

〔Effect of the invention〕

As explained above, according to the present invention, as can be seen from FIG. 9, the camber can be stably reduced, and the yield can be greatly improved by reducing the width margin and the split margin caused by the camber. Furthermore, it is possible to prevent damage to the rolling rolls and guides due to the occurrence of camber, which has great time and material benefits.

[Brief explanation of drawings]

Fig. 1 is a block explanatory diagram showing an example of the camber control logic of the present invention, Fig. 2 is a related schematic plan view of a rolled material with lateral bending and when a product is cut out from this material; Figures 3 and 4 are explanatory diagrams of the deformed state of the roll when there is no meandering, respectively.
Figures 5 and 6 are explanatory diagrams of the deformed state of the roll when there is meandering, Figures 7A and B are schematic diagrams showing the plate profile and longitudinal cross section of the plate before and after camber control, respectively, and Figure 8 is FIG. 9a is a diagram showing the relationship between the plate length and camber amount of a rolled material before and after camber control, and FIG. FIG. 9b is a diagram showing the relationship between the plate length and the maximum camber amount when estimated using model formula (4). 1... Rolled material, 2... Product, 3, 3'... Work roll, 4, 4'... Back up roll, 5,
5'...Load cell, 6,6'...Hydraulic pressure reduction device,
7...Hydraulic pressure reduction control panel, 8...Computer, 9
...Arithmetic unit for calculating hdf^, 10...ΔSdf ^*
Arithmetic unit for calculating 11...PI gain.

Claims (1)

[Scope of Claims] 1. A thickness control method in which the camber in the control path is estimated based on the camber amount and wedge amount of the material to be rolled, and the left and right leveling operations of the rolling rolls are performed so that the exit camber in this control path becomes zero. In the camber control method for rolled material in plate rolling, we actually measure the difference in the opening of the left and right rolls, the difference in load between the left and right sides, and the wedge amount of the plate in the previous pass rolling, and based on these measured values, we calculate the difference in the width of the roll in the current pass. The thickness method is characterized in that the amount of deviation from the initial set value of the roll opening degree is determined, and the next pass rolling is performed while sequentially correcting the set value of the roll opening degree during the leveling operation according to the amount of deviation of the roll opening degree. Camber control method for rolled material in plate rolling.