JPH05169120A - Method for controlling camber of rolled stock - Google Patents

Abstract

PURPOSE:To adjust the difference of a roll gap and to prevent the camber of a rolled stock by finding the rigidity of the housing post of a work side and a driving side at the roll shifting time and predicting the difference of the thickness of an outlet side plate during rolling with the predictive value of the rolling load and the rigidity before each pass rolling. CONSTITUTION:The rigidity of respective housing posts of the working side WS and the driving side DS is exactly found at the roll shifting time. Then, the difference of the thickness between the outlet side plate of the working side WS and the driving side DS during rolling is exactly predicted with the predictive value of the rolling load and the rigidity of the housing post before each pass rolling. Then, the difference between the roll gap of the working side WS and the driving side DS is preliminarily adjusted before each pass rolling so as to become zero.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a camber control method for suppressing the occurrence of camber, which is a bend that occurs when rolling a plate-shaped rolled material.

[0002]

2. Description of the Related Art Generally, a rolled sheet material such as a steel sheet is apt to have a so-called camber in which the shape after rolling is curved left and right in the longitudinal direction as shown in FIG. When such a camber occurs in the rolled material 1, the yield when the rolled material 1 is finished into a rectangular product size is reduced, which is a serious problem in terms of manufacturing cost. The amount of camber generated on the rolled material 1 is calculated by comparing the line connecting the widthwise central portions of the rolled material 1 with the width of the rolled material 1.
It is represented by the maximum separation dimension C from the line connecting the widthwise central portions at both ends of, for example, a rolled material having a thickness of 20 mm, a width of 3 m, and a length of 30 m in the rolling of a thick plate, and the dimension C is about Fifty
The value is about mm, but sometimes exceeds 100 mm.

The following factors are generally considered as the causes of such camber. WS on the work side of the housing post in the rolling mill,
There must be a rigidity difference with the drive side DS. A position shift (off-center) between the center line of the roll during rolling and the center line of the rolled material 1 in the width direction occurs. The resistance to deformation in the width direction of the rolled material is uneven due to burning on one side when the rolled material is heated. The material thickness of the rolled material in the width direction is not uniform. Among the above-mentioned factors (1) to (4), various measures have already been taken and the effects have been tentatively achieved, but the current situation is that sufficient measures have not been taken to the factor (1).

As a conventional countermeasure against the difference in rigidity between the work side WS and the drive side DS of the housing post in a rolling mill, for example, Japanese Patent Laid-Open Nos. 54-68761 and 55-141306 are known.
JP-A-55-141307 and other publications calculate the roll gap between the work-side WS and the drive-side DS based on the previously measured mill rigidity of the work-side WS and drive-side DS and the actual rolling load. , A method of adjusting the difference between both roll gaps during rolling has been proposed.

[0005]

However, these conventional techniques have the following problems, and a sufficient effect of preventing camber cannot be expected. The first problem is that in order to carry out the above-mentioned method, it is necessary to accurately obtain the mill rigidity of the work side WS and the drive side DS, so when rolling the rolls, rolling between the upper and lower work rolls is performed. Work side by roll tightening method in the absence of material
We are looking for the mill rigidity of each of WS and DS on the drive side,
During rolling, the rolled material exists between the upper and lower work rolls, and if the strip width of the rolled material changes, the mill rigidity changes accordingly. It is something you cannot ask for.

The second problem is that in the above-mentioned conventional method, the actual rolling load is used to calculate the roll gap, but the rolling load depends on the detection method, such as thrust force, hysteresis due to frictional resistance between the backup roll and the housing, etc. The error of the calculated roll gap value is large because it is affected by disturbance.

The present invention has been made in view of the above circumstances, and an object thereof is to accurately predict the rigidity of the housing posts of the work side WS and the drive side DS by the roll tightening method during roll replacement. In advance, before each pass rolling, the difference between the work side and the drive side of the plate thickness is predicted, and the roll gap is adjusted in advance so that it becomes zero. To provide a method for controlling the camber.

[0008]

A method for controlling the camber of a rolled material according to the present invention finds a roll gap target value on each of a work side and a drive side of a rolling mill, and based on the roll gap target value, a roll gap of the rolling mill. In the method of controlling the camber of the rolled material by adjusting the roll, the mill rigidity of the work side and the drive side is measured by the roll tightening method when changing the rolls, and it is derived from the mechanical deformation amount of the rolling machine in the roll tightened state. Using the relational expression between the measured value of the mill rigidity and the rigidity of the housing post, the rigidity of each housing post on the work side and the drive side is calculated, and the housing is calculated based on the mechanical deformation amount of the rolling mill during rolling. By using the relational expression between the rigidity of the post and the roll gap difference, the exit side plate thickness of each of the work side and the drive side during rolling before each pass rolling To obtain the target value of the roll gap difference between the work side and the drive side required to make the difference zero, and set and adjust the roll gaps of the work side and the drive side of the rolling mill based on the roll gap difference target value. Is characterized by.

[0009]

According to the present invention, the rigidity of each of the housing posts on the work side and the drive side is obtained when the rolls are recombined, and based on this, the predicted value of the rolling load and the rigidity of the housing post are calculated before each pass rolling. From the work side during rolling,
The camber that occurs on the rolled material can be accurately predicted and the roll gap difference between the work side and the drive side can be adjusted in advance before each pass rolling so that the difference in the output side plate thickness can be predicted to be zero. Can be prevented.

[0010]

[Principle] As described above, if there is a rigidity difference between the work side WS and the drive side DS of the housing post, if the roll gap S _W. It is the difference S _df of _{S D (= S W -S D} ) is set to be 0,
During rolling, the difference in roll gap, that is, the difference between the plate thicknesses h _W and h _D on the widthwise side at the exit side, the so-called wedge amount h _df (= h _W
-H _D ) occurs, and as a result, camber occurs.

To improve the roll gap control accuracy by the work side WS and the drive side DS respectively, the work side W
The technical points are the accuracy of predicting the rigidity of the housing post in S and the drive side DS, and the accurate prediction of the rolling load before each pass rolling. Among them, the rolling load prediction accuracy can be predicted practically enough even with the conventional technology.

[0012] Therefore, as to the rigidity of the housing post, which is another point, as a result of experiments and researches conducted by the inventor of the present invention in order to improve the measurement accuracy, the roll tightening method is used based on the theoretical analysis using the 4Hi mill roll deflection model. It was found that the rigidity of the housing post in each of the work side WS and the drive side DS can be accurately obtained from the measured values of the mill rigidity.

In the 4Hi mill roll deflection model, the roll cylinder length of the rolled material is divided into small width regions of 20 to 40, and the rolling load and the contact load between rolls are uniform in each divided section in the roll cylinder length direction. Considering that they are distributed, the backup rolls, work rolls, and rolling materials have the same displacement at the center of each divided section, that is, they are in contact with each other. Calculate the deformation theoretically. i) Flat deformation of work roll due to contact with rolled material ii) Deflection of shaft center of work roll iii) Flat deformation of contact part between work roll and backup roll iv) Deflection of axial center of backup roll v) Extension of housing post For the calculation of the roll tightening state in which there is no rolled material between the upper and lower work rolls, the condition that the thickness of rolled material is zero, the width is the same as the roll cylinder length, and the plasticity coefficient is infinite is set in this model. This can be done by

Assuming an actual thick plate rolling machine, the distance between backup roll chocks is 5900 mm, the roll body length is 4830 mm, the backup roll diameter is 2000 mm, and the work roll diameter is 1000 mm. The relation between the rigidity of the housing post between the work side WS and the drive side DS and the rigidity of the mill, and the rigidity of the housing post between the work side WS and the drive side DS, which were calculated based on the results of i) to v). The relationship between the difference and the mill rigidity difference is shown in graphs as shown in FIGS.

FIG. 2 is a graph showing the relationship with the mill rigidity M by the roll tightening method when the rigidity K _W and K _D of both housing posts on the work side WS and the drive side DS are assumed to be the same. Yes, the horizontal axis indicates mill rigidity M (ton / m
m), and the vertical axis indicates the rigidity of the housing post K (ton / m
m) is shown. Further, FIG. 3 shows the difference in rigidity K of the housing post when it is assumed that the rigidity K _W and K _D of the housing post of the work side WS and the drive side DS are different.
₆ is a graph showing the relationship between _df (= K _W −K _D ) and the mill rigidity difference M _df (= M _W −M _D ) obtained by the roll tightening method, with the horizontal axis representing the work side WS and the drive side DS. Mill rigidity difference M
_df (ton / mm) and work axis WS and drive DS on the vertical axis
The difference in rigidity K _df between the housing posts is shown.

In the graph shown in FIG. 3, the ● marks are plotted when the rigidity of the housing post is K = 1000, and the ○ marks are plotted when K = 1700.
The plots with the marks show the respective relationships when K = 2000 ton / mm. From the relationships shown in FIGS. 2 and 3, the relational expressions shown in the expressions (1) to (4) are established. K = F ₁ (M) (1) K _df = F ₂ (K, M _df ) (2) K _W = K + K _df / 2 (3) K _D = K−K _df / 2 (4)

Therefore, by measuring the mill rigidity M and the mill rigidity difference M _df by the roll tightening method, the rigidity K of the housing post and the rigidity difference K _df of the housing post can be obtained from the equations (1) and (2). Moreover, the rigidity K _W and K _D of the housing posts of the work side WS and the drive side DS can be accurately obtained from the expressions (3) and (4). By the way, the object of the present invention is the difference in rigidity between the work side WS and the drive side DS of the housing post among the factors that cause camber. You can assume that there is no unevenness. However, due to the difference in rigidity of the housing posts, even if the roll gap difference S _df (= S _W −S _D ) between the work side WS and the drive side DS before rolling is set to zero, the roll gap during rolling is reduced. A difference, that is, a wedge amount h _df (= h _W −h _D ) of the outgoing side plate thickness occurs, and as a result, a camber occurs.

Therefore, it is the next important technical point to understand the relationship between the roll gap difference S _df before rolling and the wedge amount h _df of the outgoing side plate thickness. Assuming the conditions of the thick plate rolling machine described above, the roll gap difference S is calculated by using the result of calculating the above i) to v) under the condition that the rolled material exists between the upper and lower work rolls using the 4Hi mill roll deflection model.
expressed in a graph the relationship between the wedge amount h _df of thickness at delivery side of the _df, becomes as shown in FIG.

FIG. 4 shows the work side WS and the drive side DS before rolling.
It is a graph showing the relationship between the roll gap difference between and the wedge amount of the outgoing side plate thickness, the incoming side plate thickness of the rolled material is 20 mm, the plate width is 30 mm.
00mm, plasticity coefficient 700ton / mm, predicted rolling load 3000ton, average value K of rigidity of housing post of work side WS and drive side DS is 1700ton / mm, work side WS and drive side
The results are obtained when the rigidity difference K _df with DS is changed in three ways of 0, 100, and 200 ton / mm.

It can be seen from FIG. 4 that the relationship of the following formula (5) is established between the roll gap difference before rolling and the wedge amount of the outlet side plate thickness h _df = F ₃ (B, Q, P , K _W , K _D , S _df ) (5) where B: strip width, Q: plasticity coefficient, P: predicted rolling load. Therefore, the condition for not causing camber is that the wedge amount h _df of the outlet side thickness is zero. since it is possible to, and that you put only S _df the roll gap difference prior (5) determine the roll gap difference S _df between the work side WS and drive side DS required thereto from the equation, to each path rolling If so, the occurrence of camber can be prevented in advance.

[0021]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be specifically described below with reference to the drawings showing the embodiments. FIG. 5 is a schematic view of an apparatus for carrying out the method for controlling the camber of a rolled material according to the present invention. In the figure, 1 is a rolled material, 2 and 3 are work rolls, and 4 and 5 are backup rolls. Rolling down devices 6 and 7 are provided on each roll chock on both sides (work side WS and drive side DS) of the upper backup roll 4. Roll chock of backup roll 4 and each rolling down device 6,7
Between the load detectors 8 and 9 composed of load cells and the like.
However, the respective rolling-down devices 6, 7 are provided with rolling-down position detectors 10, 11.

Reference numeral 21 is an automatic plate thickness control device (device for performing AGC), which takes in the rolling load and the reduction position from the load detectors 8 and 9 and the reduction position detectors 10 and 11, respectively. The roll gap control amount ΔS _AGC is calculated on the basis of the preset plate thickness of the rolled material 1, the rigidity of the mill, etc., and this is output to the respective rolling position command computing devices 22 and 23. Each of the rolling position command computing devices 22 and 23 operates the rolling down devices 6 and 7 based on the input roll gap control amount ΔS _AGC .

26 is a roll gap target value setting device, 27 is a roll gap difference target value setting device, and the roll gap target value setting device 26 reduces the roll gap target value S ₀ at the center position in the width direction of the rolled material 1 by the reduction. Position command calculation device 22,2
3, and the roll gap difference target value setting device 27 outputs the plate width B and the plasticity coefficient Q of the rolled material 1 which are preset and input.
And the mill rigidity M ⁰ by the roll tightening method measured by the mill rigidity measuring device 28, the work side mill rigidity M ⁰ _{W, the} drive side mill rigidity M ⁰ _D , and the predicted rolling load P input from the rolling load prediction calculation device 29. _The roll gap difference target value S ⁰ _df is calculated based on ₀ , and is output to each of the rolling position command computing devices 22 and 23.

The calculation by the roll gap difference target value setting device 27 is roughly classified into a calculation performed at the time of roll rearrangement and a calculation performed prior to each pass rolling, and the calculation contents in each will be described below.

(1) Calculation during roll combination Mill rigidity measurement device 28 measures the mill rigidity M ⁰ by the roll tightening method and stores it, work side WS and drive side
Read each mill stiffness M ⁰ _W and M ⁰ _D with DS. Next, the difference in mill rigidity between the work side WS and the drive side DS M ⁰ _df (=
M ⁰ _W −M ⁰ _D ) and calculate the rigidity K ⁰ _W and K ⁰ _D of each housing post on the work side WS and drive side DS.
It is calculated according to the following equations (1) ′ to (4) ′ corresponding to equations (1) to (4). _{^{K 0 = F 1 (M 0}} ) ... (1) 'K 0 df = F 2 (K 0, M 0 df) ... (2)' K 0 W = K 0 + K 0 df / 2 ... (3) 'K ⁰ _D = K ⁰ −K ⁰ _df / 2 (4) ′

(2) Calculations to be carried out before each pass rolling: The plate width B of the rolled material, the plasticity coefficient Q, and the rigidity K ⁰ _W and K ⁰ _{D of the} housing post which are obtained and stored when the rolls are recombined. Based on the predicted rolling load P ₀ read from the rolling load prediction calculation device 29, the roll gap difference target value S between the work side WS and the drive side DS before rolling is calculated according to the following formula (5) ′ corresponding to the above formula (5). _Calculate ⁰ _df . F ₃ (B, Q, P ₀ , K ⁰ _W , K ⁰ _D , S ⁰ _df ) = 0 (5) ′

Next, the method of the present invention will be described with reference to specific numerical values. In the example of the present invention shown in FIG. 5 and the comparative example in which the roll gap difference is adjusted from the mill rigidity of the work side WS and the drive side DS and the actual rolling load, the same plate thickness 20 mm, plate width 3000 mm,
Ten thick steel plates each having a plate length of 30 m were rolled, and the amount of camber after rolling was measured and compared. As a result, it was confirmed that the average camber amount was 40 mm in the comparative example, whereas the average camber amount was 15 mm in the present invention.

[0028]

As described above, according to the method of the present invention, the rigidity of each of the housing posts on the work side and the drive side is accurately obtained when the rolls are reassembled, and the predicted value of the rolling load and the above-mentioned values are calculated before each pass rolling. The rigidity of the housing post is used to accurately predict the difference between the output side plate thickness of the work side and the drive side during rolling, and the roll gap difference between the work side and drive side is pre-determined before each pass rolling so that it becomes zero. The present invention has excellent effects such that the effect of preventing camber can be greatly improved by adjusting the camber as compared with the conventional method.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of a camber.

2 is a graph showing the relationship between the mill stiffness M by roll tightening method in the case where the stiffness K _W and K _D of the housings posts between the work side WS and drive side DS is assumed to equal stiffness K.

[Fig. 3] Fig. 3 shows a difference in rigidity K _df of the housing post and a difference in mill rigidity M _df obtained by the roll tightening method, assuming that the rigidity K _W and K _D of the housing post on the work side WS and the drive side DS are different. It is a graph which shows a relationship.

FIG. 4 is a graph showing a relationship between a roll gap difference between a work side WS and a drive side DS before rolling and a wedge amount of a delivery side plate thickness.

FIG. 5 is a schematic view of an apparatus for carrying out the method of the present invention.

[Explanation of symbols]

 1 Rolled material 2, 3 Work rolls 4, 5 Backup rolls 6, 7 Rolling down device 8, 9 Load detector 10, 11 Rolling down position detector 21 Automatic plate thickness control device 22,23 Rolling down position command calculation device 24,25 Rolling down position Control device 26 Roll gap target value setting device 27 Roll gap difference target value setting device 28 Mill rigidity measuring device 29 Rolling load prediction calculation device

Claims (1)

[Claims] 1. A method for controlling a camber of a rolled material by obtaining a roll gap target value for each of a work side and a drive side of a rolling mill, and adjusting a roll gap of the rolling mill based on the roll gap target value to control a camber of a rolled material. Sometimes, the roll rigidity method is used to measure the mill rigidity of each of the work side and drive side, and the relational expression between the measured rigidity value of the mill and the rigidity of the housing post, which is derived from the mechanical deformation amount of the rolling mill in the roll tightened state, is used. Then, the rigidity of each of the housing posts on the work side and the drive side is obtained, and by using the relational expression between the rigidity of the housing post and the roll gap difference obtained based on the mechanical deformation amount of the rolling mill during rolling, Before the pass rolling, the roll gap between the work side and the drive side, which is necessary to reduce the difference between the output side plate thicknesses of the work side and the drive side during rolling, to zero. A method for controlling the camber of a rolled material, which comprises obtaining a target value for the roll-up difference and setting and adjusting the roll gaps on the work side and the drive side of the rolling mill based on the target value for the roll gap difference.