JP2989099B2 - Prediction method between rolls of 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 accurately predicting the flatness between rolls in a contact area between rolls of a rolling mill.

[0002]

2. Description of the Related Art In recent years, sheet crowns and sheet shapes have become very important due to the need for higher dimensional accuracy and higher quality of products in hot rolling. Therefore, accurate control of the crown and shape of a rolling mill such as a steel plate in continuous rolling is important not only to maintain the product of the rolled material but also to avoid trouble during rolling. For this reason, a roll bending device and a variable crown roll are provided in each stand of the continuous rolling mill, and in each stand, the amount of operation is adjusted to control the crown and the shape to target values.

On the other hand, in order to cancel the deflection of the roll due to the rolling load, an initial crown roll is attached to improve the thickness accuracy of the rolled product in the strip width direction. When rolling conditions such as change, it is necessary to replace the roll with another crown roll, so it is necessary to hold a roll having various types of initial crowns, Since the roll ratio is significantly changed due to the roll wear and thermal expansion accompanying the progress of the rolling operation etc., the thickness distribution in the plate width direction of the plate material can be reduced without replacing the roll conventionally. There is a need for a means to control.

[0004]

Therefore, accurate grasping of the inter-roll flatness at any point in the width direction of the inter-roll contact area based on the rolling load is necessary for predicting the roll profile or the sheet thickness by mill stretching. Because of the importance, a method of calculating the flatness between the rolls has been proposed as a means for accurately grasping the flatness between the rolls. Conventionally, the calculation of this contact load distribution between rolls is based on the assumption that roll deflection is considered as beam deflection, the contact load distribution between rolls is approximated by a simple quadratic function, and the roll bias is assumed to be spring between rolls. In addition, the bending equation of the beam can be solved. However, the distribution of the contact load between the rolls cannot be generally expressed by a simple function, so that there is a problem that a calculation error is large. Also,
A method has been proposed in which a roll is divided in the axial direction, and roll deflection and flattening are simultaneously performed for each division to obtain roll flattening. However, according to this method, a large number of divisions are required to secure calculation accuracy. Required, which has the disadvantage of requiring a long calculation time.

[0005]

Means for Solving the Problems The present inventors have intensively developed to solve the above-mentioned problems, and as a result, have made it easy to predict the flatness between rolls of a rolling mill, and to accurately and accurately grasp the flatness between rolls. A method that enables highly accurate calculation of the flatness between rolls for high-precision and high-quality products in hot rolling by enabling roll profile prediction and sheet thickness prediction by mill stretching. Is to provide. The gist of the present invention is to simply calculate the roll deflection due to the roll-to-roll contact load of the rolling mill as the beam deflection and to divide the roll-to-roll contact load calculation into terms of the optimum approximate roll curve and the deviation roll curve. The present invention provides a method for predicting the flatness between rolls of a rolling mill, wherein the flattening amount between rolls can be easily and highly accurately calculated.

Hereinafter, the present invention will be described in detail with reference to the drawings. FIG. 1 is an explanatory diagram of an effect on a work roll deflection caused by a rolling load. As shown in FIG.
In a rolling mill provided with heavy rolls, a work roll 2 for rolling a rolled material 1 and a backup roll 3 in contact with and reinforcing the work roll 2 are provided. When rolling is performed in this configuration, the rolling load is applied to the upper and lower backup rolls 3, the work rolls 2 and the backup rolls 3 come into complete contact, a contact load distribution between the rolls occurs, and the roll gap existing when there is no load. In the width direction affects the deflection of the work roll through the width distribution of the load acting on the contact surface between the work roll 2 and the backup roll 3.

FIG. 2 is an explanatory diagram showing the distribution of loads applied to the work rolls and the backup roll, and the flatness between the rolls. As shown in FIG. 2, the roll-to-roll contact load distribution 4 generated in the backup roll causes the roll axis deflection due to the load distribution 5 applied to the work roll. Reference numeral 6 denotes a backup roll lower surface profile when there is no inter-roll flattening, 7 denotes a work roll upper surface profile when there is no inter-roll flattening, 8 denotes a roll boundary profile when there is roll-to-roll flattening, and 9 denotes an inter-roll flattening amount. It is.

FIG. 3 is an explanatory diagram for calculating a roll curve in a contact area between a work roll and a backup roll by an approximate quadratic equation. That is, as shown in FIG. 3, the calculation of the roll curve in the contact area between the work roll and the backup roll can be simplified into a model, and can be determined by an approximate quadratic equation. The basic method of obtaining the approximate quadratic equation is such that the zero-order and first-order moments are balanced only on one side of the roll.
The following equation is determined, and its quadratic equation is as follows.

Y = a _i X ² (1) where a _i = −6 / X _i ³ × S _i + 12 / X _i ⁴ × G
_{i b i = 3 / X i} × S i -4 / X i 2 × G i _{Note, S i = y 1 △ X} 1 (i = 1) S i = y 1 △ X 1 + S i-1 (i = _{2,3, ...) G i = y} 1 × X 1 × △ X 1 (i = 1) G i = y i × X i × △ X i + G i-1 (i = 2,3, ...) Moreover, The approximate roll crown in the WR-BUR contact area RC _j = −aj × ( _LR / 2) ² (2)

Next, an inter-roll flatness amount δ (x) at an arbitrary point x in the roll axis direction is obtained. As prerequisites, when considering the inter-roll contact state between the work roll and the backup roll shown in FIG. 2, (1) an external force other than the contact load between the work roll and the backup roll and a contact area between the rolls are given in advance (external force). (2) The local linear load between the rolls and the flatness between the rolls (the amount of axial center approach between the two rolls) are proportional. That is, assuming that the average inter-roll flatness is δ, the sum of all the external forces applied to the A roll is the sum of all the external forces applied to the B roll, based on the assumptions (1) and (2). Contact load P between B rolls
_AB .

Accordingly, δ = P _AB / (K _AB × I _AB ) (3) where P _AB : Line load between _AB rolls K _AB : Spring constant between _AB rolls δ: _AB roll Flatness l _AB : Contact length between _AB roll

(3) The roll curve is represented by the relationship of the axial coordinates. The positive and negative values of the roll curve are positive convex curves for both A and B rolls.
The case where the roll edge is bent downward when B is defined as down is defined as positive. Further, the defined area of the roll deflection and the roll curve is the inter-roll contact area. Δ is obtained under such conditions. δ (x) = δ _SQ + δ _RND (4) where δ _SQ : flatness between rolls when the roll curve is approximated by an optimal quadratic equation δ _RND : difference between the original roll curve and the optimal quadratic approximate curve (Deviation roll curve)

[0013] The optimum roll curve is a curve obtained by quadratic approximation of an original roll curve in which the influence of the deviation roll curve on roll deformation can be regarded only as inter-roll flattening. Is as follows. δ _SQ = δ ₀ + δ ₁ + f _A + f _B (5) where, f _A , f _B : symmetric components of deflection of A and B rolls δ ₁ = δ _DEF + δ _P δ ₀ = δ + [average value of f _A ] - [f mean] [delta] _P of _B: components [delta] balances with moment of force due to an external force of a roll alone (load distribution due to [delta] _P are balanced moment of forces generated) [delta] _DEF: the asymmetric component of the deflection roll component f _a of δ counteract the moment of force produced, f _{B: a-B} between the contact load distribution a simple function (e.g.
Assuming a quadratic equation, solve the beam bending equation in material mechanics. δ _RND = δ _RND.A + δ _RND.B However, deviation curve [delta] _RND.B of [delta] _RND.A is A roll deviation curve B roll

[0014] Incidentally, δ _0, δ _DEF, specific examples of the _{δ P, (1) δ 0} δ 0 = δ- (1-α A -α B) / l AB ∫ [C B -C A +
C _RA + C _RB ] dx where C _A , C _B : simple deflection (deflection of the beam bending equation assuming that P _{AB is} constant) α _A , α _B : gap influence coefficient between rolls C _RA , C _RB : Optimum second-order approximation roll crown value (2) δ _P δ _P = 12 / (K _AB × I _AB ) [Ｐ _Pi P _i xdx] x, where N: Number of load areas P _i : External pressure for one roll (i = 1 to N)

(3) δ _DEF δ _DEF = 12 (1−α _A −α _B ) / l ³ _AB [∫ ｛C _B −
_{C A + C RA + C RB} } xdx] x (4) f A, f B f A = (1-α A) C A + α A (C B + C RA + C RB) f B = (1-α B) C B + Α _B (C _A −C _RA −C _RB ) In this manner, the calculation is performed by dividing the terms into the optimum approximate roll curve and the deviation roll curve, which can be applied to an arbitrary distribution of the contact load between rolls. Thereby, flat calculation between rolls with good calculation accuracy became possible.

[0016]

As described above, considering the contact load between the rolls of the rolling mill according to the present invention as a beam, the roll deflection can be easily calculated, and the flatness between the rolls at any point in the width direction of the contact area between the rolls can be obtained. By dividing the amount into terms of the optimal approximation roll curve and the deviation roll curve, it is easy to predict the flatness between rolls, and it is possible to accurately and accurately grasp it. Roll profile prediction, sheet thickness prediction by mill stretching, etc. High precision of products in hot rolling,
It is an excellent effect that can achieve high quality.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of an effect on a work roll deflection caused by a rolling load,

FIG. 2 is an explanatory diagram showing a load distribution applied to a work roll and a backup roll, and flatness between rolls;

FIG. 3 is an explanatory diagram for obtaining a roll curve in a contact area between a work roll and a backup roll by an approximate quadratic equation.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Rolled material 2 Work roll 3 Backup roll 4 Contact load distribution between rolls 5 Distribution of load applied to work rolls 6 Backup roll lower surface profile when there is no flatness between rolls 7 Work roll upper surface profile when there is no flatness between rolls 8 Flatness between rolls Boundary Profile with Rolls 9 Flatness between Rolls

Claims (1)

(57) [Claims] 1. A roll deflection caused by a roll-to-roll contact load of a rolling mill is easily calculated as a beam deflection, and the roll-to-roll contact load calculation is divided into terms of an optimum approximate roll curve and a deviation roll curve. A method for predicting the flatness between rolls of a rolling mill, wherein the flattening amount can be easily and highly accurately calculated.