JPH07148512A - Method for rolling - Google Patents

Abstract

PURPOSE:To control the correct plate crown, the plate shape, and the leveling even when there is difference between the actual roll profile and the preset profile. CONSTITUTION:The diameters 1u, 1d of upper and lower rolls are respectively measured at the positions in the axial direction whose number is larger than the maximum order of the profile, and when the number of the positions of measurement is same as the maximum order, the coefficients of the function to express the upper and lower roll profiles are determined by using the measured roll diameters. When the number of the positions of measurement is larger than the maximum order, the measured span of the roll is interpolated to approximate the actual upper and lower roll profiles respectively. This operation determines the actual upper and lower roll profiles Ru(x), Rd(x), the roll gap profile G(x) is obtained from the difference between the upper and lower roll profiles Ru(x), Rd(x), and the plate crown and the plate shape are controlled based on this roll gap profile G(x).

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a work roll whose profile is a polynomial function whose highest-order term with respect to the distance in the axial direction of the roll is a third order or higher, or an intermediate roll (hereinafter, higher-order function work roll, or High-order function intermediate rolls (both are collectively called higher-order function rolls) are arranged in point symmetry, and upper and lower higher-order function rolls are moved relative to each other in the axial direction to The present invention relates to a method for controlling a plate crown, a plate shape, or leveling in rolling for controlling a plate crown or a plate shape.

[0002]

2. Description of the Related Art A roll gap profile in the axial direction when high-order function work rolls are arranged symmetrically with respect to the upper and lower points, or a work roll along an intermediate roll profile when high-order function intermediate rolls are arranged with respect to the upper and lower points The axial work roll gap profile when it is assumed to be bent is the same as the axial roll gap profile of the upper and lower work rolls with symmetrical symmetrical convex or concave initial crowns whose quadratic curve is an even function profile. There is a distribution, and this initial crown is called an equivalent roll crown.

In this case, when the respective rolls are shifted in the opposite axial directions, the equivalent roll crown continuously changes according to the shift amount, so that the plate crown and the plate shape can be controlled.

[0004]

By the way, during rolling using a higher-order function roll, the meandering of the material to be rolled due to the plate crown and the plate shape and the difference in plate thickness between left and right should not be adversely affected. Therefore, it is necessary to manage the setting profile of the higher-order function roll set in the plate crown and the shape control computer so that the roll profile after grinding has the same shape. If the difference between the setting profile and the grinding profile is large. The difference between the roll gap profile obtained from the set profile and the actual roll gap profile becomes large.

1 and 2 are graphs showing the effect of the difference between the set profile and the grinding profile on the actual roll gap profile. Note that FIG. 1 (a) and FIG.
In (a), the upper higher-order function roll is ground so as to follow the set profile, and the lower higher-order function roll is displaced from this set profile by the amount shown in each figure.

If the central diameter of the grinding profile is different from the set profile as shown in FIG.
As shown in (b), the difference between the set value and the actual value of the effective crown representing the roll crown per plate crown evaluation position becomes large, which adversely affects the plate crown and the plate shape. On the other hand, when the difference between the maximum diameter and the minimum diameter of the grinding profile is different from the set profile as shown in FIG. 2 (a), the roll gap profile becomes asymmetrical as shown in FIG. A difference in strip thickness occurs and the meandering of the rolled material is caused.

Particularly in rolling using a higher-order function roll, unlike the case of using a symmetrical symmetrical convex or concave initial crown roll whose profile is an even function such as a quadratic curve, which is usually used, The deviation of the roll profile does not appear in the roll gap profile difference as a constant offset amount, but the effective crown and the left and right roll gap difference fluctuate depending on the shift amount of the higher-order function roll and the plate width of the rolled material. It was difficult to correct it accurately.

From the above, conventionally, the set profile of the higher-order function roll and the actual roll profile after grinding are made to have the same shape as much as possible, and the higher-order function roll profile is measured after the roll is ground. The rolls that were out of tolerance had to be reground. However, even if the difference between the set roll profile and the grinding roll profile is within the tolerance, there is a difference of the order of the tolerance between the roll gap profile obtained from the set profile and the actual roll gap profile. It was difficult to grasp the difference between the left and right roll gaps and perform accurate plate crown and shape control and leveling control.

Therefore, even if the tolerances are widely set as in the prior art in order to perform accurate plate crown and shape control and leveling control, there is a limit to the accurate plate crown control and shape control, and moreover, there is a limit. The number of higher-order function rolls that need to be ground is increased and the grinding time is increased. Therefore, it becomes necessary to increase the number of held rolls. In view of such circumstances, the present invention, in rolling using a polynomial high-order function roll, even if there is some difference between the actual roll profile and the set profile, accurate plate crown, plate shape and The purpose is to be able to control the leveling.

[0010]

[Means for Solving the Problems] In order to achieve the above object,
The present invention has taken the following technical means. That is, in the invention according to claim 1, the highest order term relating to the roll axial center distance is 3
The upper and lower rolls whose profile is a polynomial function that is greater than or equal to the following are arranged point-symmetrically with respect to the rolling center, and the upper and lower rolls are moved relative to each other in the axial center directions in opposite directions to control the strip crown and strip shape of the material to be rolled. In the rolling method to
The diameters of the upper and lower rolls are respectively measured at axially higher positions than the highest order of the polynomial function representing the profile, and when the number of measurement positions is the same as the highest order, the measured roll diameter is used to represent the upper and lower roll profiles. By determining the coefficient of the function, if the number of measurement positions is greater than the highest order, the actual upper and lower roll profiles are determined by interpolating the measured roll spans and approximating the actual upper and lower roll profiles. The roll gap profile is obtained from the difference between the upper and lower roll profiles, and the plate crown and the plate shape are controlled based on this roll gap profile.

According to a second aspect of the present invention, based on the roll gap profile obtained by the method according to the first aspect, the roll gap is obtained as a difference between the profile values at two positions equidistant from the axial center. The difference is obtained, and the inclination of the upper and lower rolls is corrected by the difference of the roll gap.

[0012]

In the following, as shown in FIG. 3, the roll profile is 3
The method of the present invention will be specifically described as represented by a polynomial function of degree. First, if the upper profile of the upper higher-order function roll is expressed as Y = ax ³ + bx ² + cx (1) (where a, b, and c are constants) using the axial position x, The lower profile of the lower high-order function roll is point-symmetrical to the upper roll, and is expressed as follows.

Y = ax ³ −bx ² + cx (2) Since the upper and lower roll profiles do not become exactly the same when grinding is actually performed, the respective coefficients are represented by subscripts _u and _d below. I will. In this case, the material to be rolled side profile R _u of the upper and lower rolls _{(x), R d (x} ) _{is, R u (x) = -} a u x 3 -b u x 2 -c u x R d (x) = _{^{-a d x 3 + b d x}} 2 -c d x ...... is (3).

When the number of measurement points is the same as the highest order, upper-order function roll radii R _u (x ₁ ) _, R _u (x ₂ ) _, R _u measured at axial position x _1, x ₂ , x ₃ Using (x ₃ ), the coefficients a _u , b _u , c _u are determined as follows.

[0015]

[Equation 1]

The coefficients a _d , b _d , and c _d indicating the profile of the lower high-order function roll are also determined in the same manner as the above equation. Here, when the upper and lower higher-order function rolls are moved by the shift amount s, the directions of the shifts are upside down. Therefore, the roll profiles are R _u (x−s) and R _d (x + s), respectively.
Becomes Therefore, in this case, the roll gap profile G (x) is expressed by G (x) = R _u (x−s) −R _d (x + s) (5) by taking the difference between them.

Here, this roll gap profile G
Using (x), the effective crown CE and the left and right roll gap difference L at the plate crown evaluation position x = W can be obtained as follows.

[0018]

[Equation 2]

L = G (W) -G (-W) (7) On the other hand, when the upper and lower roll diameters at three or more points are measured
Also, for example, interpolation between the measurement positions with a spline curve
Curve R that approximates the roll profile_u(X), R
_dBy using (x), the roll gap profile
The file G (x) can be determined.

Therefore, the effective crown CE and the left / right roll gap difference L can be obtained as in the case of measuring at three points. The present invention provides the effective crown C obtained as described above.
By using E and the left / right roll gap difference L, even if there is a certain difference between the actual roll profile and the set profile, more accurate control of the plate crown and plate shape and leveling control are performed than in the past. .

For example, in the plate crown control method shown in Japanese Patent Application No. 63-259503, the delivery plate crown CR is used.
Is predicted and controlled as follows. CR = (1−η) c + η (1−r) CR ′ (8) where c = a ₁ · P + A ₂ · CW + a ₃ · F + (Other influence terms) (9) where η: Crown genetic coefficient r: Reduction ratio c: Mechanical plate crown CR ′: Incoming plate crown P: Rolling load CW: Plate width Roll crown per hit F: Work roll bending force a ₁ , a ₂ , a ₃ : Influence coefficient That is, in the above formulas (8) and (9), the value obtained from the set roll profile was used as the conventional CW.
In the present invention, the effective crown CE obtained by the above-mentioned procedure is C
Instead of W, it is possible to accurately predict and control the plate crown.

Further, the plate shape of the rolled material can be predicted and controlled by obtaining the plate shape at this time from the change of the rolled material ratio crown. Leveling control is performed by always correcting the left and right screw positions by the left and right roll gap difference L, that is, as a difference between profile values at two positions equidistant from the axial center as shown in formula (7). By obtaining the gap difference L and correcting the inclinations of the upper and lower work rolls by the roll gap difference L, it is possible to eliminate the difference between the left and right plate thicknesses of the rolled material and the meandering of the rolled material due to the difference.

[0023]

[Examples] As work rolls for a four-high rolling mill, 27 sheets of hot steel were rolled using two upper and lower higher order function rolls.
However, as shown in Fig. 4, the upper high-order function roll has been ground until it reaches almost the set profile, and the lower high-order function roll has the difference between the maximum diameter and the minimum diameter as shown in Fig. 4, but the central part has the diameter. Those having a maximum deviation of 40 μm were used.

Using the actual data of each rolled material, Japanese Patent Application No.
The plate crown after rolling was calculated by the plate crown calculation method of 3-259503 and compared with the actual plate crown after rolling. The result is shown in FIG. However, in the case of using the effective crown CE shown in the formula (6) as the roll crown CW per plate width as in the method of the present invention and in the conventional case of using the set roll crown assuming that the upper and lower higher order function rolls have the same profile. And both were calculated.

The calculation plate crown of the conventional method using the set roll crown is deviated by about 20 μm at the maximum, whereas the difference between the calculation plate crown and the actual plate crown is 15 μm at the maximum in the method of the present invention. It can be seen that the difference in value is reduced. As can be seen from FIG. 1 (b), when the shift amount is positive, the difference between the effective crowns of the present invention and the conventional method is small. Therefore, in FIG. 5 as well, the difference between the calculated plate crowns is small. ing.

As described above, according to the present invention, the plate crown can be predicted more accurately than before. In the rolling of this example, the above-described leveling control method was used, so that the material to be rolled did not meander.

[0027]

As described above, according to the present invention,
When rolling using a higher-order function roll, since the plate crown and the like are controlled based on the roll gap profile obtained from the actual roll diameter, there is some difference between the actual roll profile and the set profile. Even if it occurs, the plate crown, plate shape, and leveling can be controlled more accurately than before.

[Brief description of drawings]

1A is a graph showing a difference between a set profile and a grinding profile, and FIG. 1B is a graph showing an effect of the difference on an actual roll gap profile.

FIG. 2A is a graph showing a difference between a set profile and a grinding profile, and FIG. 2B is a graph showing an effect of the difference on an actual roll gap profile.

FIG. 3 is a conceptual diagram showing a roll gap profile determination method when the highest order of a higher-order function is third order.

FIG. 4 is a graph showing roll shapes of higher-order functions used in the examples.

FIG. 5 is a graph showing prediction accuracy of a plate crown according to the present invention and a conventional method.

[Explanation of symbols]

 1u Upper higher-order function roll 1d Lower higher-order function roll 2 Rolled material

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical display location B21B 38/02 8315-4E B21B 37/00 116 T 8315-4E 116 M (72) Inventor Mikihiro Komatsu 1 Kanazawa Town, Kakogawa City, Hyogo Prefecture Kadogawa Steel Works Kakogawa Works

Claims (2)

[Claims] 1. The upper and lower rolls whose profile is a polynomial function whose highest-order term with respect to the distance in the axial direction of the roll is a third order or higher are arranged point-symmetrically with respect to the rolling center. In the rolling method of controlling the plate crown and plate shape of the material to be rolled by relatively moving in the direction, the diameters of the upper and lower rolls are respectively measured at the axial direction positions of the highest order or higher of the polynomial function representing the profile, and the measurement is performed. When the number of positions is the same as the highest order, the measured roll diameter is used to determine the coefficient of the function that represents the upper and lower roll profiles, and when the number of measured positions is greater than the highest order, the measured roll diameter is interpolated. Then, the actual upper and lower roll profiles are determined by approximating the actual upper and lower roll profiles. Determine the roll gap profile from the difference,
A rolling method characterized by controlling a plate crown and a plate shape based on the roll gap profile. 2. Based on the roll gap profile obtained by the method according to claim 1, a roll gap difference is obtained as a difference between the profile values at two positions equidistant from the axial center, and the roll gap difference is obtained. A rolling method characterized by correcting the inclination of the upper and lower rolls by the amount of.