JP3167440B2 - Endless rolling method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an endless rolling method in which rolled materials differing in one or more of sheet width, sheet thickness and steel type are joined to each other so as to be continuously processed without interruption. In particular, the present invention intends to give an appropriate crown to each rolled material.

[0002]

2. Description of the Related Art As a means for controlling the thickness of a rolled material in the width direction, a roll bending method is generally used. However, recently, the demand for the thickness accuracy of the rolled material is becoming stricter year by year, and it is not possible to perform sufficient crown control only by relying on such a roll bending method.

Therefore, as a technique for increasing the crown control ability, a rolling mill that imparts a taper to the end of the roll to shift the roll in the axial direction (see Japanese Patent Publication No. 56-20081).
A shift mill such as a so-called CVC mill (see Japanese Patent Application Laid-Open No. 56-30014) that relatively shifts a roll having a corrugated crown up and down has been proposed, and has been used in combination with roll bending.

[0004] Crown control of a shift mill used as a hot finish rolling mill is performed by setting a shift position in a rolling gap between a preceding rolled material and a subsequent rolled material, and crown control during rolling is performed by a roll bender. It is customary.

[0005]

Recently, in order to increase the efficiency of hot finishing tandem rolling, a so-called endless method in which rolled materials of different widths, thicknesses or steel types are joined and rolling is continuously performed. Rolling is taking place. In this endless rolling, it is necessary to change the roll bending force and the roll shift position to values suitable for the size of the rolled material and the type of steel during running in order to set the crowns of all the rolled materials as target crowns. . However, while the response speed of the roll bender is relatively fast, the change speed of the roll shift position is very slow. Therefore, when the shift position is changed, the target crown is particularly required near the joint of the rolled material. Cannot be achieved, and the non-stationary part frequently occurs.

Accordingly, the present invention constitutes a rolling cycle having a relatively slow response and capable of advantageously changing the roll shift position, thereby reducing an unsteady portion frequently occurring near a joint of a rolled material. Things.

[0007]

SUMMARY OF THE INVENTION The present invention relates to a hot finish rolling mill having a roll bender and a roll shift mechanism, in which different types of rolled materials are joined and continuously rolled, and the same rolling cycle is previously set. There is a common shift range in each shift range that conforms to the target crown of adjacent rolled materials in the rolling cycle is determined, and in the rolling gap between the rolled material and the next rolled material, the shift position is changed by the common shift. An endless rolling method characterized by performing crown control by adjusting the bending force of a roll bender while performing the rolling within a range.

[0008]

Generally, the prediction of the thickness distribution after rolling is performed by a simulation called a division model. In this method, the amount of deflection and flatness of a roll is calculated from the rolling load when a rolled material is deformed, and the thickness distribution is calculated from the initial crown of the roll, the thermal crown of the roll, and the amount of wear of the roll.

Here, the rolling load is determined from rolling conditions such as deformation resistance of rolled material, roll diameter, sheet width, sheet thickness and tension. The thermal crown of the roll is determined by the heat conduction model based on the difference between the heat transfer from the rolled material, the heat generated by plastic working, and the frictional heat. Can be obtained based on the actual results.

For example, as apparent from FIG. 1, by using the above-described method, the roll shift position in the shift mill and the relationship between the roll bender and the sheet crown can be obtained from the rolling conditions and the initial crown of the roll. In FIG. 1, when the target crown is determined, the bending force of the vendor is within a range from the minimum to the maximum.
A shift range for obtaining the target crown is determined. That is, by setting the shift position within this shift range, the target crown can be given to the rolled material within the bender capability of the rolling mill.

Next, a shift range in which a target crown can be given to adjacent rolled materials in the endless rolling cycle, and a change pattern of a bending force of a roll bender according to a change pattern of a shift position selected from within the shift range. 2 and 3 are shown in FIGS. FIG. 2 shows a case where there is no common shift range between adjacent rolled materials, and FIG. 3 shows a case where there is a common shift range.

As described above, the roll bender has a high response, and the time required for the change is short, but the shift position cannot be changed instantaneously at the joint of the rolled material, and the change speed is high. It will be limited. Therefore, in the case of FIG. 2, an unsteady portion where a target crown cannot be obtained is generated in the vicinity of a joint portion of one or both of the preceding rolled material and the next rolled material regardless of the shift change pattern.

On the other hand, in the case of FIG. 3, the shift position is changed just before the joint, and the joint is set to a shift position within the common shift range of the preceding rolled material and the next rolled material. Thereby, it is possible to reduce the unsteady part.

As shown in FIG. 4, when the common rolling range of the preceding rolling material and the next rolling material is far from the common shifting range of the next rolling material and the next rolling material, the shift position is changed. Therefore, it is preferable that the shift speed, the rolling speed, the length of the rolled material, and the like be sufficiently considered.

FIG. 5 is a flowchart showing the procedure of the rolling cycle configuration according to the present invention. First, assuming a thermal crown and a roll wear amount in a rolling order, each shift range in which a target crown can be obtained for each steel type, sheet width, sheet thickness and rolling order is determined in advance. Next, so as to obtain a shift range common to each shift range of the adjacent rolled material in the rolling cycle,
The rolling order, steel type, sheet width and sheet thickness may be determined. At this time, depending on the cycle configuration, the thermal crown and roll wear are slightly different from the initial assumptions.If necessary, the thermal crown and roll wear are calculated again, and it is determined whether a common shift range exists in the determined rolling cycle. You only need to verify it.

[0016]

EXAMPLE When rolling 200 steel plates having a finished plate thickness of 2 to 4 mm and a plate width of 900 to 1300 mm by a hot strip mill consisting of three stands of a roughing mill and seven stands of a finishing mill, 20 rolls of the finishing mill were used. The unit was endless rolling. The work roll diameter of the finishing mill was 800 mm for the first four stands and three for the second stand.
600 mm, work roll bender ± 200tonf / chack
The work roll was narrowed in a quadratic curve from the center and provided with a 0.6 mm taper on one side at the body end, and arranged so as to be vertically symmetrical.

In this endless rolling, the rolling cycle shown in Table 1 is set, and as shown in FIG. 6, the shift position between runs is changed by changing the common shift range between the twelfth and thirteenth adjacent rolled materials. And the operation of changing the bending force of the roll bender according to the shift position change pattern was performed.

[0018]

[Table 1]

For comparison, rolling was performed according to a conventional method in which an endless rolling cycle was formed without confirming whether a common shift range exists between adjacent rolled materials.

FIG. 7 shows the difference between the target crown of the rolled material after rolling and the actually obtained sheet crown as a ratio to the total number of rolled materials. From the figure, the conventional method:
Although there are rolled materials for which the target crown cannot be obtained, according to the method of the present invention, it can be seen that the target crown is obtained for most of the rolled materials.

[0021]

According to the method of the present invention, the rolling cycle configuration in endless rolling is optimized, and
By changing the shift position and bending force,
The target crown can be provided over the entire length of all the rolled materials in the endless cycle. Therefore, the unsteady portion in which the target crown cannot be obtained in the rolled material is greatly reduced, which greatly contributes to the improvement of the yield.

[Brief description of the drawings]

FIG. 1 is a graph showing a relationship between a sheet crown, a roll shift position, and a bending force.

FIG. 2 shows a shift range in which a target crown can be given to adjacent rolled materials in a rolling cycle, and a change pattern of a bending force of a roll bender according to a change pattern of a shift position selected from within the shift range. It is a graph.

FIG. 3 shows a shift range in which a target crown can be given to adjacent rolled materials in a rolling cycle, and a change pattern of a bending force of a roll bender according to a change pattern of a shift position selected from within the shift range. It is a graph.

FIG. 4 shows a shift range in which a target crown can be given to adjacent rolled materials in a rolling cycle, and a change pattern of a bending force of a roll bender according to a change pattern of a shift position selected from within the shift range. It is a graph.

FIG. 5 is a flowchart showing a rolling cycle configuration.

FIG. 6 shows a shift range in which a target crown can be given to adjacent rolled materials in a rolling cycle, and a change pattern of a bending force of a roll bender according to a shift position change pattern selected from within the shift range. It is a graph.

FIG. 7 is a graph showing a difference between a plate crown and a target crown.

────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Hideyuki Nikaido 1 Kawasaki-cho, Chuo-ku, Chiba-shi, Chiba Kawasaki Steel Corporation Chiba Works (56) References JP-A-6-269821 (JP, A) 6-55207 (JP, A) JP 2-39328 (JP, B2) Patent 2743126 (JP, B2) The 92nd and 93th Nishiyama Memorial Technical Lecture by the Iron and Steel Institute of Japan Advances ”(August 1, 1983), p. 113 (58) Fields investigated (Int. Cl. ⁷ , DB name) B21B 37/28-37/44 B21B 1/26

Claims (1)

(57) [Claims] When a different type of rolled material is joined and continuously rolled by a hot finish rolling mill having a roll bender and a roll shift mechanism, a target of an adjacent rolled material in the same rolling cycle is previously determined. A rolling cycle in which a common shift range exists for each shift range that conforms to the crown is determined, and in the rolling gap between the rolled material and the next rolled material, the shift position is changed within the common shift range and the roll bender is changed. A crown control by adjusting the bending force of the endless rolling.