JPS6054202A - Rolling mill - Google Patents

Abstract

PURPOSE:To control effectively a sheet crown for every sheet-width size to be rolled by providing a proper recessing roll crown to a work roll in conformity with a projecting roll crown provided to a backup roll. CONSTITUTION:In a rolling mill having a bending device consisting of work rolls and backup rolls provided with a roll crown at its body to be in contact with at least one of a pair of work rolls; a projecting roll crown CBUR of 0.5-10mm. in diameter is provided to the backup roll, and a recessing roll crown CWR which satisfies 0.40XCBUR>=CWR>=0.15XCBUR in diameter is provided to the work roll corresponding to said backup roll. In this way, a sheet-crown controlling range effective for each sheet width of rolling sheets can be obtained, and the sheet crown controlling effect by roll bending is improved.

Description

[Detailed description of the invention]

(Industrial Application Field) The present invention relates to a rolling mill for metal materials, particularly a rolling mill that can control the plate crown of rolled products over a wide range. (Prior art) For example, when rolling metal materials such as steel, a large rolling load acts on the rolling rolls, causing deflection, and the small portions on the surface of the rolls that are in contact with the material become flattened, and the edges of the rolled material become flat. As a result, the thickness distribution of the rolled plate material in the roll axis direction is
As shown in FIG. 1, it is thickest at the center and becomes thinner as it approaches the edges. This is the plate crown that occurs in the current rolling method, but the amount of plate crown changes depending on rolling conditions such as thermal expansion of the rolls, roll wear, etc. Such a change in plate crown amount in the final rolled product is unfavorable in terms of product quality and yield. In FIG. 1, B is the plate width + tM is the thickness at the center in the width direction of the plate + 'E is the thickness at the edge. tM-1E is called plate crown. When the above-mentioned plate crown occurs in the intermediate process of rolling, if the crown is large, even if an attempt is made to correct it in a subsequent rolling process, the plate material will have a corrugated shape, making the rolling operation difficult. In such a case, the rolled plate material is poor in both thickness distribution and shape. Conventionally, methods for reducing or controlling plate crown in plate rolling include (1) providing a barrel-shaped crown to the roll body in advance; and (2) imparting convex or concave deflection to the upper and lower rolls using a hydraulic cylinder or the like. A method using a so-called roll bending action, a combination of the above methods, and a mill exclusively for crown control, such as a 6Hi mill and a cross mill, have been put into practical use. However, each of these conventional methods for reducing and controlling plate crowns has its own problems. In other words, when adopting the method (2) in which a barrel-shaped crown is previously provided on the roll body, the deformation resistance of the rolled material changes depending on the chemical composition, humidity, etc., the width of the sheet changes variously, and the heat of the roll changes. expansion. Because the shape of the roll changes due to wear, etc.

[It is practically impossible to pre-apply the appropriate rounds to the rolls under these various rolling conditions. Furthermore, it is extremely difficult to change or reduce the plate crown without generating plate waves or the like, that is, without maintaining a good plate shape. ■Roll bending equipment In the case of the method of applying convex or concave bending to the upper and lower rolls from the ship to change the plate crown, current rolling mills are unable to do so due to the strength of the roll neck, the life of the bearings, etc. Strong bending forces cannot be applied. In addition, the work roll and reinforcing roll are in contact over almost the entire length of the roll, and the work roll is subjected to extra bending moment by the reinforcing roll outside the width of the rolled material, so the bending effect of one work roll is reduced accordingly. has been done. For the above-mentioned reasons, the work roll bending effect appears near the edge of the plate, but it cannot be obtained near the center of the width of the plate. Even if the method is a combination of method (2) above, as mentioned in the explanation of method (2) above, variations in the deformation resistance of the rolled material, variations in the strip width, and strip crowning due to thermal expansion and wear of the rolls will occur. The plate crown control effect is not sufficient to absorb changes. In case (2), the crown control effect is great, but there are problems in that the equipment investment is large and it is difficult to modify the current mill. Method (2) To reduce or control the plate crown of the ζ trowel, ζ trowel 1 For example, as shown in FIG. 2, one working roll l,
1' reinforcing roll 2. By providing the z' large kina convex crown, the work roll is deformed by the bending moment due to the contact load with the reinforcing roll, and the rolling material 3 is significantly prevented from being rolled thinly at both ends thereof. Also,
The roll bending effect caused by the roll pending cars 4, 4' is also remarkable because the ends of the work rolls are not restrained.1 For example, it is clear from Japanese Patent Application No. 49-84209 and Japanese Patent Application No. 50-18864. be. However, the plate width of the rolled material often varies, and the question is whether the above-mentioned effects can be obtained for any plate width. Figure 3 shows the crown control range when a crown value is given to the C-ma reinforcing roll. The crown control range can be increased by adding a large convex roll crown to the reinforcing roll, but as shown in Figure 3, when the plate width is wide, the plate crown control range becomes control of a concave plate crown.1 Normal crown control becomes unusable. Due to the above problems, it has not been possible to provide a large convex roll crown to reinforcing rolls in the past. 1. There is a track record of applying a convex roll crown as small as Orah to reinforcing rolls, but in this case as well, the sheet crown control range was not satisfied over the entire sheet width ζ, and the sheet crown control was not exceeded. Ta. (Objects, Structure, and Effects of the Invention) The present invention solves the problems in the conventional plate crown reduction control method described above. The object of this invention is to provide a rolling mill that can effectively control plate crown during plate rolling. Its feature is a pair of upper and lower working low/L. A convex roll crown CBUR with a diameter of 0.5 am to 10 mm is given to the reinforcing rolls in contact with each other, and a work roll crown CwR is given with a diameter of 0.40 x CB.
A rolling mill is provided with a concave roll crown that satisfies UR≧CwR≧0.15XCBU, H, and is configured to perform effective plate crown control over the entire rolled plate width size. The rolling mill of the present invention will be explained in detail below with reference to the drawings. As a result of examining the sheet crown control range for each sheet width on a hot steel strip tandem rolling mill, the inventors of the present invention have determined that an appropriate concave roll crown is applied to one work roll in accordance with the convex roll crown provided to the reinforcing roll. It has been found that the above problems can be solved by doing so. As a result of an experimental study on a hot steel strip tandem rolling mill by applying various types of roll crown lie, the results are shown in Figure 4 (plate crown control range evaluation: ○: good, ×: negative for wide ranges, △: control range is negative). If the concave roll crown of the work roll is too small, the wide plate crown will become concave, and conversely, if it is too thick, the plate crown control range will be too far on the plus side. That is, as shown in FIG. 4, there is an appropriate range for the amount of roll crown of the reinforcing roll and the work roll, and it is necessary to satisfy the linear relational expression. 0.40X CBUR≧CwR≧0.15XCBUR
(1) CwR: Absolute value of the concave roll crown amount of the work roll CBUR: Absolute value of the convex roll crown amount of the reinforcing roll As shown in Figure 5, by increasing the amount of convex roll crown given to the reinforcing roll, the Although the crown control range increases, as shown in Figure 6, contact stress and Hertzian stress between the reinforcing roll and the work roll are generated, and as shown in the roll contact load distribution shown in Figure 6(a), the center of the width direction The maximum line load will be present at this point, making spalling more likely to occur. The roll pending force is 90 tons and the strip width is 7 feet. Therefore, the maximum convex roll crown amount of the reinforcing roll is regulated by the spalling limits, but the maximum convex roll crown amount of the reinforcing roll regulated by these limits is naturally The wider the width, the larger it becomes. When rolling various strip widths, it is advantageous to have a larger convex roll crown amount on the reinforcing roll from the standpoint of increasing the strip crown control range, and the roll bending effect is also greater, but due to spalling limit regulations, it is advantageous to have a larger convex roll crown amount. The maximum convex roll crown amount of the reinforcing roll is determined by the spalling limit in rolling the maximum sheet width. As shown in FIG. 6 (1)), the limit at which spalling does not occur is the maximum crown amount of the reinforcing roll of 10 mm. Therefore, in view of the crown control effect and the spalling limit of the roll, the range of the convex roll crown of the reinforcing roll must be 10 mm or less in diameter. The reinforcing rolls of conventional four-high rolling mills are given a convex roll crown in consideration of the form of roll wear.
The size of the roll is about 02 questions at most in terms of the diameter of the roll. Such a conventional four-high rolling mill. The plate crown control range is at most 5 for a 3 foot wide plate.
It is 0 μmn. However, in order to control the plate crown range within the range of 0 to 60 μm, which is required from the subsequent cold rolling process, the plate crown control range of each mill in the tandem mill in the hot rolling process has recently been changed for a 3-foot plate width material. 60 μm or more is required. For this purpose, the reinforcing roll must be at least 0 in roll diameter.
．． It is necessary to provide a convex roll crown of 5 or more. On the other hand, the work rolls of conventional 4-high rolling mills have a convex roll crown of 0.2 mm, taking into account wear patterns, thermal expansion, etc. of the rolls.
From the column, a concave roll crown of about 0.2 tan was given, but in the case of the present invention, the diameter is 0.15 x depending on the size of the convex roll crown of the reinforcing roll.
The objective is to provide a large concave roll crown of 0.4XCBUR from CBUR. (Example) Next, an example of the present invention will be described. Fig. 7 shows an example of the control range of the plate crown by a proper roll crown and, for comparison, the control range of the plate crown when the reinforcing roll is not provided with a roll crown. As shown in FIG. 7, it is possible to solve the problem of giving one work roll an appropriate concave roll crown that satisfies the formula (1) for the size of the convex roll crown amount of the reinforcing roll, and We were able to widen the control range of the plate crown.As shown in Fig. 8, the shape of the roll crown can be various shapes such as a convex straight line (aL (b), a sine curve (s), and a parabola (d)). The shape of the roll crown of the work roll is a concave roll crown, which is the opposite of the convex roll crown shown in Fig. 8, but since the work roll 5 is directly injected into the material to be rolled, the shape is as shown in Fig. 8. Among the shapes, shapes like (a), (b), and (e) are not preferable.Such an effect can be obtained by arranging an intermediate roll between the work roll and the reinforcing roll, and adding a convex roll to the intermediate roll. Similar effects can also be obtained in a rolling mill in which a work roll is provided with a crown and a concave roll crown is provided in accordance with the size of the convex roll crown of the intermediate roll.As described above, according to the rolling mill of the present invention, , when rolling within the range of the minimum and maximum plate width of rolled plate products determined according to the mill specifications.A convex roll crown is given to the reinforcing roll in contact with the work roll, and the convex shape of the reinforcing roll is By providing a concave roll crown to the work roll according to the size of the roll crown, it is possible to obtain an effective plate crown control range for each plate width. The crown control effect is also significant. (Effects) Since the present invention is constructed and operated as described above, it is extremely low cost and can be applied to existing rolling mills even in their grooves, and can control the crown of a large plate. In addition, the expansion of the plate crown control range contributes to reducing the plate crown of the product and improving the plate thickness accuracy, and is effective in improving the product quality 1 yield. Since there is no need to change the work rolls depending on the size, the frequency of changing work rolls is reduced, which has great economic effects in terms of energy saving and rolling productivity.

[Brief explanation of the drawing]

Figure 1 is a diagram showing a cross section in the width direction of a plate with a crown, Figure 2
The figure shows an example of a rolling mill in which a reinforcing roll is provided with a convex roll crown, Figure 3 is a diagram showing the strip crown control range for each strip width in the rolling mill of Figure 2, and Figure 4 is a diagram showing the reinforcing roll and the rolling mill. Figure 5 shows the relationship between the plate crown control range and the convex roll crown amount of the reinforcing roll, and Figure 6 (a) shows the appropriate range of the amount of roll crown on the work roll. Width direction distribution of contact stress between rolls 6th
Figure (b) shows the relationship between the maximum Hertzian stress and the amount of convex roll crown of the reinforcing roll, and Figure 7 shows the case where the reinforcing roll has a convex roll crown and the work roll has a concave roll crown. FIG. 8 is a diagram showing an example of the roll crown shape of the reinforcing roll in the present invention. 1.1'... Work roll, 2.2'... Reinforcement roll, 3... Rolled material, 4.4'... Work roll bending device. No. rs 1s 3 Figure 4- Doichi crazy leaf convex leaf 2 Lau〉Quantity No. 5-18 Ia) fbldoit0to5, c) Eve) 卜,,,n (elyyydo1) 6 eggs Ca) Half skewer 0-Round 2 rounds

Claims (1)

[Claims] In a rolling mill equipped with a reinforcing roll whose body is crowned in contact with at least one of the upper and lower work rolls and a bending device for the work roll, the crown amount CBUR of the reinforcing roll is made into a convex shape with a diameter of 05 to 10+ nm. year,
and the amount of crown CwR of the work roll in contact with the reinforcing roll is concave, and the amount of crown of the reinforcing roll CB
The absolute value of UR and work roll crown amount CWR is 0.4XCBUR≧CwR≧O,'l 5 X C
A rolling mill characterized by having rolls that satisfy a BUR relationship.