JPH04284902A - Device for hot-finish-rolling metallic plate and method therefor - Google Patents

Abstract

PURPOSE:To provide a hot finish rolling mill and a rolling method for a metallic plate possible to positively control edge drop and to manufacture a rolled plate excellent in plate shape (flatness). CONSTITUTION:When a light rolling down having a draft <=5% is performed by the mill at the last stage by a hot finish rolling equipment arranging a mill having operation rolls 4 of a diameter each exceeding 1.2 times the diameter of the operation roll 4 of a diameter >=800mm of the mill just before the last stage of a group of finish mills consisting of plural mills, the edge drop is controlled and a rolled plate excellent in plate shape can be obtained. Further, when a roll cross system double step 3 or a double step mill having a built in a crown variable roll is adopted to the last stage mill, the edge drop and the plate shape are controlled freely to rolled plates having various plate crowns.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hot finish rolling apparatus for metal plates and a rolling method thereof for obtaining a predetermined thickness from a rolled original plate.

0002

[Prior Art] Conventionally, hot finishing rolling equipment for metal plates has six
It consists of multiple rolling mills with ~7 stands.
The work roll diameters of these rolling mills are almost the same in each rolling mill, or become smaller toward the later stages. For example, as described in "Recent Advances in Hot Strip Equipment and Manufacturing Technology in Japan" (S51, published by the Japan Iron and Steel Institute), a finishing rolling mill consists of seven stands, but the diameter of the work rolls is approximately approx. It is 800mm. In addition, in the case of a finishing rolling mill with 6 stands, the work roll diameter from the first stand to the third stand is approximately 77 mm.
0mm, approximately 600 from the 4th stand to the 6th stand
mm. The reason why the work roll diameter of this finishing rolling mill becomes smaller in the later stages is that the smaller the work roll diameter, the smaller the rolling load when the same rolling reduction ratio is given to the rolled material. The aim is to alleviate the so-called edge drop, a phenomenon where the plate thickness decreases.

[0003] This kind of thinking is described in "Tetsu to Hagane" No. 74, No. 3 (1988), 77. It is also described in ``Development of high-precision plate thickness and crown control technology in hot rolling''. In this document, the work roll diameter of the finishing rolling mill is approximately 800 mm from the first stand to the third stand, and approximately 630 mm from the fourth stand to the sixth stand. However, although edge drops have been reduced to some extent by reducing the diameter of work rolls, at present no technology has been established to actively control edge drops.

0004

[Problems to be Solved by the Invention] The present invention provides a hot finishing rolling apparatus for a metal plate, which can actively control edge drop and produce a rolled plate with a good plate shape (flatness), and a rolling process. The present invention provides a method.

[0005]

[Means and effects for solving the problem] First aspect of the present invention
The gist of this is that at the last stage of a finishing rolling mill group consisting of a plurality of rolling mills, a mill with a diameter of 1.2
The present invention relates to a hot finish rolling apparatus for metal plates, which is constructed by disposing a rolling mill having work rolls with a diameter of 800 mm or more and a diameter of 800 mm or more.

[0006] The second gist is that in the first gist of the present invention, the last stage rolling mill is a two-high rolling mill having no rolls other than work rolls, and the upper and lower work rolls are The rolling mills are characterized in that they can intersect with each other in planes parallel to .

A third aspect of the present invention is that, in the first aspect of the present invention, the last stage rolling mill is a two-high rolling mill having no rolls other than work rolls, and at least one of the upper and lower work rolls is The roll is characterized by having a roll crown variable mechanism.

The fourth gist is that the last stage of a finishing rolling mill group consisting of a plurality of rolling mills has a diameter of at least 1.2 times the diameter of the work roll of the rolling mill immediately before it, and a diameter of 800 mm.
Using a hot finish rolling apparatus for metal plates, which is configured by arranging a rolling mill having the above work rolls, the last stage rolling mill performs light reduction rolling with a rolling reduction ratio of 5% or less. A method for hot finish rolling of metal sheets.

Conventionally, roll bending devices, roll shifts (intermediate rolls, work rolls), roll crosses, variable crown rolls, etc. have been devised and put into practical use as sheet profile control means on the exit side of hot finishing rolling. Although all of these have the ability to control the plate thickness distribution except near the edge of the plate, that is, the so-called body crown, it has been said that they do not have the ability to control edge drop. On the other hand, for the purpose of edge drop control, a method of shifting a work roll having a one-side taper as disclosed in, for example, Japanese Patent Laid-Open No. 58-221601 has been proposed, and is being put into practical use. However, according to a detailed study by the present inventors, although it is possible to make the edge drop start point to some extent closer to the sheet edge in the method using the taper work roll shift, it is essentially possible to make the edge drop smaller, that is, to make the edge drop closer to the sheet edge. It became clear that it was impossible to reduce the amount of plate thickness reduction at the edges.

On the other hand, as a result of the research conducted by the present inventors, it has become clear that changes in the plate crown ratio (plate crown/plate thickness) before and after rolling cause the following changes in edge drop and plate shape (flatness). It has become. ■If rolling is performed to reduce the plate crown ratio, the edge drop will become smaller. ■When rolling is performed to reduce the plate crown ratio, the plate shape (flatness) becomes a medium elongated shape. Furthermore, as has been pointed out in the past, it has become clear that rolling reduction also has the following important effect on edge drop. ■If the rolling reduction ratio is reduced, the edge drop will become smaller.

[0011] The present invention effectively utilizes the above-mentioned phenomenon, and aims to obtain a plate having a desired flatness while controlling edge drop. Above ■
From the phenomenon (2), it can be seen that edge drop can be controlled by controlling the change in plate crown ratio before and after rolling. Generally, the smaller the edge drop, the better, so rolling should be performed to reduce the plate crown ratio. However, if this is done in the last stage rolling mill, a mid-elongated shape will remain, the shape at the exit side of the finishing mill will be poor, uneven cooling will occur on the hot run table, and the shape of the finished product will be significantly deteriorated.

Therefore, in the present invention, taking advantage of the phenomenon (2) above, rolling into a medium elongated shape is performed in a rolling mill immediately before the last rolling mill, and in the last rolling mill, light reduction rolling is carried out for the main purpose of shape correction. Implement. The rolling reduction rate of the last rolling mill at this time is
It is sufficient to set the reduction rate to such an extent that the rolled plate does not undergo local reduction, and a reduction rate of 5% or less is sufficient.For the purpose of reducing edge drop, it is preferable to set the reduction rate even lower within a range that does not cause local reduction. Furthermore, in order to enhance the shape correction effect in the last stage rolling mill, it is important to increase the work roll diameter so that the contact arc length can be long even at a low rolling reduction rate.

Therefore, in the present invention, a work roll with a diameter equal to or larger than that of the work roll in the front stage of the finishing mill of the current continuous hot rolling mill, that is, a work roll with a diameter of 800 mm or more, is adopted for the last stage rolling mill. This makes it possible to roll a plate with a good shape without causing local reduction even at a low rolling reduction rate. Furthermore, increasing the work roll diameter of the rolling mill immediately before the last rolling mill to the same extent as the last rolling mill
It should be avoided for the following reasons:

[0014] When the work roll diameter of the rolling mill immediately before the last stage rolling mill is made as large as the last stage rolling mill, the plate profile immediately before the last stage rolling mill is compared with the large diameter roll as shown in Fig. 7. Even if the size of the edge drop is reduced by medium elongation rolling to give a large reduction ratio, the range of influence of the edge drop is relatively large. Since the roll gap shape of the rolling mill is as shown by the broken line 8 in Fig. 7, the area 9 where rolling is not applied, which is estimated to have no metal flow in the width direction, becomes large, resulting in plate breakage and shape defects. . On the other hand, if the work roll diameter of the rolling mill immediately before the last-stage rolling mill is made smaller, the range of influence of edge drop becomes smaller, as shown in Figure 6, and rolling with the same roll gap shape on the last-stage rolling mill becomes smaller. Even so, a certain amount of metal flow in the width direction is expected near the edge of the plate, so it is possible to obtain a rolled plate with a small edge drop without causing plate breakage or shape defects. For this reason, in the present invention, the diameter of the work roll of the last stage rolling mill is set to be at least 1.2 times the diameter of the work roll of the rolling mill immediately preceding it.

[0015] The above explanation has been made with the case of rolling a plate with a small edge drop as shown in Fig. 4 in mind; A rolled plate with a relatively large edge drop, such as No. 5, is sometimes required. In such a case, rolling may be performed to increase the sheet crown ratio by utilizing the reverse of the phenomenon (2) above. At this time,
The plate shape is elongated at the end, but in the last rolling mill,
Shape straightening rolling with light reduction may be performed.

By the way, in the above configuration of the present invention,
The basic method is to create edge drops and plate shapes using the last stage rolling mill and the rolling machine just before it, but this is because, unlike the body crown, edge drops and plate shapes are formed on the front stand. This is because the present invention has been made in consideration of the fact that the properties that remain after a product is rolled on a subsequent rolling stand, that is, the hereditary properties are very small. In other words, because heritability is small, achieving the desired edge drop and shape in the front stage of the finishing mill has no important meaning for the final edge drop and shape of the rolled plate. be.

Now, regarding the rolling mill type of the last stage rolling mill that employs large diameter work rolls, even with large diameter work rolls, if the rolling is limited to light reduction of 5% or less, the rolling load is small. There is no need to use a multi-high rolling mill with four or more stages. Therefore, in the second and third aspects of the present invention, the last stage rolling mill is a two-high rolling mill. Two-high rolling mills have lower equipment costs than multi-high rolling mills with four or more stages, and roll consumption per unit of production,
It is advantageous in terms of manufacturing costs because running costs such as electric power consumption are also reduced. Furthermore, since the rolling mill type is significantly simplified, maintenance and management of the equipment becomes easier.

Furthermore, in the second aspect of the present invention, the last stage rolling mill is a rolling mill in which the upper and lower work rolls of the two-high rolling mill can cross each other in a plane parallel to the rolling plate surface, that is, a roll cross. A type rolling mill is used, and with this rolling mill, it is possible to create the required edge drop and plate shape for various target plate crowns by adjusting the intersection angle of the upper and lower rolls. Further, the same object can be achieved by using a roll having a roll crown variable mechanism adopted in the third aspect of the present invention.

[0019]

[Example] [Example 1] In Fig. 1, 1 is the rolling direction;
Reference numeral 2 indicates a material to be rolled, 4 a work roll, and 5 a reinforcing roll. In the finishing rolling equipment shown in Fig. 1, in the finishing rolling mill consisting of seven stands, only the work roll diameter of the sixth stand is 550 mm, and the work roll diameters of the other rolling mills are 8 mm.
00mm. The small-diameter work roll of the sixth stand makes it possible to reduce the edge drop to some extent, and the large-diameter work roll of the seventh stand makes it possible to obtain a rolled plate with a good plate shape. Furthermore, by performing rolling into a medium elongated shape in the 6th stand and light reduction rolling into a flat shape in the 7th stand, it is possible to produce a rolled plate with very small edge drop and a good shape. . In addition, if rolling is performed in the 6th stand to give an edge elongated shape, and light reduction rolling is performed in the 7th stand to give a flat shape, depending on the destination, a rolled plate with good cold rolling characteristics and a large edge drop can be shaped. It is also possible to manufacture it well.

[Embodiment 2] In the second embodiment shown in FIG. 2, a two-high rolling mill 3 with large diameter rolls is added to the rear end of a finishing mill consisting of seven stands to create an eight-stand finishing rolling machine. There is. The work rolls of the 1st to 7th stands are approximately 800 mm in diameter, but the work rolls of the 8th stand are large diameter rolls with a diameter of 1200 mm, making it possible to manufacture rolled plates with good shape even at low rolling reduction rates. It has become. Furthermore, as shown in Fig. 3, the eighth stand is designed so that the respective axes of the upper and lower rolls can intersect with each other in a plane parallel to the surface of the rolled plate, and by adjusting this crossing angle, various types of plates can be produced. It is now possible to roll the material on the entry side of the crown into a good shape.

[0021] Using this finishing rolling equipment, when the seventh stand performs rolling into a medium elongated shape and the eighth stand performs light reduction rolling into a flat shape, the edge drop is very small and the shape is good. It is possible to produce a rolled plate. In addition, if rolling is performed in the 7th stand to give an edge elongated shape, and light reduction rolling is performed in the 8th stand to give a flat shape, depending on the destination, a rolled plate with good cold rolling characteristics and a large edge drop can be shaped. It is also possible to manufacture it well.

[Embodiment 3] In the finishing rolling apparatus shown in FIG. 2, the work roll of the eighth stand is a large diameter roll with a diameter of 1200 mm, and the work roll of the third stand has a roll crown variable mechanism. This is an example. The roll crown variable mechanism has a type that changes the roll crown by changing the oil pressure in the oil reservoir provided inside the roll of the sleeve structure, and a type that changes the roll crown by changing the oil pressure in the oil reservoir provided inside the roll of the sleeve structure.A type that changes the roll crown by changing the oil pressure in the oil reservoir provided inside the roll of the sleeve structure. There are two types of roll crowns: one in which the roll crown is changed by hydraulic movement, and another in which the roll crown is changed by adjusting the position of a hydraulic ram built into a fixed arbor relative to the rotating sleeve and movable in a direction perpendicular to the roll axis. However, since the purpose of the last stage rolling mill is light rolling, it can be of any type. By adjusting the roll crown in this manner, it is possible to perform rolling with a good shape for various materials on the entry side of the plate crown.

[0023] Using this finishing rolling equipment, when rolling is carried out in the 7th stand to give a medium elongated shape, and light reduction rolling is carried out in the 8th stand to make the shape flat, the edge drop is very small and the shape is good. It is possible to produce a rolled plate. In addition, if rolling is performed in the 7th stand to give an edge elongated shape, and light reduction rolling is performed in the 8th stand to give a flat shape, depending on the destination, a rolled plate with good cold rolling characteristics and a large edge drop can be shaped. It is also possible to manufacture it well.

[0024]

[Effects of the Invention] By using the hot finishing rolling apparatus and rolling method of the present invention, it is possible to produce a rolled plate with a desired edge drop and plate shape, and by combining this with the plate crown control technology, the plate It becomes possible to freely control the plate profile in the width direction.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing a first embodiment of a hot finishing rolling apparatus for metal sheets according to the present invention.

FIG. 2 is a diagram showing a second embodiment of the hot finish rolling apparatus for metal sheets of the present invention.

FIG. 3 shows a roll cross type two-high rolling mill useful as the last stage rolling mill in the present invention, in which (a) is a side view and (b) is a plan view.

FIG. 4 is a diagram showing the thickness distribution in the width direction of a rolled plate with small edge drop produced using the finishing rolling apparatus and rolling method of the present invention.

FIG. 5 is a diagram showing the thickness distribution in the width direction of a rolled plate with a large edge drop produced using the finishing rolling apparatus and rolling method of the present invention.

[Fig. 6] When using the finishing rolling equipment of the present invention, where the work roll diameter of the rolling mill immediately before the last stage rolling mill is smaller than that of the work roll of the last stage rolling mill, the plate thickness distribution on the entrance side of the last stage rolling mill and the end It is a figure showing roll gap distribution of a corrugated rolling mill.

[Figure 7] Plate thickness distribution at the entrance of the last stage rolling mill and last stage rolling when using a finishing rolling device in which the work roll diameter of the rolling mill immediately before the last stage rolling mill is not smaller than that of the work roll of the last stage rolling mill. FIG. 3 is a diagram showing the roll gap distribution of the machine.

[Explanation of symbols]

1 Rolling direction 2 Material to be rolled 3 Large-diameter roll two-high rolling mill 4 Work roll 5 Reinforcement roll 6 Plate thickness distribution after finishing rolling 7 Plate thickness distribution on the entrance side of the last rolling mill 8 Last stage rolling mill roll gap distribution 9 Width direction metal flow Area that will not be rolled in the last rolling mill if there is no

Claims (4)

[Claims] Claim 1: A work roll with a diameter of 1.2 times or more the diameter of the work roll of the immediately preceding rolling mill and a diameter of 800 mm or more is installed in the last rolling mill of a finishing rolling mill group consisting of a plurality of rolling mills. A hot finish rolling apparatus for metal plates, which is constructed by arranging a rolling mill having a. 2. A two-high rolling mill in which the last stage rolling mill has no rolls other than work rolls, and the upper and lower work rolls can cross each other in a plane parallel to the rolling plate surface. The hot finishing rolling apparatus for metal sheets according to claim 1, characterized in that: 3. The last stage rolling mill is a two-high rolling mill having no rolls other than work rolls, and at least one of the upper and lower work rolls is a roll having a roll crown variable mechanism. The hot finishing rolling apparatus for metal plates according to claim 1. 4. At the last stage of a finishing rolling mill group consisting of a plurality of rolling mills, there is a work roll having a diameter of 1.2 times or more the diameter of the work roll of the immediately preceding rolling mill and a diameter of 800 mm or more. Using a hot finish rolling device for metal plates that is configured with rolling mills, the last stage rolling mill has a rolling reduction rate of 5.
A method for hot finish rolling of a metal plate, characterized by performing light reduction rolling of less than %.