JPH0636922B2 - Hot width rolling method for metal slabs - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a hot width rolling technique for rolling a metal slab in a width direction with a vertical rolling mill, and more specifically, during hot width rolling of a metal slab. The present invention relates to a hot width rolling technique for preventing the growth of front and rear end deformed portions that occur.

(Prior art) The size of the metal slab width is integrated for the purpose of realizing a process that directly connects the continuous casting process that can effectively use the sensible heat possessed by the continuous casting slab and the rolling process that creates the product shape. . Therefore, in order to make the slab width necessary for the rolling process, large width reduction is performed downstream of the continuous casting equipment.

The hot width rolling method of this metal slab is intended for continuous casting slabs, and the ratio of the roll contact arc length during rolling to the average strip width, that is, the roll, as compared with the conventional slab rolling method for steel ingots. The gap shape ratio is as small as 0.1 to 0.2, and the repeated vertical roll width reduction amount per one time is as large as 200 to 300 mm. For this reason, a deformed portion called a front / rear end portion tail portion of the metal slab as the material to be rolled is generated. The fish tails formed at the leading and trailing ends of this metal slab are the places that must be cut after rolling. Therefore, in the conventional width reduction rolling, the crotpros was large and the product yield was significantly reduced.

In order to reduce the crotpros which increases with the width reduction amount, many preforming methods have been conventionally proposed in which the front and rear ends of the metal slab are pressed by a press to be deformed into a narrow width. For example,
Japanese Unexamined Patent Publication (Kokai) No. 58-181401 proposes a preforming rolling (P) to narrow the widthwise sides of the leading end and the trailing end of the slab by pressing before width-stripping and rolling in hot rolling. Performing the width rolling of the slab in the width direction by means of a vertical roll (V), performing the horizontal rolling of the slab in the thickness direction by means of a horizontal roll (H), P-V -H rolling process is repeated a plurality of times, the position for performing the preforming rolling is set to a position separated by 100 to 500 mm from the slab end face, and the press reduction amount in the preforming rolling for each process is width-canceling rolling for each process. A width reduction rolling method characterized by setting the amount obtained by subtracting the slab width after horizontal rolling from the previous slab width, after repeating the PV rolling a plurality of times, the H
The width reduction rolling method is characterized by rolling.

(Problems to be Solved by the Invention) In any of these conventional methods, the rolling efficiency is significantly reduced. That is, the P-V-H, P-V ... H repeated press width reduction rolling method positions the material to be rolled for press preforming and the stop time for the press operation process every time the width reduction is repeated. is necessary. Therefore, these methods cannot be applied to the wide-width vertical rolling mill, which is made to realize the process of combining the continuous casting process and the rolling process, which can utilize the sensible heat of the continuous casting slab. Is. When manufacturing various slabs from wide slabs to narrow slabs in a width rolling process that directly connects the continuous casting process and the hot rolling process, it is necessary to have a rolling efficiency that matches the capacity of the preceding and following processes, which hinders smooth rolling. Therefore, it is required to reduce the crotpros at the front and rear ends of the rolled material without unnecessarily extending the rolling time.

It is an object of the present invention to provide an effective hot width rolling technique for metal slabs that solves the above problems.

(Means for Solving the Problems) In order to solve the above-mentioned problems, the present invention provides a metal slab having a hot rolling width in a row of hot rolling mills in which vertical rolling mills are arranged before and after a horizontal rolling mill. At the time of rolling, the width reduction device of the vertical rolling mill is provided with a hydraulic controller to change the vertical roll gap during the rolling pass to separate the metal slab from the longitudinal side end and each of the side ends. A hot slab rolling method for a metal slab is used, in which a preforming pass for preforming a narrow portion is performed before a width rolling pass for maintaining a vertical roll gap at a predetermined value during the rolling pass.

(Operation) Hereinafter, the operation of the present invention will be described with reference to the drawings.

In FIG. 2 (a), when the metal slab 1 is rolled in the width direction, a deformed portion called a fish tail is generated at the engaging end 6 and the engaging end 7. The mechanism of generation of this deformed portion is that the deformed portions 6a, 7a and the deformed portions 6a, 7a generated by partial rolling of the portion excluding both ends shown in FIG. It is considered that this is caused by the combination of the deformed portions of the end deformations 6b and 7b shown in (c). Therefore, in order to reduce the fish tail, it is only necessary to prevent the occurrence of a deformed portion due to the rolling of the constant portion and the deformation of the end portion.

In the wide width reduction rolling, the ratio of the roll contact arc length during rolling to the average plate width, that is, the roll gap shape ratio is 0.1 even though the continuous width reduction amount in the repeated width reduction rolling by the vertical roll is as large as 200 to 300 mm. As small as ~ 0.2, the rolling force does not penetrate to the central part of the width, so it is difficult to reduce the deformed part due to the end deformation. The method of the present invention is intended to improve the profiled portion caused by the rolling of the steady portion shown in FIG. 2 (b).

FIGS. 3 (a) and 3 (b) show the behavior of rolling deformation of the punch-through end of the metal slab. In FIG. 3 (a), when the metal slab 1 (one-dot chain line, plate width dimension W ₁ ) is rolled in the width direction with the vertical rolls 2 and 4, the metal slab 1 (solid line, plate width dimension W ₂ ) is obtained. Since the escape end is a free end and there is no restraint, the width edge is more likely to be deformed in the rolling direction than the width center extension as is known from the change in the plastic flow curve 8 (broken line), and the steady state described above is based on the difference in extension between the two. The deformed portion 7a is generated by the partial deformation.
For this reason, the inventors of the present invention investigated the change in the plastic flow curve by providing a pre-formation part in the middle of the length in order to prevent the deformation of both width ends. As a result, the following findings were obtained.

That is, as shown in FIG. 3 (b), in the width rolling, the metal that is more advanced in the vicinity of the width end than in the width center is buried in the preforming portion 5, and the plastic flow curve 8 at the width end is improved. That is, the positions Δl ₁ and Δl ₂ of the preforming part are the plastic flow curves 8 of the steady part deformation.
Does not change significantly depending on the position in the longitudinal direction, so the plastic flow curve is improved on the side of the bite-out end, the plastic flow curve is greatly improved by providing multiple preforming parts, etc. Deformed portion 7a due to deformation
The occurrence of (Fig. 3 (a)) is largely prevented and becomes 7c.

Based on these findings, the inventors of the present invention, in the process of reducing the width of the metal slab 1 by reversible rolling under the configuration of the vertical rolls 2 and 4 with caliber and the horizontal roll 3 shown in FIG. 1 (a). Then, the hot width rolling method was completed in which the preforming portions 5a and 5b were formed by the vertical rolls 2 and 4 as shown in FIG.

According to this rolling method, it is possible to form a plurality of preformed portions at the same time, and since the metal slab 1 does not escape in the longitudinal direction since the preformed portions are held by two rolls, end face preforming is easy. The fact is that preforming can be performed arbitrarily during the rolling process, and there is no need to separately provide a preforming process.Thus, smooth rolling can be prevented and preforming rolling can be performed without unnecessarily extending the rolling time. Yes, Crotpros can be greatly improved.

Therefore, the method of the present invention can be applied to a width reduction mill under a process in which a continuous casting process and a hot rolling process are directly connected to each other, and a great improvement in yield can be achieved.

Next, FIG. 4 shows an example of a rolling mill for carrying out the rolling of the present invention.
In the figure, the vertical roll 2 (4) of the vertical rolling mill is
And is connected to the roll driving spindle S and can be driven. The chuck 9 is integrally connected by a yoke 10, and the yoke 10 is pulled by a pull back cylinder 12 provided at the center of the fixed browsing 11 on the rear surface thereof to the right in the drawing, and each rolling screw 13 is pressed.
Is pressed and abutted to a compression block 14 provided at the tip of the. The screw-down screw 13 is screwed into a screw-down nut 15 which is installed in the fixed housing 11 via a rotation stopper so as to be able to move forward and backward by a certain length, and is also slid key-engaged with a worm wheel gear 16 at the rear end. Therefore, the adjustment of the reduction amount in the width direction is performed by rotating the reduction screw 13 by the driving force transmitted through the roll agitator 17 and the worm wheel gear 16 by the drive source (not shown) to move the yoke 10 forward or backward. Done. Further, a device including an annular piston 18 and an annular cylinder 19 is mounted so as to surround the screw 13 so that the preformed portion can be formed.
9 is fixed in the fixed housing 11, while the annular piston 18 is in contact with the back surface of the rolling nut 15. Code 2
Reference numeral 0 denotes a liquid chamber gap formed by the piston 18 and the cylinder 19, and when no pressure is applied to this gap, the gap disappears, and the right end of the piston 18 is the cylinder 1
It will come into contact with the bottom of 9.

In order to form a preformed portion on a metal slab that is a material to be rolled by the method of the present invention, this pitton 18 is used as a cylinder 19
The vertical roll is set to the width of the metal slab with the screw down screw 13 in a state of being in contact with the bottom of the piston, and the working oil is supplied to the liquid chamber gap 20 for the stroke length of the piston 18.
8, pull-down cylinder 15, pull-down screw 13, and pusher block 14 through pullback cylinder 12
The yoke 10 is pressed against the left side against the pulling force of the piston 18 and is expanded by the stroke length of the piston 18.

The stroke length can be arbitrarily adjusted by controlling the hydraulic oil.

In a rolling mill having a stand configuration in which two vertical rolling mills are arranged, by installing the roll opening hydraulic control device provided with the above-mentioned roll preforming hydraulic control device in two vertical rolling mills, It is possible to form individual preforming parts at the same time, and by adding a preforming machine etc. to the vertical rolling mill, the equipment cost and equipment space can be minimized, and the preforming process time compared to the conventional press machine Also, the rolling time including the preforming step can be significantly shortened.

(Example) Next, a specific example of rolling a metal slab by the method of the present invention will be described. The rolling conditions are as shown in Table 1, and V ₁
-H-V ₂ 3-stand reverse rolling method continuously cast slab width 1800 mm, thickness 280 mm to target slab size width 1
This is an example of manufacturing a target of 020 mm and a target of 250 mm.

At the same time, in the conventional rolling method performed as a comparative example, rolling was performed as described in JP-A-58-181401, as shown in Table 2 (a).

As shown in Table 3, in the method of the present invention, the rolling efficiency was significantly improved, and at the same time, the reduction rate of the crop was also significantly improved.

(Effects of the Invention) It is impossible to apply the conventional yield-enhancing rolling method to the width rolling mill under the process in which the continuous casting process and the hot rolling process are directly connected to each other, because smooth rolling is significantly hindered.

According to the method of the present invention, it is possible to form a plurality of preforming portions at the same time by installing the roll preforming hydraulic control device in the roll opening hydraulic control device of the two vertical rolling mills, and as a part of the rolling process. Preforming rolling allows smooth rolling without extending rolling time, economically eliminating deformed portions accurately, and significantly reducing the amount of metal slab's fish tail generated with good productivity and economic efficiency. A very effective effect is obtained industrially.

[Brief description of drawings]

FIG. 1 (a) is a diagram showing an example of a rolling mill train for carrying out the method of the present invention, FIG. 1 (b) is a plan view of a metal slab on which a preforming portion is formed, and FIGS. 2 (a) and 2 (b). ) And (c) are explanatory views of the mechanism of the generation of a fish tail that occurs during width reduction rolling, FIGS. 3 (a) and (b) are explanatory views of the plastic flow curve with and without a preforming portion, and FIG. 4 is the present invention. It is a partial cross-sectional side view showing an example of a roll preforming hydraulic control device for carrying out the above. 1 ... metal slab, 2 ... vertical roll, 3 ... horizontal roll, 4 ... vertical roll, 5,5a, 5b ... preformed part,
6 ... bite end, 7 ... bite out end, 8 ... plastic flow curve, 9 ... check, 10 ... yoke, 11 ... fixed housing, 12 ... pre-back cylinder, 13 ... rolling down screw, 14 ... Plesser block, 15 ...
… Nut down nuts, 16… Worm wheel gears, 17
...... Roll agitator, 18 ...... Ring piston, 19
…… Annular cylinder, 20 …… Liquid chamber void.

Claims (1)

[Claims] 1. When a metal slab is hot width-rolled by a row of hot rolling machines in which vertical rolling machines are provided in front of and behind the horizontal rolling machine, a hydraulic control device is provided in a width reduction device of the vertical rolling machine. By changing the vertical roll gap during the rolling pass to preform narrowly the widthwise ends of the metal slab and the parts distant from each side end of the metal slab. A hot width rolling method for a metal slab, which is performed before a width rolling pass for maintaining a predetermined value during the pass.