JPH0691315A - Method and roll for reducing thickness of billet - Google Patents

Abstract

PURPOSE:To improve the working accuracy of thickness reducing work that is executed at the time of joining billets mutually and to enable joining over the whole area in the width direction in finish rolling by revolving rolls in synchronism with the transportation of the billet and pressing the projections provided on the surface of these rolls against the biilet. CONSTITUTION:The projections 3a, 3b are provided on the outer periheral surfaces of rotors 2a, 2b and thickness reducing work is executed by acting these projections 3a, 3b in the end parts in the width direction of the billet 1 in accordance with the resolution of the rotors 2a, 2b. Then, since only the projections 3a, 3b are made to act on the billet 1 at the time of thickness reducing work, unnecessary forces are not added on worked parts, working accuracy is greatly improved and, consequently, defective joining is not caused in the joining treatment of the billet 1. Then, hot finish rolling is stably executed under joining over the whole area in the width direction.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a steel bar, a slab, a billet, a bloom, or the like, which is hot-rolled continuously for several to several tens of steel pieces in a short time. Moreover, the present invention relates to a method for reducing the thickness and a roll for reducing the thickness, which is useful when firmly joining.

[0002]

2. Description of the Related Art Conventionally, in a hot rolling line for billets, the billets to be rolled are individually heated, rough-rolled and finish-rolled to finish a hot-rolled sheet having a desired thickness. In such a rolling method, stoppage of the line due to defective biting of the rolled material is unavoidable in finish rolling, and the yield is significantly reduced due to defective shape of the leading end and the trailing end of the rolled material.

For this reason, recently, a rolling system has been adopted in which the rear end and the front end of steel pieces to be rolled are joined prior to finish rolling, and this is continuously supplied to a hot rolling line for rolling. It's starting to happen. Reference is made to JP-A-61-144203 as prior art relating to this point.

The technique disclosed in the above-mentioned JP-A-61-144203 is disclosed in the following: a steel strip that is conveyed in advance (hereinafter simply referred to as a preceding steel strip) and a steel strip that is subsequently conveyed (hereinafter referred to as "steel bill"). In other words, the leading end of the (following steel slab) is butted over the entire surface, pre-bonded, and rolling is performed until this state is maintained. However, this technique requires a long joining time in order to provide the pre-joined portion with sufficient joining strength, which is disadvantageous in that the line is extended.

In order to solve such a problem, the inventors of the present invention contact the trailing end portion of the preceding steel piece and the leading end portion of the trailing steel piece at least at both end portions in the width direction to make the steel piece in that region. Has developed a joining method consisting of a combination of heating and pressing means, in which an alternating magnetic field penetrating in the thickness direction is applied and the joining surface is heated and pressed by the induced current induced by this magnetic field. And Japanese Patent No. 4-89110. Further, in Japanese Patent Application No. 3-229755, at least both end portions in the width direction of the steel piece are subjected to a thickness reduction work, and the steel pieces are connected to each other in such a region, while the unoccluded portion generated at this time is We proposed a method of closing and pressing by the metal flow of the material in finish rolling. With the development of this joining method, the joining work has become quicker and easier than ever before.

[0006]

By the way, in the latter technique, that is, in the joining method in which at least both ends in the width direction at the time of joining steel slabs are subjected to thickness reduction processing, it is sufficiently satisfactory depending on the processing state of the thickness reduction processing. Since some pre-bonded portions cannot be obtained, break separation of the plate may occur due to this processing accuracy during finish rolling, leaving some room for improvement.

The present invention intends to improve the processing accuracy of the thickness reduction work performed at the time of joining steel pieces to each other and to perform the joining over the entire area in the sheet width direction in the finish rolling to carry out stable continuous hot rolling. It is a thing.

[0008]

According to the present invention, at least one of a rear end portion of a preceding steel piece subjected to rough rolling and a leading end portion of a trailing steel piece successively conveyed to the steel piece in the plate width direction is provided. When performing local thickness reduction processing on both ends, the roll is rotated in synchronization with the transportation of the steel slab, and the projections provided on the roll surface of the roll are pressed against the steel slab to achieve the local thickness reduction processing. It is a method for reducing the thickness of a steel slab, which is characterized in that it is applied. Further, the present invention comprises a rotor that is rotatable along the longitudinal direction of the steel slab and is movable in the width direction thereof,
On the outer peripheral surface of the rotor, there is provided a projection for locally reducing the thickness of a steel piece by the rotation of the rotor, which is a roll for reducing the thickness of a steel piece. It is advantageous that the rotor is composed of at least one set, more preferably two sets, which sandwich the steel strip in its thickness direction.

FIGS. 1a and 1b schematically show a thickness-reducing roll according to the present invention in an example in which two pairs of rotors are provided on the left and right to form a pair of steel strips sandwiching the steel piece in the thickness direction. 1 is a steel piece, 2a and 2b are rotors, and these rotors 2a and 2b
b is held by a shaft f having bearings supported at both ends and is configured to rotate together with the shaft f. The rotors 2a and 2b have a structure that can be individually moved along the axial direction of the shaft f (screws, etc.), although the specific structure is not shown, and the thickness of steel pieces of different sizes can be reduced. It can also handle processing.

Reference numerals 3a and 3b denote projections arranged on the outer peripheral surfaces of the rotors 2a and 2b, and the projections 3a and 3b are located at predetermined positions (steel in this example) on the steel piece 1 according to the rotation of the rotors 2a and 2b. The thickness is reduced by acting on the widthwise end portion of the piece.

[0011]

Operation: Using the equipment shown in FIG. 2, the preceding steel slab 1a
In order to continuously connect this with the trailing steel slab 1b and to continuously roll it, first the trailing end of the preceding steel slab 1a and the leading end of the following steel slab 1b that have passed through the rough rolling machine R in the cutting device 4 are used. Is subjected to a cutting process (at this stage, as shown in FIG. 3, there is no gap between the abutting portions of the preceding steel piece 1a and the following steel piece 1b),
Next, at least one of the rear end of the preceding steel slab 1a and the front end of the following steel slab 1b is processed by the thickness reducing device 5 so that at least both ends in the width direction thereof are in contact as shown in FIG. 4, Further, the heating / pressing device 6 makes the rear end portion and the front end portion of the steel pieces come into contact with each other and presses them while heating them to gradually increase the joining area of the steel pieces as shown in FIG. Then, when the required joining margin W is obtained, the heating / pressing is stopped to complete the pre-joining, and in this state, it is fed to the finishing rolling mill group 8 via the scale breaker 7. Was there.

Here, at the time of completion of the pre-joining by the heating / pressing device 6, the steel pieces 1a and 1b have a width of approximately 5 at the center in the width direction.
Although there is a gap of about 50 mm, even if there is such a gap g, if the steel pieces are joined to each other, the rear end and the tip of the steel pieces 1a and 1b in the finish rolling will be treated. By advancing the metal flow in the center part in the width direction, it is possible to join over the entire area in the plate width direction.Therefore, the joining time can be shortened in the form of joining by reducing the thickness of the steel pieces before the joining process. It can be said to be an extremely effective means in terms of measures.

By the way, in the normal thickness reduction processing using a flat roll or a press die as shown in FIG. 6, the processing accuracy is stable because the shape of the processing portion changes and the thickness reduction degree becomes uneven on the left and right. Since this is not the case, it often results in defective joints, which has the disadvantage of causing breakage separation of the plate during rolling.

In the present invention, the rotors 2a, 2b are provided with the protrusions 3a, 3b, and only the protrusions 3a, 3b act on the steel slab during the thickness reduction work as shown in FIGS. No excessive force is applied to the portion, and the working accuracy is extremely high, and therefore, joining failure does not occur in the joining process of the steel pieces.

The protrusion 3 having the shape shown in FIG. 1 above.
In the thickness reduction process using a and 3b, the plan view of the steel piece after processing, especially the trailing end of the preceding steel piece 1a is as shown in Fig. 8, and the plan shape of the tip of the following steel piece 1b is However, in the present invention, the shapes of the protrusions 3a and 3b are not limited to this, and various shapes are applied according to the processing situation and the joining situation. Further, in FIG. 1 above, an example is shown in which two pairs of rotors are provided on the left and right, which form a pair of steel pieces sandwiching the steel piece in the thickness direction, but the time required for the thickness reduction process is particularly problematic. If not, it is possible to provide only one set of such rolls and use it to reduce the thickness at both ends of the steel strip in the plate width direction, or use only a single rotor for the front and back of the steel strip. It is also possible to reduce the thickness of either one of them.

In FIG. 2 above, the case where the thickness reducing process is performed on the exit side of the cutting device 4 is shown as an example, but the thickness reducing process may be performed prior to the cutting process.

By interlocking the cutting process and the thickness reduction process of the steel slab, the processing position of the steel slab can be stabilized, which is advantageous for improving the processing accuracy.

[0018]

[Example] A machine having a 7-stand tandem rolling mill and having a facility as shown in FIG.
When continuously hot-rolling a sheet bar having m and widths of 1200 mm and 1400 mm, respectively, a thinning roll according to the present invention was used for thinning, and a press die as shown in FIG. We investigated the processing accuracy and the rolling situation when the thickness reduction processing was performed using.

As a result, in the thickness reduction processing using the roll according to the present invention, the standard deviations of the processing length L _p and the thickness reduction amount ΔH _p / 2 from the target values are 10% or less and 15% or less, respectively. Therefore, a good joining state was obtained, and no fracture separation of the plate during rolling was observed. On the other hand, when the thickness reduction processing is performed using the press die, the standard deviations of the processing length L _p and the thickness reduction amount ΔH _p / 2 from the target values are
It was about 30% and 50%, and the fracture separation of the plate due to the poor joining was unavoidable.

[0020]

According to the present invention, it is possible to improve the working accuracy when performing the thickness reduction work on the steel slab, so that the hot finish rolling can be stably performed under the joining over the entire width direction of the plate. It is possible to improve productivity as well.

[Brief description of drawings]

1A and 1B are configuration explanatory views of a roll for thickness reduction processing according to the present invention.

FIG. 2 is a diagram showing a hot finish rolling facility for billets.

FIG. 3 is a diagram showing the shape of a steel slab after cutting.

FIG. 4 is a view showing the shape of a steel slab after the thickness reduction processing.

FIG. 5 is a diagram showing a joined state of steel pieces.

FIG. 6 is a view showing a condition of reducing the thickness of a steel slab using a press die.

7A, 7B, 7C, 7D, 7E, 7F, 7G, 7G, 7G, 7A, 7B, 7A, 7B, 7C, 7D, 7E, and 7F are views showing a situation in which a steel sheet is subjected to a thickness reducing process using a roll according to the present invention.

FIG. 8 is a view showing a planar shape of a steel slab after thickness reduction processing.

FIG. 9 is a diagram showing a planar shape of a steel slab after thickness reduction processing.

[Explanation of symbols]

 1 Steel piece 1a Leading steel piece 1b Trailing steel piece 2a Rotor 2b Rotor 3a Projection 3b Projection 4 Cutting processing equipment 5 Thickness reduction processing equipment 6 Heating / pressing equipment 7 Scale breaker 8 Finish rolling mill f Shaft

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kunio Isobe, 1 Kawasaki-cho, Chuo-ku, Chiba, Chiba Prefecture Technical Research Division, Kawasaki Steel Co., Ltd. (72) Inventor Norio Takashima, 1 Kawasaki-cho, Chuo-ku, Chiba-shi, Chiba Kawasaki Steel Co., Ltd. Chiba Works

Claims (3)

[Claims] 1. At least one of a rear end portion of a preceding steel piece subjected to rough rolling and a front end portion of a following steel piece which is subsequently conveyed to the steel piece is locally reduced in thickness at both end portions in the plate width direction. In performing the processing, the roll is rotated in synchronization with the transportation of the steel slab, and the projection provided on the roll surface of the roll is pressed against the steel slab to perform the extreme thickness reduction processing. Thickness reduction method. 2. A rotor, which is rotatable along the longitudinal direction of the steel slab and is movable in the width direction thereof, is provided on the outer peripheral surface of the rotor, and the steel slab is locally reduced by the rotation of the rotor. A roll for reducing the thickness of a steel slab, which is provided with a protrusion for thickening. 3. The roll for reducing thickness according to claim 1, wherein the rotor comprises at least one pair of steel strips sandwiching the steel strip in the thickness direction.