JPH06339703A - Joining method of steel slab in continuous hot rolling - Google Patents

Abstract

(57) [Summary] [Structure] After joining the steel pieces to each other by bringing the trailing end portion of the preceding steel piece and the leading end portion of the succeeding steel piece subsequent thereto into contact with each other and pressing while heating,
When feeding to the finishing rolling mill group and performing hot rolling continuously, the reduction distribution in the thickness direction and width direction of the billet is adjusted in the rough rolling process to adjust the trailing edge and trailing edge of the preceding billet. At least one of the front end portions of the steel pieces is finished into a planar shape in which at least both ends in the width direction are in contact with each other in a state where the steel pieces are butted against each other. [Effect] Since the flat shape required for joining steel pieces can be obtained without performing cutting work, it is possible to omit the installation of a device dedicated to cutting, which can reduce the cost involved and shorten the joining time. The line length can also be shortened.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a continuous hot rolling method suitable for continuously rolling several to several tens of steel pieces such as sheet bars, slabs, billets and blooms. .

[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 in finish rolling is unavoidable, and the yield reduction due to defective shape of the leading end and the trailing end of the rolled material has a significant disadvantage. .

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

The technique disclosed in the above-mentioned Japanese Patent Laid-Open No. 61-144203 is such that a steel piece that is conveyed first (hereinafter referred to as a preceding steel piece) and a steel piece that is conveyed subsequently. (Less than,
The leading end portion of a trailing steel piece) is butted over its entire surface, both widthwise end portions thereof are pre-joined, and rolling is performed while maintaining this state. However, this technique requires a long joining time in order to give a sufficient joining strength to the pre-joint portion, which is disadvantageous in that the line is extended.

The inventors of the present invention have attempted to solve such a problem by alternating the rear end portion of the preceding steel piece and the front end portion of the following steel piece so that the steel piece penetrates in that region in the thickness direction of the steel piece. We have developed a joining method consisting of a combination of heating and pressing, in which a magnetic field is applied and the joint surface is heated and pressed by the induced current induced by this alternating magnetic field.
No. 109 and No. 4-89110. With the development of this joining method, the joining work has become quicker and easier than ever before.

[0006]

By the way, according to the above joining method, at the time of joining the preceding steel piece and the following steel piece to each other, at least one of the ends of the joining pieces is butted against each other and at least both ends in the width direction. Since it is essential to install a cutting device (a device for shearing, gas fusing, laser fusing, etc.) that processes into a shape that makes contact with each other, it requires an extra cost for this and The installation hinders the shortening of the rolling line and the joining time, leaving some room for improvement in this respect.

The present invention proposes a joining method which is advantageous for shortening the processing line and shortening the time required for joining when a plurality of steel pieces are joined together for continuous hot rolling. That is the purpose.

[0008]

SUMMARY OF THE INVENTION According to the present invention, the rear end portion of a preceding steel piece and the leading end portion of a succeeding steel piece subsequent thereto are brought into contact with each other and pressed while being heated, so that the steel pieces are pressed against each other. After joining, when feeding to the finishing rolling mill group and continuously performing hot rolling, the rolling distribution is adjusted in the thickness direction and width direction of the billet in the rough rolling process, and A method for joining steel strips in continuous hot rolling, characterized in that at least one of the end portion and the leading end portion of the subsequent steel strip is finished into a flat shape in which at least both ends in the width direction are in contact with each other in a butting state with each other. .

FIG. 1 shows a continuous hot rolling facility suitable for carrying out the present invention. In the figure, 1 is a vertical rolling mill 1.
a, 1b and a horizontal reversing rolling mill 1c, a rough rolling mill group, 2
Is a heating and welding device that is movable along the steel piece conveying line L. The heating and welding device 2 makes the rear end portion of the preceding steel piece and the leading end portion of the following steel piece contact each other and heats them. The two steel pieces are joined together by pressing, and a system in which an alternating magnetic field penetrating in the thickness direction of the steel pieces is applied and heated by an induction current induced thereby is applied. Further, 3 is a scale breaker, and 4 is a finishing rolling mill group for continuously rolling the joined steel pieces into strips having a predetermined thickness and width.

In order to continuously hot-roll steel slabs by applying the equipment shown in FIG. 1, the reduction distribution (thickness direction, width direction) is adjusted in the rolling stage by the rough rolling mill group 1. While rolling (reverse), at least one of the trailing edge of the preceding billet and the leading edge of the trailing billet has a shape as shown in Fig. 2 (fishtail shape, the protrusion amount e at both ends is 5 to 50).
mm is preferable). And Figure 3a,
As shown in b, the steel pieces are joined together using the heating joining apparatus 2 and then passed through the finishing rolling mill group 4 to finish into strips having a predetermined thickness and width.

[0011]

In the case where continuous hot rolling of a steel slab is carried out using the equipment having the structure shown in FIG. 4, the cutting device 5
Since the end of the steel slab is processed into a shape as shown in FIG. 5, the line is lengthened by the space for arranging the cutting device 5, which is disadvantageous for shortening the welding work time. There is also an unavoidable increase in equipment costs, so it is desirable to omit such a device. In the present invention, at least one of the trailing end of the preceding billet and the leading end of the following billet is adjusted by adjusting the reduction distribution of the billet in the rough rolling stage, and at least both ends in the width direction in the state where the billets are butted against each other. Since it is finished in a planar shape that makes contact with each other, it is possible to obtain the desired shape without cutting.
Therefore, the line can be shortened by the space required for the installation of the cutting device, and the equipment cost required therefor can be reduced.

[0012]

[Example] Thickness 260 using the equipment as shown in FIG.
A low carbon steel slab with a width of 1060 mm and a width of 1060 mm was subjected to rough rolling (both leading and trailing steel billets) under the pass cage according to Table 1 (see Fig. 6). After the sheet bar having a flat shape as shown in the drawing, the leading sheet bar and the trailing sheet bar were joined to each other on the exit side under the following conditions, and the working time required to complete the joining was investigated. Joining conditions Heating method: Heating by the transverse method by applying an alternating magnetic field Heating temperature: 1400 ° C Pressing force: 3 kgf / mm ² Heating time: 3 seconds Joining form: Heating while pressing Joining allowance: One side 100 mm (total on both sides 200 mm)

[0013]

[Table 1]

As a result, on the exit side of the rough rolling mill, a cutting process as shown in FIG.
It was confirmed that the working time from the end of joining (after using a drum shear having 6.5 m) to the joining (same conditions) can be shortened by about 5 seconds (distance about 5 m). .

[0015]

According to the present invention, when the preceding steel piece and the following steel piece are joined, the flat shape required for joining the steel pieces can be obtained without using a cutting device. It's optional and you can save money on this,
It is also possible to reduce the joining time and the line length.

[Brief description of drawings]

FIG. 1 is a diagram showing a configuration of equipment suitable for carrying out the present invention.

FIG. 2 is a diagram showing a shape of an end portion of a steel slab after rough rolling.

3A and 3B are views showing a joining state of steel pieces.

FIG. 4 is a diagram showing a configuration of a conventional continuous hot rolling facility.

FIG. 5 is a view showing a shape of an end portion of a steel piece when processed by a cutting device.

FIG. 6 is a diagram showing a rolling situation in rough rolling.

FIG. 7 is a diagram showing a shape of an end portion of a steel slab after rough rolling.

FIG. 8 is a view showing a shape of an end portion of a steel piece when processed by a cutting device.

[Explanation of symbols]

 1 Rough rolling mill group 2 Heating and joining device 3 Scale breaker 4 Finishing rolling mill group 5 Cutting device

Front page continuation (72) Toshisada Takechi Inventor Toshisada Takechi 1 Kawasaki-cho, Chuo-ku, Chiba-shi, Chiba Inside the Chiba Steel Works, Kawasaki Steel (72) Inventor Hideyuki Nikaido 1 Kawasaki-cho, Chuo-ku, Chiba, Chiba Kawasaki Steel Inside the Chiba Steel Works (72) Inventor Takeshi Hirabayashi 1 Kawasaki-cho, Chuo-ku, Chiba-shi, Chiba Inside the Kawasaki Steel Works (72) Inventor Toshiaki Amagasa 1 Kawasaki-cho, Chuo-ku, Chiba-shi Kawasaki Steel Inside Chiba Works (72) Inventor Kanji Hayashi 4-6-22 Kannon Shinmachi, Nishi-ku, Hiroshima City, Hiroshima Prefecture Mitsubishi Heavy Industries, Ltd. Inside Hiroshima Works (72) Yoshinori Mito 4-6 Kannon Shinmachi, Nishi-ku, Hiroshima City, Hiroshima Prefecture No. 22 Mitsubishi Heavy Industries Hiroshima Works

Claims (1)

[Claims] 1. A group of finishing rolling mills after joining the steel pieces to each other by bringing the rear end portion of the preceding steel piece and the leading end portion of the succeeding steel piece subsequent thereto into contact with each other and pressing with heating. In the rough rolling process, the distribution of reduction in the thickness direction and width direction of the steel slab is adjusted during the continuous hot rolling to the rear end of the preceding slab and the tip of the following slab. A method for joining steel pieces in continuous hot rolling, characterized in that at least one of the portions is finished into a planar shape in which at least both ends in the width direction are in contact with each other in a butted state.