JPH06234005A - Joining method for billet in continuous hot rolling - Google Patents

Abstract

PURPOSE:To simply join a preceding and a succeeding billets with a high strength in a short time by obliquely cutting a rear end part and a tip part placed one upon another by cooperative operations of a shearing blade and an intermediate shearing blade, putting them together and pressurizing each clean cut surface. CONSTITUTION:In a shearing and joining device, the rear end part area of a preceding billet 1 and the tip part area of the succeeding billet 2 are placed one upon another at intervals one another. These billets are held by pinching up and down with shearing blades 5a and 5b and intermediate shearing blades 5c and 5d arranged in a prescribed position. Next, the shearing blade 5a and the intermediate shearing blade 5d are moved, and respective end part areas 1a and 2a are cut away at an angle of theta respectively by cooperative operations of these shearing blades 5a to 5d. It is preferable that this cutting angle theta is 20 to 80 deg., especially approximately 45 deg.. A clean and fresh surface appears along with a broken line by this shaping cut. At that time, it is preferable to blow inert gas or reducing gas into between the billets to prevent oxidation. Just after that, the cut surfaces are put together and pressurized each other to join them.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to joining of steel pieces in continuous hot rolling suitable for continuously rolling several to several tens of steel pieces such as a sheet bar, slab, billet or bloom. It is about the method.

[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. Japanese Patent Laid-Open No. 60-40601 is referred to as prior art relating to this point.

The technique disclosed in the above-mentioned Japanese Patent Laid-Open No. 61-40601 is a steel piece that is conveyed subsequently and a rear end portion of a steel piece that is conveyed in advance (hereinafter referred to as a preceding steel piece). (Less than,
Each of the leading end portions of the following steel pieces is cut, and immediately after that, both cutting surfaces are pressed to join them, and then the steel is rolled. However, this technique has the following problems because it cuts a steel strip vertically.

That is, in order to press the cut surfaces of the steel slabs together, the preceding steel slab and the trailing steel slab are clamped in the plate thickness direction (to prevent position variation), and then force is applied in the longitudinal direction of the steel slab. Since it is necessary to add and press, the quality around the joint will be poor after finish rolling due to buckling at the joint and local temperature drop due to the clamp. Since a sufficient pressing force cannot be applied in the process, the joint strength may not be sufficient. In such a case, there is a possibility of causing a serious accident in which the joint portion breaks and separates during finish rolling. Furthermore, in such a joining method, since it takes some time from the cutting of steel slabs to the completion of joining, scale is generated on the cut surface (when the cut surface is exposed to air for 0.1 seconds, the thickness of the surface is 1 μm or more. However, this adversely affects the bonding strength and cannot be said to be a reliable bonding technology.

[0006]

DISCLOSURE OF THE INVENTION An object of the present invention is to propose a method capable of simply and quickly joining a preceding steel piece and a following steel piece over the entire width without causing local temperature drop at the time of joining and causing deformation. There is a place to do it.

[0007]

According to the present invention, after joining a trailing end of a preceding steel slab and a leading end of a succeeding slab subsequent to this, the slab is fed to a finishing rolling mill group and continuously heated. During the hot rolling, the trailing edge area of the preceding steel piece and the leading edge area of the following steel piece are overlapped vertically with an interval between them, and the intermediate shear between the shear blade and the steel piece that sandwich this steel piece up and down. It is characterized by cutting off each steel slab end area diagonally by joint work of blades and matching and pressing the cutting surface of each steel slab by moving at least one of the preceding steel slab and the preceding steel slab accompanying this cutting off. In the present invention, it is preferable to blow an inert gas or a reducing gas between the steel pieces. The cutting angle of the steel slab is preferably about 20 ° to 80 °.

FIG. 1 shows the configuration of equipment suitable for carrying out the present invention. In the figure, reference numeral 1 is a preceding billet that has passed through the rough rolling mill R, and 2 is a trailing billet following the preceding billet 1. Also, 3
Removes scale on the surface of the slab (especially at the edge of the slab)
Descaling device, 4 is a leading billet 1 and a trailing billet 2
Is a device for vertically stacking the end regions of the device on top of each other with at least one of the rollers 4a, 4b provided on the device 4 being in contact with the steel strip to move the steel strip above or below the transport line. Let

Reference numeral 5 denotes shear blades 5a and 5b for sandwiching the steel pieces 1 and 2 vertically and an intermediate shear blade 5 located between the steel pieces.
A shearing / joining device equipped with c and 5d (a looper with a small stroke can be installed on the inlet side of this device to avoid local cooling of the trailing billet). The shear blades 5c and 5d have a structure capable of advancing and retracting in the width direction of the steel slab, or have a structure having a rotation axis in a direction orthogonal to the longitudinal direction of the steel slab (an intermediate shear blade after joining the steel slabs. (Function to return to the initial position)
Apply. 6 is a looper for stopping the joining region of the steel slab in the line (it can be omitted if the descaling device 3, the device 4 for stacking the steel slabs, and the shear welding device 5 can be moved synchronously with the steel slab), 7 Is a scale breaker for removing the scale formed on the surface of the billet prior to finish rolling, 8 is a group of finish rolling machines, 9 is a table roller, and the table roller 9 avoids local cooling of the billet. Therefore, a mechanism capable of moving in the longitudinal direction of the billet or in the thickness direction of the billet can be provided. And
Numeral 10 is an entrance side pinch roll which is preferably equipped with the same mechanism as the table roller 9.

In order to join the preceding steel piece 1 and the following steel piece 2, the steel pieces are overlapped in the end region thereof with a gap by using the above-mentioned device 4. In the shearing / joining device 5, the shearing blades 5a, 5b and the intermediate shearing blades 5c, 5d are shown in FIG.
2b and c, as shown in FIGS. 2b and c, the shear blades 5a and 5b and the intermediate shear blades 5c and 5d are jointly operated so that the end regions 1a and 2a of the respective steel pieces are angled by Θ.
And cut off. In this cutting operation, at least one of the preceding steel piece 1 and the following steel piece is pushed and moved by the shear blade (in this example, the following steel piece 2 is pushed by the shear blade 5a and moves downward). 2d, the cut surfaces of the steel pieces are made to coincide with each other in accordance with this movement, and together with this, the steel pieces are pressed and joined in the plate thickness direction.

[0011]

The function of joining steel pieces according to the present invention will be described below. In the state shown in FIG. 3, the shear blade 5
When a load is applied to a and 5d, the steel pieces 1 and 2 are cracked along the broken line in the figure and cut. Since a clean new surface appears due to the shaving shear by the intermediate shear blades 5c and 5d, the cut surfaces serving as the joining interfaces between the steel pieces 1 and 2 immediately follow the cut surfaces c ₁ and c ₂ as shown in FIG. When pressed, a strong joint is formed without being affected by the generation of scale.

The cutting angle Θ of the steel slab has a larger joining area as the cutting angle Θ becomes smaller, so that the strength of the joint becomes higher, but if it is less than 20 °, shearing becomes difficult and exceeds 80 °. Since the bonding area is reduced, the bonding strength is greatly reduced. In the present invention, the cutting angle Θ
Is between 20 ° and 80 °. In the present invention, it is most preferable to perform shearing at an angle of about 45 ° at which maximum shear stress is obtained when pressed from above and below. Further, since the intermediate shear blades 5c and 5d are for making new surfaces for joining the steel pieces to each other appear, it is necessary to prepare especially sharp ones.

In the joining of steel slabs according to the present invention, the temperature of the slab (particularly the temperature of the joining region) is short, although it takes a short time (about 2 to 6 seconds) from the cutting of the steel slab to the matching of the cut surfaces. It is about 1000 ° C and the new surface will come into contact with the atmosphere, so it cannot be said that there is no scale effect on that surface. In order to surely prevent the generation of scale in such an area, as shown in FIG. 5, a gas containing no oxygen is interposed between the intermediate shear blades 5c and 5d so as to prevent the generation of scale.
(For example, an inert gas such as Ar gas or N gas or a reducing gas containing a minute amount of H ₂ gas) may be blown in for purging, whereby a more reliable joint portion can be obtained. In the above-mentioned FIG. 5, a gas blowing nozzle N is provided in the intermediate shear blade 5c, and an inert gas or the like is blown into this nozzle N.

[0014]

EXAMPLE A descaling device 3 was used to perform continuous hot rolling of a sheet bar having a width of 1200 mm and a thickness of 30 mm in the equipment shown in FIG. 1 equipped with a seven-stand tandem rolling mill. The scale in the overlap area is removed, the sheet bars are overlapped by the device 4, and the shear joining device 5 is used.
The ends of the sheet bar were cut and joined in sequence, and the joining condition of the obtained joints was investigated. As a result, it was confirmed that the preceding sheet bar and the succeeding sheet bar were strongly metal-bonded.

[0015]

According to the present invention, the preceding steel piece and the following steel piece can be simply and quickly spread over the entire area in the plate thickness direction without causing local temperature drop or shape deterioration of the steel piece. It is possible to carry out continuous hot rolling with high productivity and joining with sufficient strength.

[Brief description of drawings]

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

FIG. 2A to FIG. 2D are explanatory views of a joining procedure of steel pieces.

FIG. 3 is an explanatory diagram of a shearing condition of a steel slab.

FIG. 4 is an explanatory diagram of a joining state of steel pieces.

FIG. 5 is a diagram showing an example of a gas blowing structure.

[Explanation of symbols]

 1 Leading steel slab 2 Trailing steel slab 3 Descaling device 4 Steel slab stacking device 5 Shearing / joining device 5a Shearing blade 5b Shearing blade 5c Intermediate shearing blade 5d Intermediate shearing blade 6 Looper 7 Scale breaker 8 Finishing mill group 9 Table Roller 10 Entry side pinch roll

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

Claims (3)

[Claims] 1. When joining the trailing end portion of a preceding steel piece and the leading end portion of a succeeding steel piece following this, when feeding the finishing steel strip to a group of finishing rolling mills for continuous hot rolling, The rear end region and the front end region of the trailing steel piece are stacked vertically with a space between each other, and the steel blades are sandwiched by the shear blades and the intermediate shear blades between the steel pieces work together. A continuous hot work characterized by cutting off one end region diagonally and matching and pressing the cut surface of each steel piece in accordance with the movement of at least one of the preceding steel piece and the trailing steel piece accompanying this cutting off work. Method of joining steel slabs during rolling. 2. The method according to claim 1, wherein an inert gas or a reducing gas is blown between the steel pieces. 3. The method according to claim 1, wherein the cutting angle of the steel slab is 20 ° to 80 °.