JPH064164B2 - Method for trimming joints in continuous hot rolling - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for trimming a joint in continuous hot rolling of a hot strip.

(Prior art and its problems) In hot rolling of hot strips, a strip of a predetermined thickness is rolled by a rough rolling mill group (hereinafter referred to as a sheet bar), and this sheet bar is finish rolled by a finishing rolling mill group. Then, this strip is wound up on a down coiler, but in recent years, in order to improve the production efficiency and make the quality and dimensions uniform over the entire length of the strip, the preceding sheet between the rough rolling mill group and the finishing rolling mill group is used. The rear end of the bar and the leading end of the succeeding sheet bar are joined by an appropriate means such as welding, and continuously finish-rolled, and each sheet bar is cut and wound before the down coiler. There is.

In such continuous hot rolling, the preceding sheet bar B
The rear end of ₁ and the front end of the following seat bar B ₂ are welded by abutting or superposing the end portions (see FIG. 11) or by meshing in a jigsaw method (weld portion 12). (See the figure).

Although various joining methods have been developed and proposed,
In any of the joining methods, not only when the leading sheet bar and the trailing sheet bar have different widths, but even when the widths are the same, there are variations, centering variations, jigsaw teeth and cutting of the jigsaw teeth due to width variation. However, due to poor welding, there are many cases where the ends of the joints are not uniform, the joints are poor, or the joints are insufficient.

In such a state, stress concentrates on this joint end,
When it becomes the starting point of breakage, or as shown in FIG. 11 and FIG.
If it is caught in the roll, it causes serious troubles such as breakage of the roll, flaws on the roll, or breakage of the plate.

This invention has been proposed in order to solve such problems, the purpose is to prevent the occurrence of troubles such as roll breakage and can prevent the stress concentration of the joint portion of continuous hot rolling It is to provide a method for trimming a joint.

(Means for Solving the Problems) The joining portion trimming method for continuous hot rolling according to the present invention is provided with a joining machine between the rough rolling mill group and the finish rolling mill group,
This joining machine joins the trailing edge of the preceding sheet bar and the leading edge of the following sheet bar (for example, butting, overlapping,
Alternatively, in a continuous hot rolling in which a jigsaw type is engaged and welded, and is continuously finish-rolled, in the latter stage of the joining machine, at both ends in the sheet bar width direction at the joining portion between the preceding sheet bar and the following sheet bar, In the plan view, a notch having an arcuate cutting line that is convex toward the inside of the seat bar is formed.

(Work) The arc-shaped notch prevents stress concentration and
The corners and cutouts of the joint that cause trouble are removed.

(Examples) Hereinafter, the present invention will be described based on illustrated examples.

As shown in FIG. 4, the coil box 3, the joining machine 4, and the looper 5 as an accumulator are installed between the rough rolling mill group 1 and the finishing rolling mill group 2, and the looper 5 is used for welding. The succeeding seat bar B ₂ which stores the strip S for a required time and is stored in the coil box 3
2 is an example of a continuous hot rolling line in which the front end of the sheet and the rear end of the preceding sheet bar B ₁ are joined by a fixed type joining machine 4.

In such a rolling line, the joining machine 4 is used in the present invention.
And a looper 5, a side shear 6 capable of traveling in the longitudinal direction of the line is installed, and the side shear 6 is fixed,
While the seat bar B is moving or at rest, or the side shear 6 travels integrally with the seat bar B to trim both ends of the joint.

This trimming is, as shown in FIGS. 1 to 3,
A notch 7 that is convex toward the center axis of the seat bar in a plan view and is formed only by an arcuate cutting line, or a notch 7 that is formed by an arcuate cutting line and a straight cutting line continuous with this arc is joined by shear cutting. Form on both ends of. In the case of the overlapping shown in FIG. 2, the overlapping portion is cut so as to completely cover it, and in the case of the jigsaw type shown in FIG. 3, the meshing portion is cut so as to completely cover it. in this case,
If the width of the seat bar B is known, the cutting depth l can be automatically set because the jigsaw shape can be predicted from the jigsaw blade.

Further, as shown in FIGS. 1 to 3, when the preceding seat bar B ₁ and the following seat bar B ₂ have different widths, the succeeding seat bar B ₂ is continuously curved in an arc and inclined rearward. Taper 7
a is formed. By providing such a taper 7a, it is possible to prevent two corner portions from overlapping when the roll is engaged.

Next, FIGS. 5 to 10 show examples of a jigsaw type joint portion having specific dimensions.

As shown in FIG. 5, if the leading seat bar B ₁ side is not tapered, the trailing seat bar B ₂ side is tapered by 15 °, and the radius of the arc is 25 mm, the yield is reduced due to the narrow width. Was found to be small, and rolling trouble was found to be small.

In the case of FIG. 6, the cut amount is reduced.
When the depth of cut is large as shown in FIGS. 7 and 8, it may be configured by an arc and a straight line portion, and both the straight line portions may not be tapered, or both may be tapered.

FIG. 9 and FIG. 10 show cases of different widths, and a 15 ° taper 7a is attached to the seat bar B ₂ side of the subsequent line.

Such arcuate notches 7 prevent stress concentration, and eliminate corners and breaks in the joint that cause trouble.

Further, such a notch 7 can also be used for detecting a joint portion, so that the joint portion can be detected before being wound up by a down coiler, and cut into each sheet bar unit by a cutting machine. Is helpful.

Needless to say, the present invention can be applied not only to a rolling line having a looper and a fixed-type bonding machine, but also to a rolling line having a traveling-type bonding machine.

(Advantages of the Invention) As described above, according to the present invention, in the latter stage of the joining machine, the notches having the arcuate cutting lines protruding toward the inside of the seat bar in plan view are provided at both ends of the joining portion of the seat bar. As a result, the defective and unstable parts at the end of the joint are smoothly cut, stress concentration is prevented, and
Since only the stable joint is provided for the entire length of the joint width, it is possible to perform smooth continuous hot rolling without trouble.

Further, there is an advantage that the notch can be used for detecting the joint portion.

[Brief description of drawings]

1, FIG. 2, and FIG. 3 are front views showing a butting, superposing, and jigsaw type joint portion according to the present invention,
(A) has the same width, (B) has different widths, FIG. 4 is a schematic view showing an example of a continuous hot rolling line, FIG. 5, FIG. 6, FIG.
Figures 8 are plan views showing various specific examples of jigsaw type joints having the same width, (A) before cutting, (B) after cutting, and FIG.
(C) is a sectional view thereof, FIGS. 9 and 10 are plan views showing specific examples in the case of different widths, (A) is before cutting, (B) is after cutting, and 11th.
FIG. 12 and FIG. 12 are plan views showing a conventional example. 1 ・ ・ Rough rolling mill group 2, ・ Finishing rolling mill group 3 ・ ・ Coil box, 4 ・ ・ Joining machine 5 ・ ・ Looper, 6 ・ ・ Side shear 7 ・ ・ Notch B ₁・ ・ Preceding seat bar B ₂・ ・・ Succeeding seat bar S ・ ・ Strip

Claims (1)

[Claims] 1. A joining machine is provided between a group of rough rolling mills and a group of finish rolling machines, and the trailing end of a preceding sheet bar and the leading end of a succeeding sheet bar are joined by this joining machine, and finish rolling is performed continuously. In the continuous hot rolling to, in the latter stage of the joining machine, at both ends of the sheet bar width direction at the joint between the preceding sheet bar and the following sheet bar, a convex arc-shaped cutting line toward the inside of the sheet bar in plan view. A method for trimming a joint in continuous hot rolling, which comprises forming a notch having