JPS61126902A - Production of cold rolled steel strip - Google Patents

Abstract

PURPOSE:To obtain a rolled strip which decreases edge drop and has high quality by extruding the trimmed steel strip in the transverse direction to form bulging parts at the edges of the steel strip and rolling the steel strip. CONSTITUTION:Two side rolls 81 and 82 are provided to an edger 8 along the width of the steel strip. The steel strip S passing along the rolls 81, 82 is pressed in the transverse direction thereof and the bulges, i.e., dogbones Sd, Sd are formed at both ends thereof. The dogbones Sd, Sd formed in such a manner offset the edge drop to be generated in the cold rolling stage of said steel strip. The rolled strip which decreases the edge drop and has the high quality is thus obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a method for producing a rolled steel strip, and particularly to a method for producing a cold rolled steel strip with less edge drop.

[Conventional technology]

In general, cold-rolled steel strip is produced by hot rolling a continuous cast slab or a bloomed slab, and after cooling, the oxide layer, or scale, is removed through a descaling process such as mechanical descaling or pickling. It is then manufactured by cold rolling.

One of the important control items during hot rolling and cold rolling is the plate shape, and several methods have been put into practical use to control the plate shape, such as roll bender and intermediate roll shift method. There is.

[Problem that the invention seeks to solve]

However, since this shape control method is performed by deflecting the work roll, edge drops are generated at both ends of the steel strip. Particularly during hot rolling, the deformation resistance is extremely small and the thickness of the edge of the steel strip becomes thinner rapidly. Such edge drops cannot be corrected by cold rolling, and therefore the edge portions have to be trimmed, resulting in a decrease in yield.

[Purpose of the invention]

The present invention was made in view of the drawbacks of the prior art, and an object thereof is to avoid the generation of edge drops and improve the yield.

[Means for solving problems]

The method for manufacturing a cold rolled steel strip according to the present invention involves removing scale on the surface of the hot rolled steel strip through a descaling process such as pickling, and then trimming the hot rolled steel strip to a predetermined width. , and then cold or warm pressing in the width direction, followed by cold rolling.

[Effect]

By performing cold rolling with appropriate bulges at both ends of the hot-rolled steel strip, the bulges and edge drops during cold rolling are offset, and the generation of large edge drops is avoided.

〔Example〕

Figure 1 shows the main parts of a processing line to which the method for producing cold rolled steel strip according to the present invention is applied. 4 is an output side looper; 6 is a side trimmer for trimming the edge of the steel strip S; 7 is a heating device; 8 is an edger 111 for forming bulges on both sides of the steel strip S; And 12 is a winding machine. Note that 3.5.9 and 10 indicate prydle rolls for applying a predetermined tension to the steel strip S.

Although the left side of the pickling device 2 is omitted, the steel strip S to be processed in the processing device 2 is unwound from the coil by an unwinding machine, and the trailing edge of the preceding steel strip and the following The leading edge of the steel strip is welded and continuously fed through an entry louver (not shown).

After the scale on the surface of the steel strip S introduced into the pickling device 2 is removed, it passes through a prydle roll 3, an outlet looper 4, and a prydle roll 5, and is sent to a side trimmer 6.

The steel strip S introduced into the side trimmer 6 is trimmed there so as to have a predetermined width, and then passed through the heating device 7.
is heated to the desired temperature.

Next, as will be described in detail later with reference to FIG. 2, the F-jer 8 compresses the steel strip S in the width direction to form a bulge, that is, a dog bone, at both ends in the width direction. efjar 8
The steel strip S passing through the priddle rolls 9 and 10 enters the shearing machine 11, where it is cut into a predetermined length and then sent to the winding machine 1.
It is wound up at 2. The coil wound in this way is
It will be cold rolled by being passed through a tandem cold rolling mill.

Referring now to FIG. 2, there is shown how the steel strip S passing through edger 8 in FIG. 1 is treated. As shown in the drawings, the edger 8 is provided with two lateral rolls 81 and 82 along the banding width, roll 81 centered on its longitudinal axis in the direction of arrow A; The roll 82 is centered on its longitudinal axis in the direction of arrow B.
The steel strip S passing between the rolls 81 and 82 is sent forward at right angles to the plane of the paper. Side rolls 81 and 82
The distance i between the outer circumferences of the wire strip S passing through the rolls 81 and 82 is adjustable.
is pressed in its width direction, and bulges, that is, tongue bones Sd, are formed at both ends thereof. The dog bones Sd, Sd formed in this way cancel out the edge drop that occurs during the cold rolling process of the copper strip.

In the above-mentioned embodiment, the reason why the place where the width of the band is pressed, that is, the edger 8 is located after the side trimmer 6 and the heating device 7 of the pickling line is as follows.

This is because the treatment in the pickling line is performed continuously under a state in which tension is applied to the steel strip S, so that the pressing operation by the F-ger 8 can be performed stably.

In addition, during hot rolling, the width of the steel strip S changes due to factors such as width fluctuation due to the difference in deformation resistance such as longitudinal tongue bones and skid marks caused by hot edger, and flaring at the front and rear due to horizontal rolling. Not constant. Therefore,
It was placed after the side trimmer to keep the width constant.

Note that the heating of the steel strip S by the heating device 7 is performed by the edger 8.
This is done in order to reduce the deformation resistance during width pressing, so it is sufficient to heat only the edge portion to about 200 to 400°C. In addition, local heating of only the edge portion is effective in preventing buckling of the steel strip S during width pressing.

Now, Fig. 3 shows another embodiment of the edger 8 shown in Fig. 2.
In particular, this is an example in which a total of four presser rolls 83 are added, two at the top and two at the bottom, for the purpose of preventing buckling during width pressing. The presser rolls 83 are mechanically simple because they only need to be able to restrain at least the edge portions of the steel strip S, and their positions can be adjusted according to the width and thickness of the steel strip S. The side rolls 81, 82 and four presser rolls 83 in the edger 8 are controlled by feedback based on signals from a board width meter (not shown) provided on the edger exit side.

As is clear from the above description, in this example, the surface of the hot-rolled steel strip is descaled using a pickling device, the edge portion is trimmed to a predetermined width, and then the copper strip is pressed in the width direction. Since bulges, or dog bones, are intentionally generated before cold rolling, the dog bones are offset by the edge drop that occurs during cold rolling, resulting in a cold rolled steel strip with a good shape and small edge drop. is obtained.

In the specific example pickling device 2, a hot rolled steel strip with a plate thickness of 2.30 mm is pickled to remove scale, and then the side trimmer 6
The edges were cut to make the board width 850 mm, and heating device 7
The edge portion was heated to about 200°C. after that,
It was pressed in the width direction with an edger 8 at a pressing amount of 3ta on one side, and finally rolled in a tandem cold rolling mill.

FIG. 4 shows the results of the above specific example, with the horizontal axis representing the distance from the edge and the vertical axis representing the plate thickness.

Curve A shows the result here, and curve iB shows the result by the conventional method using a tuning band of the same size as above.
is virtually constant, but in the song NfAB it is approximately 7% ((
0,58-0,54) X10010.58) shows fluctuation.

Although this invention has been explained above based on an example in which the edger is arranged on the outlet side of the pickling equipment, the edger is installed on the entry side of a continuous tandem cold rolling mill and downstream of the welding machine. Alternatively, a similar effect can be obtained using a line in which pickling and tandem cold rolling are performed continuously.

Further, although a heating device is used in the above-mentioned embodiment, it is only an additional device and may be omitted, as is clear from the explanation.

〔Effect of the invention〕

In the method for manufacturing a rolled strip according to the present invention, the trimmed strip is extruded in the width direction, and a bulge is formed at the edge of the copper strip before rolling, so the bulge offsets the edge drop. A high quality rolled strip with small edge drop can be obtained.

As a result, trimming after cold rolling becomes unnecessary, and an improvement in yield is achieved.

[Brief explanation of drawings]

FIG. 1 is an extracted view of the main parts of a processing line to which the method for manufacturing cold rolled steel strip according to the present invention is applied, FIG. FIG. 3 is a perspective view of another embodiment of the edger, and FIG.
The figure is a graph showing the plate thickness characteristics obtained in the specific example of the present invention and the corresponding plate thickness characteristics according to the conventional method.

Claims (1)

[Claims] (1) A method for producing a cold-rolled steel strip, which comprises pressing an edge-cut hot-rolled steel strip in the width direction to form a bulge in the edge portion of the steel strip, and then cold rolling the strip.