JPH09314201A - Method for rolling hot rolled steel strip and device therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To manufacture a hot rolled steel strip excellent in the shape and precision in the width direction at high yield by straightening defective flatness of the rough bar, also correcting deviation from the center line in the width direction of the rough bar and heating the rough bar without generating temp. difference between both rdge parts and the middle part at the time of executing finish rolling of the rough bar which is rolled with a roughing mill. SOLUTION: A rough bar flatness straightening device 6, rough bar heating device 7 and side guides 3a, 3b, 3c are provided between the roughing mill 1 and the finishing mill 10, camber detecting devices 4a, 4b are provided on the inlet side and outlet side of the rough bar flatness straightening device 6. Based on the detected amount of camber of the rough bar 2, after straightening defective flatness of the rough bar with the flatness straightening device 6, the rough bar 2 is heated over the whole of the width direction with the heating device 7 and guided with the side guides during this time so that the center line line in the width direction of the rough bar 2 is made to coincide with the center lines of the flatness straightening device 6 and heating device 7.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hot rolling steel strip rolling method and apparatus for producing a hot rolling steel strip having a uniform temperature distribution in the width direction and a small quality variation with a high yield by a continuous hot rolling mill. It is about.

[0002]

2. Description of the Related Art Generally, a hot-rolled steel strip is manufactured by heating a slab to a predetermined temperature in a heating furnace, rolling the heated slab to a predetermined thickness by a rough rolling machine to form a rough bar, and then rolling the rough bar. After heating both ends with edge heaters, finish rolling with a continuous hot finishing mill consisting of multiple stands to form hot-rolled steel strips with a predetermined thickness.The hot-rolled steel strips are cooled on a run-out table. After cooling in a stand, it is manufactured by winding with a coiler.

In such continuous hot rolling, defective shapes such as "warp" and "earing" may occur at the tip of the rough bar rolled to a predetermined thickness by the rough rolling machine. When the rough bar has the above-mentioned defective shape, when the rough bar is heated by the edge heater, the rough bar may collide with the edge heater and be damaged.

In order to prevent the above-mentioned problems, for example, Japanese Patent Laid-Open No. 329519/1993 (hereinafter referred to as prior art) discloses a device as shown in FIG. As shown in FIG. 4, a flatness straightening device 6 is provided on the inlet side of the edge heater 9 between the rough rolling mill 1 and the continuous hot finish rolling mill 10, and the flatness straightening device 6 is provided. The warp detectors 4a and 4b are provided on the inlet side and the outlet side of the.

A rough bar 2 roughly rolled by a rough rolling mill 1.
The shape defects such as "upward warp" and "earing" that occur at the tip of the flatness are detected by the warp detectors 4a and 4b provided on the inlet side and the outlet side of the flatness straightening device 6, and based on the detection signals. The flatness correction device 6 is controlled to correct the flatness defect of the rough bar 2. The rough bar 2 whose flatness defect has been corrected in this way is sent to the edge heater 9, and both edge portions in the width direction are heated by the edge heater 9 so that the temperature distribution in the width direction becomes uniform, and then the continuous heat treatment is performed. Finishing and rolling mill 1
0 is used to finish rolling to a predetermined plate thickness.

[0006]

According to the prior art, the edge heater 9 caused by the poor flatness of the rough bar 2 is formed.
Collisions are prevented and damage from collisions is avoided,
The lateral “deviation” (Δx: of the coarse bar 2 as shown in FIG.
Off-center) cannot be corrected. as a result,
The side surface of the rough bar 2 may collide with the edge heater 9 and be damaged.

Although not shown in FIG. 4, when an induction heating device is provided on the entrance side of the edge heater 9 and the rough bar 2 is heated in its entire width direction by the induction heating device,
If the center of the induction heating device is deviated from the center of the rough bar 2 in the width direction, the temperature distribution is biased in the width direction of the rough bar 2, that is, the heat is biased. When the rough bar 2 has such an uneven heat distribution, the deformation resistance varies in the width direction of the rough bar, so that the shape of the steel strip after finish rolling deteriorates. In an extreme case, the steel strip may be deformed during finish rolling. Meanders and collides with a side guide installed between finish rolling mills composed of a plurality of stands, causing a problem that the rear end of the steel strip 2 is bent.

Therefore, an object of the present invention is to solve the above-mentioned problems, to correct the flatness defect of the rough bar when finishing rolling the rough bar rough-rolled by the rough-rolling mill, Correcting the deviation from the center line in the width direction of the bar, heating the coarse bar with a uniform temperature distribution in the width direction without causing a temperature difference between both edge parts and the vicinity of the center part, It is an object of the present invention to provide a method and an apparatus capable of manufacturing a hot-rolled steel strip having an excellent shape and accuracy in the width direction with high yield.

[0009]

SUMMARY OF THE INVENTION From the above-mentioned viewpoints, the present inventors have developed a method capable of heating a rough bar on the entrance side of a finish rolling mill so as to have a uniform temperature distribution in the width direction thereof. As a result, he conducted extensive research. As a result, the warp detector provided between the rough rolling mill and the finish rolling mill detects the amount of warp of the rough bar, and the detected amount of warp causes the rough bar flatness correction device to detect the flatness of the rough bar. The rough bar in which the flatness defect is corrected in this way is guided by the side guides so that the center line in the width direction thereof coincides with the centers of the flatness straightening device and the rough bar heating device.
It was found that the rough bar can be heated so as to have a uniform temperature distribution in the width direction by sending it to the rough bar heating device and the edge heater.

The present invention was made on the basis of the above findings, and the method of the present invention according to claim 1 rough-rolls a slab with a rough-rolling machine, and then continuously rough-rolls the rough bar. Finish rolling with a hot finishing mill to produce a hot-rolled steel strip with a predetermined thickness, in a method for rolling a hot-rolled steel strip, between the rough rolling mill and the finish rolling mill, a rough bar flatness correction A device, a rough bar heating device and a side guide are provided, and further, a warp detector is provided on the inlet side and the outlet side of the rough bar flatness correction device, and based on the warp amount of the rough bar detected by the warp detector. Correcting the flatness defect of the rough bar by the flatness correcting device, heating the coarse bar having the flatness defect thus corrected over the entire width direction by the rough bar heating device, and By the guide The bar, in which the width direction center line characterized in that the guide to match the center of the flatness correcting device and the rough bar heating device.

According to a second aspect of the present invention, there is provided a flatness between a rough rolling mill and a continuous hot finish rolling mill for correcting the flatness of a rough bar roughly rolled by the rough rolling mill. A straightening device, a heating device for heating the rough bar over the entire width direction thereof, and a side guide for passing the rough bar through the center of the heating device are provided. The apparatus of the invention according to claim 3 is characterized by using an induction heating device as the heating device.

[0012]

1 is a schematic side view showing an embodiment of the apparatus of the present invention. As shown in the drawings, a rough hot rolling mill 1 and a continuous hot finish rolling mill 10 including a plurality of stands
A leveler 6 as a rough bar flatness correcting device, an induction heating device 7 for heating the rough bar, and an edge heater 9 are provided in this order between and.

A side guide 3a is provided on the entrance side of the flatness straightening device 6, a side guide 3b is provided between the leveler 6 and the induction heating device 7, and a side guide 3b is provided between the induction heating device 7 and the edge heater 9. Side guides 3c are provided respectively. The warp detector 4 is provided on the inlet side and the outlet side of the leveler 6.
a and 4b are provided, and the leveler 6 is controlled by the controller 5 based on the detected value.

The rough bar 2 rolled by the rough rolling mill 1 is sent to the leveler 6, and the leveler 6 corrects the flatness defect such as the warp or corrugation of the tip portion thereof. At that time, the coarse bar 2 detected by the warp detectors 4a and 4b
The leveling device 6 is appropriately controlled by the control device 5 depending on the degree of warp of the leveler 6.

The rough bar 2 whose flatness defect has been corrected in this manner is then continuously heated by the induction heating device 7 over the entire width thereof, and the temperature of the entire bar rises.
Further, both edge portions are heated by the edge heater 9 to compensate for the decrease in temperature, resulting in a uniform temperature distribution in the width direction.

In the meantime, the coarse bar 2 is moved by the side guides 3a, 3b and 3c as shown in FIGS. 1 and 2, and the widthwise center line 12 of the coarse bar 2 and the center line of the rolling line shown in FIG. It is conveyed so that the deviation (Δx) from 13 is zero. Therefore, the conveyed coarse bar 2 does not collide with the induction heating device 7 and the edge heater 9, and the widthwise temperature distribution of the coarse bar 2 does not deviate during heating by the induction heating device 7. .

The rough bar 2 is finish-rolled by a finish rolling machine 10 into a predetermined plate thickness to form a hot-rolled steel strip, but the uneven temperature distribution in the width direction caused by heating in the induction heating device 7 and the edge heater 9 is produced. This prevents a shape defect in the width direction of the steel strip and a meandering phenomenon of the steel strip during finish rolling.

[0018]

Next, the present invention will be described in more detail with reference to Examples. A slab made of carbon steel having a thickness of 226 mm, a width of 1050 mm, and a length of 9200 mm, which was heated to a temperature of 1230 ° C. in a heating furnace, was roughly rolled in a rough rolling mill 1 by the equipment shown in FIG. 30 mm in width and 10 in width
A 50 mm coarse bar 2 was used. Next, after passing the rough bar 2 through the leveler 6 and correcting the flatness in the leveler 6, the rough bar 2 is heated by the induction heating device 7 and the edge heater 9 so as to have a predetermined temperature distribution in the width direction. The continuous hot finish rolling mill 10 was used for finish rolling.
Thus, a hot-rolled steel strip having a thickness of 2 mm and a width of 1050 mm was prepared.

A radiation thermometer 8 installed on the outlet side of the induction heating device 7 measures the temperature of the coarse bar 2 at a position approximately 30 m from the tip end portion in the rolling process, and shows the temperature distribution in the width direction. Shown in 3. In FIG. 3, the ● marks convey the rough bar 2 by the side guides 3a, 3b, 3c so that the deviation (Δx) between the center line of the rough bar 2 in the width direction and the center line of the rolling line becomes zero. Shows the temperature distribution in the case of the above, and ○ indicates that Δx is 20 without the side guide installed.
It is a temperature distribution in the case of 0 mm.

As is apparent from FIG. 3, when the side guide is not installed and Δx is 200 mm, the temperature distribution in the width direction is biased, but when the side guide is provided and Δx is set to 0, it is almost the same. The temperature distribution is symmetrical, the coarse bar 2 does not collide with the induction heating device 7 and the edge heater 9, and the widthwise temperature distribution of the coarse bar 2 may be biased during heating by the induction heating device 7. It was possible to manufacture a hot-rolled steel strip with good shape accuracy.

[0021]

As described above, according to the present invention,
When finish rolling the rough bar rough-rolled by the rough rolling mill by the finish rolling mill, the flatness defect of the rough bar is corrected, and the deviation from the center line in the width direction of the rough bar is accurately corrected, The bar can be heated with a uniform temperature distribution in the width direction without a temperature difference between both edges and the vicinity of the center, and a hot rolled steel strip with excellent shape and accuracy in the width direction can be obtained. Industrially useful effects that can be manufactured with high yield are brought about.

[Brief description of drawings]

FIG. 1 is a schematic side view showing one embodiment of the device of the present invention.

FIG. 2 is a partially enlarged plan view of the device of the present invention.

FIG. 3 is a view showing a temperature distribution in a width direction of a rough bar after heating according to the present invention in comparison with a conventional technique.

FIG. 4 is a schematic side view showing an example of a conventional device.

FIG. 5 is a partially enlarged plan view of a conventional device.

[Explanation of symbols]

 1 Rough rolling mill 2 Rough bar 3a, 3b, 3c Side guide 4a, 4b Warp detector 5 Control device 6 Leveler 7 Induction heating device 8 Radiation thermometer 9 Edge heater 10 Finishing rolling mill 11 Table roll 12 Center of width of rough bar Line 13 Center line of rolling line

Continuing from the front page (72) Inventor Masaaki Yamamoto 1-2-1, Marunouchi, Chiyoda-ku, Tokyo Nihon Kokan Co., Ltd. (72) Inventor Naoshichi Eda 1-2-1, Marunouchi, Chiyoda-ku, Tokyo Nihon Kokan Co., Ltd. (72) Inventor Takuya Terauchi 1-2-1, Marunouchi, Chiyoda-ku, Tokyo Nihon Kokan Co., Ltd.

Claims (3)

[Claims] 1. A hot-rolled steel for producing a hot-rolled steel strip having a predetermined thickness by rough-rolling a slab by a rough-rolling mill and then finish-rolling the rough-rolled rough bar by a continuous hot finishing mill. In the strip rolling method, between the rough rolling mill and the finish rolling mill, a rough bar flatness straightening device, a rough bar heating device and a side guide are provided,
Further, a warp detector is provided on the entrance side and the exit side of the rough bar flatness correcting device, and the flatness of the rough bar is flattened by the flatness correcting device based on the warp amount of the rough bar detected by the warp detector. Of the flatness is corrected, and thus the rough bar having the flatness thus corrected is heated over the entire width direction by the rough bar heating device, and the side bar guides the coarse bar to the width thereof. A method for rolling a hot-rolled steel strip, characterized in that the direction centerline is guided so as to coincide with the centerlines of the flatness straightening device and the rough bar heating device. 2. A flatness straightening device for straightening the flatness of a rough bar roughly rolled by the rough rolling mill between the rough rolling mill and the continuous hot finish rolling mill, and the rough bar, A heating device for heating the entire width direction, and a side guide for passing the rough bar through the center of the flatness straightening device and the heating device are provided. Rolling equipment for rolled steel strips. 3. The device according to claim 2, wherein an induction heating device is used as the heating device.