JP2002219503A - Manufacturing method of hot steel strip and row of facilities - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a manufacturing method of a hot steel strip and a row of its facilities capable of solving problems of an intermittent sheet bar having good temperature distribution in a longitudinal direction by providing an intermediate coiler between a plate-thickness reduction press and a group of finish rolling mills. SOLUTION: In a row of facilities manufacturing a hot steel strip with a designated plate thickness from a slab, the row of the facilities is comprised of the plate-thickness reduction press forming material with a designated plate thickness, the intermediate coiler winding the material formed in a designated plate thickness, and a group of the finish rolling mills in which the material wound by the intermediate coiler arranged in a downstream side of the intermediate coiler is fed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a hot steel strip from a slab, and a production equipment line provided for the method.

[0002]

2. Description of the Related Art Conventionally, the production of a hot steel strip is performed by multi-pass rough rolling and multi-pass finish rolling. FIG. 6 shows a conventional hot steel strip manufacturing facility line. In the figure, reference numeral 2 denotes a heating furnace, 33 denotes a vertical scale breaker (VSB) for applying a width reduction to a slab, 34, 35, and 36 vertical rolling mills for applying a width reduction to a material, 37, 38, and 39 horizontal rolling mills. 6 is a shear, 41 is a finishing mill group, 9 is a coiler,
51 is a slab and 52 is a hot steel strip. The slab 51 having a normal length of about 10 m extracted from the heating furnace 2 is
The sheet width is adjusted by vertical rolling mills 34, 35 and 36, and the sheet is rolled into sheet bars of a predetermined thickness by horizontal rolling mills 37, 38 and 39. Thereafter, the sheet bar is cut into a crop by the shear 6, rolled to a predetermined thickness by the finishing mill group 41, and then wound up by the coiler 9.

[0003] In the hot rolling method, it is desired that the number of rolling mills is small and the equipment line is short from the viewpoint of equipment cost.
In rolling, since there is a critical reduction amount, rolling in multiple passes is necessary. Further, it is desired that the temperature change is small from the aspect of the heating unit.

As a method of performing rolling with a small number of rolling mills, reversing rolling can be considered. However, in reversal rolling, the equipment length before and after the rolling mill becomes very long. Tandem rolling is effective as a method of rolling in a short equipment row. However, in tandem rolling, the same number of rolling mills as the number of passes is required, and equipment costs increase. Therefore, it is difficult to satisfy both of the above conditions by rolling.

In recent years, there has been proposed a method in which the thickness reduction on the upstream side of the slab is performed by a thickness reduction press without using a rolling mill (for example, Japanese Patent Application Laid-Open No. 11-226601). According to this method, the slab can be subjected to high pressure, so that a large amount of reduction can be obtained as compared with the rolling, and one press has the capacity of a plurality of rough rolling mills. Therefore, the equipment cost can be reduced. Further, since the equipment row is shortened due to the large pressure reduction, the temperature drop is small.

However, since the thickness reduction press intermittently reduces the thickness and feeds the material in the longitudinal direction, the longitudinal speed of the material has intermittent fluctuations. If the thickness reduction press and the subsequent rolling mill are tandemed to shorten the equipment length, it is necessary to intermittently vary the rolling speed. As the contact time between the material and the material increases, the heat removal by the roll increases,
A longitudinal temperature distribution occurs in the material. Since the structure and the deformation resistance of the material depend on the temperature, it is difficult to produce a uniform structure and a thick hot strip in the longitudinal direction.

[0007]

SUMMARY OF THE INVENTION An object of the present invention is to provide an intermediate coiler between a thickness reduction press and a finishing mill group so that the rolling speed of the finishing mill group must be intermittently varied. It is an object of the present invention to provide a hot steel strip manufacturing facility line and a manufacturing method which have a uniform structure and a plate thickness and have a small temperature change.

In the row of hot steel strip manufacturing equipment according to the present invention, the term "finishing mills" refers to a set of all rolling mills arranged downstream of the thickness reduction press.

[0009]

SUMMARY OF THE INVENTION The present invention provides: (1) a sheet thickness reduction press for forming a sheet having a predetermined thickness in a row of equipment for producing a hot strip having a predetermined thickness from a slab; A hot steel strip comprising: an intermediate coiler for winding a material formed into a sheet thickness; and a finishing mill group arranged downstream of the intermediate coiler and supplied with the material wound by the intermediate coiler. Manufacturing equipment column.

(2) A step of pressing and rolling the slab in the thickness direction, a step of winding the material pressed in the thickness direction into a coil, and a finishing mill on the downstream side of the rolled material. And supplying to the group.

In the hot steel strip manufacturing equipment line of the present invention, a sheet thickness reduction press for intermittent reduction in thickness and longitudinal feeding of material and a downstream side for continuous reduction and longitudinal feeding of material are provided. As means for eliminating the speed difference between the finishing mill group and the finishing mill group, an intermediate coiler is provided between the thickness reduction press and the finishing mill group arranged downstream of the thickness reduction press. The intermediate coiler winds the material after the thickness reduction press in synchronization with the forming speed of the thickness reduction press, rotates the material appropriately after the winding in the rolling direction, and downstream of the rolled material after the thickness reduction press. Continuous rewinding is performed to the finishing mill group on the side. Therefore, there is no need to intermittently change the rolling speed of the finishing mill group. Therefore, the above-described problems do not occur, and a hot steel strip having a uniform structure and plate thickness can be manufactured.

In the method of manufacturing a hot-rolled steel strip according to the present invention, the slab cast by the continuous casting equipment is cooled in the same manner as in the conventional method of manufacturing a hot-rolled steel strip, then reheated in a heating furnace, and then subjected to rough rolling. (So-called cold slab rolling) may be performed on a hot steel strip. Further, in the present invention, since a hot steel strip can be manufactured (so-called direct-feed rolling) without cooling a slab continuously cast by a continuous casting facility, the heat intensity is high. In addition, when a continuously cast slab is further heated and extracted in a heating furnace without cooling, and then subjected to rough rolling and then hot strip is manufactured (so-called hot slab rolling), the heating unit consumption is improved, and the slab production is improved. This is advantageous because the temperature distribution is reduced and a hot steel strip having a uniform structure can be manufactured. Furthermore, the production of a hot-rolled steel strip in which only the slab edge is heated and rough-rolled without reheating the slab, or even if the slab is heated (so-called direct-feed rolling), is more effective than the continuous casting speed of the slab in the direct-feed rolling. Since the production speed of the hot-rolled steel strip is faster, the slab can be extracted from the heating furnace during continuous casting of the slab, and the gap in the production of the steel strip can be filled, which is advantageous in terms of productivity.

Further, by winding the sheet bar in a coil shape by the intermediate coiler, the temperature distribution generated in the longitudinal direction and the width direction of the material can be made uniform. The heat retention function of the intermediate coiler prevents the average temperature drop of the sheet bar. Therefore, it is easy to secure the required temperature on the side of the finishing mill at which the desired material is obtained.

By the way, the longer the time the sheet thickness is thin, the greater the temperature drop of the material.
Rolling is performed for 6 passes or more in a finishing mill group with the distance being about 0 mm. However, in the present invention, it is possible to keep the temperature of the sheet bar high, and the reduction amount of the sheet thickness reduction press is not limited to the reduction amount per pass unlike rolling, so that the sheet bar thickness is smaller than before. However, the number of passes in the finishing mill group can be reduced. For this reason, it is possible to reduce the number of rolling mills in the finishing mill group and further reduce the equipment cost.

The temperature distribution of the cast slab immediately after production by the continuous casting facility is such that the inside of the slab is higher than the outer surface of the slab due to the solidification process. In the direct-feed processing method, since this temperature distribution is maintained even after the thickness reduction press, the sheet bar after the thickness reduction press is wound around an intermediate coiler, and is retained for a certain period of time. The entire sheet bar wound in a shape is soaked. For this reason, it becomes easy to manufacture a hot steel strip having a uniform structure.

[0016]

FIG. 1 shows an embodiment of the present invention. 1 is a continuous casting facility, 2 is a heating furnace, 3 is a sheet width control means (sizing press), 4 is a sheet thickness reduction press, 5 is an intermediate coiler, 6 is a shear, 7 is a sheet width control means (edger), 8 is The finishing mill group 9 is a coiler.

A sheet thickness of 100 mm or more and a sheet width of 500 to 2500 extracted from the continuous furnace 1 or extracted from the heating furnace 2.
mm slab is changed in width by 400 mm or less by a width control means 3 (sizing press), and a material feed speed is 100 m / min or less by a thickness reduction press 4 and a press cycle 2
00 cycle / min or less, average material speed on press exit side 1
Rolling is performed at a rolling reduction of 60 mm / min or less and a rolling reduction of 30 mm or more, and winding is performed intermittently by the intermediate coiler 5. 250m thick
m, slab with a length of 10m and mandrel diameter of 750m
m, the outer diameter of the coil is 2m
And the coil length is about 40 m. Next, the sheet is continuously rewound, the sheet width is adjusted by the sheet width control means 7 (edger), the crop is cut by the shear 6, and the finishing mill group 8 is cut.
Then, the steel strip is wound by a coiler 9 after rolling to a predetermined thickness.

In the conventional hot steel strip manufacturing equipment row (FIG. 6) and the hot steel strip manufacturing equipment row of the present invention (FIG. 1), the sheet thickness is 25 mm.
When a hot steel strip having a thickness of 60 mm is manufactured from the slab having a thickness of 0 mm, a length of 10 m, and an average temperature of 1200 ° C. on the entrance side of the finishing mill group, the material descending from the exit side of the heating furnace to the entrance side of the finishing mill group. FIG. 4 shows the result of calculating the average in the length direction of the temperature. Compared with the conventional hot steel strip manufacturing equipment line, the temperature drop amount is about ２ in the hot steel strip manufacturing equipment line of the present invention. Therefore, according to the present invention, the slab temperature required to make the finish rolling mill exit side temperature equal to or higher than the A3 transformation point of the material can be lower than that of the conventional production equipment line.

Further, in the case of the present invention, the temperature of the material wound in the intermediate coiler in the longitudinal direction becomes uniform, and since the subsequent rolling can be performed continuously, the hot steel having a uniform structure in the longitudinal direction is obtained. Manufacture of belts is possible. FIG. 5 shows a method for producing a hot steel strip in which the rolling speed on the downstream side of the thickness reduction press is intermittently changed, and a hot steel strip on the finishing rolling mill exit side in the method for producing a hot steel strip according to the present invention. Shows the amount of temperature distribution in the longitudinal direction.
In the method of manufacturing a hot steel strip in which the rolling speed on the downstream side of the thickness reduction press is intermittently changed, a temperature distribution close to 20 ° C. exists in the longitudinal direction. No temperature distribution.

FIG. 2 shows an example of the intermediate coiler. In the figure, reference numeral 21 denotes a speedometer for detecting a material speed, 22 denotes a table roller group, 23 denotes a bending roll for applying a bending process to the material, 24 and 25 denote # 1 and # 2 cradle rolls for forming coils, and 26 denotes a coil. This is a coil transfer arm for transferring. The material whose speed is detected by the speedometer 21 is conveyed by the table roller group 22,
The sheet is bent by the bending roll 23 and wound up by the # 1 cradle roll 24. The table roller group 22, the bending roll 23, and the # 1 cradle roll 24 can rotate in synchronization with the discontinuous speed measured by the speedometer 21. After winding is completed,
The coil is rotated in the rolling direction to perform rewinding. The coil being rewound is transferred onto the # 2 cradle roll 25 by the transfer arm 26. Thereby, the following material can be wound up while rewinding the preceding coil.

In the drawing, an intermediate coiler having two positions is used, but an intermediate coiler having three or more positions may be used.

Of course, if there is no problem from the viewpoint of productivity, winding and rewinding may be performed by a one-position intermediate coiler. In this case, winding cannot be performed until coil rewinding is completed, so that productivity is slightly reduced.

Heating / heat keeping equipment may be provided as appropriate, but heating / heat keeping equipment located before the plate thickness reduction press, equipment for heating / holding the material in the intermediate coiler, edge heater, and coarse bar heating equipment are provided. Especially effective. Since the slab has a large plate thickness and a small temperature change, the heating / heat retaining equipment located before the plate thickness reduction press need only be a heat retaining cover. As described above, in the intermediate coiler, the temperature drop of the material is small, but the temperature of the edge drops. In the intermediate coiler, the responsiveness is not a problem since the material does not move until winding is completed. Therefore, as a facility for heating / keeping the material in the intermediate coiler, a burner heating facility for heating the edge is effective. Edge heater,
As the rough bar heating equipment, it is only necessary to heat a very small part (such as the rear end) in the longitudinal direction of the material, and therefore, an induction heating equipment which has a good responsiveness and is capable of rapid heating is particularly effective. FIG. 3 shows an embodiment in this case. Reference numeral 11 denotes a heating / heat keeping facility located before the plate thickness reduction press, 12 denotes an edge heater, and 13 denotes a rough bar heating facility.

In FIG. 1 and FIG. 3, the sizing press is used as the sheet width control means on the upstream side of the sheet thickness reduction press, and the edger is used as the sheet width control means on the downstream side of the intermediate coiler. I don't care. Although only two board width control means are shown, three or more board width control means may be used. Further, the sheet width control means may be installed anywhere except between the thickness reduction press and the intermediate coiler and between the last rolling mill of the finishing mill group and the coiler. In addition, cooling by a run-out table is performed between the finishing mill group 8 and the coiler 9,
Control the material. In the figure, the shear 6 is an intermediate coiler 5
Although it is shown between the sheet width control means 7 and the sheet width control means 7, it may be installed anywhere if it is on the downstream side of the sheet thickness reduction press 4. In the figure, the strand and heating furnace 2 of the continuous casting equipment 1 are shown.
Are shown only one each, but a plurality of each may be arranged. Although only one coiler 9 is shown, two or more coilers may be installed.

The coiler 9 may be a coiler with a shear during running.

The coiler 9 may be a carousel coiler.

It should be noted that the present invention is not limited to the above-described embodiment, but can be variously modified without departing from the gist of the present invention.

[0028]

According to the hot rolling method and the manufacturing equipment line according to the present invention, a sheet thickness reduction press is provided between a plate thickness reduction press and a group of finishing mills arranged downstream of the plate thickness reduction press. An intermediate coiler that performs winding in synchronization with the forming speed, rotates appropriately in the rolling direction after winding, and continuously rewinds the rolled material after the thickness reduction press to a downstream finishing mill group. Is provided. Therefore, it is not necessary to intermittently change the rolling speed of the finishing mill group, so that it is possible to manufacture a hot steel strip having a uniform structure and a plate thickness.

[Brief description of the drawings]

FIG. 1 is a diagram showing one embodiment of the present invention.

FIG. 2 is a diagram showing an example of an intermediate coiler.

FIG. 3 is a diagram showing another embodiment of the present invention.

FIG. 4 is a diagram showing, in a batch rolling method, the amount of temperature change in a row of equipment for manufacturing a hot steel strip of the present invention in comparison with a conventional one.

FIG. 5 is a diagram showing, in a batch rolling method, a longitudinal temperature distribution amount of a row of hot steel strip manufacturing equipment of the present invention in comparison with a conventional one.

FIG. 6 is a diagram showing an example of a hot steel strip manufacturing equipment train in a conventional batch rolling method.

[Explanation of symbols]

1. . . Continuous casting equipment 2. . . Heating furnace 3. . . 3. Width control means (sizing press) . . 4. Thickness reduction press . . Intermediate coiler 6. . . Shah 7. . . 7. Width control means (edger) . . Finishing mill group 9. . . Coiler 21. . . Speedometer to detect material speed 22. . . Table roller group 23. . . Bending rolls 24, 25 for bending the material . . # 1, # 2 cradle roll forming coil . . 42. Coil transfer arm for transferring coils . . Rapid cooling device

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Yasuhiro Soya 1-2-1, Marunouchi, Chiyoda-ku, Tokyo, Japan Inside Nihon Kokan Co., Ltd. (72) Inventor Masaru Miyake 1-2-1, Marunouchi, Chiyoda-ku, Tokyo, Japan (72) Inventor: Sato Murata, 1-2-1 Marunouchi, Chiyoda-ku, Tokyo, Japan Inventor: (72) Inventor: Shiro Nagata 1st, Shinnakaharacho, Isogo-ku, Yokohama-shi, Kanagawa Prefecture Stone Kawashima-Harima Heavy Industries Co., Ltd. Yokohama Engineering Center (72) Inventor Masao Mikami 1 Shin-Nakahara-cho, Isogo-ku, Yokohama-shi, Kanagawa Prefecture Kawashima-Harima Heavy Industries Machinery & Plant Development Center (72) Inventor Takashi Nishii Ishikawashima-Harima Heavy Industries Co., Ltd. Machinery & Plant Development Center F-term (reference) 4E002 AB03 AD04 BA01 BD01 BD03 CB01 CB08

Claims (2)

[Claims] 1. A thickness reduction press for forming a slab into a material having a predetermined thickness, an intermediate coiler for winding a material formed to a predetermined thickness, and a downstream roll disposed on the intermediate coiler and wound by the intermediate coiler. And a finishing mill group to which the material is supplied. 2. A step of pressing and rolling the slab from the thickness direction, a step of winding the material pressed from the thickness direction into a coil, and a group of finishing mills on the downstream side of the rolled material. And a step of supplying a hot steel strip.