JPS5910845B2 - Method for manufacturing hot strips - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a hot strip manufacturing method that can roll a plurality of hot strips of different sizes from one slab. is heated to a predetermined temperature in a heating furnace, the heated slab is passed through a group of rough rolling mills for rough rolling, and then passed through a group of finishing mills for finishing rolling to a predetermined width and thickness. After that, it is manufactured by winding it into a coil.

The slabs that are used as hot strip materials are as follows:
For the following reasons, it is considered advantageous for operations to have as much weight as possible within the equipment capacity.

(1) The energy input efficiency in the heating furnace of the hot strip mill, that is, the fuel consumption rate is improved.

(2) In the heating furnace, mill scale of the slab that is oxidized and desorbed, that is, scale loss is reduced.

(3) The amount of crop cut at the front and rear ends of the strip, that is, the crop loss required in the rolling process of a hot strip mill is reduced.

(4) Since the weight of the ingot can be increased during the blooming process for producing slabs, the fuel consumption rate in the soaking furnace is improved, and scale loss, clot loss, etc. are reduced.

(5) When a slab is manufactured by continuous casting, the number of times the slab is cut is reduced, so cutting loss is reduced.

(6) Scale loss during slab care is reduced in the blooming or continuous casting process.

(7) As the number of slabs decreases, the effort required for process control work such as management and operation of slabs is reduced by one hour.

However, at present, the slab weight is almost determined by the hot strip coil weight. For example, even if you try to increase the slab weight in a narrow strip, the coil diameter will inevitably become smaller, and the coiler equipment and later Since it is limited by the equipment capacity, the weight of the slab cannot exceed a certain level, and therefore the weight of the slab must be small.

Also, in wide strips, the slab weight can be increased up to the capacity of the coiler equipment or later;
In any case, in the conventional rolling method in which only one hot coil is rolled from one slab, the weight of the slab is restricted by the weight of the hot coil. There were no words to put the weight on the dog.

From the above-mentioned viewpoint, the present invention takes the weight of the slab, which is a rough material, into consideration when rolling hot strips, and by manufacturing a plurality of hot strips with different dimensions from one slab, the fuel consumption rate can be reduced. improvement, scale loss,
The present invention provides a hot strip manufacturing method that can reduce cut loss, cut loss, etc., improve product yield, and reduce manufacturing costs. After rolling into a rough rolled bar having a plurality of steps with different dimensions and cutting and dividing the stepped rough rolled bar from the stepped portion, each of the divided rough rolled bars is sequentially passed through a finishing mill. This method is characterized in that a plurality of hot strips having different dimensions are rolled from one slab by rolling the same slab.

Next, the present invention will be explained using examples and drawings.

Now, let the weight of the hot coil having the thickness (t )
The slab weight (ws) in the case where a hot coil having a weight of
is determined by the yield rate), and the slab dimensions are determined by the thickness (Ts)
X width (Bs) X length (Ls).

In Figure 1, the above (Ts)
) using a slab with dimensions of (tx) x (bX)
The manufacturing process for rolling a hot coil having dimensions of (ty) x (b) and a hot coil having dimensions of (ty)

In the drawings, 1a, lb...1X indicates a plurality of coarse vertical rolling mills, 2a, 2b...2
X is a roughing main rolling mill, 3a, which is connected next to each stand of the roughing vertical rolling mills 1a, 1b, .
3X is a width detector provided in front of each stand of the roughing vertical rolling mills 1b...1X, and the above-mentioned lines constitute a roughing mill group (5).

4 is a heat retention furnace installed next to the final stand of the rough rolling mill group; 5 is a crop shear;
Following that, several finishing rolling mills 6a, 6b...
...6X constitutes a finishing rolling mill ffB).

7 is a winder. 8 is a rough vertical rolling mill 1a, 1b...
A rolling speed detection device 9 detects the rolling speed of the slab at 1 Rolling mills 1a, 1b...
. . . A calculation device for calculating the rolling length of tentering rolling in 1X; 10 is a pass schedule switching control that performs pass schedule switching control based on the calculation result of the calculation device 9 and the rolling speed of the roughing vertical rolling mill. Equipment, 11 is the pass schedule RB of rough vertical rolling mills 1a, Ib...1X
i, pass schedule RHi of roughing main rolling mills 2a, 2b...2x, and finishing rolling mills 6a, 6b
This is a path schedule program setting device in which a 6x path schedule FHi is set.

In the method of this invention, as shown in the explanatory diagram in FIG. 2, there is a portion Thickness (Ts) x Width (Bs) x Length (L
The slab 12 of s) is rolled by the rough rolling mill group (5), and as shown in FIG.
(bx) into a rough rolled bar 13a having the necessary dimensions to finish roll it into the hot coil 14a, and also to finish roll the Y portion into the (ty) X (by) hot coil 14b. By forming the rough rolled bar 13b having the following dimensions, the rough rolled bar 1 is made up of at least two portions 13a and 13b having different width dimensions.
3 will be manufactured.

In manufacturing the rough rolled bar 13, as shown in FIGS. 1 and 3, the rolls 15 and 1 of the rough vertical rolling mill 1a are
5 is set by the pass schedule program setting device 11, as shown by the dotted line in FIG. 3, the rough rolling bar 13a is
After setting the opening degree RBiX necessary to achieve this, the slab 12 heated to a predetermined temperature is passed through the rough vertical rolling mill 1a to perform tentering rolling.

The rolling speed in the rough vertical rolling mill 1a at this time is detected by the rolling speed detection device 8 and sent to the pass schedule switching control device 10. is calculated and sent to the path schedule switching control device 10.

In this way, when rolling has been carried out to the length required to form the rough rolling bar 13a, the opening degree of the rolls 15, 15 of the roughing vertical rolling mill 1a is adjusted according to the pass schedule as shown by the solid line in FIG. In response to a signal from the program setting device 11, the opening degree RBiY is instantaneously changed to the one required to form the rough rolled bar 13b, and thereafter, the remaining portion is subjected to tentering rolling according to the opening degree RBiY.

Thereafter, in the same manner, the rough vertical rolling mills 1b...
...1X, the roll opening degree is changed from RBiX to RBiY for each stand, and the material to be rolled is rolled using the two different roll opening degrees.

In addition, in this embodiment, the roll opening degree of each of the rough vertical rolling mills 1b...1X is as follows:
Width detector 3a installed at a fixed point in front of each stand of 1X...3X detects the width change part of the rolled material rolled in the upstream stand, and detects the width change part of the rolled material at that time. along with the speed of the path schedule switching control device 10.
The pass schedule program setting device 11 is used to set the rolling length for each stand using the pass schedule program setting device 11. In addition, the rolling length is calculated from the thickness of the rolled material rolled at the upstream stand, and the roll opening degree of each stand is changed. Then, the coarse main rolling mills 2a, 2b...
- In 2X, the opening degree of the horizontal rolls is controlled for each stand according to the pass schedule RHi according to the command from the pass schedule program setting device 11, and the material to be rolled is rolled to a predetermined thickness by the horizontal rolls.

Note that the pass schedule RHi is constant within the same rolling bar.

As described above, the path schedule program setting device 11
As shown in Fig. 2, by rolling by the rough rolling mill group (5) with the roll opening controlled by The slab 12, which includes a portion X that becomes a hot coil and a portion Y that becomes a hot coil having a thickness (ty) The stepped rough rolled bar 13 may be formed by rolling the Y portion and the Y portion into shapes 13a and 13b having at least different width dimensions.

The rough rolling bar 13 is
Part a! : Cut into different width units from the boundary line with part 13b, as shown in Figure 2C, 13a and 13
It is completely divided into two parts.

Next, the one rough rolling bar 13a is transferred to the finishing rolling mill group (
B) through the path schedule program setting device 11
Finishing mill group pass schedule FHi x sent from
The finishing rolling mills 6a, 6b, whose roll opening degrees are set by
... Finish rolling is performed by 6x, and the thickness (tx
) x width (bx) and is wound by the winder 7 into a coil 14a as shown in FIG. 2d.

After finishing rolling of the rough rolling bar 13a is performed in this way, the pass schedule of the finishing rolling mill IWB) is changed to F according to the command from the pass schedule program setting device 11.
Changed to HiY.

The other rough rolled bar 13b is finish rolled by the finish rolling mill B) set in the pass schedule FHiY to form a desired hot strip with dimensions of thickness (t) x width (by). is wound up by the winding machine 7 in the same manner as above to form a coil 1 as shown in FIG. 2d.
It becomes 4b.

Note that the trailing rough rolling bar 13b is operated until the preceding rough rolling bar 13a finishes passing through the finish rolling mill B).
Since it is necessary to temporarily wait, if there is a risk that the temperature will drop during that time, the temperature drop can be prevented by storing it in the heat retention furnace 4 and slightly heating it.

Note that the rough rolled bar may be wound up before being sent to the finishing rolling mill group, and then the rolled up rough rolling bar may be sequentially fed out to the finishing rolling mill group for finishing rolling.

Next, examples will be described.

Thickness 9. 0mm, width 1410im, weight 10T hot coil and thickness 5. Om turtle width 1512m - weight 10
When manufacturing T hot coil from one slab, the dimensions of the slab are: thickness 22011L width 1550m
Tortoise length: 7500m - weight: 20T.

Table 1 shows the pass schedule when such a slab is rolled by the method of the present invention.

In the same table, E indicates a roughing vertical rolling mill, R indicates a lees main rolling mill, and F indicates a finishing mill, and the slab extraction temperature is 1200°C.

Next, by the above-mentioned method of the present invention, the 20T slab 1
We will discuss the effects of comparing the case where two hot coils are rolled from a sheet and the case where two hot coils are rolled from two IOT slabs as in the past.

(1) Productivity hot rolling efficiency is 600T/H compared to the conventional 400T/H.
H, which increases by about 50%, and the blooming efficiency increases by about 40%.

(2) Yield In the case of conventional LOT slabs, the amount of scraping at both ends after rolling was 120 yu for one slab and 240 kg for 2 slabs, but this is almost halved to about 6 kg/T. , Also, the amount of end trimming in the blooming process was also approximately halved, about 35%.
Only kg/T.

Furthermore, the amount of cut waste generated during the continuous casting process is lower than that of conventional 5. 7
kg/T, it only costs 3.1 kg/T.

Therefore, the total reduction in generated waste is about 8.4 kg/T from continuous casting to hot rolling, and about 40.8 kg/T from blooming to hot rolling.

(3) Fuel input efficiency in heating furnace The required amount of heat when rolling two 10T slabs is 3 4
While it is 4.000Km/T, in the case of one 20T slab, it is 305.000Km/T, which increases the fuel injection efficiency by about 11%.

In the embodiments described above, the slabs 12 are divided into pieces of different dimensions.
An example has been described in which stepped rolling is performed from the first roughing vertical rolling mill 1a when rolling into a rough rolling bar 13 consisting of sections 3a and 13b. However, depending on the size of the slab, etc. It is not necessary to perform stepped rolling from the stand, and step rolling may be performed at a second or subsequent appropriate stand, or in some cases, at the final stand.

Further, in the roughing main rolling mills 2a, 2b, . An appropriate number of stepped portions can be selected from two or more.

As explained above, according to the method of the present invention, it is possible to manufacture a plurality of hot strips with different width dimensions from one slab, so the unit weight of the slab can be reduced from the conventional one-slab, one-size hot coil. It is possible to increase the size without being restricted.

Therefore, in addition to improving the fuel consumption rate and reducing scale loss in the heating process of slabs and reducing clotsupuros in the rolling process, it also improves the fuel consumption rate and reduces scale loss, clotsupuros, and cutting loss in the blooming or continuous casting process. It is possible to reduce process control work due to the reduction in the number of slabs, and to improve the product yield and reduce manufacturing costs, resulting in excellent industrial effects.

[Brief explanation of drawings]

Fig. 1 is a schematic process diagram showing an example of the hot strip manufacturing process according to the method of the present invention, Fig. 2 is an explanatory drawing showing the rolled shape of the slab, and Fig. 3 is an explanatory drawing showing the roll opening of the rough vertical rolling mill. It is. In the drawings, 1a...1X...rough vertical rolling mill, 2a...
...2X... Roughing main rolling mill, 3a...
...3X...width detector, 4...heat retention furnace, 5...crop shear, 6a...6
X... Finishing rolling mill, 7... Winding machine, 8
...Rolling speed detection device, 9...Arithmetic device, 10...Pass schedule switching iU control device, 1 1...Pass schedule program setting device, 12 ... Slab, 13 ... Rough rolled bar, 14 ... Hot coil, 15 ...
・Rough vertical rolling mill roll.

Claims (1)

[Claims] 1. When rolling a slab using a rough rolling mill and a finishing rolling mill to produce a hot strip, the slab is
A rough rolled bar having at least a plurality of steps having different width dimensions is rolled by a rough rolling mill having a vertical rolling mill, and the stepped rough rolled bar is cut and divided from the stepped portion, and then the divided rough rolled bar is 1. A method for producing hot strips, which comprises rolling a plurality of hot strips having different dimensions from 11 slabs by sequentially rolling each rough rolled bar using a finish rolling mill.