JP5453955B2 - Width reduction method for slab for hot rolling - Google Patents

Description

  The present invention relates to a hot rolling slab width reduction method in which a steel slab is width reduced by a sizing press in a width direction in a hot rolling line in which a sizing press is installed.

  As one type of equipment for adjusting the width, a sizing press for reducing the width of a steel slab in the width direction before rolling with a roughing mill and a finishing mill is installed in a hot rolling line (for example, Patent Document 1). By reducing the width of the steel slab in the width direction with this sizing press, the width adjustment amount is increased in the hot rolling process, the width of the slab cast in the continuous casting process is integrated, and the width of the hot rolled steel strip is created. It is divided.

  Patent Document 1 discloses a technique for changing the opening of a sizing press in the slab longitudinal direction in accordance with the width of the tapered slab. In this technique, in order to set the exit width of the rough rolling mill R1 within a predetermined width variation, setting calculation is performed as follows to set the opening of the sizing press. That is, based on the initial data such as steel grade, slab size, slab temperature, etc. transmitted from the host computer to the hot rolling process computer that controls the hot rolling line, the target width and target thickness are determined by the hot rolling process computer. The setting calculation is performed as follows. Conventionally, as the initial value of the slab width data for performing the setting calculation, the slab width calculation value in the continuous casting process or the actual measurement value of the loader grip width in the slab yard is used, and the width reduction amount is previously calculated by setting calculation. I was asking.

Japanese Unexamined Patent Publication No. 2000-15301

However, the calculated value of the slab width in the continuous casting process or the actually measured value of the loader grip width in the slab yard is as follows: The width fluctuation is not reflected.
(A) The slab width calculation value in the continuous casting process includes the slab width variation that occurs during continuous casting.
(B) The slab measurement value of the loader grip width in the slab yard is the amount of heat shrinkage of the slab that occurs in the process where the slab is subsequently transferred from the slab yard onto the transfer table of the hot rolling line and cooled. Width variation due to thermal expansion of the slab, which occurs when the slab is charged into the furnace and heated in the furnace

For this reason, there has been a problem that a setting error occurs in the opening of the sizing press set in the setting calculation.
That is, in the hot rolling process computer, when the setting calculation is performed so that the target width and the target thickness are obtained by the hot rolling process computer based on the initial data such as the steel type, the slab size, the slab temperature, etc., An extra width is provided so that the width of the hot-rolled steel strip does not fall below the product width even if the width varies. In other words, by setting the target width to be wider than the product width by the extra width, it is intended to absorb the slab width fluctuation.

  In order to reduce this extra width, it is necessary to bring the target width closer to the product width, but the extra width has already been reduced by conventional improvements, and it has been difficult to achieve this. In addition, if a large-scale facility modification that further reduces the margin is attempted, the hot rolling line operation suspension period becomes longer, which leads to disruption of the hot rolling process, which is difficult to realize. It was.

  Conventionally, the opening of the sizing press is preset while the width reduction amount error is included in the opening of the sizing press. As a result, in an abnormal slab including a portion where the slab width variation is large at the longitudinal position of the slab (referred to as an abnormal width portion), the width reduction amount of the abnormal width portion is considerably smaller than the other portions, and the subsequent rough slab Rolling and finishing rolling are not wide enough, the hot-rolled steel strip is not wide enough, the hot-rolled steel strip becomes a non-conforming product that deviates from the width tolerance, and not only the yield is lowered but also the delivery date is not delayed. Therefore, another alternative material was urgently produced, resulting in a problem that the hot rolling process was confused.

In addition, in the case of a tapered slab that includes an abnormal width part that is significantly different from the width predicted by the setting calculation, the actual width in the longitudinal center part of the slab is not measured for the actual width press entry side slab width, A similar problem arises because the actual width reduction amount differs greatly from the width reduction amount obtained by the setting calculation.
In addition, there are the following problems due to the fact that the actual width press entry side slab width is not measured. When the measured loader grip width cannot be obtained due to trouble with the equipment that actually measures the loader grip width, and the difference between the slab width calculation value in the continuous casting process and the actual width slab width on the press side is large, The actual width reduction amount becomes excessive, and a press load exceeding the equipment capacity repeatedly acts on the sizing press, resulting in equipment damage of the sizing press. Further, since the loader grip width can be measured only at several points in the longitudinal direction of the slab, there is a problem that the shape of the slab whose width is reduced by the sizing press cannot be accurately determined.

  The present invention eliminates the above-mentioned problems of the prior art, does not significantly modify the equipment, does not disrupt the hot rolling process, and provides extra width in the hot rolling line where the sizing press is installed. It aims at providing the rolling method of the hot-rolled steel strip which can be reduced further.

  The present inventor installs a slab width meter on the entry side of the sizing press, and measures the actual width press entry side slab width with the slab width meter, so that the sizing press After presetting the opening, based on the measured width press entry side slab width data, by performing feed-forward control under the width reduction that changes the opening of the sizing press, the width reduction amount by the sizing press can be optimized, It has been found that the above problems can be solved, and the present invention has been made based on this finding.

That is, the present invention is (1) a hot rolling line in which a sizing press that performs setting calculation based on data including slab dimensions and sets the opening based on the width reduction obtained by the setting calculation is installed. A slab width meter is installed on the entry side of the sizing press, and the actual width press entry side slab width is measured at a plurality of locations in the longitudinal direction of the slab with the slab width meter, and the width is measured with the sizing press while transporting the slab. When rolling down, after presetting the opening of the sizing press based on the width reduction amount obtained in the setting calculation, from the width press entry side slab width used in the setting calculation, the width press entry side measured with the slab width meter pull the minimum width of the slab width, you have rows feedforward control of the width reduction for changing narrowing the opening of that much sizing press at the feed-forward control, from the slab tip The relationship between release and width press entry side slab width sent to hot rolling for a process computer in the measurement order, characterized in rows Ukoto the rotational speed control of the conveying table roller sizing press control managed for hot rolling process computer The width reduction method of the slab for hot rolling.

( 2 ) The timing for presetting the opening of the sizing press is a time when the slab is extracted from one of the heating furnaces, or a time when the slab is directly sent onto the conveying table of the hot rolling line. This is the method for reducing the width of the slab for hot rolling described in (1 ) .

  According to the present invention, after presetting the opening of the sizing press based on the width reduction amount obtained by the setting calculation, the width reduction of changing the opening of the sizing press based on the measured width press entry side slab width data. Since feed-forward control is performed, the amount of width reduction by the sizing press can be optimized, and the extra width can be further reduced without greatly modifying the equipment and confusing the hot rolling process.

It is an example of the top view which shows the structure of the hot rolling line which enforces this invention method. It is a top view which shows the opening degree of a sizing press. (A) is a plan view of an abnormal slab 10 showing that the actual width press entry side slab width includes a width abnormal portion 10a that is considerably narrower than the other portions, and (b) is the actual slab length It is a top view of the taper-shaped slab 11 which shows that the width | variety of the center part of a direction contains the width | variety abnormal part 11a largely different from the width | variety estimated by setting calculation. It is a characteristic view of an example which shows the relationship between the distance from a slab front-end | tip, and the width press entry slab width about the abnormal slab 10 and the taper-shaped slab 11 shown in FIG. It is a characteristic view of an example which shows that the amount of fluctuations in the width of a hot-rolled steel strip is smaller than the conventional method when the method of the present invention is carried out.

Hereinafter, the method of the present invention will be described.
FIG. 1 is a plan view showing the configuration of a hot rolling line for carrying out the method of the present invention, and 1 shows a steel slab. The slab 1 may be sent directly onto the conveyance table 2 of the hot rolling line, or may be heated in a heating furnace and extracted onto the conveyance table 2. Reference numeral 3 denotes a slab width meter installed on the entry side of the sizing press 4. The slab width meter 3 is preferably of a lower light source type or an infrared type.

  The lower light source method is a part where the light from the lower light source installed below the pass line is blocked inside the width direction end of the object to be measured and to the upper side outside the width direction end of the object to be measured. The boundary of the passing part is detected by a detector installed above the pass line. On the other hand, the infrared method is to detect a boundary between a high temperature object to be measured that emits infrared rays and a low temperature ambient by a detector installed above the pass line.

  As shown in FIGS. 1 and 2, the sizing press 4 has a pair of press dies 4 a disposed so as to sandwich the slab 1 being conveyed, and has a predetermined width in the longitudinal direction while conveying the slab 1. The width can be sequentially reduced by the reduction amount ΔB. FIG. 2 is a plan view showing a state in which a normal slab 1 having a constant width press entry side slab width W is being reduced in width, and the opening G of the sizing press is a pair of press dies. This is the value when the interval 4a is the narrowest. Further, when the width of the slab 1 is successively reduced in the longitudinal direction while the slab 1 is being conveyed, the feed amount P in the conveyance direction of the slab 1 is set so as not to exceed the length L of the mold parallel part.

  Conventionally, the setting of each equipment is set based on the steel grade, slab size data, slab temperature, etc. transmitted from the host computer 6 to the hot rolling process computer 5 including calculation of the opening degree G of the sizing press 4. The calculation is performed by the hot rolling process computer 5. The opening degree G of the sizing press 4 is determined in advance by obtaining a width reduction amount ΔB of the sizing press by setting calculation, and is set via an opening setting driving device (not shown) of the sizing press 4.

The opening G of the sizing press 4 described above is obtained by substituting the values of W and ΔB into the following formula (1) and performing setting calculation in the subsequent rough rolling and finish rolling to obtain the target width and target thickness. The convergence is calculated as follows.
G = W−ΔB (1)
However, W: width press entry side slab width, ΔB: width reduction amount.

  Here, since the slab width meter 3 is not conventionally installed on the entry side of the sizing press 4, the slab width in the continuous casting process transmitted from the host computer 6 as the initial value of the slab width of the setting calculation. The calculated value or the actual value of the loader grip width at the slab yard was used. The slab width data transmitted from the host computer 6 does not take into account the slab width variation that occurs during continuous casting and the slab width variation that occurs during the subsequent cooling or heating process. ), In the abnormal slab 10 including the abnormal width portion 10a, the actual width reduction amount in the abnormal width portion 10a is considerably smaller than the width reduction amount obtained by the setting calculation, resulting in an abnormal width. The width reduction amount ΔB in the portion 10a could not be optimized.

In addition, as shown in FIG. 3B, in the case of the tapered slab 11 including the width abnormal portion 11a in which the actual width of the center portion in the longitudinal direction of the slab is significantly different from the width predicted by the setting calculation, the actual width press Since the entry-side slab width is not measured, the actual width reduction amount at the abnormal width portion 11a is considerably smaller than the width reduction amount obtained by the setting calculation.
3 (a) and 3 (b), the feed amount P in the slab conveyance direction is less than the length L of the mold parallel part, as in the normal slab 1 in which the width press entry side slab width W is constant. And a state in which the slab tip was struck with a pair of press dies 4a incorporated in a sizing press. FIG. 4 shows the relationship between the distance from the slab tip and the width press entry-side slab width for the abnormal slab 10 and the abnormal tapered slab 11 shown in FIG. In the conventional method, when the steel slab 1 is transported by the sizing press while the width is reduced, only the preset control for presetting the opening G of the sizing press is performed so that the width reduction amount obtained by the setting calculation is obtained.

  On the other hand, in the method of the present invention, the slabs such as the abnormal slab 10 including the abnormal width portions 10a and 11a, the abnormal tapered slab 11 and the like, where the actual width reduction amount is considerably smaller than the width reduction amount obtained by setting. When the width is reduced by the pair of press dies 4a, the opening G of the sizing press 4 is preset based on the width reduction amount obtained by the setting calculation, and the slab width meter 3 sets the width press entry side slab width in the slab longitudinal direction. The width reduction feed forward that changes the opening degree G of the sizing press 4 by optimizing the width reduction amount ΔB obtained by the setting calculation based on the measured width press entry side slab width data. This is a method for performing control.

As a method for optimizing the width reduction amount ΔB, for example, for each feed amount P in the transport direction, the minimum width or average value in the width abnormal portions 10a and 11a is calculated, and then the width press input used in the setting calculation is performed. A preferred method is to subtract the minimum width from the side slab width to obtain a correction amount for the width reduction amount obtained by the setting calculation.
Further, when performing feed-forward control under width reduction to change the opening degree G of the sizing press 4, the relationship between the distance from the slab tip and the width press entry side slab width is transferred to the hot rolling process computer 5 in the order of measurement. It is preferable to perform the rotation speed control of the conveying table roller of the sizing press 4 under the control of the feeding because the tracking accuracy of the abnormal width portion in the slab can be increased. This is because the slab tip can be detected by a sudden temperature rise of the slab temperature sensor installed at the same position as the slab width meter 3, and the slab tail end can be detected by a sudden temperature drop of the same slab temperature sensor. The feed amount in the slab conveyance direction is controlled by controlling the rotation speed of the conveyance table roller of the sizing press 4 until the tail end of the slab passes directly under the slab temperature sensor after passing directly under the slab temperature sensor. This is because the tracking accuracy of the abnormal width portion can be improved for each P.

The timing for presetting the opening degree G of the sizing press 4 is No. The point of time when extracted from any one of the heating furnaces 1 to n, or the point of time when it is directly sent onto the conveying table 2 of the hot rolling line, is the end of the calculation calculation of various facilities including the sizing press 4 Therefore, it is preferable in the operation of the sizing press 4.
Thus, by carrying out the method of the present invention, the width of the sheet bar after rough rolling can be made substantially constant as compared with the conventional method. As shown in FIGS. The width fluctuation amount of the hot-rolled steel strip obtained by rolling can be reduced.

  The steel slab is reduced in width by a sizing press according to the method of the present invention and the conventional method, followed by rough rolling and finish rolling, and a hot rolled steel strip having a target width of 600 to 2300 mm and a target thickness of 1.2 to 25.4 mm Got. According to the method of the present invention, a hot-rolled steel strip having a surplus width of +5 mm (per one side) could be stably obtained over the entire length of the steel strip regardless of the slab type. The conventional method is within a surplus width of +20 mm (per one side), and it can be seen that the method of the present invention can greatly reduce the surplus width of the hot-rolled steel strip as compared with the conventional method.

G Sizing press opening W Width press entry side slab width ΔB Width reduction amount SW Fluctuation amount of hot-rolled steel strip L Length of mold parallel part R Total length of slab S Total length of hot-rolled steel strip 1 Steel slab 2 Transport table 3 Slab width meter 4 Sizing press 4a A pair of press dies 5 Hot rolling process computer 6 Upper computer 10 Abnormal slab 11 Abnormal taper slab 10a, 11a Abnormal width portion

Claims (2)

In the hot rolling line where a sizing press is installed that performs setting calculation based on data including slab dimensions and sets the opening based on the width reduction obtained by the setting calculation, on the entry side of the sizing press When a slab width meter is installed and the actual width press entry side slab width is measured at a plurality of locations in the longitudinal direction of the slab with the slab width meter, and the width is reduced by the sizing press while transporting the slab, it is obtained by setting calculation. After presetting the opening of the sizing press based on the width reduction amount, the minimum width of the width press entry side slab width measured by the slab width meter is subtracted from the width press entry side slab width used in the setting calculation, There line feedforward control of width reduction to be changed by that amount narrowing the sizing press opening at the feed-forward control, distance and width press entry side slabs from the slab tip Relationship measurement order to feed the hot rolling for the process computer and, hot width of the hot rolled slab for the rotational speed control, characterized in row Ukoto the conveying table roller sizing press control managed for rolling process computer Reduction method. The timing for presetting the opening of the sizing press is a time point when the slab is extracted from any heating furnace, or a time point when the slab is directly sent onto a conveying table of a hot rolling line. The method for reducing the width of a slab for hot rolling described in 1 .

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