JP3068289B2 - Inlet temperature control method for hot continuous finishing mill - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for controlling the temperature of a material to be rolled when a steel strip is continuously hot-rolled, and more particularly to maintaining the temperature of the material to be rolled supplied to a finishing mill at a predetermined target temperature. Meanwhile, the present invention relates to a temperature control method capable of minimizing a standby time at an entrance side of a finishing mill as much as possible.

[0002]

2. Description of the Related Art A material to be rolled supplied to a hot continuous finishing rolling mill (hereinafter simply referred to as a finishing rolling mill) is subjected to finish rolling based on so-called mill pacing control regulations so as not to collide with a tail end of a preceding rolling material. Standby time (hereinafter referred to as MPC stand-by time) and stand-by time (FET stand-by time based on the regulation of the target side entrance temperature of the finishing mill set to obtain the required material and to suppress the occurrence of secondary scale. ), It is necessary to wait on the delay table on the entry side of the finishing mill for the longer time.

Conventionally, as shown in, for example, Japanese Patent Application Laid-Open No. 62-289308, the FET standby time is treated as one condition of MPC, and the FET standby time is not particularly controlled.

[0004]

The MPC waiting time is inevitably determined by the pass schedule and mill capacity of the material to be rolled successively by the finishing mill, and cannot be avoided. However, although the FET standby time can be reduced as long as the target temperature can be obtained, the material to be rolled is allowed to cool on the delay table by cooling, and waits for the temperature to drop to the target temperature. Was.

[0005] In the case of ordinary rolling, since the rolling is performed on the high temperature side in the rough rolling mill because it is necessary to secure the FET, the FET standby time is often longer than the MPC standby time. Therefore, in the finishing mill, the rolling pitch is affected by the FET standby time, and productivity is impaired. In particular, the tip of the material to be rolled has a higher temperature than the center because it is affected by the radiant heat from the furnace wall in the heating furnace, and the lock-on thickness and lock-on load for automatic thickness control can be accurately determined. It is necessary to properly manage the FETs in order to obtain it and to prevent the tip from being inserted between the table rollers.

The present invention solves the above-mentioned problem in the prior art by using a scale breaker on the entrance side of a finishing mill.
It is an object of the present invention to provide a method for controlling the inlet side temperature of a finishing mill in which the productivity can be prevented from being impaired as much as possible by approaching the C standby time.

[0007]

SUMMARY OF THE INVENTION The present invention relates to a method for controlling the inlet temperature of a continuous hot rolling mill, wherein a plurality of descaling headers for high-pressure water injection can be selectively used on the inlet side of the finishing mill. In addition, the temperature of the material to be rolled is measured further on the entry side of this descaling header, and the milling time for the standby time on the entrance to the finishing mill based on the temperature regulation is measured from this measured temperature and the target temperature on the entrance to the finishing mill. Select the combination of the descaling header that provides the cooling capacity necessary to approach the standby time on the finishing mill based on the control of the rolling mill, and perform rolling while injecting high-pressure water using the selected descaling header. By passing the material, the above-mentioned problems of the conventional technology are overcome, and the measurement temperature is the temperature of the leading end of the material to be rolled, and the combination of the descaling header is selected. While jetting high-pressure water and,
At the leading end of the material to be rolled, the standby time of the material to be rolled supplied to the finishing mill can be made closer to the standby time based on the regulation of the mill pacing control by adjusting the transport speed and passing the material through the finishing mill. is there.

[0008]

A plurality of descaling headers installed on the entrance side of the finishing mill can be selectively used by combining one or more pairs of upper and lower units, and the material to be rolled can be cooled at a wide range simultaneously with the descaling. The required cooling can be implemented under the choice. Then, the temperature of the material to be rolled is measured further on the entry side of the descaling header. This temperature measurement position is desirably at the tip of the material to be rolled. This is because the temperature at the tip is high as described above, the lock-on plate thickness and lock-on load for automatic thickness control can be obtained accurately, and the tip is prevented from spilling between table rollers. by.

From the temperature measured in this way, a predetermined FET can be obtained by taking into consideration the subsequent cooling during transport of the material to be rolled and the cooling by ordinary descaling.
Find the waiting time. Then, a combination of descaling headers that provides a cooling capacity that can make the FET standby time as close as possible to the MPC standby time is selected. In this case, instead of the FET standby time, the temperature at the finishing mill entry side is estimated from the measured temperature and the MPC standby time of the material to be rolled, and the descaling header is deduced from the cooling capacity required to bring the estimated temperature closer to the FET. The same is true even if a combination of is selected. By using the descaling header selected in this manner and passing the material to be rolled through while injecting high-pressure water, the FET standby time can be reduced to the
It becomes possible to approach C standby time.

[0010] When temperature control is performed more finely, after selecting a combination of the descaling headers as described above, the leading end of the material to be rolled passes through the position of the descaling header to adjust the cooling during the descaling. When adjusting the transfer speed of the roller table. For example, when the combination of the selected descaling headers is slightly overcooled, the roller table transport speed is increased, and when the cooling is insufficient, the transport speed is reduced to allow the plate to pass through the high-pressure water being sprayed. A highly accurate FET can be obtained with a standby time almost equal to or slightly longer than the standby time.

Since the FET is not required to be so accurate except at the tip of the material to be rolled, it is possible to represent the measured temperature only at the tip, or, if necessary, to measure the temperature by sampling and descaling header. It is also possible to change the combination of use, and because it is easy to cool due to rising water except at the tip, the injection of high-pressure water from one or two sets of descaling headers is automatically stopped after passing the tip You may make it do. However, the conveying speed depends on the rolling speed because the leading end of the material to be rolled is already bitten by the finishing mill.

Here, the temperature measurement position at the tip is not particularly strict at a position of about 1 to 2 m from the tip of the material to be rolled, and the length of the tip is the length when it exits the finishing mill. The length is equivalent to about 40 to 100 m in conversion.

[0013]

FIG. 1 shows an example of the arrangement of equipment on the entrance side of a finishing mill for carrying out the present invention, FIG. 2 shows an example of selecting a descaling header, and FIG. An example in which speed adjustment is added will be described. In FIG. 1, F
Is is F ₁ a finishing mill first stand, F ₂ is the stand of the subsequent stage in the second stand is not shown.
FS is a flying shear that cuts and removes a crop at the tip of the material S to be rolled. In this example, four sets of upper and lower de-scaling headers 21 to 24 are installed on the inlet side of the finishing mill F in this example as a finishing inlet-side scale breaker FSB, and shut-off valves 41 to 44 are provided in the respective pipelines 31 to 34. The four sets of descaling headers 21 to 24 are selectively used in one or a plurality of sets. 10 is a radiation thermometer further provided on the entry side of the descaling headers 21 to 24 performs the rolled material temperature measurement of S ₂ to be supplied to the next finish rolling mill F the temperature measurement result to the arithmetic unit 11 Transmit. The computing unit 11 stores the MPC waiting time TM obtained from the rolling schedule and the FET by this computing unit or a higher-order computing unit, and the cooling capacity SB by each combination of the descaling header as follows, for example. Has been entered. Therefore, the cooling capacity at that time can be easily calculated from the sheet thickness, temperature, sheet passing speed and the like of the material to be rolled.

(1) When only SB ₁ = 24 is used (2) When SB ₂ = 24 and 22 are used (3) When SB ₃ = 24 and 23 are used (4) SB ₄ = 24 (5) SB ₅ = When all de-scaling headers are used. Then, in the arithmetic unit 11, the de-scaling header normally used from the temperature measured by the thermometer 10 and the FET ((in this example, ( 1))
Seeking FET waiting time T in the case of transport while descaling using, as close as possible to the MPC waiting time for this T does not collide with the preceding rolled material S _1, selecting a combination of the descaling headers I do.
FIG. 2 shows an example in this case. 2, the cooling capacity when the using only descaling header 24 as described above (1) in SB _1, FET wait time in this case is T
_{It is 1} , which is longer than the MPC standby time TM by Td. Therefore calculation unit 11 selects a combination (3) is a cooling capacity SB ₃ that waiting time closest longer than TM from the combinations of descaling header is obtained. That is, the waiting time will be capable of time-saving of T ₃ next Td '. In the above description, the FET standby time T ₁ is obtained and the value is approximated to the TM. However, the temperature of the material to be rolled when the standby is performed at a predetermined TM is estimated, and this temperature is determined by the FET and the FET. As described above, the same result can be obtained even when the combination of the descaling headers is selected as follows.

Next, in the case of more detailed temperature control,
An example will be described with reference to FIG. In the case shown in FIG._Three
(3) was selected, but in the case of FIG.
Material S _TwoThe transport speed of the
Cooling capacity when passing through the headers 21 to 24
_Three'. Therefore, the waiting time T_ThreeIs T_Three′
And saves Ta time more than in the case of FIG.
As a result, the time of Td ″ can be reduced.

It is also conceivable to install a flow control valve in the high pressure water pipes 31 to 34, but this is not preferable because of a maintenance problem. The method for controlling the inlet temperature of the finishing mill according to the present invention shown in FIG. 3 was carried out by a hot continuous finishing mill having an average coil weight of 20 tons.
The waiting time under the ET regulations was 23.7 hours / month, but it was reduced by about 30% to 16.4 hours / month.

[0017]

According to the present invention, the standby time of the material to be rolled at the entrance of the finishing mill can be greatly reduced, so that not only the productivity is improved but also the operation rate is improved. The economic effects they bring are enormous.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram showing an example of arrangement of equipment on the entrance side of a finishing mill for carrying out the present invention.

FIG. 2 is an explanatory diagram showing an example of selecting a descaling header according to the present invention.

FIG. 3 is an explanatory diagram in a case where a transport speed adjustment of a leading end portion of a material to be rolled is further added to the example of FIG. 2;

[Explanation of symbols]

 10 Thermometer 11 Computer 21-24 Descaling header 31-34 Line 41-44 Shut-off valve F Finish rolling mill S Material to be rolled

Claims (2)

(57) [Claims] 1. A method for controlling an inlet temperature of a continuous hot rolling mill, comprising: installing a plurality of descaling headers for high-pressure water injection on the inlet side of the finishing mill so as to be selectively usable; The temperature of the material to be rolled is measured further on the entry side of the header, and from the measured temperature and the target temperature on the entrance to the finishing mill, the standby time on the entrance to the finishing mill based on the temperature regulation is determined based on the mill pacing control. Selecting a combination of the descaling headers capable of obtaining a cooling capacity necessary for approaching the standby time, and passing the material to be rolled while injecting high-pressure water using the selected descaling headers. A method for controlling the inlet temperature of a continuous hot rolling mill. 2. The measurement temperature is the temperature of the leading end of the material to be rolled, and a combination of descaling headers is selected to inject high-pressure water, and the conveying speed is adjusted at the leading end of the material to be rolled. A method for controlling an inlet temperature of a continuous hot rolling mill, characterized by passing a sheet.