JPH05220511A - Method for controlling thickness in continuous hot rolling mill - Google Patents

Abstract

(57) [Summary] [Objective] To provide a plate thickness control method capable of obtaining a good plate thickness from the tip of a hot strip. [Structure] In a hot continuous rolling mill, at least one thickness gauge 11 and a thermometer 12 are installed between stands, and at the time when the tip of a material 13 to be rolled is bitten into a stand immediately before the thickness gauge 11, The rolling load and the rolling position of the stand are detected, and the plate thickness of the rolled material 13 on the delivery side of the stand is calculated from these detected values using the gauge meter formula. The rolling position after the next stand is corrected based on the deviation, and when the tip of the rolled material 13 passes through the thickness gauge 11 and the thermometer 12, the rolled material 13 is rolled.
It detects the thickness and temperature of each of them, and based on the deviation between the detected value and the output side thickness calculated previously, the rolling position after the next stand, which has already been corrected, is corrected again. ..

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a strip thickness control method for a hot continuous rolling mill.

[0002]

2. Description of the Related Art In order to obtain a target thickness from the tip of a hot strip, it is necessary to set the rolling position (roll gap) of each stand of a hot continuous rolling mill to an appropriate value, which is used for calculation. It was difficult to obtain the desired plate thickness due to errors in the theoretical rolling formula, looseness of the mill in actual rolling, wear of rolling rolls, errors in the gauge meter system due to thermal expansion, etc.

Therefore, in order to obtain a good strip thickness from the tip of the hot strip, it is necessary to correct the rolling position of each stand to an optimum value during strip passing of the material to be rolled.

For the plate thickness control at the tip of the material to be rolled, feed-forward type plate thickness control is effective to correct the rolling position after the next stand based on the deviation between the plate thickness detected at the rolling mill entrance side and the target plate thickness. Is considered to be.

Regarding the feedforward type plate thickness control in a hot continuous rolling mill, for example, Japanese Patent Laid-Open No. 59-14451.
In 0, a method is proposed in which a thickness gauge is installed between stands, and the rolling position after the next stand is corrected based on the deviation between the detected sheet thickness and the target sheet thickness.

Further, Japanese Patent Laid-Open No. 60-247408 discloses a method of calculating a plate thickness deviation and a temperature deviation of a material to be rolled by the rolling load detected by the stand and correcting the rolling position of the next stand based on the calculated deviation. Disclosure.

[0007]

[Patent Document 1] Japanese Unexamined Patent Application Publication No. Sho 59
In the plate thickness control method using the detection result of the thickness gauge as in -144510, it is considered that the correction of the rolling position may be delayed. That is, when the rolling speed is fast and the correction amount of the rolling position is large, the rolling position correction is completed before the next stand bites due to the time delay at the rise of the detection signal of the thickness gauge at the tip of the rolled material. There is a problem in that the thickness deviation cannot be achieved and the thickness deviation remains.

Further, as in JP-A-60-247408,
In the plate thickness control method using the detection result of the rolling load and the like, an error occurs when calculating the plate thickness deviation and the temperature deviation.

An object of the present invention is to provide a plate thickness control method capable of obtaining a good plate thickness from the tip of a hot strip.

[0010]

According to the present invention, in a hot continuous rolling mill, at least one thickness gauge and a thermometer are installed between stands, and the tip of the material to be rolled is placed on the stand immediately before the thickness gauge. At the time of biting, the rolling load of the stand,
The rolling position is detected, and the gauge thickness is used from these detected values to calculate the strip thickness of the rolled material on the outlet side of the stand.Based on the deviation between this strip thickness and the target strip thickness, the next stand and later The rolling position of the material to be rolled was corrected, and when the tip of the material to be rolled passed the thickness gauge and thermometer, the thickness and temperature of the material to be rolled were respectively detected, and this detected value and the previously calculated value were calculated. The rolling position after the next stand, which has already been corrected, is corrected again based on the deviation from the side plate thickness.

[0011]

According to the present invention, the outgoing side plate thickness is calculated from the rolling load and the rolling position detected at the time when the tip of the material to be rolled passes in advance in the stand by using the gauge meter formula, and based on this, the output side plate thickness Outputs a correction command for the rolling position,
Furthermore, when the tip of the rolled material passes through the thickness gauge, the exit side plate thickness is detected, and the rolling position of the next stand is corrected based on this and the deviation of the exit side plate thickness calculated previously. It is possible to obtain a good plate thickness from the tip of the strip.

A thickness gauge and a thermometer are installed on the outlet side of the ith stand of a hot rolling finishing continuous rolling mill having n stands.
A procedure when the present invention is applied will be described with reference to FIG.

Incidentally, FIG. 2 shows the construction of a hot continuous rolling mill used for carrying out the present invention. In FIG. 2, 10 is a work roll, 11 is a thickness meter, 12 is a thermometer, 13 is a material to be rolled, 14 is a load meter, and 15 and 16 are reduction position control devices.

[0014] First, the material to be rolled 13 in step 1 the rolling load P _ai by the load meter 14 after biting into rolls 10 of the i stands, also detects the pressing position S _ai by rolling position control device 15.

In step 2, using these detected values, (1)
The plate thickness h _{Gi of the} material to be rolled on the outlet side of the i-th stand is calculated from the gauge meter formula shown in the formula. h _Gi = S _ai + f (P _ai ) + ΔS ₀ (1) where ΔS ₀ : Gauge meter offset f (): Mill elongation function

Then, based on the deviation between the _delivery side plate thickness h _Gi and the target plate thickness h _Ci obtained by the above-described calculation in step 3, the rolling position correction amount ΔS of the (i + 1) th stand is calculated from the equation (2).
_{Find Gi + 1} .

[0017]

[Equation 1]

In step 4, a command is sent to the rolling down control device 16 of the (i + 1) th stand so as to carry out rolling down correction by this ΔS _{Gi + 1} .

Next, in step 5, when the tip of the material to be rolled passes through the thickness meter 11 and the thermometer 12 installed on the exit side of the i-th stand, the plate thickness h _xi and surface temperature T _ai of the material to be rolled are determined. To detect.

In step 6, based on the deviations of these values from the target plate thickness h _Pi and the predicted temperature T _Ci , the i + th value is calculated from the equation (3).
Calculate the rolling position correction amount ΔS _{xi + 1} for one stand.

[0021]

[Equation 2]

As a result of the above, in step 7, the difference (ΔS _{Xi + 1} −Δ) between ΔS _{xi + 1} and ΔS _{Gi + 1} which has already been corrected.
A command to correct the rolling position of the next stand by S _{Gi + 1} ) is sent to the rolling control device 16.

[0023]

[Examples] In a 7-stand hot continuous rolling mill, a thickness gauge and a thermometer were installed between the 5th stand and the 6th stand, and for a hot strip having a target final delivery thickness of 1.8 mm and a width of 1000 mm, Table 1 shows the tip plate thickness accuracy when each of the method of the present invention and the comparative method in which the reduction was corrected based only on the detection by the thickness gauge and the thermometer.

That is, Table 1 shows the standard deviation of the plate thickness deviation at a position 6 m behind the front end of the rolled hot strip coil from the result of continuous measurement of the thickness gauge installed on the exit side of the seventh stand. It is a thing. In the method of the present invention, the allowable value of the plate thickness deviation is already within 30 μm at this position. On the other hand, in the comparison method, the position is still outside the allowable value at this position, and finally falls within the allowable value further rearward than this position, and the coil length that becomes an off gauge is smaller than that when the method of the present invention is adopted. It is recognized that it becomes extremely large.

[0025]

[Table 1]

[0026]

According to the present invention, since the rolling reduction can be performed in the hot continuous rolling mill without delay, a good strip thickness can be obtained from the tip of the hot strip even when the rolling speed is high. The length of the coil that becomes an off gauge can be shortened.

[Brief description of drawings]

FIG. 1 is a flow chart showing a procedure of a plate thickness control method of the present invention.

FIG. 2 is a schematic diagram showing a configuration of a hot finish continuous rolling mill used for carrying out the present invention.

[Explanation of symbols]

 10 Work Roll 11 Thickness Meter 12 Thermometer 13 Rolled Material 14 Load Meter 15, 16 Rolling Position Control Device

Claims (1)

[Claims] 1. In a hot continuous rolling mill, at least one thickness gauge and a thermometer are installed between stands, and when the tip of the material to be rolled is caught in the stand immediately before the thickness gauge, the stand is rolled. The rolling load and rolling position of the roll are detected, and the plate thickness of the material to be rolled on the stand outlet side is calculated from these detected values using the gauge meter formula, and based on the deviation between the outlet plate thickness and the target sheet thickness. Then, the rolling position after the next stand is corrected, and when the tip of the rolled material passes through the thickness gauge and thermometer, the plate thickness and temperature of the rolled material are detected,
A strip thickness control method for a hot continuous rolling mill, characterized in that the rolling position after the next stand, which has already been corrected, is corrected again based on the deviation between the detected value and the delivery side plate thickness calculated previously.