JP4720271B2 - Hot rolling method and finish rolling mill in hot rolling line - Google Patents

Description

The present invention relates to a hot rolling method, and a rolling mill finishing in the hot rolling line. The metal plate to be rolled is mainly strip steel, but is not limited to this, and may be made of copper, aluminum or other materials.
Incidentally, the strip steel, as defined in JIS G 3193, refers to a steel sheet in the form of a thin plate with a thickness of 1.2 mm or more and a width of 600 mm or more, which is wider than a flat steel (specifically, It means a steel material having a width of more than 500 mm. In addition, there are areas where the steel strip wraps with the steel plate and part of the product thickness and product width, but the difference between the steel strip and the steel plate is that the former is wound after rolling, while the latter is not wound. There is.

  Hot rolling means that a metal material is heated to several hundred to several hundreds of degrees Celsius, then extracted onto a hot rolling line, and the roll is rotated while being pinched by a pair of rolls, thereby extending thinly. . FIG. 5 shows an example of a hot rolling line 100 that has been conventionally used. The metal material 8 having a thickness of 150 to 300 mm heated to several hundred to several hundreds of degrees Celsius by the heating furnace 10 is rolled to a thickness of 0.8 to 25 mm by the rough rolling mill 12 and the finish rolling mill 18 to be a metal plate (hereinafter, Rolled thinly into the shape of the material to be rolled 8).

In the case of the hot rolling line 100 shown in FIG. 5, the rough rolling mill 12 has three groups of R1, R2, and R3, but the number of bases is not necessarily limited thereto. In addition to one or two, the most common one is four, and the one with a large number is up to six.
In the case of the most general four units, a type called 3/4 continuous (three quarters) in which a part of the four units (in many cases, one) is reciprocally rolled, and the remaining rolling mill performs one-way rolling. There are many. However, three of the four aircraft are not limited to the one-way type, and for example, as shown in FIG.

Some have a width press 9 installed immediately upstream of the roughing mill 12. In the case of the hot rolling line 100 shown in FIG. 5, the number of rolling mills (stands) constituting the finish rolling mill 18 is seven of F1 to F7, but there are six.
Although there are differences in these various radixes, the rough rolling machine 12 performs rough rolling six times or seven times in general by reciprocating rolling or unidirectional rolling or both, and the material 8 to be rolled after rough rolling. Is fed to the finishing mill 18 that follows. Rolling a plurality of times such as 6 times or 7 times is also referred to as rolling with 6 passes or 7 passes.

The finishing mill 18 takes the form of a hot tandem finishing mill that simultaneously rolls a high-temperature rolled material 8 of several hundred to several hundreds of degrees Celsius with a plurality of rolling mills. Often called. 19 is a roll.
By the way, in the hot rolling line 100, except for between the stands of the finish rolling mill 18, a large number (100 or more) of table rollers (not shown) are installed between the other rolling mills (stands). The material 8 is conveyed.

  By the way, when extracted from the heating furnace 10, an oxide layer (hereinafter referred to as scale) is formed on the front and back surfaces of the high-temperature rolled material 8 heated to several hundred to several hundreds of degrees Celsius as described above. is doing. In addition, since the rolled material 8 is exposed to the atmosphere at a high temperature even in the process of being rolled and thinned and lowered in temperature by heat radiation, new scales are generated on the front and back surfaces of the rolled material 8. For this reason, on the entry side of each rolling mill in the rough rolling mill 12, descaling is performed by spraying high-pressure water inside and outside 10 to 30 MPa on the front and back surfaces of the material to be rolled 8 as the supply pressure from the pump. A device 16 is installed to remove the scale.

In FIG. 5, reference numeral 14 denotes a crop shear, which cuts and removes the crop at the front and rear ends of the material 8 to be rolled (finished flat shape portion at the front and rear ends of the material 8 to be rolled) before finish rolling. It is shaped into a substantially rectangular planar shape that is easy to bite smoothly.
50 is a control device, 70 is a process computer, and 90 is a business computer.
The upper and lower roll gaps of the rolling mills 12 of the rough rolling mill 12 and the finishing rolling mill 18 are stored as data in the process computer 70, and the planned (desired) thickness of the material 8 to be rolled on the delivery side of each rolling mill. On the other hand, the result of calculating the elongation of the rolling mill housing due to the rolling reaction force (rolling load) is calculated in the process computer 70 so as to be added, and is set before the tip of each rolled material 8 is bitten. Adjusted. The rotation speed of each roll is also calculated in the process computer 70, and is set and adjusted before the tip of each material to be rolled 8 is bitten.

  15 is a finish entry side thermometer, which measures the temperature of the material to be rolled 8 before finish rolling, and sets various settings (setup) such as a roll gap when the material to be rolled 8 bites into the finish rolling mill 18. The role of starting the calculation and the role of providing the temperature data to the control device 50 and the process computer 70 to be performed based on the result of determining the set value by calculation in the process computer 70 Play as well.

Reference numeral 21 denotes a finisher side thermometer, which serves to provide temperature data to the control device 50 and the process computer 70.
Reference numeral 22 denotes a finishing delivery thickness gauge, which plays a role of providing thickness data to the control device 50 and the process computer 70.
23 is called a run-out table. It is a table roller group of the cooling zone which water-cools the to-be-rolled material 8 after finish rolling.

24 is a coiler and winds up the to-be-rolled material 8 after cooling.
Reference numeral 25 denotes a coiler inlet side thermometer, which serves to provide temperature data to the control device 50 and the process computer 70.
In such a hot rolling line 100, the material to be rolled 8 is rolled once and then the next material to be rolled 8 is rolled, and the rolling in the finishing mill 18 is performed. Intermittent finish rolling one by one is sometimes referred to as batch rolling.

By the way, in recent years, in hot rolling, rolling may be performed while supplying lubricating oil between the roll 19 and the material to be rolled 8 during rolling in one or more of the rolling mills constituting the finish rolling mill 18. is there.
This is to supply lubricating oil between the roll 19 and the material to be rolled 8 during rolling and to reduce the friction between the roll 19 and the material to be rolled 8 as shown in FIG. 6 (to reduce the friction coefficient μ). Thus, the degree of deformation so that the material 8 to be rolled is simply crushed is increased, whereby the crystals of the material 8 after rolling are parallel to the front and back surfaces of the material 8 {1, 1, 1 } The main purpose is to increase the degree of accumulation in the orientation to form the surface, and as a result, to remarkably improve the elongation performance represented by the r value of the product metal plate and to improve the press forming performance.

Patent Document 1 includes mass%, C: 0.01% or less, Si: 2.0% or less, Mn: 3.0% or less, P: 0.2% or less, S: 0.05% or less, Al: 0.005% or more, 0.1% or less, N: 0.01% or less, Ti: 0.001% or more, 0.2% or less, and Nb: 0.001% or more , When hot-rolling a steel slab comprising one or two of 0.2% or less and the balance being Fe and inevitable impurities, at least one pass of finish rolling is performed with a centerline average roughness Ra of 0.05 μm. Using the above work roll, lubrication is performed by supplying a lubricating oil having a viscosity of less than 450 mm ² / s at 40 ° C. to the roll at a rate of 0.2 to 10 ml / m ² by the water injection method. While rolling in a temperature range below the Ar ₃ transformation point, and the temperature range, A method for producing a hot-rolled steel sheet for deep drawing is described, in which the rolling rate under lubricating conditions is 50% or more in total, and then recrystallization treatment is performed by winding or annealing.

  In the case of batch rolling, if the lubricant oil is sprayed onto the roll 19 before the tip of the material 8 to be rolled into the roll 19 of the rolling mill (this is the case with the water injection method), it slips when biting. Otherwise, there is a strong possibility that rolling cannot be continued any further. Therefore, after the tip of the material to be rolled 8 has bitten into the roll 19 of the rolling mill, the lubricating oil has to be started to be injected.

  Further, if the lubricating oil is continuously sprayed until the tail end of the material 8 to be rolled passes through the roll 19 of the rolling mill, the lubricating oil remains on the roll 19, and the tip of the next material 8 to be rolled is removed. Slip when biting. Therefore, before the tail end of the material to be rolled 8 passes through the roll 19 of the rolling mill, the lubricating oil is sprayed and stopped at least before the roll 19 makes one round, and the lubricating oil adhering to the roll 19 is removed. It must be burned and depleted with heat to prevent slipping.

Since it takes about 1 minute on average to roll one material to be rolled 8, as a flow rate per unit time, the lubricating oil is directed to the roll 19 at a rate of 0.2 to 10 ml / m ² / min. It is preferable to make the injection.
On the other hand, rolling the material to be rolled 8 to a uniform plate thickness over the entire length in the longitudinal direction as much as possible after finish rolling is also strongly required as the quality of the product metal plate. Automatic plate thickness control (AGC: Automatic Gauge Control) is widely adopted and applied to rolling of the material 8 to be rolled.

  In particular, after rolling for a transitional period corresponding to a transitional period of biting of the tip of the material 8 to be rolled, called a lock-on, the rolling load at that time and the upper and lower roll gaps are assumed to be virtual in the control device 50 as representative values. After that, according to the following formula, the deviation of the current load with respect to the rolling load at the time of lock-on was multiplied by an appropriate gain according to the momentary fluctuation of the actual rolling load. A method of automatic plate thickness control called gauge meter AGC, in which the gap between the upper and lower rolls is adjusted from moment to moment, such that the rolling load is narrower when the rolling load increases than when it is locked on, and conversely it is expanded when it decreases. Is the most commonly adopted.

Δs = GΔP
Δs: Upper and lower roll gap adjustment amount with respect to upper and lower roll gap at lock-on G: Gain ΔP: Deviation of current load with respect to rolling load at lock-on Also, finish finish side plate provided on exit side of finish rolling mill 18 The thickness meter 22 is used to perform feedback control so as to adjust the upper and lower roll gaps of one or more rolling mills of the finish rolling mill 18 in order to compensate for a deviation from a desired sheet thickness. An automatic plate thickness control method may be used in combination.

  However, when rolling is performed while supplying a lubricant between the roll 19 and the material 8 during rolling in one or more of the rolling mills constituting the finish rolling mill 18, a gauge meter AGC is employed. If this is the case, the desired thickness of the rolled material 8 after rolling cannot be obtained, and as a previous problem, rolling of the rolled material 8 cannot be continued. This is because, when a lubricant is supplied between the roll 19 and the material 8 during rolling, the friction is reduced, resulting in a reduction in rolling load. Due to

  Then, it goes without saying that a desired sheet thickness of the rolled material 8 after rolling cannot be obtained, but there is a further rolling mill on the downstream side in the conveying direction of the rolled material 8 than the rolling mill, When one rolled material 8 is being rolled at the same time, the rolled material 8 is thicker than planned between the rolling mill and one downstream rolling mill, and the rolled material. Since 8 is pulled, the material to be rolled 8 will soon be broken.

This is not improved even if the monitor AGC is used together. This is because the monitor AGC is feedback control, and in many cases, the material to be rolled 8 has already been broken before the response time. This is especially true when feedback control is performed by integral control.
I want to solve this kind of problem.

By the way, although the purpose is completely different, in Patent Document 2, when the thickness of the rolled material 8 after rolling is as thick as, for example, 50 mm or more, the thickness gauge is damaged due to warpage of the rolled material 8 after rolling. In order to prevent sheet thickness gauges from being used and the monitor AGC cannot be used together, it is possible to avoid the possibility of improving sheet thickness control accuracy by feedback control. The first and second plate speedometers are provided at positions close to the rolling mill, the thickness gauge is provided at a position 3 m or more from the entrance side of the rolling mill, and the same position as this thickness gauge or with respect to this position. A third plate speedometer is provided at a position distant from the rolling mill, and the thickness of the entry side of the material to be rolled that is moved toward the rolling mill by the plate thickness meter is measured, and the third plate speedometer is Measure the thickness of the material to be rolled The time when the minute reaches the rolling mill, and the entry side plate thickness of the material to be rolled every moment, the entry side speed of the material to be rolled passing through the rolling mill measured by the first and second plate speedometers, and A method for measuring the thickness of a material in a hot rolling mill is described in which the thickness of the exit side of the material to be rolled is estimated based on the principle of constant mass flow on the entry side and the exit side of the rolling mill from the exit side speed. Yes.
JP-A-11-279657 Japanese Patent Laid-Open No. 08-047707

The inventors considered whether the method as described in Patent Document 2 could be applied when rolling while supplying a lubricant between the roll 19 and the material to be rolled 8 during rolling.
However, first, even if the sheet thickness on the exit side of the rolling mill is estimated, if the deviation between the sheet thickness and the desired sheet thickness is fed back to the adjustment of the upper and lower roll gaps of the rolling mill, it responds as described above. There is a problem that there is a strong possibility that the material to be rolled 8 has already broken without being in time.

The present invention has been made to solve the problems of the prior art as described above.
That is, the present invention
(1) When a metal plate is rolled with a rolling mill by hot rolling, the thickness of the metal plate on the entry side of a certain rolling mill, the measured thickness of the metal plate on the exit side of the rolling mill, and the rolling From the measured plate speed of the metal plate on the machine entrance side and the measured plate speed of the metal plate on the exit side of the rolling mill, the rolling mill obtained by the calculation by the following equation (A) With the thickness of the metal plate on the entry side as an input, and with the goal that the thickness of the metal plate on the delivery side of the rolling mill is a desired value, the upper and lower roll gaps of the rolling mill are expressed by the following formula (B) The method of hot rolling a metal plate, characterized in that it is adjusted from time to time.
h _{input, guess} = h _{output, actual} x V _{output, actual} ÷ V _{input, actual} (A)
h _{input, thrust} : Estimated thickness on the rolling mill _input side
h _{Departure, Actual} : Measured thickness on the delivery side of the rolling mill
V _{input, actual} : Measured sheet speed on the rolling mill _input side
V _{output, actual} : _Actually measured plate speed on the rolling mill exit side
Δs = GΔh (B)
Δs: Adjustable amount of the upper and lower roll gaps of the rolling mill with respect to the upper and lower roll gaps of the rolling mill when locked on
G: Rolling mill gain
Δh: Deviation of the current rolling mill entry side estimated plate thickness relative to the rolling mill entry side estimated plate thickness at lock-on

The present invention also provides:
(2) In (1), the thickness of the metal plate on the outlet side of the rolling mill that is one upstream in the conveying direction of the metal plate, which is in tandem with the rolling mill, is calculated by the calculation. A hot rolling method for a metal plate, characterized in that the upper and lower roll gaps of the rolling mill on the one upstream side are adjusted from moment to moment for the purpose of achieving the thickness of the metal plate on the side.

And this invention,
(3) A rolling mill in a hot rolling line used for carrying out the hot rolling method for a metal sheet described in (1) or (2), and rolling to a certain rolling mill outlet side in the hot rolling line A hot thickness characterized by comprising a plate thickness meter for actually measuring the thickness of the metal plate, and a plate speed meter for measuring the plate speed of the metal plate to be rolled on the inlet side and the outlet side of the rolling mill. It is a rolling mill in a rolling line .

  According to the present invention, even when rolling is performed while supplying a lubricant between the roll and the material to be rolled during rolling, the material to be rolled is rolled to a desired thickness without breaking the material to be rolled. Can do.

(First embodiment)
FIG. 1 is a diagram showing an embodiment of the present invention. In the case where the present invention is applied to the final rolling mill (F7) in the conveying direction of the material to be rolled 8 in the finishing rolling mill 18 of the hot rolling line 100 shown in FIG. It shows.
The sheet thickness of the material 8 to be rolled on the F7 outlet side is measured by using the finishing side thickness gauge 22 originally provided on the outlet side of the finishing mill 18. Then, the plate speed of the material 8 to be rolled on the entry side of F7 and the plate speed of the material 8 to be rolled on the exit side of F7 are measured by laser Doppler plate speed meters 26 and 27 newly installed on the entry side and the exit side of F7. And actually measured.

The measured thickness of the material 8 to be rolled on the F7 delivery side and the plate speed of the material 8 to be rolled on the F7 entry and exit sides are also sent to the controller 50 as measured data from time to time.
Based on these data, the thickness of the material 8 to be rolled on the F7 entry side is obtained by calculation from moment to moment according to the following equation (1).
h _{6 guess} = h _{7 actual} × V _{7 actual} ÷ V _{6 actual} (1)
h _{6 guess} : F7 inlet side (F6 outlet side) estimated plate thickness h _{7 actual} : F7 outlet side measured plate thickness V _{6 actual} : F7 inlet side (F6 outlet side) actually measured plate speed V _{7 actual} : F7 outlet side actually measured plate speed According to the above equation (1), the thickness of the material 8 to be rolled on the F7 entry side calculated by the calculation is used as an input, and the thickness of the material 8 to be rolled on the F7 exit side is set to a desired value. The upper and lower roll gap is adjusted from time to time according to the following equation (2).

Δs ₇ = G ₇ Δh ₆ (2)
Δs ₇ : F7 vertical roll gap adjustment amount with respect to F7 vertical roll gap at lock-on G ₇ : F7 gain Δh ₆ : Current F7 relative to F7 inlet (F6 outlet) estimated plate thickness at lock-on Deviation of the input side (F6 output side) estimated plate thickness After rolling the rolling length corresponding to the transitional period of biting of the tip of the material 8 to be rolled, the rolling load at that time and the upper and lower roll gaps are called lock-on. The process of virtually storing the representative value in the control device 50 is performed in the same manner as in the above-described gauge meter AGC. Thereafter, according to the above equation (2), the F7 inlet side (F6 outlet side) planned plate thickness is F7 inlet side (F6 outlet side) estimated plate thickness with respect to F7 inlet side (F6 outlet side) estimated plate thickness at the time of lock-on as the F7 inlet side (F6 outlet side) estimated plate thickness changes every moment Multiplied by the appropriate gain The upper and lower roll gaps of F7 are adjusted from time to time, such that when the estimated thickness on the F7 entry side (F6 exit side) increases compared to the lock-on state, it narrows, and conversely, when it decreases, it increases. This corresponds to feedforward control.

If the F7 delivery side actual measured thickness measured by the F7 delivery side thickness gauge 22 has a deviation from the desired thickness calculated in the process computer 70, it is reflected in the adjustment of the upper and lower roll gaps of F7. The control may be used in combination, including the case of taking the form of integral control.
Alternatively, if the estimated thickness on the F7 entry side (F6 exit side) is deviated from the planned plate thickness, feedback control that reflects this in the adjustment of the upper and lower roll gaps in F6 may take the form of integral control. You may make it use together.
(Second Embodiment)
FIG. 2 is a diagram showing another embodiment of the present invention. The main part is expanded in the case where the present invention is applied to the fourth rolling mill (F4) in the conveying direction of the material to be rolled 8 in the finish rolling mill 18 of the hot rolling line 100 shown in FIG. As shown.

  The thickness of the material to be rolled on the F4 exit side is measured using an F4 exit side thickness gauge 224 newly installed on the exit side of F4. However, if a thickness gauge is already provided on the F4 exit side, it may be diverted. Then, the plate speed of the material 8 to be rolled on the entry side of F4 and the plate speed of the material 8 to be rolled on the exit side of F4 are measured by laser Doppler type plate speedometers 26 and 27 newly installed on the entry side and the exit side of F4. And actually measured.

The measured sheet thickness of the material to be rolled on the F4 exit side and the sheet speed of the material to be rolled 8 on the F4 entry side and the exit side are also sent to the control device 50 as measured data from time to time.
Based on these data, the thickness of the material 8 to be rolled on the entry side of F4 is obtained by calculation every moment according to the following equation (3).
h _{3 guess} = h _{4 actual} × V _{4 actual} ÷ V _{3 actual} (3)
h _{3 guess} : F4 inlet side (F3 outlet side) estimated plate thickness h _{4 actual} : F4 outlet side actually measured plate thickness V _{3 actual} : F4 inlet side (F3 outlet side) actually measured plate speed V _{4 actual} : F4 outlet side actually measured plate speed According to the above equation (3), the thickness of the material 8 to be rolled on the F4 entry side obtained by calculation is input, and the thickness of the material 8 to be rolled on the F4 exit side is set to a desired value. The upper and lower roll gaps are adjusted from time to time according to the following formula (4).

Δs ₄ = G ₄ Δh ₃ (4)
Δs ₄ : F4 vertical roll gap adjustment amount with respect to F4 vertical roll gap during lock-on
G ₄ : F4 gain Δh ₃ : Deviation of the current F4 inlet side (F3 outlet side) estimated plate thickness with respect to the F4 inlet side (F3 outlet side) estimated plate thickness at the time of lock-on. The process of virtually storing the rolling load at that time and the upper and lower roll gaps as representative values in the control device 50 after rolling for a rolling length corresponding to the transitional period is the gauge meter AGC described above. After that, according to the above equation (4), the F4 inlet side (F3 outlet side) estimated plate thickness with respect to the F4 inlet side (F3 outlet side) estimated plate thickness is changed according to the momentary fluctuation. Lock on the upper and lower roll gaps of F4 by multiplying the deviation of the estimated F4 inlet side (F3 outlet side) estimated plate thickness from the F4 inlet side (F3 outlet side) estimated plate thickness at the time of ON by an appropriate gain. F4 entry side (F3 exit side) estimated plate thickness increases than time Narrow If you, spread if decreased Conversely, adjusted to momentarily so on. This corresponds to feedforward control.

If the F4 delivery side actual measured thickness measured by the F4 delivery side thickness gauge 224 has a deviation from the desired thickness calculated in the process computer 70, the feedback reflects it in the adjustment of the upper and lower roll gaps of F4. The control may be used in combination, including the case of taking the form of integral control.
Alternatively, if the estimated plate thickness on the F4 entry side (F3 exit side) has a deviation from the planned plate thickness, feedback control that reflects this in the adjustment of the upper and lower roll gaps of F3 may take the form of integral control. You may make it use together.

  As described above, the above-described embodiment is only a part, and the embodiment of the present invention is not limited to this. That is, various changes can be made. For example, the material to be rolled is not limited to steel but can be any type of metal, and the rolling mill to which the present invention can be applied is not limited to the example of F7 or F4 described above, and other finish rolling mills 18 Any of the rolling mills may be used, and any of the roughing mills 12 may be used. Finally, in addition to the hot rolling line 100 as shown in FIG. 5, the present invention includes a hot rolling line 200 directly connected to the continuous casting line 28 as shown in FIG. 3 and a stickel mill as shown in FIG. Of course, it may be applied to 300 grades.

  In the hot rolling method of the present invention, the molten metal is made into a slab-like metal material by a continuous casting method or an ingot forming method, and then the hot rolled line 100 as shown in FIG. When heating, rolling and winding in other various hot rolling lines, this can be realized by rolling by the method of the present invention described above.

It is a figure for demonstrating one embodiment of this invention. It is a figure for demonstrating another embodiment of this invention. It is a figure which shows an example of another hot rolling line to which this invention is applied. It is a figure which shows an example of another hot rolling line to which this invention is applied. It is a figure which shows an example of the conventional hot rolling line. It is a figure for demonstrating a prior art. It is a figure for demonstrating a prior art.

Explanation of symbols

8 Rolled material (metal material)
9 Width press 10 Heating furnace 12, R1, R2, R3 Rough rolling mill 14 Crop shear 15 Finishing side thermometer 16 Descaling device 18, F1, F2, ... F7 Finishing rolling mill 13, 19 Roll 21 Finishing side thermometer 22 Finishing side thickness gauge 224 F4 Delivery side thickness gauge 23 Runout table 24 Coiler 25 Coiler entry side thermometer 26 F7 (F4) entry side (F6 (F3) exit side) plate speedometer 27 F7 (F4) exit side plate speed gauge 28 Continuous Casting Line 40 Furnace Coiler 50 Controller 70 Process Computer 90 Business Computer 100, 200 Hot Rolling Line 300 Hot Rolling Line (Steckel Mill)

Claims (3)

When rolling a metal plate with a rolling mill in hot rolling, the thickness of the metal plate on the inlet side of a certain rolling mill, the measured thickness of the metal plate on the outlet side of the rolling mill, and the inlet side of the rolling mill From the measured plate speed of the metal plate and the measured plate speed of the metal plate on the rolling mill exit side, the following (A) is obtained by calculation every moment in the following formula (A) , on the rolling mill entry side obtained by the calculation With the plate thickness of the metal plate as an input, with the goal that the plate thickness of the metal plate on the delivery side of the rolling mill becomes a desired value, the upper and lower roll gaps of the rolling mill are sometimes expressed by the following formula (B): A method of hot rolling a metal plate, characterized by adjusting the moment.
h _{input, guess} = h _{output, actual} x V _{output, actual} ÷ V _{input, actual} (A)
h _{input, thrust} : Estimated thickness on the rolling mill _input side
h _{Departure, Actual} : Measured thickness on the delivery side of the rolling mill
V _{input, actual} : Measured sheet speed on the rolling mill _input side
V _{output, actual} : _Actually measured plate speed on the rolling mill exit side
Δs = GΔh (B)
Δs: Adjustable amount of the upper and lower roll gaps of the rolling mill with respect to the upper and lower roll gaps of the rolling mill when locked on
G: Rolling mill gain
Δh: Deviation of the current rolling mill entry side estimated plate thickness relative to the rolling mill entry side estimated plate thickness at lock-on   In claim 1, the thickness of the metal plate on the outlet side of the rolling mill on the upstream side in the conveying direction of the metal plate, which is in tandem with the rolling mill, is obtained by the calculation, A hot rolling method for a metal plate, characterized in that the upper and lower roll gaps of the one upstream rolling mill are adjusted from time to time for the purpose of achieving the thickness of the metal plate. It is a rolling mill in the hot rolling line used for implementation of the hot rolling method of the metal plate described in Claim 1 or 2 , Comprising: The plate of the metal plate which should be rolled to a certain rolling mill outlet side in a hot rolling line A rolling mill in a hot rolling line, comprising a plate thickness meter that measures the thickness, and a plate speed meter that measures the plate speed of the metal plate to be rolled on the inlet side and the outlet side of the rolling mill .

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