JP2007253223A - Method for controlling thickness in rolling mill and rolling equipment - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To achieve highly accurate thickness control by bringing the thickness of a rolled stock close to the target value even when draft is increased. <P>SOLUTION: The draft, thickness deviation on the inlet side and thickness deviation on the outlet side are determined from the actual value of the thickness on the inlet side of a rolling mill and the actual value of the thickness on the outlet side. When the draft exceeds a prescribed value, the absolute value of the thickness deviation on the inlet side and the absolute value of the thickness variation on the outlet side are compared. When the thickness deviation on the outlet side is larger than the thickness deviation on the inlet side, thickness control is stopped. After that, when the relationship that the thickness deviation on the outlet side is larger than the thickness deviation on the inlet side is further continued under the situation where the thickness control is stopped, the thickness on the outlet side is brought close to the target value by lowering the draft. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a sheet thickness control method for a rolling mill and a rolling apparatus to which this control method can be applied.

For example, in rolling spring steel or the like, it is necessary to make the material hardness (hardness) uniform at the same time as the plate thickness is constant. That is, if a hard part and a soft part are mixed in the longitudinal direction of the rolled material, it becomes a defective spring steel. However, when conventional sheet thickness control is performed, the rolling reduction becomes different in the longitudinal direction of the rolled material, and there is a problem that the hardness of the rolled material after rolling becomes non-uniform.
In order to avoid such a problem, the rolled material is subjected to a heat treatment such as annealing or a technique disclosed in Patent Document 1 is employed.

The rolling mill disclosed in Patent Document 1 is provided with an automatic reduction ratio control controller that keeps the rolling reduction ratio of the rolling mill constant, and an automatic sheet thickness control controller that keeps the outlet side sheet thickness constant. A switching determination unit is provided that allows the controller to be switched freely. This switching judgment unit sets the automatic sheet thickness controller to “OFF” and the automatic reduction ratio controller to “ON” when the delivery side plate thickness is within the predetermined tolerance, and sets the automatic reduction rate when the delivery side plate thickness is outside the predetermined tolerance. The controller is set to “OFF” and the automatic thickness controller is set to “ON”.
In Patent Document 2, the ratio of the inlet side thickness deviation (ΔH) and the outlet side thickness deviation (Δh) is expressed by the thickness deviation attenuation rate (Δh / ΔH). A method is disclosed in which automatic plate thickness control is performed by changing a predetermined control gain and changing the setting to a smaller value as the control gain approaches an optimum value.

In both of the above-mentioned technologies of Patent Document 1 and Patent Document 2, in order to solve the problem of fluctuations in the plate thickness or deviating from the tolerance range, the plate thickness control unit is mainly used appropriately. Or the control gain of the plate thickness control unit is changed to an optimum value to make the exit side plate thickness of the rolled material appropriate.
JP-A-7-96313 JP-A-3-254308

However, when the techniques of Patent Document 1 and Patent Document 2 are applied to an actual site, if the rolling reduction becomes larger than a predetermined value, the thickness of the sheet thickness can be changed even if the control gain of the sheet thickness control unit is changed. There have been cases where the accuracy does not improve to a predetermined value or more and good thickness control cannot be realized. The reason for this is considered that when the rolling reduction is large, the thermal expansion / contraction of the roll increases, the roll gap amount changes more than the set value, and the deviation of the exit side plate thickness increases.
The present invention has been made in view of the above circumstances, and is a sheet thickness control method and sheet for a rolling mill that can bring the sheet thickness of a rolled material closer to a target value even when the rolling reduction increases. An object is to provide a thickness control device.

In order to achieve the above object, the present invention has taken the following measures.
That is, the thickness control method of the rolling mill according to the present invention, when rolling the rolled material using the rolling mill for which the thickness control is performed,
From the actual values of the entry side plate thickness and the exit side plate thickness of the rolling mill, the reduction rate, the entry side plate thickness deviation, and the exit side plate thickness deviation were obtained, and the reduction rate exceeded a predetermined value and “absolute value of the exit side plate thickness deviation> In the case of “the absolute value of the entry side plate thickness deviation”, the plate thickness control is stopped, and in the situation where the plate thickness control is stopped, “the absolute value of the exit side plate thickness deviation> the absolute value of the entry side plate thickness deviation”. When the relationship further continues, the reduction plate thickness is controlled so as to control the outlet side plate thickness.

In other words, the sheet thickness control method of the rolling mill of the present invention considers the cause that the deviation of the exit side sheet thickness does not become the predetermined value or less, and the reduction ratio is controlled to be the predetermined value or less. To do.
Thereby, even if it is a case where a rolling reduction becomes larger than a predetermined value, the delivery side board thickness of a rolling material can be made into a predetermined thing, and highly accurate board thickness control can be realized.
Preferably, after the plate thickness control is stopped, the control gain of the plate thickness control unit may be adjusted when “the absolute value of the exit side plate thickness deviation <the absolute value of the entry side plate thickness deviation”.

Moreover, the rolling device according to the present invention is applicable to the plate thickness control method described above,
From the rolling mill that rolls the rolled material while controlling the sheet thickness, and the actual values of the inlet side sheet thickness and the outlet side sheet thickness of the rolling mill, the reduction ratio, the inlet side sheet thickness deviation, and the outlet side sheet thickness deviation are obtained. When the predetermined value is exceeded and “absolute value of the delivery side thickness deviation> absolute value of the entry side thickness deviation”, the plate thickness control is stopped, and in the situation where the plate thickness control is stopped, When the relationship of “absolute value of deviation> absolute value of input side plate thickness deviation” further continues, a control unit that controls the output side plate thickness by reducing the rolling reduction is provided.

By using the control unit provided in this rolling apparatus, even if the rolling reduction becomes larger than a predetermined value, the exit side plate thickness of the rolled material can be set to a predetermined value, and a highly accurate plate Thickness control can be realized Preferably, the control unit changes a rolling reduction ratio of the rolling mill and a rolling thickness control unit that controls the rolling mill so that the exit side thickness of the rolled material becomes a predetermined one. A rolling reduction rate control unit, and a switching determination unit that switches the control of the rolling mill to one of a rolling reduction control unit and a sheet thickness control unit. From the actual values of the entry side plate thickness and the exit side plate thickness, the rolling reduction rate, the entry side plate thickness deviation and the exit side plate thickness deviation are obtained, and the reduction rate exceeds a predetermined value and “absolute value of the exit side plate thickness deviation> input side plate thickness deviation In the case of `` absolute value of '', the rolling mill control is controlled from the sheet thickness control unit. Switch to the control unit, and reduce the rolling reduction when the relationship of “absolute thickness deviation on the outlet side> absolute value on the inlet side thickness deviation” continues further under the situation where the sheet thickness control does not reach the rolling mill. Thus, it is preferable that a command is issued to the rolling reduction control unit.

  More preferably, an inlet side thickness detector for measuring an inlet side thickness of the rolled material is provided on the inlet side of the rolling mill, and an outlet side thickness of the rolled material is measured on the outlet side of the rolling mill. It is preferable that a side plate thickness detection unit is provided, and the measurement results of the entry side plate thickness detection unit and the exit side plate thickness detection unit are input to the control unit.

  By using the rolled material thickness control method and rolling apparatus according to the present invention, the rolled material thickness can be brought close to the target value even when the rolling reduction increases.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[First Embodiment]
FIG. 1 shows a first embodiment of a sheet thickness control method and a rolling apparatus of a rolling mill according to the present invention.
The rolling device 1 includes a rolling mill 4 having a rolling roll, that is, work rolls 2 and 2 arranged in a pair of upper and lower sides and a pair of backup rolls 3 and 3.
A rolling material 5 serving as a base plate is introduced into the rolling mill 4 and rolled, and then wound up by a winding machine 6 installed on the downstream side. An entry side thickness gauge 7 for measuring the entry side thickness H of the rolled material 5 is installed on the entry side of the rolling mill 4, and an exit side thickness h of the rolling material 5 is measured on the exit side of the rolling mill 4. A side thickness gauge 8 is installed. As the entrance side thickness gauge 7 and the exit side thickness gauge 8, a γ-ray thickness gauge or the like can be adopted.

The main rolling device 1 is provided with a control unit 9 that controls the rolling load and the roll gap amount of the rolling mill 4.
The control unit 9 includes a plate thickness control unit 10 that controls the rolling mill 4 so that the exit side plate thickness of the rolled material 5 falls within a predetermined range or is constant. As a control method performed by the plate thickness control unit 10, a known method can be adopted, and feed forward AGC, BISRA AGC, monitor AGC, mass flow AGC, tension AGC, and the like can be applied. The sheet thickness control unit 10 is input with the exit side plate thickness and rolling material tension of the rolling mill 4, and the roll gap and roll speed of the rolling mill 4 are output.

In addition, the control unit 9 is provided with a rolling reduction control unit 11 that changes the rolling reduction rate with respect to the rolled material 5 to be a predetermined one.
The rolling reduction is defined as shown in Equation (1).

Reduction ratio R = (H−h) / H (1)
Where H: Thickness on the entry side
h: Outboard thickness

The entry side plate thickness cannot be changed because it is the thickness of the rolled material 5 introduced into the rolling mill 4, but the exit side plate thickness h can be changed because it is the result after rolling. Therefore, when it is desired to reduce the rolling reduction R, the rolling load or the roll gap of the rolling mill 4 is set so that the delivery side thickness h is increased (when the reduction rate is desired, the delivery side thickness h is reduced). Adjust it.

Further, the control unit 9 is provided with a switch means 12 for switching the plate thickness control unit 10 and the rolling reduction control unit 11 so that they can be used, and a switching determination unit 13 for operating the switch means 12.
As disclosed in Japanese Patent Application Laid-Open No. 7-96313, the switching determination unit 13 switches so that only the control signal of the plate thickness control unit 10 is transmitted to the rolling mill 4 when the exit side plate thickness h is outside a predetermined tolerance. When the means 12 is operated, the switch means 12 can be operated so that only the control signal of the rolling reduction control unit 11 is transmitted to the rolling mill 4 when the delivery side plate thickness is within a predetermined tolerance. Details of the operation of the switching determination unit 13 in this embodiment will be described later.

The switching determination unit 13 stores in advance target values H _aim and h _aim for the inlet side plate thickness and the outlet side plate thickness. In addition, the actual value H of the inlet side thickness measured by the inlet side thickness meter 7 and the actual value h of the outlet side thickness measured by the outlet side thickness meter 8 are input, and the inlet side thickness deviation ΔH and the outlet side thickness are input. Deviation Δh is calculated and output.
The control unit 9, that is, the plate thickness control unit 10, the rolling reduction control unit 11, the switching determination unit 13, and the switch unit 12 described above is realized by a process computer and a PLC.
Hereinafter, the thickness control method of the rolling mill 4 performed in the control part 9 is demonstrated based on the flowchart of FIG.

First, the control unit 9 captures the actual value H of the inlet side thickness measured by the inlet side thickness meter 7 and the actual value h of the outlet side thickness measured by the outlet side thickness meter 8. After that, the switching determination unit 13 uses the inlet side plate thickness H _aim and the outlet side plate thickness h _aim set in advance, and uses the inlet side plate thickness deviation ΔH (ΔH = H _aim −H) and the outlet side plate thickness deviation Δh (Δh = h _aim -h) is calculated (S1, S2).
Thereafter, the inlet side plate thickness H and the outlet side plate thickness h are substituted into the equation (1) to obtain the rolling reduction ratio R. When the rolling reduction ratio R is larger than a preset value C ₁ (= 0.1 to 0.4), the thermal expansion or contraction of the work roll 2 or the backup roll 3 becomes large, and the roll gap amount changes more than the set value. Thus, it is determined that a situation such as the increase in the delivery thickness deviation Δh has occurred (S3, Yes). Otherwise, it is considered that no abnormal thickness has occurred, and the process returns to step S1 (S3, No).

When the rolling reduction ratio R> C ₁ , the switching determination unit 13 obtains the absolute value | ΔH | of the inlet side plate thickness deviation and the absolute value | Δh | of the outlet side plate thickness deviation, and | ΔH | Investigate the size relationship.
In the case of | Δh | <| ΔH |, the thickness of the outlet side thickness deviation of the rolled material 5 becomes smaller than the amount of the inlet side thickness deviation as rolling is performed. In this case, there is no abnormality in the rolling situation), and normal rolling is performed. Therefore, it is good to return to step S1 (S4, No).

In the case of | Δh |> | ΔH |, the absolute value of the deviation becomes large every time the rolling is performed, and thus the plate thickness is clearly abnormal. In that case, the switching determination unit 13 determines such a situation, operates the switch unit 12, switches the control of the rolling mill 4 from the plate thickness control unit 10 to the rolling reduction control unit 11, and controls the plate thickness control unit 10. The signal is not transmitted to the rolling mill 4. The function of the plate thickness control unit 10 itself may be turned off (S5).
Thereafter, while continuing rolling, the switching determination unit 13 obtains the absolute value | ΔH | of the inlet side thickness deviation and the absolute value | Δh | of the outlet side thickness deviation, and the magnitude relationship between | Δh | and | ΔH | Investigate.

In the case of | Δh | <| ΔH | (S6, No), it is considered that the control gain in the plate thickness control unit 10 is not optimal. Therefore, the optimization of the control gain may be performed by a separately provided optimization unit ( S7, S8). For example, when the absolute value | Δh | of the outlet side thickness deviation is hunting, it is preferable to reduce the control gain.
In the case of | Δh |> | ΔH | (S6, Yes), it is considered that the rolling reduction rate R is an inappropriate value, for example, too large, and the rolling reduction control unit 11 changes the rolling load small. Thus, the outlet side plate thickness h is increased and the rolling reduction R is decreased (R = C ₂ <C ₁ ). Here, C ₂ may be a predetermined value (= 0.1 to 0.4) (S10).

Then, while continuing rolling, the switching determination unit 13 obtains the absolute value | ΔH | of the inlet side thickness deviation and the absolute value | Δh | of the outlet side thickness deviation, and the magnitude relationship between | Δh | and | ΔH | It is confirmed that | Δh | <| ΔH | is realized (S11, S12).
After | Δh | <| ΔH | is realized, whether or not to continue the plate thickness control according to the present invention described above, in other words, the control source of the rolling mill 4 is transferred from the rolling reduction control unit 11 to the plate. Whether or not to switch to the thickness control unit 10 is appropriately determined, and rolling is continued (S13).
When the rolled material 5 is rolled using the plate thickness control method described above, for example, even when the rolling reduction R is a very large value of 0.3, the exit side plate thickness of the rolled material 5 The deviation Δh can be within ± 10 μm and can be within the tolerance range. If the sheet thickness control method of the present invention is not used, when the rolling reduction R is 0.3, the exit side sheet thickness deviation Δh of the rolled material 5 is ± 15 μm, which exceeds the predetermined tolerance range of ± 10 μm. Therefore, it becomes difficult to manufacture a specified product.

[Second Embodiment]
FIG. 3 shows a second embodiment of the rolling apparatus according to the present invention.
The rolling device 1B according to the present embodiment has only the plate thickness control unit 10 adopting feedforward AGC or the like as the control unit 9, and as in the first embodiment, the switching determination unit 13 or the rolling reduction rate. The control unit 11 is not provided.
In that case, the target values H _aim and h _aim of the inlet side plate thickness and the outlet side plate thickness are stored in the plate thickness control unit 10 and measured by the input side plate thickness meter 7 in the plate thickness control unit 10. The actual value H of the inlet side plate thickness and the actual value h of the outlet side plate thickness measured by the outlet side plate thickness meter 8 are input, and the inlet side plate thickness deviation ΔH and the outlet side plate thickness deviation Δh are calculated and output.

Also in the rolling apparatus 1B, as shown in the flowchart of FIG. 2, in the control unit 9 (plate thickness control unit 10), the inlet side plate thickness H and the outlet side plate thickness h are substituted into the formula (1), and the reduction ratio R is calculated. Ask.
If the rolling reduction R is larger than a preset value C ₁ (= 0.1 to 0.4) and | Δh |> | ΔH |, the control function of the plate thickness control unit 10 itself is automatically turned off. (S5).
Thereafter, while continuing rolling, the absolute value | ΔH | of the inlet side thickness deviation and the absolute value | Δh | of the outlet side thickness deviation are obtained, and the magnitude relationship between | Δh | and | ΔH |
When | Δh |> | ΔH | continues (S6, Yes), it is considered that the rolling reduction ratio R is an inappropriate value, for example, too large, for example, the operator changes the rolling load to be small. Thus, the outlet side plate thickness h is increased and the rolling reduction R is decreased (R = C ₂ <C ₁ ).

Thereafter, while | Δh | <| ΔH | is realized while continuing the rolling, the operator turns on the control function of the plate thickness control unit 10 (S13).
The operation by the operator described above may be performed by a calculation unit (not shown) provided in the control unit 9.
Since the effect which this embodiment has is the same as that of a 1st embodiment, explanation is omitted.
The present invention is not limited to the above embodiment.
The rolled material 5 rolled by the rolling device 1 is not limited to a thin plate, and may be a thick plate. The rolling device 1 may be a tandem type equipped with a plurality of rolling mills 4.

It is a block diagram of the rolling device of 1st Embodiment. It is a flowchart which shows a plate | board thickness control method. It is a block diagram of the rolling device of 2nd Embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Rolling apparatus 2 Work roll 3 Backup roll 4 Rolling mill 5 Rolled material 6 Winding machine 7 Entry side thickness gauge 8 Delivery side thickness gauge 9 Control part 10 Sheet thickness control part 11 Reduction ratio control part 12 Switch means 13 Switching judgment part

Claims (5)

When rolling a rolled material using a rolling mill in which sheet thickness control is performed,
From the actual values of the entry side plate thickness and the exit side plate thickness of the rolling mill, find the rolling reduction and the entry side plate thickness deviation and the exit side plate thickness deviation,
In the case where the rolling reduction exceeds a predetermined value and “absolute value of outlet plate thickness deviation> absolute value of inlet plate thickness deviation”, the plate thickness control is stopped,
In the situation where the plate thickness control is stopped, when the relationship of “absolute value of outlet plate thickness deviation> absolute value of inlet plate thickness deviation” continues further, the reduction rate is reduced to reduce the outlet plate thickness. A sheet thickness control method for a rolling mill, characterized by controlling.   The control gain of the plate thickness control unit is adjusted when the absolute value of the outgoing plate thickness deviation is smaller than the absolute value of the incoming plate thickness deviation after the plate thickness control is stopped. Item 2. A method for controlling the thickness of a rolling mill according to Item 1. A rolling mill for rolling the rolled material while controlling the plate thickness;
From the actual values of the entry side plate thickness and the exit side plate thickness of the rolling mill, the reduction rate, the entry side plate thickness deviation, and the exit side plate thickness deviation were obtained, and the reduction rate exceeded a predetermined value and “absolute value of the exit side plate thickness deviation> In the case of “the absolute value of the entry side plate thickness deviation”, the plate thickness control is stopped, and in the situation where the plate thickness control is stopped, “the absolute value of the exit side plate thickness deviation> the absolute value of the entry side plate thickness deviation”. If the relationship continues further, a controller that controls the outlet side plate thickness by reducing the rolling reduction,
A rolling apparatus comprising: The controller is
A sheet thickness control unit that controls the rolling mill so that the exit sheet thickness of the rolled material is a predetermined one;
A rolling reduction control unit for changing the rolling reduction of the rolling mill;
A switching determination unit that switches the control for the rolling mill to either one of a rolling reduction control unit and a sheet thickness control unit,
The switching determination unit obtains a rolling reduction rate, an inlet side plate thickness deviation, and an outgoing side plate thickness deviation from the actual values of the inlet side plate thickness and the outlet side plate thickness of the rolling mill, the rolling reduction exceeds a predetermined value, In the case of “absolute value of thickness deviation> absolute value of entry side plate thickness deviation”, the control for the rolling mill is switched from the plate thickness control unit to the rolling reduction control unit, and under the situation where the plate thickness control does not reach the rolling mill, When the relationship of “absolute value of outlet plate thickness deviation> absolute value of inlet plate thickness deviation” continues further, a command is issued to the rolling reduction control unit to reduce the rolling reduction. Item 4. The rolling apparatus according to Item 3. The entry side of the rolling mill is provided with an entry side plate thickness detector that measures the entry side plate thickness of the rolled material,
The exit side of the rolling mill is provided with an exit side thickness detector that measures the exit side thickness of the rolled material, and the measurement results of the entrance side thickness detector and the exit side thickness detector are input to the controller. The rolling apparatus according to claim 3 or 4, wherein the rolling apparatus is configured as described above.

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