JP3224052B2 - Thickness control method for continuous rolling 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 thickness of a continuous rolling mill, and more particularly to a method for controlling the thickness of a continuous rolling mill suitable for a continuous rolling mill including a hydraulic rolling stand.

[0002]

2. Description of the Related Art When a sheet (rolled material) is rolled by a hot continuous rolling mill, the leading end of the sheet is controlled to a target thickness by rolling the sheet before it is bitten by the continuous rolling mill. There is a method in which a roll gap and a roll speed in each stand constituting a continuous rolling mill are set so that a target plate thickness is obtained on the exit side of the final stand.

In this method, the temperature of the sheet material at the entrance of each stand is predicted based on the temperature of the sheet measured at the entrance of the continuous rolling mill, and the target sheet material enters at the entrance of each stand. On the premise, the initial setting of the roll gap (roll-down position) is determined so that the plate thickness on the exit side of each stand becomes the exit-side target plate thickness.

However, in the above method, if there is an error in the temperature measured on the entrance side of the rolling mill or an error exists in the predicted temperature of the sheet material on the entrance side of each stand, the thickness of the sheet on the exit side of each stand becomes the target. In some cases, this may be a deviation from the target value of the incoming side plate thickness of the next stand, and the difference from the target value of the outgoing side plate thickness of the stand may be further increased.

Techniques for avoiding such a phenomenon include:
For example, Japanese Patent Application Laid-Open No. 4-75709 discloses that when the leading end of the material to be rolled passes through the i-th stand, the exit side plate thickness, surface temperature, rolling position, and rolling load of the stand are detected. The gauge meter type offset amount at the stand is obtained, and the gauge meter type offset amount at the (i + 1) th stand is predicted from the offset amount.
At the same time that the rolling load at the + 1st stand is detected, the rolling position correction amount based on the i + 1st stand exit side plate thickness obtained by using the gauge meter equation corrected by this offset amount, and the exit side plate thickness of the ith stand and A plate thickness control method is disclosed in which the roll-down position correction amount of the (i + 1) -th stand is determined based on both the roll-down position correction amount by feedforward control of the (i + 1) -th stand obtained from the surface temperature.

Japanese Patent Application Laid-Open No. 3-151109 discloses a hot continuous rolling mill in which a thickness gauge is provided between stands, and detects when the leading end of a material to be rolled passes a stand on the upstream side of the thickness gauge. Rolling load deviation and rolling position deviation of the same stand,
From the thickness detected at the time when the tip passed through the thickness gauge, the correction amount of the gauge meter type, and the rolling temperature deviation and the entry side thickness deviation at the trailing stand where the tip is not yet caught. A sheet thickness control method for predicting and correcting the rolling position of the succeeding stand based on these predicted values is disclosed.

Each of the methods disclosed in the above publications has the advantage that the thickness can be controlled with high precision within the intended range.

[0008]

However, as a result of various studies by the present inventor, when the continuous rolling mill has a hydraulic rolling stand, the moment the leading end of the plate material is bitten by the stand. It becomes clear that the oil column in the cylinder sinks, which causes a change in the roll gap.For example, starting with the technology disclosed in the above publication, With the conventional method of controlling the plate thickness by correcting the rolling position of the stand, it is not possible to compensate for the variation in the plate thickness caused by the above-mentioned roll gap variation, and the target plate thickness is maintained until the oil column subsidence is restored. Was found to be a problem.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned conventional problems. In controlling the thickness of a continuous rolling mill having a hydraulic rolling stand, the height of the target material from the leading end of the material to be rolled is increased. An object of the present invention is to provide a method for controlling the thickness of a continuous rolling mill that can be controlled with high accuracy.

[0010]

SUMMARY OF THE INVENTION The present invention relates to a continuous rolling mill having a hydraulic rolling stand, using a sheet thickness deviation measured by a sheet thickness detector installed between stands, and downstream of the sheet thickness detector. In the sheet thickness control method of the continuous rolling mill for correcting the roll gap of the rolling stand on the side and controlling the sheet thickness, the roll gap correction amount ΔS _i set in the hydraulic rolling stand of the i-th stand at the time of threading is determined by the hydraulic pressure In consideration of the roll gap fluctuation caused by the sink of the oil column in the cylinder, which occurs when the leading end of the material to be rolled is caught in the rolling stand , the following equation ΔS _i = ΔS _i0 (t ) + ΔS _i1 (t ) ΔS _i1 (t ) = − A {1−exp (−t / T)} (where ΔS _i0 (t ): Considering the sinking of the oil column of the pressure reduction cylinder)
Rolling position correction amount ΔS _i1 (t ) when there is no correction : Corrects the sinking amount of the oil column of the rolling cylinder
The above-mentioned problem is solved by determining the amount of correction of the rolling position A: the amount of sinking of the oil column t: the time T: the time constant) .

[0011]

According to the present invention, the roll gap correction amount set in the hydraulic rolling stand at the time of threading is adjusted to the sinking of the oil column in the cylinder which occurs when the leading end of the material to be rolled is caught in the rolling stand. Since the rolled material is determined in consideration of the resulting roll gap fluctuation amount, the material to be rolled can be rolled from its tip with a target thickness.

[0012]

Embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 1 is an explanatory view showing a schematic configuration of a main part of a continuous hot rolling mill applied to an embodiment according to the present invention.

The continuous rolling mill has a plurality of hydraulic rolling stands (only i-1 and i-th two stands are shown in the figure).
Each stand includes a work roll 12 for rolling a material to be rolled (hot strip) 10, a backup roll 14 for reinforcing the work roll 12, and a roll for detecting a rolling load via the backup roll 14. A load detector 16, a hydraulic pressing device 18 for adjusting the pressing position of the work roll 12, a pressing position detector 20 for detecting the pressing position, and a driving device for driving the work roll 12. An electric motor 22, a speed detector 24 for detecting a roll speed, and a
A plate thickness detector 26 (also having a function of detecting a plate temperature) installed between the stands.

The continuous rolling mill is provided with a computer 28 for performing control according to the present invention. The computer 28 includes a load detection signal by the load detector 16 and a speed detection signal by the speed detector 24. Signal and the thickness detector 2
6, the respective detection signals of the plate thickness and the plate temperature are input, and from the computer 28, the pressing position correction signal calculated based on the input detection signal is output from the hydraulic pressing device 18. In addition, a speed correction signal is output to the drive motor 22.

The input / output of each signal in the computer 28 is shown only for the i-th stand, and is omitted for the (i-1) -th stand. Has become.

In this embodiment, the sheet thickness deviation and the sheet temperature are detected by the sheet thickness detector 26 installed between the (i-1) th to (i) th stands, and the sheet thickness on the exit side of the (i) th stand becomes a target value. In this way, the roll gap and the roll speed of the ith stand are corrected for each calculation cycle of the computer 28.

In the present embodiment, the roll gap correction amount ΔS _i for the hydraulic pressure reduction device 18 of the ith stand is set by the following equation (1).

ΔS _i = ΔS _i0 (t) + ΔS _i1 (t) (1)

Here, ΔS _i0 (t) is a rolling position correction amount (first correction amount) when the sinking of the oil column is not taken into account, Δ
S _i1 (t) is a roll-down position correction amount (second correction amount) for correcting the oil column sinking amount.

The first correction amount ΔS _i0 (t) in the above equation (1)
Can be set by the following equation (2), for example, according to the method disclosed in the above-mentioned Japanese Patent Laid-Open No. 4-75709.

ΔS _i0 (t) = α · ΔS ′ _i + β · ΔS ″ _i (2)

Here, α and β are coefficients (0 ≦ α, β ≦
1).

ΔS ′ _{i in} the above equation (2) is a rolling position correction amount by a gauge meter equation given by the following equation (3).

ΔS ′ _i = G ′ _i · (M + Q) / M · (h _i −h _0i ) (3)

Where G ′ _i is a constant, M is a Mill constant, Q
Is the plasticity coefficient, h is the exit thickness, and h ₀ is the target exit thickness.

Further, ΔS ″ _i in the above equation (2) is a rolling-down position correction amount by feedforward control of the i-th stand calculated using the following equation (4).

ΔS ″ _i = −G ″ _i · (1 / M _i ) · ｛(∂P / ∂H) _i × (h _i−1 −h _0i−1 ) + (∂P / ∂T) _i × ｛(∂T / ∂T ₀ ) _i · T _i −T _0i … (4)

Here, G ″ _i is a constant, (∂T / ∂H)
Is the coefficient of influence of the entry side plate thickness H (outside plate thickness h of the former stage stand) on the rolling load P, and (∂P / ∂T) is the coefficient of influence of the rolling temperature T of the material to be rolled on the rolling load P. , (∂T / ∂
T ₀ ) is the coefficient of influence of the surface temperature T ₀ of the material to be rolled on the entry side that affects the rolling temperature T.

On the other hand, the second correction amount ΔS in the equation (1)
_i1 (t) is set as follows.

The sinking of the oil column occurs in a pattern as shown in FIG. The sinking amount A shown in this figure changes depending on the load applied to the rolling roll.
Is the thickness deviation Δh detected between the i-th stand and the i-th stand.
_i-1 - predicts load when the leading end of the rolled material is caught from _{(= h i-1 h 0i} -1) and actual temperature, can be determined from the predicted load.

The recovery in the event of the occurrence of the sinking is substantially similar to the response of a temporary delay, and the time constant T is a value specific to the hydraulic pressure reduction control system and is a value known from measurements during operation or the like. Therefore, the amount of change in the roll gap due to the oil column sinking after biting can be obtained by the following equation (5).

A {1−exp (−t / T)} (5)

Therefore, the second correction amount is set by the following expression (6) in order to cancel the roll gap change amount of the above expression (5), and the roll gap is changed over time by the rolling-down device 18. I do.

ΔS _i1 (t) = − A ｛ 1−exp (−t / T)｝ (6)

Next, the correction amount ΔS _i of the roll gap is
The pressure reduction device 1 is set by the above-described equation (1) described in detail above.
FIG. 3 shows the result obtained when No. 8 was operated. For comparison, FIG. 4 shows the result when the second correction amount is not considered, that is, when the same control is performed only by the first correction amount ΔS _i0 (t) by the conventional method.

FIG. 4 shows a state in which the roll gap of the i-th stand is corrected according to the thickness deviation between the i-th stand and the (i-1) -th stand. It can be seen that the thickness of the exit side of the i-th stand is thicker than the target value until the sink of the oil column recovers due to the opening of the roll gap due to the sink of the oil column.

However, according to the present embodiment, as shown in FIG. 3, the roll gap fluctuation due to the sinking of the oil column is taken into consideration, so that it is possible to control with extremely high precision from the leading end of the material to be rolled. You can see that.

According to the present embodiment described in detail above, based on the thickness deviation measured by the thickness detector installed between the stands of the hot continuous rolling mill, the stand at the stand downstream of the thickness detector is used. When the roll gap is corrected, the roll gap (roll-down position) is corrected in consideration of the change in the roll gap when the rolled material is bitten. It becomes possible to roll with a thickness.

Although the present invention has been specifically described above, the present invention is not limited to the above-described embodiment, and can be variously modified without departing from the gist thereof.

For example, in the above-described embodiment, the case where the first correction amount of the expression (1) is set by the method disclosed in the above-mentioned Japanese Patent Application Laid-Open No. 4-75709 has been described, but the present invention is not limited to this.

[0042]

As described above, according to the present invention,
When controlling the sheet thickness with a continuous rolling mill having a hydraulic rolling stand, it is possible to control the target sheet thickness from the leading end of the material to be rolled with high accuracy.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram showing a main part configuration of a continuous rolling mill applied to one embodiment according to the present invention.

FIG. 2 is a diagram for explaining roll gap fluctuation caused by sinking of an oil column;

FIG. 3 is a diagram showing the effect of the present invention.

FIG. 4 is a diagram showing a result of thickness control by a conventional method.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 ... Rolled material 12 ... Work roll 14 ... Backup roll 16 ... Load detector 18 ... Hydraulic pressure reduction device 20 ... Reduction position detector 22 ... Driving motor 24 ... Speed detector 26 ... Thickness detector 28 ... Computer

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) B21B 37/00-37/78

Claims (1)

(57) [Claims] In a continuous rolling mill having a hydraulic rolling stand, a roll gap of a rolling stand downstream of the thickness detector is determined using a thickness deviation measured by a thickness detector installed between the stands. In the method for controlling the thickness of a continuous rolling mill for correcting and controlling the thickness, a roll gap correction amount ΔS _i to be set in a hydraulic rolling stand of an i-th stand at the time of passing a sheet is supplied to the hydraulic rolling stand by using In consideration of the roll gap fluctuation caused by the sink of the oil column in the cylinder, which occurs when the tip is bitten , the following equation is used: ΔS _i = ΔS _i0 (t ) + ΔS _i1 (t ) ΔS _i1 (t ) = − A {1-exp (-t / T)} (where, ΔS _i0 (t ): Considering the sinking of the oil column of the rolling cylinder
When there is no reduction position correction amount ΔS _i1 (t ): Corrects the sinking amount of the oil column of the reduction cylinder
The thickness control method of the continuous rolling mill is characterized by determining the amount of correction of the rolling position A: the amount of sinking of the oil column t: the time T: the time constant) .