JP3283431B2 - Head thickness control method for hot finishing tandem 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 head thickness control method for a hot finishing tandem rolling mill.

[0002]

2. Description of the Related Art In a hot-finishing tandem rolling mill, it is necessary to appropriately set the amount of reduction of each stand in advance in order to control the thickness of the head of a rolled material. In recent years, the reduction amount of each stand is set by a computer using theoretical formulas such as rolling load, deformation resistance of a rolled material, and temperature.

As described above, a method of setting the rolling reduction by using a theoretical calculation by a computer is disclosed in JP-A-3-15110.
No. 9 discloses a thickness gauge disposed between stands to detect the exit side thickness, rolling load and rolling position deviation of the preceding stand, and from these detected values, the correction amount of the gauge meter type and the rolling temperature of the succeeding stand. There has been proposed a method of obtaining a good plate thickness from the head of a rolled material by predicting a deviation and a thickness deviation on an entrance side, and correcting a rolling position of a succeeding stand from the predicted values.

However, in practice, it is difficult to measure and estimate the temperature of the material itself, and it is particularly difficult to predict the temperature of the inside of the material. Although it is possible to improve the thickness accuracy if the conditions are limited, it is not possible to accurately predict the plastic coefficient of the material required for correcting the rolling reduction of the subsequent stand, and there is also a slight variation in the mill rigidity due to operating conditions. There is a problem that the thickness deviation on the exit side of the final stand cannot be stably approached to zero because it is not taken in.

[0005]

SUMMARY OF THE INVENTION The present invention provides a hot finish capable of improving the accuracy of thickness control by minimizing a control error due to operating conditions and obtaining a good thickness from the head. An object of the present invention is to provide a head thickness control method in a tandem rolling mill.

[0006]

SUMMARY OF THE INVENTION According to the present invention, there is provided a head thickness control method for a hot finishing tandem rolling mill, wherein the leading end of a rolled material exits from one stand and moves to the next stand. Before biting into, the following process: detecting the outlet plate thickness of the one stand, and based on this detection value, adjusting the rolling reduction of the next stand so that the outlet plate thickness deviation of the next stand becomes zero. A process of temporarily calculating the first term,
The step of calculating the exit side sheet thickness deviation of the next stand from the actual exit side sheet thickness deviation of the rolling mill of the material just rolled and as a learning term, and the step of adding the first term and the learning term, This is achieved by a head thickness control method in a hot finishing tandem rolling mill, characterized in that the rolling material is rolled at the next stand using the value obtained by the addition as an actual draft correction amount.

In the present invention, not only the rolling correction of the succeeding stand is performed so as to minimize the deviation of the sheet thickness on the exit side of the succeeding stand on the basis of the sheet thickness on the exit side of the preceding stand as in the prior art, but also, Since the learning is performed by taking in the actual thickness deviation at the final stand exit side of the material, the control error due to the operating conditions can be minimized.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS As a typical embodiment of the present invention,
And the i-th F_iThickness deviation with stand gauge meter type
And the (i + 1) th F_{i + 1}Predict the thickness deviation of the stand
An example in which the measurement pressure is corrected will be described. First, the head of the rolled material
Is F_iWhen passing through the stand,
_iSampling the deviation from the outlet set plate thickness (constant)
You. Of course, if a thickness gauge is installed, use it
You may. The higher the sampling frequency, the higher the reliability
But the sampling time is too long
And the time for the reduction operation and the corrective action are shorter
It becomes. For example, F_i0.2 seconds passed from stand biting
Sample about three times later. When the threading speed is fast
Is F_i~ F _{i + 1}Rolled material transit time between stands
Since it is about 0.4 seconds, the sampling time is 0.2
The extent after a lapse of seconds is considered to be a practical limit. Sun pudding
Is performed three times with a cycle of 20 msec.
_{i + 1}0.4 seconds remaining time before biting into the stand
0.2 seconds−0.02 seconds × 3 = 0.14 seconds.
It is necessary to complete the calculation and the rolling reduction operation within the extra time.

[0009] In addition, not only from the plate thickness deviation detection value of F _i stand in F _{i + 1} stand of pressure correction, the subsequent i + j
It is also possible to perform the rolling-down correction of the (j ≧ 2) F _{i + j} stand. In any case, it suffices to secure a time for detecting, calculating, and actually completing the rolling reduction operation after the plate thickness detection enters a stable period. Then, F _i exit side thickness deviation which is the sampling average value from (detected value) Δh _i, F _{i + 1} delivery side thickness deviation (estimated value)
Δh _{i + 1} ′ is estimated by the following equation (1).

[0010] Δh_{i + 1}'= (Q_{i + 1}/ (M_{i + 1}+ Q_{i + 1})) × Δh_i+ C_{i + 1}... (1) where Δh_{i + 1}'= F_{i + 1}Stand exit side thickness deviation (estimated
Value) Q_{i + 1} = F_{i + 1}Plasticity coefficient of rolled material when passing through stand M_{i + 1} = F_{i + 1}Mill rigidity of stand Δh_i = F_iOuter side thickness deviation of stand (detected value) C_{i + 1} = Learning term Learning term C_{i + 1}Is a feature of the present invention.
Conventionally, using this learning term as in the method of Japanese Patent Publication No. 109
did not exist. That is, in the above equation (1), the first term (Q
_{i + 1}/ (M_{i + 1}+ Q_{i + 1})) × Δh_iIs F_iExit deviation detection
F based on bid price _{i + 1}Outgoing deviation estimate, up to this point
In the present invention, the learning term C
_{i + 1}Is added to the actual F_{i + 1}Outgoing deviation estimated value Δh
_{i + 1}' And later, equation (2)
As described above, the actual F_{i + 1}Output side deviation estimate
F used_{i + 1}Through the calculation of the stand reduction correction amount, the reduction
The learning term is taken into the correction amount.

This learning term is updated for each rolled material based on the actual deviation of the immediately preceding rolled material, as will be described later with respect to equation (3). Before updating, the learning term Ci _{+ 1} in the above equation (1) has the unupdated value used for the immediately preceding rolled material. Naturally, the learning value that has not been updated is performed up to the update based on the actual deviation of the immediately preceding rolled material. When the first rolling material is rolled, an appropriate initial value based on past rolling results is given to the learning term C _{i + 1} .

[0012] Equation (1) F _{i + 1} exit side deviation estimate Δh i _{+ 1} 'which is calculated by giving the value of the updated learning section C _{i + 1} in the substitutes on the rear left of the formula (2) Thus, the value of ΔS _{i + 1} is F
The actual amount of rolling reduction at the ( _{i + 1)} -th stand is obtained, thereby performing the rolling reduction operation of the (F _{+ 1} ) -th stand. The operations up to pressure corrective action from Delta] h _i detected as described above, completed before the rolling material bite after leaving the F _i stand F _{i + 1} stand.

The calculation of the rolling reduction amount and the updating of the learning term will be described in detail below. The rolling reduction amount is calculated from Δh _{i + 1} ′ obtained by equation (1) as the rolling correction amount ΔS _{i + 1} of the Fi _{+ 1} stand by the following equation (2). In equation (1), the learning term C
_{If i + 1} has an unupdated value, ΔS _{i + 1} calculated by the equation (2) naturally has a temporary value before update corresponding thereto.

ΔS _{i + 1} = −α _{i + 1} × ((M _{i + 1} + Q _{i + 1} ) / M _{i + 1} ) × Δh _{i + 1} '(2) where α _{i + 1} is The control gain for the _{Fi + 1} stand, and a minus (-) sign indicates that the rolling reduction is corrected in the direction of narrowing the roll gap (closing operation).
The speed of the _Fi stand is also corrected by an amount corresponding to the Fi _{+ 1} stand pressure reduction amount in order to correct the reduction of the Fi _{+ 1} stand and at the same time adjust the mass flow disturbance (adjust the loop). For example, when the pressure reduction of the F _{i + 1} stand is corrected in the closing operation direction (the direction for narrowing the roll gap), the F _i
Stands and earlier each stand slows, modifying the pressure of F _{i + 1} stand opposite to the opening operation direction (direction to expand the roll gap), F _i stand and earlier each stand causes accelerated.

The update of the learning term, which is an important feature of the present invention, is performed as follows. Assuming that the above rolling material is Nth,
For the (N-1) -th material rolled immediately before that, the thickness deviation of the head when the head passes the exit side of the rolling mill (final stand) has already been detected by a thickness gauge. This detection time varies depending on where the head is detected in the longitudinal direction of the material, but for example, about 1 to 2 seconds after the hunting of the thickness gauge ends the initial detection and enters the stable detection period. Is detected as an average value. As described above, when the sampling period is set to, for example, 20 msec, an average of one second is an average value of five sampling values.

The value obtained by converting the output thickness difference of the rolling mill detected as the average value of the output value of the output thickness gauge of the rolling mill to the output thickness deviation F _{i + 1} is ΔhX _{i + 1} (Equation (4)). . F _{i + 1} F i _{+ 1} to be improved by the reduction correction amount [Delta] S i _{+ 1} of the stand
From the predicted value of the exit side sheet thickness deviation and the actual F _{i + 1} exit side sheet thickness deviation ΔhX _{i + 1} (the above conversion value) for the immediately preceding rolled material,
The learning term is calculated by the following equation (3), and the learning value is updated for each rolling material.

C_{i + 1}[N] = C_{i + 1}[N-1] + β_{i + 1}× (ΔhX_{i + 1}− (Δh_{i + 1}'+ (M_{i + 1}/ (M _{i + 1} + Q_{i + 1})) × ΔS_{i + 1}) ... (3) where C_{i + 1}[N]: Learning value for Nth rolled material
(Learning value after update) C_{i + 1}[N-1]: Learning value for N-1 rolled material (updated)
Learning value before new) β_{i + 1} : Learning update gain ΔhX_{i + 1}: F for N-1 rolled material_{i + 1}S
Tand exit thickness deviation (from rolling mill exit thickness detection value
(Converted value) Δh_{i + 1}': F_{i + 1}Stand exit side sheet thickness deviation estimated value M_{i + 1} : F_{i + 1}Mill rigidity of stand Q_{i + 1} : F_{i + 1}Plasticity of rolled material when passing through stand
Number ΔS_{i + 1} : F_{i + 1}Provisional value of the amount of correction of the stand rolling reduction, and ΔhX_{i + 1}Is obtained by the following equation (4).

ΔhX _{i + 1} = m _{i + 1} (h _{GMi + 1} −h _{aimi + 1} )
_{+ N i + 1 (hX-} hX aim) h GMi + 1: F i + 1 exit side of the gauge meter thickness actual value _{h aimi + 1: F i +} 1 delivery side thickness target value hX: thickness gauge Actual hX _aim : target value of thickness gauge m _{i + 1} , ni _{+ 1} : gain Here, the thickness gauge of hX, hX _aim is installed on the exit side of the finish rolling process or between any rolling mills. Arbitrarily selected one of the obtained thickness gauges.

In this way, the value updated by the equation (3) based on the (N-1) th rolling result is used as the learning term C in the equation (1).
_{i + 1} , and the calculated F _{i + 1} exit-side sheet thickness deviation estimated value Δh
'the value of Delta] h i _{+ 1} of the formula (2)' _{i + 1} by applying the actual reduction correction amount of F _{i + 1} stands for the N-th rolling material is obtained as the value of [Delta] S i _{+ 1} . That is, the value of ΔS _{i + 1} tentatively calculated above is updated as an actual value by the learning.

As described above, in the present invention, the rolled material
Is [N] out stand F _i carrying out the reduction modifications when bite to the next stand F _{i + 1,} in addition to the correction term according to the delivery side deviation F _i stand as is done conventionally,
By taking in the learning term updated for each rolled material based on the actual results of the last stand deviation of the last rolled material [N-1] and correcting the rolling down of the next stand F _{i + 1} , subtle fluctuations in operating conditions can be reduced. Since this can be reflected in the control, the head thickness deviation can be suppressed to a minimum, and good thickness accuracy can be obtained from the head.

[0021]

1 shows an example of a conventional control flow without learning, and FIG. 2 shows an example of a control flow for performing learning according to the present invention. 3 shows an actual example of the F ₇ stand delivery side of the head plate thickness deviation when performing controlled respectively by a conventional method and the method of the present invention of FIG. 2 in FIG. 1. FIG. 2A is a chart for measuring the thickness deviation, and FIG. 2B is an enlarged view of the head (circle portion of (A)).

As shown in FIG. 3A, the sheet thickness deviation is the largest at the head of the rolled material in both the conventional method and the method of the present invention, but as shown in FIG. It can be seen that the thickness deviation is reduced by the learning effect of the present invention. In this example, it was estimated that the head thickness deviation was reduced by about 90 μm as an effect of learning.

[0023]

As described above, according to the present invention,
Provided is a head thickness control method for a hot finishing tandem rolling mill capable of improving the accuracy of thickness control by minimizing a control error due to operating conditions and obtaining a good thickness from the head. You.

[Brief description of the drawings]

FIG. 1 is a flowchart and an arrangement diagram showing an example of conventional control without learning.

FIG. 2 is a flowchart and an arrangement diagram illustrating an example of control for performing learning according to the present invention.

FIG. 3 (A) is a chart of actual measurement of thickness deviation, and FIG. 3 (B) is an enlarged view of a head (circle portion in FIG. 3 (A)).

──────────────────────────────────────────────────の Continued on the front page (72) Inventor Hiroyuki Tachibana 1 Kimitsu, Kimitsu City, Chiba Prefecture Nippon Steel Corporation Kimitsu Works (56) References JP-A-9-239422 (JP, A) JP JP-A-8-300027 (JP, A) JP-A-4-13411 (JP, A) JP-A-60-247408 (JP, A) JP-A 8-57508 (JP, A) JP-A 8-267111 (JP , A) (58) Field surveyed (Int. Cl. ⁷ , DB name) B21B 37/00-37/78

Claims (1)

(57) [Claims] 1. A method for controlling the thickness of a head in a hot finishing tandem rolling mill, comprising the following steps until the leading end of a rolled material comes out of one stand and bites into the next stand: Detecting the exit side sheet thickness, and temporarily calculating the rolling reduction amount of the next stand based on the detected value so that the exit side sheet thickness deviation of the next stand becomes zero; The step of calculating the exit side sheet thickness deviation of the next stand from the actual deviation of the exit side sheet thickness of the rolling mill to obtain a learning term, and the step of adding the first term and the learning term, and obtained by the addition. A head thickness control method for a hot finishing tandem rolling mill, wherein the rolling is performed at the next stand on the rolled material using the value as an actual rolling reduction amount.