JPH04143011A - Method for controlling sheet thickness on hot finish rolling mill - Google Patents

Abstract

PURPOSE:To keep the balance of rolling driving power between stands by actually measuring the rolling sheet pressure between stands, and controlling the thickness of sheet with feed forward control in consideration of the balance of roll reduction of all stands for the purpose of obtaining the target sheet thickness in the final stand. CONSTITUTION:When the top part of the steel sheet 1 is rolled out from the final stand F7, the rear stand rolling reduction correcting amount calculator 26 obtains the deviation h7 between the output of the outlet side thickness meter 12 and the target sheet thickness of the rolling schedule. By calculating S5- S7 from the deviation h7, each rolling reduction is adjusted through each adjusting mechanism for each stand F5-F7. The preceding stand rolling reduction correcting amount calculator 23 calculates the rolling reduction based on the deviation h4 from the sheet thickness deviation calculator 22, and adjusts the amount of rolling reduction through the adjusting mechanism F1-F4. By this adjusting, the drawing down load is distributed following approximately to the target balance of rolling reduction of the rolling schedule, and the sheet thickness is also approximated to the target value.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a method for controlling plate thickness in a hot finishing rolling mill, particularly to control of rolling balance.

[Prior Art and Problems to be Solved by the Invention] Many control methods have been proposed in the past for controlling the thickness of a hot rolled steel plate to a target thickness over its entire length. Among these methods, there is monitor AGC as a method of controlling based on actual thickness information, which is disclosed in, for example, Japanese Patent Laid-Open No. 123512/1983.

However, in this control method, all the stands are controlled based on the board thickness information after the last stand, which has the problem of generating wasted time.

Therefore, a feedforward control method in which the actual thickness between the stands is measured and the subsequent stands are controlled based on the measured thickness is also proposed, for example, in Japanese Patent Application Laid-open No. 80-24032.
This method has been proposed in Publication No. 8, Japanese Unexamined Patent Application Publication No. 62-72419, and the like. However, the balance of rolling of all the stands was not taken into account, which caused an imbalance in load and rolling power between the stands.

This invention was made to solve these problems, and is a hot finishing method that controls the thickness of the final stand to the target thickness and maintains a good rolling balance of all stands. The purpose of this invention is to provide a method for controlling plate thickness in a rolling mill.

[Means and effects for solving the problem] The method for controlling plate thickness of a hot finishing mill according to the present invention includes the following steps.

(a) A step in which the thickness of the tip of the steel plate is detected at the middle part of the rolling stand, and the deviation between the thickness and the target thickness at the measurement point is determined.

(b) A step of correcting the reduction amount of the subsequent stand based on the deviation so that the plate thickness on the exit side of the final stand matches its target value.

(C) When the tip of the steel plate passes through the final stand, the thickness of the steel plate is measured at the exit side of the final stand, the deviation between the thickness and the target value is determined, and the subsequent step is determined based on the deviation. In addition to correcting the amount of reduction of the stand, find the deviation between the plate thickness at the intermediate portion and the target thickness at the measurement location, and correct the reduction of the stand upstream from the intermediate portion based on the deviation. The process of doing.

[Embodiment] FIG. 1 is a block diagram showing the configuration of a control device and related equipment for implementing a control method according to an embodiment of the present invention. In the figure, (1) is a steel plate, and (10) is a hot finishing rolling stand consisting of rolling stands F1 to F7. (11) is the inter-stand thickness gauge attached to the exit side of intermediate stand F4, and (12) is the exit side stand F4.
This is an exit side thickness gauge attached to the exit side of 7.

(21) is a rolling schedule setting storage device, which stores thicknesses h1 to h7 of the rolling schedule of each stand. (22) is a plate thickness deviation calculator, which calculates the thickness H4 according to the rolling schedule of stand F4 from the rolling schedule setting storage device (21) and the inter-stand thickness gauge (11).
) is calculated and outputs the deviation Δh4 from the thickness H4 calculated in step a]. (23) is a front-stage rolling reduction correction amount calculator, which manually calculates the rolling schedule thickness hl-H7 and deviation Δh4 of each stand from the rolling schedule setting storage device (21) to reduce the rolling of the front-stage stands F1 to F4. Correction amount ΔS1~Δ
S4 is determined and output, and the previous stage stands F1 to F
The amount of reduction is corrected via the adjustment mechanism (not shown) at No. 4. (24) is a roll-down correction amount storage device, which stores the roll-down correction amounts ΔS1 to ΔS4 from the previous stage roll-down correction amount calculator (23). (25) is a tracking device which tracks the position of the steel plate (1) and outputs these data by sequentially inputting and sending out the reduction correction amounts ΔS1 to ΔS4.

(26) is a rear-stage reduction correction amount calculator, which receives the thicknesses h1 to h7 of the rolling schedule of each stand from the rolling schedule setting storage device (21), the deviation Δh1, and the reduction correction amount ΔS1 to ΔS1 from the tracking device (25). Input ΔS4 to adjust the reduction amount ΔS5 for the subsequent stands F5 to F7.
ΔS7 is determined, and the reduction amount is corrected via the adjustment mechanism (not shown) of the stands F5 to F7 in the subsequent stage.

Next, the operation will be explained. Each of the stands F1 to F7 is set to a rolling reduction amount based on the thickness h1 to h7 of the rolling schedule stored in the rolling schedule setting storage device (21). In such a state, the steel plate (1)
When the tip is rolled in stands F1 to F3 and further rolled in stand F4 and appears on the exit side, the inter-stand thickness gauge (11) measures the thickness H4 of the tip and calculates the plate thickness deviation. output to the device (22). Plate thickness deviation calculator (2
2) determines the deviation Δh4 between the thickness H4 in the rolling schedule and the actual thickness H4 at the tip thereof.

The rear rolling reduction correction amount calculator (26) calculates the rolling reduction correction amounts ΔS5 to ΔS7 for each of the subsequent stands F5 to F7 as follows (1) based on the deviation Δh4 and the thicknesses h1 to h7 of the rolling schedule.
It is calculated as follows using the formula.

The following equation is an equation showing what happens to the exit side thickness by the amount of change Δh when there is an entry side change ΔH and a reduction amount change ΔS in stand i, using the rolling influence coefficient method. Note that in the following equation, the partial differential coefficient (6P/ah) 1, etc. is obtained by model calculation or estimation from an actual machine.

i Nisland No.

M: Mill rigidity S: Reduction amount (ΔS: Reduction change amount) P: Rolling load H: Stand entrance thickness (ΔH: Inlet side change amount: Stand exit side thickness (Δh: Inlet side change amount ) First, Δh4−Δ
Based on H5, Δh5 (=ΔH6), Δhe (−ΔH
7), Δh7 (-Δt2) is predictively calculated. That is, in equation (1), ΔH→Δh can be calculated as ΔS−0. This is sequentially repeated for each stand i.

b) Δh5 to Δh7 determined in a) above. ΔH5～ΔH
7, for each stand i, ΔSt is calculated by equation (1).
(i-5 to 7) are calculated. That is, the predicted plate thickness is obtained by adding the predicted plate thickness deviation to the initial setting plate thickness.

Initial setting plate thickness h4 h5 h6 h7 Predicted plate thickness deviation Δh4 Δh5 Δh6 Δh7 Predicted plate thickness
h4-, h5- h6- h7 (However, Δh4
(Actually measured value) Then, in the end, Δh7 → 0, calculate ΔS7 as ΔH → Δh6, Δh → Δh7 in equation (1), and change the reduction amount of stand F7 for this 687 minutes. good. However, if Δh7 is large, ΔS7 will become excessive, causing a lack of setting time and extreme imbalance with other stands. Therefore, Δh5.
Δh6 is also kept small. That is, ΔS5 to ΔS7 are obtained by simultaneously using equation (1) as follows: Δh5→Δh5 Δh6→Δh6 Δh7→0.

The rear reduction correction amount calculator (26) calculates ΔS as described above.
5 to ΔS7, each stand F5 is calculated based on it.
- The respective reduction amounts are adjusted via adjustment mechanisms (not shown) at F7.

FIG. 2 is a characteristic diagram showing the rolling load of each stand.

The target rolling balance of the rolling schedule will be different from the rolling balance when the rolling amount of the subsequent stand is corrected.

FIG. 3 is a characteristic diagram showing the thickness of the outlet side of each stand. As mentioned above, when the rolling reduction amount of the subsequent stand is corrected, the rolling balance will be different from the target rolling balance, but the plate thickness at the exit side of the final stand will be approximately the same as the target plate thickness in the rolling schedule. It becomes a match.

When the tip of the steel plate (1) passes through the final stand F7, the rear reduction correction amount calculator (2B)
2) Deviation Δ between the output and the target plate thickness of the rolling schedule
Find h7, and further calculate ΔS5 to ΔS based on the deviation Δh7.
7 using the following formula, and based on that, each stand F5
- The respective reduction amounts are adjusted via adjustment mechanisms (not shown) at F7.

Mi+Qj I Qi ; ΔS calculated by equation (2) when the plasticity coefficient Δh of the material (steel plate) occurs is the reduction correction amount. This is generally an X-ray monitor AGC
This is a method called. The distribution to each stand is ΔSi
is multiplied by a gain, and this gain is set higher for later stages.

The front stage reduction correction amount calculator (23) is a plate pressure deviation calculator (22).
) based on the deviation Δh4 from
The respective rolling reduction amounts are adjusted through adjustment mechanisms (not shown) at No. 4.

As shown in Figures 2 and 3, after the steel plate (1) exits the final stand F7, the load is adjusted to achieve the target reduction balance of the rolling schedule by modifying the reduction amounts of the preceding and subsequent stands as described above. As a result, the plate thickness also has a distribution that approximates the target plate thickness of the rolling schedule, and the output of the outlet thickness gauge (12) matches the target value.

[Effects of the Invention] As described above, according to the present invention, the reduction amount of the subsequent stand is corrected based on the deviation between the thickness of the steel plate when the tip end passes the middle part and the thickness of the steel plate at that point. When the tip of the steel plate passes through the final stand, the reduction amount of the subsequent stand is corrected based on the deviation between the plate thickness at the exit side of the final stand and the target value, and the plate thickness at the intermediate part and its Since the amount of reduction of the stand located upstream of the intermediate portion is corrected based on the deviation from the target plate thickness at the measurement location, the reduction balance regularly approximates the rolling schedule.

[Brief explanation of the drawing]

Fig. 1 is a block diagram of a control device and related equipment for implementing a control method according to an embodiment of the present invention, Fig. 2 is a characteristic diagram showing the load of each stand, and Fig. 3 is a thickness of the outlet side of each stand. FIG.

Claims (1)

[Claims] The thickness of the tip of the steel plate is detected at the middle part of the rolling stand,
a step of determining the deviation between the plate thickness and the target plate thickness at the measurement point; and a step of determining a stand downstream from the measurement point so that the plate thickness at the exit side of the final stand matches the target value based on the deviation. (hereinafter referred to as the second stage stand), and when the tip of the steel plate passes through the final stand, the thickness of the steel plate is measured on the exit side of the final stand, and the thickness is compared with the target value. The deviation is determined, and the reduction amount of the subsequent stand is corrected based on the deviation, and the deviation between the plate thickness at the intermediate portion and the target plate thickness at the measurement location is determined, and the reduction amount is corrected based on the deviation. 1. A method for controlling plate thickness in a hot finishing rolling mill, comprising the step of correcting the rolling reduction amount of a stand located upstream from an intermediate portion.