JPH10128419A - Plate thickness control method in thick plate finishing mill and its device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To largely improve yield by regulating the roll gap of a finishing mill at the minimum plate thickness value compared with a central part plate thickness and an edge part plate thickness. SOLUTION: The crown quantity of a steel plate 4 is obtained with plate thickness gages 5, 6 in the downstream side of a thick plate finishing mill 1. The edge part plate thickness is presumed based on the outlet side crown quantity of the last time rolling pass and the central part plate thickness value of this time rolling pass until the steel plate reaches the edge part plate thickness gate 6. The minimum plate thickness value is selected to regulate the roll gap of the rolling mill 1 compared with the presumed edge part plate thickness and the central part plate thickness. Also, after the steel plate 4 reaches the edge part plate thickness gage 6, the minimum plate thickness value is selected compared with the central part plate thickness measured with the central part plate thickness gage 5 and both edge part plate thicknesses, and the roll gap of the finishing mill 1 is regulated using a computing element 7, a controller 8 and a roll reduction device 9 based on the minimum plate thickness value. By this way, the plate thickness is controlled with a high precision.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for controlling the thickness of a rolling mill in a thick rolling process.

[0002]

2. Description of the Related Art In recent years, monitor AGC control has been performed in a hot rolling mill in order to obtain a predetermined thickness. As the control of the monitor AGC, for example, Japanese Patent Laid-Open No. 4-591
There is a method as shown in No. 14. In this method, the thickness of the material to be rolled at the edge in the width direction and the center in the width direction are measured by two thickness gauges, and the actual measured value of both or a smaller one is a predetermined thickness (target thickness). The roll gap of the finishing mill is adjusted based on the thickness deviation between the actually measured value and the target thickness to control the thickness of the material to be rolled. As a result, it is possible to control the sheet thickness in consideration of the difference (sheet crown) between the sheet thickness at the center part and the edge part in the width direction measured.

[0003] In a continuous hot rolling process, etc., it is relatively easy to install a thickness gauge at a position close to a finishing mill, and the process is relatively long in elongation. Control is possible,
The monitor AGC control is generally used.

[0004] However, in the plate rolling process, the vicinity of the finishing mill is in a bad environment and the space is not sufficient due to vibrations caused by strong deske water injection performed during rolling and high load rolling. A thickness gauge that measures the thickness of the central portion or the edge portion in the width direction of the steel sheet is installed at a position where there is room for the environment and space relatively, that is, at a position far from the finishing mill, It is common practice to control the thickness using a thickness gauge. As in the continuous hot rolling process, two or more thickness gauges are installed near the rolling mill, and the width direction center and edge There is no plate rolling mill that implements the monitor AGC control that measures the sheet thickness.

[0005]

In the case of thick plate rolling in which the length of the steel plate is shorter than that of continuous hot rolling and the difference in the thickness (plate crown) between the central portion and the edge portion in the width direction is large, as described above. In the thickness control using only the thickness gauge at the central portion or the edge portion in the width direction of the steel sheet, the thickness must be excessively large in order to secure the thickness without the thickness gauge.

A thickness gauge for measuring the width direction edge requires a large space for moving the measurement position following the rolling width. However, a thickness gauge for measuring the width direction edge in an existing rolling mill is required. Securing a large space under a complicated facility environment such as a side guide and a desk hood near the finishing mill to install the gauge requires enormous remodeling costs, and the effect on investment efficiency becomes extremely small.

An object of the present invention is to enable the monitor AGC control from the point in time when the thick plate after the rolling mill reaches the vicinity of the rolling mill outlet side without requiring a large modification in the existing rolling mill. Is what you do.

[0008]

Means for Solving the Problems The present invention has been made to solve the above-mentioned problems, and the means 1 comprises a center plate thickness and an edge plate thickness of a steel plate on the exit side of a thick plate finishing mill. Control of the thickness of the exit side plate of the thick plate finishing mill to adjust the rolling mill roll gap so that the selected minimum thickness becomes the predetermined target thickness. In the method, a central thickness gauge for measuring the thickness of the central portion in the width direction near the downstream side of the finishing mill, and an edge for measuring the thickness of both edges in the width direction downstream of the central thickness gauge. Each part thickness gauge is provided, and the center part thickness gauge and the edge part thickness gauge are measured at the center part thickness gauge and the edge part thickness gauge for each rolling pass in the plate finishing mill, and From the measured plate thickness, the exit crown amount of the finish rolling mill for each rolling pass is determined. Until the steel sheet reaches the edge part thickness gauge, the edge portion is determined by the calculated outgoing crown amount in the previous rolling pass and the central part thickness value measured by the central part thickness gauge in the current rolling pass. The thickness of each part is estimated, and the estimated thickness of the edge portion is compared with the central thickness measured by the central thickness gauge to select the minimum thickness, and this minimum thickness is used. Adjusting the roll gap of the rolling mill, and (2) after the steel sheet discharged from the rolling mill reaches the edge part thickness gauge, the central part thickness measured by the central part thickness gauge and the edge part thickness. By selecting the minimum thickness value by comparing the thickness of both edge portions measured by the thickness gauge, in the thickness control method of the plate rolling mill to adjust the roll gap of the finishing mill at this minimum thickness value. is there.

Further, in the means (2) of the means (1), if the difference in thickness between the two edges measured by the edge thickness gauge exceeds an allowable value, it is determined that the measurement is abnormal. Instead of the edge part thickness measured by the thickness gauge, estimated by the center crown thickness measured by the center thickness gauge in the previous rolling pass and the outgoing crown amount in the previous rolling pass and the current rolling pass. This is a method for controlling the thickness of a plate rolling mill using the edge thickness.

The means 3 compares the central part thickness and the edge part thickness of the steel sheet on the exit side of the thick plate finishing mill to select a minimum thickness value, and the selected minimum thickness value is set in advance. In a thick plate finishing rolling mill exit side sheet thickness control device that adjusts the rolling mill roll gap so as to have a target plate thickness, a central plate that measures the thickness of a central portion in the width direction near the downstream side of the finishing mill. A thickness gauge, and an edge part thickness gauge for measuring the thickness of both edges in the width direction are provided on the downstream side of the central part thickness gauge, respectively, and the central part thickness value measured by the central part thickness gauge and the Outgoing crown prediction unit for predicting the outgoing crown amount of the finishing mill from the thickness values of both edges measured by the edge part thickness gauge,
Until the thick plate tip coming out of the thick plate finishing rolling mill reaches the installation position of the edge part thickness gauge, the delivery crown amount in the previous rolling pass predicted by the delivery crown prediction unit. The thickness of the edge portion of the current rolling pass is estimated from the center thickness value measured by the center thickness gauge in the current rolling pass, and the estimated thickness of the edge portion and the center in the current rolling pass are estimated. The minimum thickness is selected by comparing the center thickness measured by the thickness gauge, and after the thick plate tip reaches the installation position of the edge thickness gauge, the middle thickness is measured. The minimum thickness calculation unit that selects the minimum thickness by comparing the thickness of both edges measured by the edge thickness gauge with the center thickness measured by the gauge, and the target thickness of rolling. The target thickness setting section to be set, and the minimum thickness value from the minimum thickness calculating section is the target thickness setting section. A plate thickness control device for thick plate rolling mill constituting a roll gap setting unit for setting the roll gap so as to aim the thickness of the extending.

The present inventors have conducted various studies in order to carry out a good monitor AGC even in a plate rolling mill under the above-mentioned bad environment. As a result, a thickness gauge having good thickness measurement accuracy has emerged in recent years even in a bad environment such as vibration. In order to install a thickness gauge that measures the width direction edge, a large space for moving the measurement position following the rolled steel sheet width is required, but measure the width direction edge with the existing plate rolling mill. Securing a large space under a complicated facility environment such as a side guide and a desk hood near the finishing mill in order to install a thickness gauge to be performed requires enormous remodeling costs. On the other hand, a thickness gauge that measures the center in the width direction can be relatively easily installed even in a complicated place near the finishing mill if there is a small space in the center in the width direction without a moving device, We found that it was cheaper than installing a thickness gauge to measure the width direction edge.

Therefore, the present inventors provided a thickness gauge having good thickness measurement accuracy in the vicinity of the downstream side of the finishing rolling mill even in a bad environment having the vibration and the like, and the thickness gauge was used in the width direction of the steel sheet. An edge plate for measuring the thickness of the central portion, and further measuring the thickness of both edges in the width direction on the downstream side of the central thickness gauge, where vibration and the like are small and there is room in space. We found that installing a thickness gauge was the cheapest in terms of equipment costs.

However, the monitor AGC which is conventionally performed in the continuous hot-rolling process cannot be performed until the steel plate tip coming out of the rolling mill reaches the edge thickness gauge. For this reason, in plate rolling, in general, utilizing the fact that the entrance crown amount and the exit crown amount of the rolling mill have a constant crown ratio on average, first, the center plate in the previous rolling pass is used. The outgoing crown amount, that is, the incoming crown amount in the current rolling pass, is obtained from the central plate thickness value and both edge portion thickness values measured by the thickness gauge and the edge portion thickness gauge. Estimate the edge thickness in the current rolling pass from the central thickness measured by the central thickness gauge in the current rolling pass, and estimate the estimated edge thickness and the measured central thickness in the above-mentioned rolling pass. By performing the above-mentioned monitor AGC, the target plate thickness could be obtained with an accuracy having no problem in actual operation.

Further, when the thickness is measured with the center thickness gauge and the edge thickness gauge, and an abnormality occurs in the edge thickness gauge while performing the monitor AGC based on the measured values, it is determined. Instead of the edge part thickness measured by the edge part thickness gauge, both edge parts estimated by the exit crown amount in the previous rolling pass and the central part thickness measured by the central part thickness gauge. The monitor AGC could be continued using the thickness value.

[0015]

FIG. 1 shows a system configuration diagram of an example of the present invention. This is an example in which the present invention is applied to a thick plate reverse type hot finishing mill. 1 is a thick plate finishing and rolling mill composed of a backup roll 2 and a work roll 3, 4 is a material to be rolled (steel plate),
5 is provided in the vicinity of the downstream side of the finishing mill 1 to measure the thickness of the central portion in the width direction, and 6 is provided on the downstream side of the central thickness gauge 5. An edge portion thickness gauge for moving and measuring the thickness of each edge portion in the width direction, 7 is a calculator, and 8 is a control device for controlling the roll pressing device 9.

FIG. 2 is a block diagram showing a control method until the tip of the steel plate 4 exiting the finishing mill 1 reaches the edge thickness gauge 6 from the installation position of the central thickness gauge 5.

The outgoing crown predicting section 22 shown in FIG. 1 includes a central section thickness value measured by the central section thickness gauge 5 and both edges measured by the edge section thickness gauge 6 for each rolling pass in the finishing mill 1. The part thickness value is input, and the outgoing crown amount Cp of the finishing mill 1 is obtained by the following equation (1) and stored.

Cp = C · Heb / H Equation (1) where C = Hcb−Heb Heb: average thickness of both edges measured by the edge thickness gauge 6 in the previous rolling pass Hcb: previous thickness The central part thickness value H measured by the central part thickness gauge 5 in the rolling pass H: the target plate thickness value of the steel sheet edge on the exit side of the rolling mill in the current rolling pass The minimum thickness calculating section 24 is the exit side crown predicting section. 22 and the center part thickness value Hγc measured by the central part thickness gauge 5 in the current rolling pass and the edge part thickness value Cp + in the current rolling pass.
Hγc is estimated, the estimated edge plate thickness is compared with the central plate thickness measured by the central plate thickness meter 5, and the smaller plate thickness Min (Hγc, Cp + Hγc) is selected and stored. I do.

The roll gap setting unit 25 calculates a thickness deviation ΔH from the target thickness Ha set by the target thickness setting unit 23 and the minimum thickness value stored in the minimum thickness calculation unit 24 as shown in the following equation (2). Then, the sheet thickness deviation ΔH is added to the current roll gap amount of the finishing mill 1 to determine the roll gap amount.

ΔH = G1 · (Min (Hγc, Cp + Hγc) −Ha) Equation (2) where G1: gain and the control device 8 controls the roll pressing device 9 based on the obtained roll gap amount. I do.

By the thickness control 5 based on the thickness gauge 5 and the crown amount prediction at the center in the width direction in the vicinity of the finishing mill 1 as described above, the thickness control in consideration of the difference between the thickness at the center and the edge at the width direction. I do.

Thus, when the computing unit 7 recognizes that the edge thickness gauge 6 has started the thickness measurement, it shifts to the control state of FIG.

In FIG. 3, the normality checking unit 31 determines that the wedge amount is normal if the thickness values of both edges measured by the edge thickness gauge 5 are equal to or less than the wedge amount allowable value W as shown in the following equation (3). If it exceeds the wedge amount allowable value W, it is determined to be abnormal. And
When it is determined to be normal, the measured plate thickness value is output, and when it is determined to be abnormal, an abnormal signal is output.

| Hγed−Hγew | ≦ W (3) where Hγed: the thickness of one edge measured by the edge thickness gauge 5 Hγew: the other thickness measured by the edge thickness gauge 5 The thickness value W of the side edge portion W: the allowable value of the wedge amount The minimum thickness calculating portion 24 confirms the “normal” by the normality checking portion 31 and the central portion thickness value which is the actually measured value of the steel plate input and both edges By comparing the thickness values, the minimum thickness value Min (H
γc, Hγed, Hγew) are selected. When the abnormality is confirmed by the normality confirmation unit 31 and an abnormal signal is input, the exit crown amount Cp in the previous rolling pass stored in the exit crown prediction unit 22 is read, and the exit crown amount Cp is read. The edge thickness Cp + Hγc in the current rolling pass is estimated from the amount Cp and the central thickness Hγc measured by the central thickness gauge 5, and the estimated edge thickness and the central thickness gauge are estimated. 5. Compare the central plate thickness values measured in Step 5 with the smaller plate thickness value Min (Hγc, Cp + Hγc).
Is selected and stored.

The roll gap setting unit 25 calculates the thickness deviation ΔH from the target thickness Ha set by the target thickness setting unit 23 and the minimum thickness value stored in the minimum thickness calculation unit 24 according to the following equation (4).
<When the normality is confirmed by the normality confirming unit 31> or by the following formula (5) <when the normality is confirmed by the normality confirming unit 31>, the current roll gap amount of the finishing mill 1 The roll gap amount is obtained by adding the thickness deviation ΔH.

ΔH = G2 · (Min (Hγc, Hγed, Hγnew) −Ha) Equation (4) ΔH = G2 · (Min (Hγc, Hγc + Cp) -Ha) Equation (5) where G2: gain The control device 8 controls the roll pressing device 9 based on the obtained roll gap amount.

By the thickness gauge 5 at the center in the width direction near the finishing mill 1 and the thickness control based on the crown amount prediction as described above, the thickness control taking into account the difference in thickness between the center at the width direction and the edge portion. I do.

[0028]

According to the present invention, in the plate rolling process,
The difference in thickness between the center part and the edge part in the width direction is measured by an edge part thickness gauge that measures both edges in the width direction at the end of the finishing mill and a central part thickness gauge that measures the center part in the width direction near the finishing mill It is possible to control the thickness with high accuracy while taking into account the above, and it is possible to achieve a great effect such as a great improvement in yield and a reduction in facility remodeling costs.

[Brief description of the drawings]

FIG. 1 is a control block diagram of the present invention.

FIG. 2 is a functional block diagram of a calculator 7;

FIG. 3 is a functional block diagram of a calculator 7;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Thick plate finishing rolling mill 2 Backup roll 3 Work roll 4 Rolled material (steel plate) 5 Central thickness gauge 6 Edge thickness gauge 7 Calculator 8 Control device 9 Roll reduction device

Claims (3)

[Claims] 1. A minimum thickness value is selected by comparing a central thickness and an edge thickness of a steel sheet on the exit side of a thick plate finishing mill, and the selected minimum thickness value is set to a preset target value. A method for controlling the thickness of the exit side of a thick plate finishing mill in which the roll gap is adjusted so as to obtain a sheet thickness, wherein a central part thickness gauge for measuring a thickness of a central part in a width direction near the downstream side of the finishing mill. An edge part thickness gauge for measuring the thickness of both edges in the width direction is provided on the downstream side of the central part thickness gauge, and the central part thickness is provided for each rolling pass in the thick plate finishing mill. The thickness of the central portion and the thickness of both edges are measured with a thickness gauge, and the crown of the finishing mill at each rolling pass is determined from the measured thicknesses. Until the obtained steel sheet reaches the edge part thickness gauge, The thickness of the edge portion is estimated from the amount of crown on the delivery side and the thickness of the central portion measured by the central thickness gauge in the current rolling pass, and the estimated thickness of the edge portion and the thickness of the central portion are estimated. The minimum plate thickness value is selected by comparing the central plate thickness measured by the gauge, and the roll gap of the rolling mill is adjusted with the minimum plate thickness value. After reaching the thickness gauge, select the minimum thickness value by comparing the center thickness measured with the central thickness gauge and both edge thickness measured with the edge thickness gauge, A method for controlling the thickness of a thick rolling mill, comprising adjusting a roll gap of the finishing mill with the minimum thickness. 2. The apparatus according to claim 1, wherein when the difference in thickness between the two edges measured by the edge thickness gauge exceeds an allowable value, it is determined that the measurement is abnormal. The thickness of the edge part estimated by the central crown thickness value measured by the central part thickness gauge in the current rolling pass and the outgoing crown amount in the previous rolling pass instead of the edge part thickness value measured by the A method for controlling the thickness of a plate rolling mill, comprising using the thickness. 3. A minimum plate thickness value is selected by comparing the central plate thickness and the edge plate thickness of the steel plate on the exit side of the thick plate finishing mill, and the selected minimum plate thickness is set to a preset target plate. In the control device of the plate thickness on the exit side of the thick plate finishing rolling mill to adjust the roll gap of the rolling mill so that the thickness becomes thick, a central part thickness gauge for measuring the thickness of the central part in the width direction near the downstream side of the finishing rolling machine An edge thickness gauge for measuring the thickness of both edges in the width direction is provided on the downstream side of the central thickness gauge, respectively, and a central thickness value measured by the central thickness gauge and the edge thickness. An exit crown predicting unit for estimating the exit crown amount of the finishing mill from the thickness values of both edges measured by a thickness gauge, and a thick plate tip coming from the thick finishing mill is the edge portion plate. Until it reaches the installation position of the thickness gauge, the previous crown predicted by the outlet crown prediction unit Estimate the thickness of the edge portion of the current rolling pass from the exit crown amount in the rolling pass and the center thickness value measured by the center thickness gauge in the current rolling pass, and estimate the thickness of the edge portion. And the central plate thickness value measured by the central plate thickness gauge in this rolling pass, and the minimum plate thickness value is selected, and the thick plate tip reaches the installation position of the edge plate thickness gauge. After that, the center thickness measured by the center thickness gauge is compared with the thickness of both edges measured by the edge thickness gauge to select the minimum thickness. Section, a target thickness setting section for setting a target thickness of rolling, and the roll gap is set such that a minimum thickness value from the minimum thickness calculating section becomes a target thickness for rolling from the target thickness setting section. A plate thickness control device for a plate rolling mill, comprising a roll gap setting unit.