JPS6199505A - Optimum sheet-thickness setting method - Google Patents

Abstract

PURPOSE:To restrain an excessive sheet thickness, to improve a yield of product and to eliminate a sheet-thickness change in a longitudinal direction, by using the correcting quantity of sheet crown, obtained by adding a rolling order, a sheet width, a sheet thickness and a deformation resistance to a correcting factor of sheet crown, to set an aimed thickness at every rolling stock. CONSTITUTION:Meters 52 of sheet thickness and temperature are provided to the outlet side of a roughing mill 20, and their outputs are inputted to a controlling computer 50. A sheet-thickness meter 56 is also provided to the outlet side of a finishing mill 30, and its output is also fetched by the computer 50. The computer 50 computes an optimum finished sheet-thickness (aimed thickness) based on these detected values and a separately inputted information such as a kind of steel, a rolling order, a sheet width and a deformation resistance, and performs a finishing mill setting computation by using the aimed thickness, to perform the setting of each stand through a finishing mill setting device 54.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to an optimum plate thickness setting method for optimizing the outlet side plate thickness setting value to improve yield.

[Conventional technology]

For products made of rolled materials such as steel strips, the thickness at a position slightly inward from the side edge of the material is adopted, and products whose thickness falls within the tolerance are considered to be within the standard (calculated weight sales standard). On the other hand, automatic plate thickness control (AGC) is generally adopted in steel strip rolling, and in AC and C, the thickness of the central part is the thickness of the steel strip (this method is also used in secondary processing such as pressing). )
, and since the rope belt has a crown, for products to which the above standards are adopted, the thickness at a position a minute distance inward from the material side edge should be within the standard (this thickness is referred to as Hl). ), and the thickness Hl is the maximum value Cm of the crown (
This is determined in advance according to the deformation resistance (hardness) of the strip, width, crown variation process capacity, etc.) to 6), H++Cm is set as the target thickness of AGC, and rolling is performed using this value. There is. Figure 2 is a diagram explaining the procedure for determining the target thickness.The crown correction amount is added to the lower limit of the tolerance, and then an appropriate value such as the amount of acid loss in pickling or the amount of reduction in skin pass is added to determine the target thickness. Set it to an appropriate value that is thinner than the upper limit. In the conventional method, the crown correction amount is the maximum value of the expected crown of the rolled material during the rolling schedule.

However, the plate crown changes depending on various factors such as roll grinding conditions, roll wear, roll expansion, rolling load, roll bender force, etc. Therefore, if the actual crown is C, the above method rolls the plate thicker by Cm - C. There is.

The amount of steel material obtained by multiplying this thickness Cm-C by the plate width and plate length (more precisely, since Cm-C is different in each part, it is an integral) is not subject to sales, so Cm-C is the product yield. It is desirable that it be as small as possible.

As mentioned above, there are various factors that determine the plate crown, but in general, it can be said to be the roll profile in a broad sense, and each can be said to be a static or dynamic determining factor of the roll profile. The determining factor of the roll profile or plate crown is the rolling position (the order in which the steel strip is rolled in the rolling schedule).
can be mentioned. To explain this with reference to FIG. 1, (al indicates the roll profile after rolling a large number of steel strips of the same width.

The part of the work roll 10 that contacts the steel strip is worn and a recess 12 is formed.
The corner 14 of the recess rests on the edge of the steel strip, which is a particularly deep depression as the temperature decreases and the edge increases in hardness. If a steel strip wider than the width of the recess 12 is rolled with a roll having such a profile, the edge of the steel strip will naturally be thin and the middle part thick, and the boundary between these edges and the middle part will be There will be a difference in level. Therefore, the conventional rolling schedule is such that a wide width is rolled at first, and then the width is gradually shifted to a narrow width, as shown in FIG. 1(d). However, if the rolling order is determined in this way, there will be various problems in actual operation, and if possible, it is desirable that the strip width be wide or narrow (schedule-free) as shown in FIG. 1 (C1).

When the work roll is shifted left and right in the range of ±α to change the contact position of the steel strip, the roll profile becomes as shown in Fig. In this case, it is possible to reverse the width of the sheet W to W+2α (rolling a wider sheet later).

However, it is inevitable that the crown will become larger, 11!1
1. Perform a work roll shift and change the width of the rolled steel plate to the first
When the width is changed from wide to narrow as shown in Figure 1 (C1), the crown of the narrow material does not change significantly as shown in Figure 1 (21), but the crown of the wide material changes to 51 gm as the rolling order becomes later.
, 84 μm, 108 μm, ...
It's getting bigger.

[Problem that the invention seeks to solve]

If some of the crowns are large in this way, the largest of these crowns must of course be adopted as the Cm, resulting in a decrease in yield.

To deal with this problem, we measure the crown multiple times at the tip of the material, treat the average value CR as the crown of the material, and send the CR to the target plate thickness calculator to calculate the appropriate target thickness. There is a method in which AGC is performed based on the result (Japanese Patent Laid-Open No. 58-187210). However, in this method, the target plate/thickness is an inappropriate value until the appropriate thickness is calculated, and therefore, during this period, A decrease in yield is unavoidable, and if the target plate thickness is changed to an appropriate value, the plate thickness will change by the difference between the initial plate thickness and the appropriate thickness.

The present invention aims to improve these points and provide an optimum plate thickness setting method that can improve the yield as much as possible and prevent the plate thickness from changing midway.

Means for Solving Problem c] The present invention performs work roll shift and automatic plate thickness control, and the target thickness of the plate thickness control is determined by adding a plate crown correction amount to the lower limit of tolerance of product plate thickness. In the optimum plate thickness setting method for equipment, the determining factors for the plate crown correction amount are:
The rolling order and F of the material to be rolled in the rolling schedule
The method is characterized in that the target thickness is determined for each material to be rolled by adding j, @, plate thickness, and deformation resistance, and using the plate crown correction amount obtained in this way.

As shown in Figure 1 (bl), the roll profile of a rolling mill that performs work roll shifting is such that the concave portion 12 is gentle, the width can be reversed, and schedule freedom can be achieved. It changes depending on the thickness and deformation resistance of the material.The plate crown is determined by the roll profile, specifically the roll grinding curve, subsequent roll wear, roll thermal expansion, rolling load, roll bending force, etc. Input the width of the target plate material and the rolling order within the relevant pass schedule into a needle counter,
It is possible to estimate the plate crown C of the plate after rolling. For example, the following model is used to estimate the plateau.

Basic equation % formula %] Equation (2) is called the uniform load plate crown, and the pressure m
It consists of a load p, a roll pending force F, and a roll profile term.

→2 ・・・・・・(5) CRO=-2(1+α)CR Here, b: middle plate, 11: roll body length.

12: Moment arm length.

E: Young's modulus, G: rigidity modulus.

ct: inter-roll gap correction coefficient.

CR two-roll profile (thermal crown 10 roll wear + initial curve) Equation (1) means that the uniform load plate crown determined by Equation (2) is printed on the plate at a certain rate, and furthermore, the front side of the front stand exit crown is printed on the plate. It is said to be inherited and affect the outcome from the next stand onward.

Also, regarding roll wear and roll expansion, see Section 5.
Use a model like the one shown in the figure. If the plate crown C obtained in this way is used in place of the above-mentioned Cm and the target thickness is H++C1 in Figure 2, the lower limit of tolerance + the predetermined value of the crown correction quantum, C<Cm, so the yield can be improved. Can be done. Since the plate crown C is a value determined according to each material to be rolled, the target thickness is set for each material to be rolled and changes for each material to be rolled, but it does not change while the individual material to be rolled is being rolled. , the plate thickness does not change in the slope length direction.

In addition to estimating the plate crown as described above, it is also effective to use actual values or to learn from actually measured values.

For example, the following methods are available for learning the crown estimation calculation. Letting the calculated value of CT' 1 be Ci for the metallic odor test plate crown, ΔC1-C''''-Ci becomes the plate crown amount to be corrected by learning.

The control amount ΔCi of the uniform load plate crown is determined from ΔCi using the following equation, which is obtained by reversing the above-mentioned basic equation (1).

The amount of modification of the uniform load plate crown determined by equation (6) is learned by the following procedure.

Ci Mi cp ” Pi +CF ” F+ ”CR
”Since it is expressed as CP, +Cp, cF, and cR learning coefficients, if all the estimation errors can be summarized as being based on the roll profile term, then this ΔCRi can be used as the learning term.

If the estimation error approaches 0 through learning, the roll profile CRO4 can be derived from the above-mentioned equation (2).

In other words, if the plate crown is actually measured using a profilometer on the exit side during plate rolling and, for example, the average plate crown is determined, this reflects the static and dynamic roll profiles during the rolling process, and therefore the difference between the rolled material and the plate material. If the above estimated roll profiles are grouped and stored on the plate side crown influence factors such as deformation resistance FC (hardness) and plate width, then when rolling a plate, the same type of plate as the current plate is selected from the stored roll profile group. The estimated roll profile obtained from the previous (most recent) rolling is taken out and corrected by the roll profile change due to roll elastic deformation such as the current rolling load and roll bender force to accurately estimate the plate crown and calculate the target thickness. can be determined. In this case, since the most recent data is used for the correction based on the rolling position, omitting it will not cause a large error, especially when the deformation resistance (hardness) and width of the plate are the same or gradually change. If this changes significantly, use the same type of rolling results so far (preferably the latest one), or add the trend changes to the same type of results to estimate and use the current result. It is best to take the following method.

Furthermore, the actual performance data to be stored may be the plate crown itself; that is, the roll profile is of the same type as the plate crown, including the elastic deformation.

Figure 3 shows the processing procedure when determining the target thickness using the rolling results.As shown in Figure 3, the roll profile is estimated and calculated based on the rolling results up to the bent material, and the results are stored for each type of plate. (When calculating the target thickness for the plate to be rolled, data on the rolled material on the inlet side of the finishing rolling equipment, specifically M type, outlet side plate width, plate thickness, and temperature of the rough rolling equipment, are taken in and the pass Calculate the rolling load of the finish rolling stage determined from the schedule and the roll elastic deformation due to the roll bender force,
Using this calculation result, the stored roll profile is corrected, and the finished exit crown is estimated. Once this crown value has been determined, the appropriate target thickness (target thickness) at the center of the strip in the width direction is calculated from the lower tolerance limit, etc., as described above, and automatic strip thickness control is performed using this. Crown measurement is performed during rolling. The deviation between the obtained measured crown value and the predicted crown value estimated and calculated is determined, and learning for the crown estimation calculation is performed. Crown changes due to the rolling position can be incorporated to a considerable extent in this learning.

FIG. 4 shows the configuration of a rolling mill and its control device, and as shown in the figure, 20 is a rough rolling mill, R6 is its final stand, and 30
is the finishing rolling mill, F1 to F7 are its 1st to 7th stands,
40 is a coiler. A plate thickness needle and a thermometer 52 are provided on the outlet side of the rough rolling equipment, and their outputs are taken into a control computer 50. There is also a plate thickness gauge of 56 on the exit side of the finishing rolling equipment.
is provided, and its output is taken into the control computer 50.

The calculator 50 inputs these and the separately inputted sli! The optimum finished plate thickness (target thickness) is calculated from the information such as the seed, and this is used to calculate the finishing mill settings, and the settings for each stand are performed via the finishing mill setting device 54.

〔Effect of the invention〕

As explained above, in the present invention, the crown value estimated for each rolled material is used instead of the maximum crown value to determine the target thickness, and the target thickness is determined for each material, thereby automatically controlling the plate thickness. This makes it possible to suppress excessive plate thickness as much as possible, thereby improving yield.Since the plate is rolled at the target thickness from the tip of the plate and is not changed mid-way, the plate thickness is reduced in the longitudinal direction. This has the advantage that it does not change with time.

[Brief explanation of drawings]

Figure 1 is an explanatory diagram of the work roll shift, Figure 2 is an explanatory diagram of the procedure for determining the target thickness, Figure 3 is an explanatory diagram of the procedure for determining the sheet crown based on actual data, Figure 4 is an explanatory diagram of the rolling equipment, and Figure 5 is an explanatory diagram of the procedure for determining the plate crown based on actual data.
The figure is an explanatory diagram of a roll expansion model and a wear model. In the drawing, 10 is a work roll, and 12 is a concave portion produced by rolling. Applicant Nippon Steel Corporation Representative Patent Attorney Minoru Aoyagi (Re (d) - ML Fuku→
φ Sail width → Figure 1

Claims (2)

[Claims] (1) Perform work roll shift and automatic plate thickness control,
The target thickness of the plate thickness control is determined by adding the plate crown correction amount to the lower limit of tolerance of the product plate thickness. In the optimum plate thickness setting method for rolling equipment, the determining factor of the plate crown correction amount is An optimal plate thickness setting method, comprising adding the rolling order, plate width, plate thickness, and deformation resistance of the rolled material, and determining the target thickness for each rolled material using the plate crown correction amount obtained in this way. (2) Perform work roll shift and automatic plate thickness control,
The target thickness of the plate thickness control is determined by adding the plate crown correction amount to the lower limit of tolerance of the product plate thickness. The results are grouped and stored according to deformation resistance (stiffness of the plate), plate width, and plate thickness, and the plate crown correction amount used for determining the target thickness is applied to the rolled material in the stored plate crown correction amount group. An optimum plate thickness setting method, characterized in that the target thickness is determined for each material to be rolled using the plate crown correction amount obtained from the same type of material.