JPH04319011A - Method for controlling edge drop in sheet rolling - Google Patents

Abstract

PURPOSE:To control edge drop so that the edge drop on the outlet side of the final pass satisfies required accuracy without repeatedly calculating a numerical formula model at the time of sheet rolling. CONSTITUTION:In a method for controlling the edge drop of sheet using a multiple rolling mill with plural passes, the numerical formula model of the edge drop of rolled stock is preliminarily prepared and, using this numerical formula model, the edge drop at one or more points on the outlet side of the final pass rolling mill are estimated. Control of edge drop is executed by successively setting the relative position between the starting point of the taper of work roll and the side end parts of the width of rolled stock from an upstream pass rolling mill so that all of them is in the target range. The yield of product is improved, the cost of computer is reduced, also rolling can be executed with high accuracy and high accuracy of product can be held.

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an edge drop control method for rolling a plate using a multi-pass rolling mill. [Prior Art] In continuous cold rolling of a plate,
In order to roll the rolled material at high speed and improve edge drop, multiple rolling mills are installed on the rolling line to control edge drop. In such equipment, a target edge drop of the material at a predetermined position on the rolling line is determined as a target value for edge drop control. That is, edge drop control performs preset control that outputs a set value before rolling the material. In this preset control, within a range that satisfies control constraints, the end of the roll body of the rolling mill is tapered (hereinafter referred to as tapered) as far as possible upstream of the rolling passes of the multi-pass multi-rolling mill and in as few passes as possible. It is optimal to adjust the shift in the sheet width direction of the work rolls (called ``rolling'') from the standpoint of both quality assurance and production cost reduction. Therefore, in preset control, the shift amount of the work roll from upstream of the rolling pass is determined and preset is performed so that the edge drop at the exit side of the final pass becomes the target edge drop and satisfies the above constraints and optimal conditions. required to do so. However, in actual rolling, the optimum value of the work roll shift changes due to the influence of rolling conditions such as changes in the tapered part of the work roll, rolling load, and the thickness or width of the original sheet. [0007] Therefore, the inventors of the present invention previously filed Japanese Patent Application No. 2-36
No. 211, the edge drop of the plate at the exit side of the final pass rolling mill is expressed by a mathematical model using the above rolling conditions as parameters, and using this mathematical model, the edge drop of the plate at the exit side of the final pass rolling machine is expressed from the viewpoint of both quality assurance and production cost reduction. We proposed a method to determine and preset the work roll shift amount of the rolling mill from upstream so that the edge drop becomes the target value and satisfies the optimum conditions under the above constraints. Problem to be Solved by the Invention: The above-mentioned patent application No. 2-36
In the method of No. 211, the amount of work roll shift that minimizes the evaluation function that evaluates the deviation from the target value of edge drop is determined by repeated calculations using a mathematical model, and the number of calculations may vary depending on rolling conditions and initial values. may become large. In view of the above problem, the present invention determines and sets the work roll shift amount of the rolling mill from upstream so that the edge drop on the exit side of the final pass satisfies the required accuracy without repeating calculations using a mathematical model. An edge drop control method is provided. [Means for Solving the Problems] In order to achieve the above object, the present invention has a plurality of work rolls having a shift mechanism in the direction of the cylinder axis of a work roll whose roll body end is tapered during plate rolling. In a method of controlling plate edge drop using a multi-pass rolling mill, the work roll shift amount (
A mathematical model of the edge drop of a rolled material (hereinafter referred to as an edge drop prediction model) is created in advance using parameters including HCW (hereinafter referred to as HCW), and this edge drop prediction model is used to In order to predict edge drops on the exit side of the rolling mill and to ensure that all of them fall within the target range, the relative position of the tapering start point of the work roll to the width side end of the rolled material is set sequentially from the upstream pass rolling mill. This is a characteristic method for controlling edge drop in plate rolling. [Embodiments] Hereinafter, embodiments of the present invention and their effects will be explained with reference to the drawings. FIG. 1 shows an embodiment of a multi-pass rolling mill to which the present invention is applied. In FIG. 1, numeral 7 indicates a multiple-pass multi-rolling mill, and numeral 1 indicates a steel plate to be rolled by the mill. The starting point of the line is the S point, the end point is the O point, 5 is an edge drop detector for measuring the strip widthwise strip pressure distribution on the rolling machine entry side, and 8 is the strip widthwise strip pressure distribution on the rolling machine exit side. 6 is a strip width detector on the entrance side of the rolling mill. A target value of edge drop is given to the steel plate 1 at point O. There is an n-pass (5 passes in this example) multiple rolling mill on the line, and each rolling mill includes a work roll 2 whose roll body end is tapered and which can be shifted in the sheet width direction, and a backup roll 3. Equipped with The edge drop is improved by shifting the work roll, the amount of which is controlled by the control computer and controller 4. When the edge drop of the plate on the entry side of the rolling mill is large, in order to prevent deterioration of the plate shape, the HCW of each rolling mill is adjusted so that the contact length of the tapered part of the work roll becomes larger in the upstream rolling mill. Set. As a result, the edge drop of the plate is reduced, so the edge drop of the rolled plate is reduced, resulting in a plate with uniform thickness in the width direction. [0015] When setting the HCW, the magnitude of the bender force is also set at the same time so that the tension at the end of the plate does not become excessive. The details of the edge drop prediction model and edge drop control related to the edge drop control method of the present invention will be explained below. In the present invention, edge drop refers to the deviation between the plate thickness at the reference point and the plate thickness at the plate end point in the plate width direction. In that case, the reference point is any point closer to the center of the plate than the plate end point, and the plate end point is one or more points closer to the edge of the plate than the reference point. In this embodiment, the reference point is 10 points from the plate side edge.
Example 2 where the 0mm point and the plate end point are 15mm from the plate side edge.
An example in which the thickness is 5 mm will be explained. The edge drop is calculated using the following equations 1 and 2. [Equation 1] D15=h100 - h15 [Equation 2] D25=h100 - h25 [0021] Here, D15 and D25 are the 15 mm point and 2
Edge drop (μm) at 5mm point, h100, h
15, h25 are 1 each from the side edge of the board toward the center of the board.
These are the plate thicknesses (μm) at distances of 00 mm, 15 mm, and 25 mm. The edge drop prediction model is expressed by Equations 3 and 4.
It is expressed using the structure shown in . [Equation 3] D15=a15・1*P(HCW1)+
a15・2*P(HCW2)+...
+a15・ *P(HCWn)+e15 [
[Equation 4] D25=a25・1*P(HCW1)+
a25・2*P(HCW2)+...
+a25・m *P(HCWm)+e25[
[0025] Here, HCW1 is the i-th HCW (m
m), a15.1 to a15., a25.1 to a25.
m is an influence coefficient, and e15 to e50 are influence terms of various rolling conditions such as the edge drop of the original plate, the material, the radius of the tapered part, the rolling load, and the plate width. n and m are determined by HCW selecting a stand that has a large influence on the edge drop at each point. P() represents arbitrary arithmetic processing. In this embodiment, an example in which the edge drop prediction model is set to the following Equations 5 and 6 will be explained. [Formula 5] D15=a15・1*HCW12+a15
・2*HCW22+a15 ・3*HCW32
+C15*Г15+e15] [Formula 6] D25=a25・1*HCW12+a25
・2*HCW22+a25 ・3*HCW32
+C25*Г15+e250029]
Here, Г15 and Г25 are the 15mm point and 25mm point of the original plate.
The edge drop (μm), C15, and C25 of the points represent the influence coefficients. FIGS. 2 and 3 show examples of comparisons between estimates based on Equations 5 and 6 and actual values. It can be seen that Equations 5 and 6 express edge drops with high accuracy. Next, a method of setting the operation amount for edge drop control in plate rolling using a multi-pass rolling mill will be explained. In this method, the work roll shift amount is set so that the estimated value of the edge drop on the exit side of the final pass rolling mill based on the edge drop prediction model falls within the target range.In this example, several edge drop prediction models are used. 5,
Given by Equation 6, the edge drop at the 15 mm point and the 25 mm point is predicted respectively, so the work roll shift amount of the rolling mill from the 1st pass to the 3rd pass is adjusted so that the estimated edge drop values at these two points fall within the target range. An example of setting will be explained. [0032] The target upper limit values (μm) of the edge drop at the 15 mm point and the 25 mm point are PDMAX15 and P, respectively.
DMAX25, edge drop target lower limit (μm)
are respectively defined as PDMIN15 and PDMIN25. 4, 5, and 6 show the procedure for determining HCW. First of all, from the edge drop prediction model of Equations 5 and 6, the edge drop estimated values D15*, D25* on the output side of the final path are calculated.
Find (μm). At this time, HCW uses an initial setting value (mm) given in advance. Next, an edge drop target range TD for determining HCW1 is set. At this time, if the edge drop estimated value is larger than the edge drop upper limit value, that is, in a case as shown in Equation 7, Equation 8 is set. [Formula 7] Di * > PDMAXi i=15, 25 [Formula 8] TDi = [FMINi, FMAXi
] = [PDMINi, (a
i. 1 *PDMAXi + (ai.2
+ai. 3)*Di*)/(a
i. 1 +ai. 2 +ai. 3)]
i=15,2500
36] Here, [a, b] represents [a or more and b or less],
FMINi (μm) is determined as PDMINi from the edge drop target lower limit value mentioned above, and FMAXi (μm) is determined as the deviation (Di) of the edge drop estimate value from the target upper limit value.
*-PDMAXi) as the influence coefficient ai. 1,
ai. 2, ai. Divide according to the ratio of 3 and calculate the deviation a
i. This is set in order to eliminate 1/(ai.1 +ai.2 +ai.3) by the first pass work roll shift. On the other hand, if the estimated edge drop value is smaller than the edge drop lower limit value, ie, as shown in Equation 9, Equation 10 is set for the same reason. [Formula 9] Di * < PDMINi i=15,25 [Formula 10] TDi = [FMINi , FMAXi
] = [(ai.1 *PDM
INi + (ai.2 + ai.3 ) * Di * )
/(ai.1 +ai.
2 +ai. 3), PDMAXi]
i=15,2500
[40] Furthermore, when the edge drop estimated value is greater than or equal to the edge drop lower limit value and less than the edge drop upper limit value, that is, in the case shown in Equation 11, Equation 12 is set. [Formula 11] PDMINi ≦Di * ≦PDMINi i=15
, 25 [Formula 12] TDi = [FMINi, FMAXi]
=[PDMAXi, PDMAXi]i=15,25 Next, for the edge drop target range set by Equation 8, Equation 9, or Equation 10, the solution set of HCW1 is found as shown in Equation 13 below. . [Formula 13] HCW1 i = [HCW1, mini , HCW1
, maxi]i=15,25 Normally, the larger W is, the smaller the edge drop on the output side of the final path becomes, so HCW1,mini is FM
Found from AXi, HCW1, maxi is FMI
Determined from Ni. Specifically, in numbers 5 and 6, FM is applied to D15 and D25.
It can be found by substituting AXi or FMINi and calculating backwards for HCW1. At this time, HCW2 and H
CW3 uses the initial setting value. From the solution set of Equation 13, the 15mm point and the 25m point
To satisfy all edge drop target ranges of m points, H
CW1 must take a value within the range shown in Equation 14 below. [Formula 14] HCW1 F = [Max(HCW1
, min15, HCW1, min25),
Min(HCW1,
max15, HCW1, max25)]0048
】Here, Max( ) represents the maximum value, and Min( )
represents the minimum value. Considering operational stability, it is desirable that HCW be as small as possible. Therefore, as the setting value of HCW1, the minimum value among HCW1 F, that is, the equation 15 is adopted. [Formula 15] HCW1 = Max (HCW1, m
ix15, HCW1, min25)] However, in the case of Equation 16 below, the initial setting value of HCW1 is used as the setting value. With the above steps, the HCW for the first pass has been determined. [Formula 16] Max(HCW1, mix15, HCW1, mix
25)>Min(HCW1, max 15, HCW1,
man25) [0052] Next, with HCW1 as the value obtained using Equation 15, and HCW2 and HCW3 as initial setting values, the estimated value of the edge drop on the output side of the final path D15*, from the edge drop prediction model of Equations 5 and 6, is calculated. D25
Find *. Next, an edge drop target range TD for determining HCW2 is set. Similarly to Equations 7 and 8, Equation 18 is set in the case of Equation 17 below. [Formula 17] Di * > PDMAXi i=15,25 [Formula 18] TDi = [FMINi , FMAX
i ] = [PDMINi
, (ai.2 *PDMAXi
+ai. 3 *Di*)/
(ai.2 +ai.3)]
i=15,25 [0056] Here, FMAXi (μm) is the deviation of the estimated edge drop value from the target upper limit value (Di*−PDMAXi
) is the influence coefficient ai. on the edge drop of HCW from the second pass to the third pass. 2, ai. 3 according to the ratio of deviation ai. 2/(ai.2 +ai.3
) is set to eliminate this by the work roll shift in the first pass. On the other hand, similarly to Equations 9 and 10, in the case of Equation 19, Equation 20 is set. [Formula 19] Di * < PDMINi i=15,25 [Formula 20] TDi = [FMINi , FMAX
i ] = [(ai.2
*PDMINi +ai. 3 *Di*)/
(a
i. 2 +ai. 3), PDMAXi]
i=15,
25 [0060] Similarly to equations 11 and 12, equation 21
In the case shown in , it is set as Equation 22. [Formula 21] PDMINi ≦Di * ≦PDMINi i=15
,25 [Formula 22] TDi = [FMINi, FMAXi] = [PDM
AXi, PDMAXi]i=15,25 Next, for the edge drop target range set by Equation 18, Equation 20, or Equation 22, HCW2
Find the solution set as shown in Equation 23 below. [Formula 23] HCW2 i = [HCW2, mini , HCW2
, maxi )]i=15,25 Normally, the larger the HCW, the smaller the edge drop on the output side of the final path, so HCW2, mini
is found from FMAXi, HCW2, mixi
is determined from FMINi in the same manner as in Equation 13. At this time, as the value obtained with HCW1 HA number 15, HC
W3 is the initial setting value. From the solution set of number 23, 15
In order to satisfy all edge drop target ranges at the mm point and the 25 mm point, HCW2 must take a value within the range shown in Equation 24 below. [Formula 24] HCW2 F = [Max(HCW2
, min15, HCW2, min25),
Min(HCW
2, max15, HCW2, max25)]00
67] As the setting value of HCW2, the equation 25 is adopted in the same way as the equation 15. [Formula 25] HCW2 = Max (HCW2, m
(in15, HCW2, min25) However, in the case shown in Equation 26, the initial setting value of HCW2 is used as the setting value. With the above steps, the work roll shift amount for the second pass is determined. [Formula 26] Max(HCW2, min15, HCW2, min
25)>Min(HCW2, max15, HCW2,
max25) Next, the edge drop target range TD for determining HCW3 is set as shown in Equation 27. [Formula 27] TDi = [FMINi, FMAXi] = [PDM
AXi, PDMAXi ]i=15,25 [0073] In the case of the third pass, since this is the last pass to set the work roll shift amount, the deviation between the edge drop estimated value and the edge drop target upper and lower limits is All must be eliminated by the work roll shift on the first pass. Therefore, the edge drop target range is uniformly determined as shown in Equation 27. Next, for the edge drop target range in Equation 27, the solution set of HCW3 is obtained as shown in Equation 28 in the same way as in Equation 13. [Formula 28] HCW3 i = (HCW3, mini , HCW3
, maxi )i=15,25 At this time, HCW1 is the value obtained by equation 15, and HCW2 is the value obtained by equation 25. From the solution set of Equation 28, HCW3 must take a value in the following Equation 29 range in order to satisfy all the edge drop target ranges of Equation 27. [Formula 29] HCW3 F = [Max(HCW3
, min15, HCW3, min25),
Min(HCW
3, max15, HCW3, max25)][00
[78] Then, the number 30 is adopted as the setting value of HCW3. [Formula 30] HCW3 = Max (HCW3, min15, HCW
3, min25) However, in the case shown in Equation 31, the initial setting value of HCW3 is used as the setting value. With the above steps, the work roll shift amount for the third pass has been determined. [Formula 31] Max(HCW3, min15, HCW3, min
25)>Min(HCW3, max15, HCW3,
max25) [0082] By manipulating the work roll, the shape at the edge of the plate may become unstable. Therefore, the HCW is set from the 1st pass to the 3rd pass, and the shape (flatness) of the plate side edge during this period is changed to the extent that the plate can be threaded or the work roll bender settings are changed within a range that does not cause plate breakage. However, the HCW setting range is limited depending on the degree of the shape defect, so in the embodiment, upper and lower limits that can be set for each stand are determined when calculating the HCW. [0083] As described in detail above, according to the present invention, in the edge drop control method in plate rolling, each rolling is performed such that all edge drops at one or more points on the exit side of the final pass are within the target range. Since the HCW of the machine can be determined and set and output without repeatedly calculating the edge drop estimation model, the following effects are achieved. ■ High-precision rolling can be achieved reliably. ■ Improved product yield. ■
Since the load on the computer is small, costs can be reduced. ■
Maintain high product accuracy even against errors in the edge drop estimation model.

[Brief explanation of the drawing]

FIG. 1 is a drawing showing an example of a cold rolling mill in which the present invention is implemented.

[Figure 2] Estimated value (D
15) and the actual measured value (D15).

[Figure 3] Estimated value (D
25) and the actual measured value (D25).

FIG. 4 is a drawing showing a HCW setting calculation procedure.

FIG. 5 is a diagram showing a HCW setting calculation procedure following FIG. 4;

FIG. 6 is a drawing showing the HCW setting calculation procedure following FIG. 5;

[Explanation of symbols]

1 Steel plate 2 Work roll 3 Backup roll 4 Control computer and controller 5 Edge drop detector 6 Strip width detector 7 Multiple pass multi-rolling mill 8 Edge drop detector O point End point S point Start point

Claims (1)

[Claims] 1. A method for controlling the edge drop of a plate during plate rolling using a multi-pass multi-rolling mill having a mechanism for shifting the work roll in the direction of the axis of the work roll having a tapered end portion of the roll body, the method comprising: A mathematical model of the edge drop of the rolled material expressed by parameters including the work roll shift amount for each pass is created in advance, and this mathematical model is used to predict the edge drop at one or more final passes on the exit side of the rolling mill. edge drop control for plate rolling, characterized in that the relative position of the tapering start point of the work roll to the width side end of the rolled material is sequentially set from an upstream pass rolling mill so that all of them fall within a target range. Method.