JPH0312964B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method for controlling the thickness in the width direction of a rolled material such as a steel strip rolled by a rolling mill equipped with an AGC.

(Prior art) In the rolled material (hereinafter simply referred to as material) extracted from a walking beam type heating furnace, skid marks are generated at the position where it hits the skid for transporting the material in the heating furnace, and the material is The temperature decreases and the temperature distribution of the material becomes uneven. As the material with the non-uniform temperature distribution is continuously rolled, the skid marks become enlarged and are distributed non-uniformly in the width direction. As a result, temperature deviation occurs in the width direction of the material, and the deformation resistance of the material differs in the width direction, resulting in uneven thickness of the product in the width direction. In addition, recent energy-saving rolling methods increase the material thickness and lower the heating furnace extraction temperature, but this operation method increases the amount of heat dissipation at the edges of the material and further increases the temperature deviation in the width direction. This tends to increase the non-uniformity of the thickness of the product in the width direction. Recent customer needs have strongly demanded not only product quality but also products that are uniform in the width direction, and there is a great need to solve the above problems.

In continuous rolling mills, gauge meter type
AGC (automatic plate thickness control) has been widely adopted and has had a great effect on increasing the accuracy of plate thickness control. on the other hand,
Although this has been adopted for roll bending equipment, it only presets the bending pressure to a set value using a pass schedule before rolling, and the bending pressure within a single piece of material has hardly been changed. However, recently, the problem of material shape (flatness) has become a hot topic, and various control methods and devices have been developed for this purpose. The main method is to use a roll bending device to change the bending pressure within a single piece of material according to the thickness deviation of the material in the width direction, thereby creating a uniform thickness in the width direction over the entire length. This is the method we are trying to achieve.

However, there is a problem in that plate thickness control and shape control interfere with each other. In other words, when the shape control system changes the roll bending force in an attempt to control the shape, the roll reduction force (rolling reaction force) changes;
When the AGC system is operated, and when the AGC system operates and changes the roll gap, the rolling reaction force changes, which changes the plate shape (crown), so the shape control system operates,
It turns out that. It has been considered to eliminate such mutual interference so that each device can operate independently, and JP-A-58-138508 is an example of this. This is because there is mutual interference when the exit plate thickness variation is Δh, the exit side crown variation is ΔCr, the reduction operation amount is ΔS, and the bending pressure operation amount is Δr. Δh ΔCr=g ₁₁ g ₂₁ g ₂₁ g ₂₂ ΔS Δr＝〓ΔS Δr Therefore, if the manipulated variables ΔS and Δr are corrected to the manipulated variables ΔS ^* , Δr ^* ΔS ^* Δr ^* =〓 ^-1 ΔS Δr (E is the unit matrix), Δh ΔCr= Since ΔS ^* Δr ^* = G・G ^-1 ΔS Δr = ΔS Δr, the manipulated variables ΔS and Δr no longer interfere with each other. However, in this method, the bending pressure operation amount (Δr) is a single loop (work side and drive side are integrated), and if the wedge ratio of the material differs at the entrance side of the rolling mill, the rolling Since it is necessary to change the amount of bending pressure operation on the work side and drive side of the machine, it is impossible to control the thickness to be uniform in the width direction with this method.

Feedback control of plate crown detects the crown,
This is done by operating the operating end, in this example a roll bender, so that the difference from the target crown is zero. The crown indicates the height of the board, and since the thickness distribution is assumed to be symmetrical, crown measurement can be performed by measuring the thickness at the center of the board and determining the thickness at one edge of the board. However, since wedges indicate left-right asymmetry in the thickness distribution, it is necessary to measure the thickness at the left and right ends of the plate, and in order to control the shape by taking wedges into consideration, multiple thickness gauges are required. It turns out that.

The present invention aims to improve these points and make it possible to perform shape control including wedges without interfering with AGC and without using a large number of plate thickness gauges.

(Structure and operation of the invention) The present invention provides a method for automatically controlling the thickness of a material in the width direction of a material rolled in a continuous rolling mill equipped with a roll bender on the work side and the drive side. A thickness gauge that moves in the width direction and then rests on one edge of the material, and a thickness gauge that is fixedly placed on the center line of the material, measure the thickness distribution in the width direction at the starting edge of the material and the center of the material in the length direction. Measure the plate thickness distribution at the edge and edge parts, correct the meandering for the edge plate thickness using the meandering amount of the material and the width direction plate thickness distribution, calculate the wedge rate from the width direction plate thickness distribution, and calculate the wedge rate from this. Calculate the weighting coefficient to be added to the operation amount of one bender for each bender on the work side and drive side, and use the variations in the thickness of the central part of the material, the thickness of the edge part, and the weighting coefficients to automatically The operation amount obtained by removing mutual interference between plate thickness control and bender control is calculated on the work side,
The method is characterized in that the information is input to each bender on the drive side to uniformly control the thickness distribution of the material in the width direction over the entire length in the longitudinal direction.This will be explained next with reference to examples.

First, the method for measuring the plate shape will be explained. This can be done simply by arranging a large number of plate thickness gauges across the width of the plate and measuring the thickness directly below each plate thickness gauge.If this is done continuously during plate rolling, the plate thickness Capable of measuring full length crowns and wedges. The plate meanderes during rolling, and in order to correct this, the plate thickness gauge group can be reciprocated in accordance with the meandering. However, this method requires high equipment costs. In this regard, the method developed by the present inventor and filed separately requires only two plate thickness gauges, and is extremely effective.

To explain this shape measurement method with reference to FIGS. 2 and 3, numeral 10 indicates a rolled material, and the arrow indicates its moving direction. 12 is a plate thickness gauge fixedly attached so as to aim at the center line 10a of the material 10, and 14 is a scanning type plate thickness gauge which is movable in the width direction of the plate. As the material 10 moves, the plate thickness gauge 12 samples and measures the thickness of the center line of the material 10 (the black dots are the sampling points), and the plate thickness gauge 14 first moves the entire width and then returns to a position slightly. Since it is fixed, the line 14a, 1
The thickness of the plate on 4b is sampled and measured. line 14a
In the plate thickness measurement above, the crown and wedge at the tip of the material are measured, and in the plate thickness measurement on line 14b, the crown at each point in the length direction of the material 10 is measured (also using the output of the plate thickness meter 12). .

That is, at the tip of the material 10, the crown and wedge are determined by measuring the thickness at each point in the width direction, and then the thickness at the center of the material and one end of the material ((a point 25 mm from the edge, generally such a point The crown can be found over the entire length of the material by measuring the plate thickness at .

If the material meanderes, the thickness measurement will no longer be performed correctly on the centerline 10a and one end 14b of the material. Crown and wedge measurements at the material tip address this meandering. The thickness distribution shape in the width direction of the material edge portion, that is, the third
Assuming that the shape of the function f(x) in the figure does not change throughout the entire length of the material, and that there is no change in the plate thickness,
The meandering can be considered as a simple parallel movement, which means that the material surface 10b has moved to the position 10b' or vice versa, as shown in FIG. The position of the plate thickness gauge 14 does not change, so when meandering, the measurement point will be P1 to P3
Therefore, it is no longer the correct measurement point that is 25mm from the edge. The correct measurement point after meandering is P2, so the plate thickness gage 14 should be moved above point P2, but
This requires a servo mechanism and is troublesome. Therefore,
The method is to correct it by calculation. That is, since the function f(x) representing the surface 10b is found by measuring the thickness on the first line 14a, the measurement value of the plate thickness meter 14, where x ₀ is the width direction position of measurement point P1, is f(x ₀ ). , b after meandering, the measured value is f(x ₀ -b). In reality, there is a change in the plate thickness, so the output of the plate thickness gauge 14 includes the actual plate thickness change ±Δ and the above change due to meandering f(x ₀ ).
−f(x ₀ −b) is included, and by subtracting the latter from the plate thickness gauge output, the former, that is, the actual plate thickness change can be found.

If the meandering occurs, the plate thickness meter 12 will no longer be able to accurately measure the thickness at the center of the material, but the change in plate thickness near the center line is not large and the amount of meandering is generally 5.
Since it is a minute value such as mm, correction can be omitted. Further, the wedge may also remain unchanged over the entire length.

The wedge ratio _hWD of the material is defined by the following formula.
Here, h _W and h _D are the work side and drive side edge parts αmm obtained by scanning the width direction of the plate thickness 14.
This is the plate thickness at the point, and α is also 25 mm.

h _WD = h _W / h _D ... (1) If the bending pressure operation amounts on the work side and drive side are Δb _W and Δb _D , if the material has a wedge, the bending pressure operation amount will be symmetrical in the width direction of the material. Δb _W =W·Δb _D and Δb _D = Δb _D (2). Here, W is a weighting coefficient corresponding to _hWD for the bender operation amount on the work side and drive side. Since the h _WD is obtained by the width direction scan, the bending forces on the work side and drive side can be continuously controlled to values suitable for each.

FIG. 4 shows the temperature profile in the longitudinal direction of the material, where A shows the temperature profile at the center of the width, and B shows the temperature profile at the ends of the width.
From these A and B, a temperature deviation of approximately 50°C in the width direction is observed. The amplitude of A is about twice that of B, and it is clear from this that the skid mark of the material is large at the center of the width and becomes smaller toward the ends.

FIG. 5 shows the thickness profile in the longitudinal direction of a material of the same size when AGC is turned off (a) and when AGC is turned on (b). In the figure, A indicates the plate thickness variation at the width center portion, B indicates the plate thickness variation at the width end portion, and C indicates the variation amount (crown amount) of the thickness deviation in the width direction of the material.
When AGC is turned off, as shown in Figure 4, the amount of temperature variation at the edges is smaller than that at the center, so the thickness variation at the edges is much smaller than at the center. It has fallen within the control limits.
However, since the temperature fluctuation in the longitudinal direction is large at the center of the width, the thickness fluctuation is also large, about 2
There are about twice as many. AGC is effective in reducing this amount of variation. Figure b shows the case when AGC is turned on, and the thickness variation in the center area is clearly reduced.
The control effect appears. However, on the contrary, the amount of plate thickness variation at the edge increases by about twice compared to case a when AGC is turned off. This allows AGC
It is clear that this interferes with the plate thickness at the end.

The controlled objects are the thickness variation Δh _C on the exit side at the center, the variation Δh _W on the exit side at the work side edge, and the variation Δh _D in the plate thickness at the end on the drive side. When the amount Δb _W and the drive side bending operation amount Δb _D are corrected so that there is no mutual interference, the following relational expression is established between the controlled object and the operation amount.

Δh _C Δh _W Δh _D =100 010 001・ΔS Δb _W Δb _D +0 f(ΔS, Δb _D ) g(ΔS, Δb _W ) …(3) Here, f(ΔS, Δb _D ), g(ΔS, Δb _W ) is a non-interference term for the bending operation amount on each of the work side and drive side. In order to make the plate thickness uniform in the width direction, the following relationship is required: Δh _C −Δh _W = Δh _C −Δh _D 0 ...(4) From equation (4), Δh _W = Δh _D = Δh _C ...(5) If Δh _C is set to 0 by AGC, then from equations (3) and (5), Δb _W +f (ΔS, Δb _D ) = Δb _D +g (ΔS, Δb _W )
0...(6) Using the relationship Δb _W ]=W・Δb _D in equation (2) above, g(ΔS, Δb _W )=g(ΔS, W・Δb _D )...(7) Yotsute( From equation 6), Δb _W = -f (ΔS, Δb _D ) Δb _D = -g (ΔS, WΔb _D ) (8) Using equation (2), Δb _W in equation (8) becomes Δb _W = -W・g (ΔS, W・Δb _D ) ...(9) From these equations (8) and (9), the bending operation amount for each of the work side and drive side when AGC is "on" is given by equation (10). Given.

Δb _W =−W·g(ΔS, W·Δb _D ) Δb _D =−g(ΔS, W·Δb _D ) (10) FIG. 1 shows an embodiment of the present invention. Rolled material 10 placed on the exit side of the final stand 20 of a continuous rolling mill
A thickness meter 12 measures the thickness of the central part in the width direction, and a scan scans the entire width at least once to detect the thickness profile in the width direction. The plate thickness is measured using the mold thickness gauge 14, and the calculation device 28 calculates the wedge ratio of the material and the width direction plate thickness distribution curve.
The weighting coefficient W of the bender operation amount on the work side and drive side is determined. Rolling constant (mill characteristics,
Information on material properties, etc.) is sent from the upper computer 38 to the lower computer (DDC computer) 30, and the lower computer 30 also uses a reaction force meter 22 and a pressure detector 2 in the work side and drive side bending control systems.
4 and 26 continuously, outputs a roll gap command signal to the AGC control system 32, and uses functions g (ΔS, Δb _D ) and weighting coefficients W to eliminate mutual interference between AGC and bender control. by
Bending operation amount command Δb _W given by equation (10),
Send Δb _D to the work side (WS) and drive side (DS) bending control systems 34 and 36,
By continuously performing AGC and bender control, it is possible to produce uniform plate thickness in the length and width directions of the material.

In this example, we focused on the final stage stand and explained the control of this stand, but in reality, bending devices are placed independently on the work side and drive side of several later stages or all stands, and the amount of operation is controlled for each stand. By performing load distribution control, AGC and bender control are performed continuously on each stand, producing uniform plate thickness in the width direction of the material.

[Effects of the Invention] As explained above, according to the present invention, uniform plate thickness can be achieved in the length direction and width direction of the rolled material, and only two plate thickness gauges are required for this control.
It's extremely beneficial.

[Brief explanation of the drawing]

Fig. 1 is a block diagram showing an embodiment of the present invention, Figs. 2 and 3 are explanatory diagrams of the plate shape, Fig. 4 is a graph showing the temperature distribution in the plate length direction, and Fig. 5 is a graph showing the plate length. It is a graph showing plate thickness change and crown change in the direction. In the drawing, 32 is an automatic plate thickness control (AGC) device,
20 is a rolling mill, 10 is a rolled material, 34 and 36 are work side and drive side bending control systems, and 12 and 14 are plate thickness gauges.

Claims (1)

[Claims] 1. A method for controlling the thickness in the width direction of a material rolled in a continuous rolling mill that performs automatic thickness control and is equipped with roll benders on the work side and the drive side, comprising: moving in the width direction at the starting end of the material; Then, a plate thickness gauge that is stationary on one edge of the material and a plate thickness gauge that is fixedly placed on the center line of the material are used to measure the thickness distribution in the width direction at the starting edge of the material and the center and edge of the material in the length direction. Measure the plate thickness distribution, and correct the meandering of the edge plate thickness based on the meandering amount of the material and the width direction plate thickness distribution, calculate the wedge rate from the width direction plate thickness distribution, and use this to determine the work side and drive. A weighting coefficient to be added to the operation amount of one side bender relative to the operation amount of the other bender is determined, and using each variation in the material center thickness, edge thickness, and the weighting coefficient, automatic thickness control is performed. The operation amount obtained by removing mutual interference in bender control is input to each bender on the work side and drive side, and the thickness distribution in the width direction of the material is controlled uniformly over the entire length in the longitudinal direction. A method for controlling the thickness of rolled material in the width direction.