JPS6038206B2 - Automatic slab width control method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for automatically controlling the width of a slab, and more particularly, to an automatic width control method for a slab that is performed in a process where the plate thickness is relatively large in hot strip rolling equipment that manufactures thin plates by hot rolling. Regarding control method.

In hot strip rolling equipment that manufactures thin plates by hot rolling, a plate material (hereinafter referred to as a slab) is rolled in the width direction of the plate in an initial process when the plate material is relatively thick.

By the way, in general, in such slab width rolling,
Due to non-uniformity of temperature in the longitudinal direction of the slab (mainly caused by skit marks generated in the heating furnace), it is not always possible to obtain a constant plate width accuracy.

That is, the rolling load increases in the skid mark portion where the temperature is low, and the sheet width dimension increases accordingly. Conventionally, in order to deal with such problems, methods such as the so-called Bisler control method, which detects the entrance slab temperature and other factors and performs predictive control, and the so-called Bisler control method, which detects the rolling load applied to the rolling mill and controls the roll position, have been implemented. However, the reality is that sufficient plate width accuracy has not yet been achieved. SUMMARY OF THE INVENTION An object of the present invention is to propose a new automatic slab width control method capable of solving the above-mentioned conventional problems.

Therefore, the present invention has investigated the different aspects of rolling between plate thickness rolling and plate width rolling, and in particular, in plate width rolling, the plate width is extremely large compared to the plate thickness, and this is due to the fact that the plate width is extremely large compared to the plate thickness. Among the deformations accumulated in the slab itself in the width direction, the deformation that restores itself in the width direction after rolling is large, and we found that this has a large effect on the accuracy of the width of the slab. In the first invention, in width rolling of a slab in which the width of the slab is reduced by rolling the slab in the width direction between a pair of rolls, the slab is produced by the deformation characteristics of the slab itself based on the elastic recovery and plastic deformation of the material. An error in the plate width dimension is predetermined as a restoring spring constant of the slab, and during width rolling of the slab, a fluctuation value of the rolling load corresponding to the restoring spring constant is feedback-controlled as a control signal to suppress variations in the plate width dimension of the slab. It is characterized by this. Also the second
In the second invention, in width rolling of a slab in which width reduction is performed by rolling the slab in the width direction between a pair of rolls, a restoring spring of the slab itself based on the spring constant Ke of the rolling mill, the elastic restoring of the material and the plastic deformation is used. Constant Kb, rolling car P, rolling load variation value △P, roll opening degree S, roll relationship variation value △S
, when a constant Q is used, the plate width reduction amount is controlled so that Q・△P(house+old)+Δs=0.

Next, before explaining the control method of the present invention, the deformation characteristics of the slab itself will be explained first.

In general, in width rolling of slabs, the width of the slab is about 900 to 1,500 ribs, and the amount of width reduction at one time is about 10 mm, compared to the thickness of the slab in thickness rolling, which is about 2 to 5 sides at most. , the plate width amount and the width reduction amount are both significantly large. For this reason, the slab undergoes elastic strain in the width direction during width rolling, and this causes the slab to elastically restore its width again after rolling. During width rolling, the slab may bend in the width direction, or local bulges (usually called dock bones) may occur at the edge of the plate that comes into contact with the rolling rolls, and these may occur immediately after rolling or during the next process. The plate is restored in the width direction by thickness rolling. However, since these restoring deformations occur in relation to the rolling load, as mentioned above, the deformation stress is large in the skid mark area where the temperature is low, and the amount of restoring is correspondingly large, resulting in a deterioration of sheet width accuracy. It turns out. On the other hand, the error in the plate width dimension caused by the spring constant of the rolling mill is extremely small because the rolling load is smaller than that during plate thickness rolling. FIG. 1 explains the influence of the elastic recovery of the slab itself on the plate width accuracy.

In the figure, when width rolling is performed with the entrance side plate width B and the roll reduction setting amount S, at the normal temperature of the slab, it is rolled down to the above S with the deformation stress curve omo, but the plate width changes due to elastic recovery after rolling. Becomes a body. On the other hand, at the skid mark part, the temperature is low, so the deformation stress is high and the sheet is rolled down to the above S along the deformation stress curve om, but after that it elastically recovers and the plate width becomes b. In this way, even if the rolling weight is the same, a difference Δb will occur in the amount of elastic recovery, resulting in an error in the sheet width accuracy. In addition, if this amount of elastic restoration is calculated based on the longitudinal elastic modulus E in the slab width direction using FIG. 1, then △b=b(om
−.

m. )/E=b△. m/E), where E=15
00k9f/fence, b=1300 fence, △. m=3k9f/
If it is a square, △b=2.61 skin. By the way, as mentioned above, the restoring deformation of the slab is not only due to the above-mentioned elastic restoring, but also due to elastic restoring, which causes bowing in the width direction when the slab is width-rolled between a pair of rolling rolls, and dog-shaped restoring. It also includes so-called plastic deformation caused by bone parts.

In the embodiments of the present invention, the width deformation characteristics of the slab itself based on the elastic recovery and plastic deformation of such materials are determined in advance and taken as the recovery spring constant after width rolling, and the corresponding rolling load is calculated. Board width control is performed based on the fluctuation value. That is, △. If the rolling load variation due to m is △P and the total rolling load is Po, then △P=P.

△. m/. m. It is also expressed by △P, which is the plate width error, △b, and the deformation stress of the slab at steady temperature without skid marks.

Deformation stress of the slab under low temperature conditions with skit marks. Assuming the deviation from mo, the restoration spring constant Kb is expressed as Kb=△P/△b=magazine. It is now a kiln.

Here, for example, Po = 135 tons f, △b = 3 ribs, om
. =13k9f/masu, △. If m=3kgf/association,
Kb=10.4 tons f/side. When setting this Kb, actually attempt width rolling of the slab in advance, and calculate the deformation stress of the slab in the steady temperature area mo and the deviation stress Δ of the slab in the skid mark area from the rolling load Po. m, and Ab is determined by measuring the plate width dimension of the width-rolled slab material, the above-mentioned Kb is calculated many times according to the above formula, and the average value of this value is used to set the restoring spring constant Kb of the slab material. It is. - The spring constant Ke of the rolling mill during width rolling is approximately 135 tons f/side, which is more than 10 times the above-mentioned restoring spring constant Kb, so the error in strip width accuracy during width rolling is almost the same as above. It is clear that this is caused by the restoring spring constant Kb. Therefore, by using the restoring spring constant Kb of the slab material preset by the method described above, and during actual slab rolling, feedback control is performed based on the rolling load variation ΔP using this fluctuation value ΔP as a control signal. This enables automatic slab width control that can suppress fluctuations.

In addition, another slab width control can be performed using the sum Km of these two types of spring constants; in this case,
Hadashi = ; Ten deri kunure, using the above calculation example, Km = 9
．． 7 tons f/ side.

FIG. 2 shows an embodiment of an automatic plate width control device to which the present invention is applied. The slabboo is rolled by a pair of rolls 3 attached to a chock 4.

The roll 3 is configured to be positioned by a hydraulic actuator using a jack 8, a piston 6 and a cylinder 7 supported by a screw 9. Such pressure mechanisms are provided symmetrically within the frame 2 with the slab 1 in between. To control the plate width using the hydraulic actuator, the signals from the two load cells 5 provided between the piston 6 and the chock 4 are processed by the calculator 15, and then this signal is converted to a constant Q.
Q・Kb・Ke/(Ke+
Kb) is calculated.

If there is a difference between this value and the command unit 18, the distributor 14
gives a signal to the left and right servo valves 11, and pump 1
2 and a tank 13 to supply oil to the cylinder 7.
to control the position of the roll 3. When the roll 3 moves, a signal is output from the left and right position detectors 10, which is calculated by the calculator 17 and returned to the main control circuit, so that it operates as a so-called closed loop. In addition, in this control circuit, the left and right loads P. , P2 and the positions S, , S2, independent signals are output from the command device 18 for each left and right, and q, Kb, Ke/
Plate width control using (Ke+Kb) may also be performed.

Further, as described above, since the spring constant Ke of the rolling mill is extremely large compared to the restoring spring constant Kb, this may be ignored in the control. In other words, the slab restoration spring constant Kb
When using only the actual rolling load value Po detected by the calculator 15 and the desired rolling load value corresponding to the restoring spring constant Kb output from the command unit 18, the calculator 1
6 to calculate the rolling load fluctuation value △P, and
What is necessary is to perform feedback control on the distributor 14 so that this load fluctuation value ΔP becomes zero. As described above, in the present invention, since the plate width is continuously feedback-controlled by capturing load fluctuations corresponding to the restoring spring constant of the slab itself, extremely accurate plate width control is possible.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a diagram illustrating the influence of the elastic restoration of the slab itself on strip width accuracy, and FIG. 2 is an embodiment of an automatic strip width control device to which the method of the present invention is applied.

1...Slab, 3...Roll, 5...
...Load cell, 10...Position detector, 11...
...Servo valve, 14...Distributor, 15,
16, 17... Arithmetic unit, i8... Command unit.

Traditional drawing Hiiragi 2

Claims (1)

[Claims] 1. In width rolling of a slab in which width reduction is performed by rolling down the slab in the width direction between a pair of rolls, the slab is produced by the deformation characteristics of the slab itself based on the elastic recovery and plastic deformation of the material. The error in the width dimension of the slab is determined in advance as a multiple spring constant of the slab, and during width rolling of the slab, the fluctuation value of the rolling load corresponding to the multiple spring constant is used as a control signal for feedback control, and the width dimension of the slab is An automatic slab width control method characterized by suppressing fluctuations. 2. In width rolling of a slab in which width reduction is performed by rolling down the slab in the width direction between a pair of rolls, the spring constant Ke of the rolling mill is
When the multiple spring constant Kb of the slab itself based on the elastic recovery and plastic deformation of the material, the fluctuation value ΔP of the heavy P rolling load during rolling, the roll opening degree S, the fluctuation value ΔS of the roll opening degree, and the constant α, α・ΔP(1/(Ke)+1/(Kb))+ΔS
An automatic plate width control method for a slab, characterized by controlling the plate width reduction amount so that = 0.