JPH04305304A - Method for controlling camber in hot rolling mill - Google Patents

Abstract

PURPOSE:To control chamber by moving a rolled stock in the width direction with edger rolls of a hot rolling mill. CONSTITUTION:In a rolling line which is arranged with a 1st rolling equipment which is provided with a 1st stand in which a rolling load measuring means and roll gap adjusting means are provided, means for measuring the temp. and thickness of rolled stock which are provided on the inlet side of the 1st stand and means for detecting the position in the width direction of the rolled stock arranged on the inlet and outlet sides of a (n-1)th stand, and an n-th rolling equipment which is provided with a position detecting means which is provided on the inlet and outlet sides of an n-th stand provided with a rolling lead measuring means and roll gap adjusting means; feed forward control that is implemented with the edger rolls so as to correct the camber of the rolled stock by calculating wedge ratio, camber ratio and temp. difference in the width direction of the rolled stock from the measured value of the 1st rolling equipment and feedback control that the position of the edger rolls is adjusted so as to correct chamber by calculating camber by the position ion the width direction of the rolled stock on the inlet and outlet sides of the n-th rolling mill are involved.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention relates to a camber control method in a hot rolling mill, and in particular to a method for moving a rolled material in the width direction by an edger roll (a rigid roll that corrects the width of the rolled material). This invention relates to a control method for correcting camber.

0002

[Prior Art] Conventionally, rough rolling equipment in a hot rolling line generally consists of a rough rolling mill equipped with a rolling load meter and a roll gap adjustment device, and a pair of edger rolls installed on the entry side of the rough rolling mill. The rough rolling mill is used to roll a 250 mm thick slab into a 20 to 40 mm thick steel strip. The roll gap adjustment device provided in this rough rolling mill has the function of adjusting the gap between the upper and lower rolls and adjusting the level of the upper and lower rolls (also referred to as leveling) so that the rolled material has a predetermined thickness. Further, a pair of edger rolls are provided to adjust the roll interval and control the width of the rolled material. Slabs rolled in a rough rolling mill are heated to a predetermined temperature in a heating furnace, but the slabs may be heated uniformly in the width direction, or there may be temperature deviations in the width direction depending on heating conditions, slab charging conditions, etc. There are things that have occurred.

[0003] The above-mentioned slab is rolled to a predetermined thickness and width using a rolling mill and an edger roll, but depending on the shape, temperature, rolling conditions, etc. of the slab, the steel strip (hereinafter referred to as rolled material) may have camber. (bending) or wedges may occur. Conventionally, such camber has been corrected by adjusting the roll level (leveling).

0004

[Problems to be Solved by the Invention] However, it is difficult to correct all shapes of the camber and wedge that occur as described above by leveling alone, and the following problems have existed. For example, (1) When rolling a slab with a temperature difference in the width direction, as shown in Figure 2, when rolling a slab with a temperature difference in the width direction, the WS (work side) and DS (drive side) Even if it is possible to correct camber and meandering to some extent by adjusting the roll level of the slab, this temperature difference is not necessarily uniform in the longitudinal direction, and depending on the state of charging the slab in the heating furnace, etc. In some cases, the high temperature part changes to the WS side or the DS side, and it is impossible to correct it simply by adjusting the leveling. (2) When rolling a rolled material with camber, when rolling a rolled material with camber in the previous stage rolling mill, the approach angle of the rolled material bitten by the rolls will change; As a result, camber is further exacerbated, and conventional leveling adjustment alone is no longer sufficient to deal with it. (3) When rolling a rolled material with thickness deviation (wedge), it is theoretically possible to correct the exit camber by leveling adjustment without changing the wedge ratio. When the deviation direction changes, an electric rolling device with slow response cannot cope with the change, and a rolling mill equipped with a hydraulic rolling device with excellent responsiveness is required. (4) If there is a misalignment (referred to as off-center) between the center of the rolling mill and the width center of the rolled material, this off-center difference may cause a difference in the rolling reduction on the left and right sides, resulting in camber. . In such a case, the function of the conventional edger roll (in the past, the edger roll was provided only to adjust the width, and the function was simply to adjust the roll interval, but it did not have the function of moving the entire rolled material in the width direction. ), it was impossible to correct the off-center by moving the rolled material in the width direction. Also, camber cannot be corrected only by leveling adjustment. (5) Difference in friction coefficient of work rolls between WS side and DS side
If the friction coefficient of the rolls differs in the longitudinal direction, the rolled material will shift laterally and camber will occur. In such cases, the solution was to change the roles. Camber occurs under the above conditions,
A general theoretical formula showing this phenomenon will be explained based on the case of temperature deviation shown in FIG. In other words, the exit camber ρ0 is

[Math 1] It can be expressed by the following equation (1).

The present invention has been made to solve the above-mentioned problems, and in particular, based on the phenomenological theory shown in the above-mentioned equation (1), there is a method other than the conventional method of correcting camber by leveling adjustment. An object of the present invention is to provide a camber control method in a hot rolling mill in which camber is corrected by moving a rolled material in the width direction while calculating a camber ratio and the like.

[0006]

[Means for Solving the Problems] A camber control method for a hot rolling mill according to the present invention includes a first stand provided with at least a rolling load measuring means and a roll gap adjusting means, and a camber control method provided on the entry side of the first stand. a first rolling facility equipped with a temperature measuring means and a plate thickness measuring means for the rolled material, and a position detecting means for detecting the position of the rolled material in the width direction on the entrance/exit side of the n-1 stand; An edger roll for moving the rolled material in the width direction of the rolled material is provided on the entry side of the n-th stand provided with a load measuring means and a roll gap adjustment means, and an edger roll for moving the rolled material in the width direction of the rolled material is provided on the entry and exit side of the n-th stand. In a rolling line equipped with an n-th rolling equipment equipped with a position detection means for detecting the position, the thickness and temperature of the rolled material measured in the first rolling equipment, the position in the width direction of the rolled material, the rolling load, and the roll The wedge ratio, camber ratio, and temperature difference in the width direction of the rolled material are calculated from the gap, and the positional relationship between the center of the rolled material in the width direction and the center of the rolling mill is determined based on these values to correct the camber of the rolled material. Feedforward control adjusted by the edger roll and feedback that calculates the camber based on the position in the width direction of the rolled material at the entrance and exit side of the n-th rolling mill, and adjusts the position of the edger roll to correct the camber from this value. The method includes control.

More specifically, the wedge ratio, camber ratio, and width direction of the rolled material are calculated from the thickness and temperature of the rolled material measured in the first rolling equipment, the position of the rolled material in the width direction, the rolling load, and the roll gap. The temperature difference is calculated, and based on these values, the roll level of the first rolling mill is adjusted to correct the camber of the rolled material, and the positional relationship between the widthwise center of the rolled material and the center of the nth rolling mill is adjusted to the nth rolling mill. Feed forward control is adjusted by the edger roll of the rolling equipment, and the camber is calculated based on the position in the width direction of the rolled material at the entrance and exit side of the n-th rolling mill, and the position of the edger roll is adjusted so that the camber is corrected from this value. This is a method of adjusting the roll level of the n-th rolling mill along with feedback control to adjust the roll level of the n-th rolling mill.

[0008]

[Operation] In the method for controlling camber in a hot rolling mill according to the present invention, the thickness and temperature of the rolled material measured at the n-1 rolling equipment, the position in the width direction of the rolled material, the rolling load, and the roll gap are The wedge ratio, camber ratio, and temperature difference in the width direction are calculated, and from these values, the positional relationship between the widthwise center of the rolled material and the center of the rolling mill is adjusted through feed-forward control to correct the camber of the rolled material. The camber is adjusted by the edger roll, and the camber is calculated based on the position in the width direction of the rolled material at the entrance and exit side of the nth rolling mill, and the position of the edger roll is controlled by feedback control so as to correct the camber from this value. Camber can be controlled by adjusting it. Note that the camber can be corrected more effectively by using the above-mentioned edger roll controlling means and the conventional leveling adjustment method together.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the camber control method in a hot rolling mill according to the present invention will be described in detail below with reference to the drawings. 1 to 14 show a camber control method in a hot rolling mill according to the present invention, FIG. 1 is a block diagram showing the hot rolling mill, and FIGS. 2, 5, 8, 11, and 13 show the rolling state. Plan configuration diagram, Figures 3, 4, 6, 7, 9, 10
, 12, 14, and 15 are cross-sectional views showing rolled materials (plates).

In FIG. 1, the reference numeral 1 indicates a first stand constituting a first rolling equipment 50, and this first stand 1 is connected to a pair of first horizontal mills 3 for rolling a rolled material 2.
, a pair of intermediate rolls 4, a load cell 5 which is a rolling load measuring means, and a first screw 6 which is a roll gap adjusting means.
, a first reduction 7, and a first leveling detection signal 8a from a first leveling detector 8 of the first reduction 7 is input to a first stand wedge ratio/camber ratio control device 10.

The first load signal 5a from the first load cell 5, the first inlet side lateral displacement gauge 11 and the outlet side lateral displacement gauge 12 provided on both sides of the first stand 1 (in the width direction of the rolled material 2) A first inlet side lateral shift signal 11a and a first outlet side lateral shift signal 12a from the stand (which constitutes a position detection means for detecting the position) are input to the first stand wedge rate/camber rate control device 10.

Furthermore, a wedge signal 13a from a wedge gauge 13 serving as a plate thickness measuring means and a thermometer 14 serving as a temperature measuring means provided upstream of the first entrance side lateral deviation gauge 11.
And the temperature measurement signal 14a is the first stand wedge rate.
The first stand leveling correction signal 10a from the camber rate control device 10 is also input to the first reduction 7.

Input wedge rate 1 from the control device 10
0b, entrance camber ratio 10c, entrance width direction temperature difference 10
d is input to the n-th stand camber rate control device 15, and the leveling signal 15 from this control device 15
The a and n-th camber control signals 15b are input to the leveling device 16 and the hydraulic jack control section 17, respectively.

Next, what is indicated by the reference numeral 20 is an n-th stand forming an n-th rolling equipment 51, and this n-th stand 20 is connected to a pair of second horizontal mills 21 for rolling the rolled material 2.
, a pair of intermediate rolls 22, an n-th load cell 23, an n-th screw 24, and an n-th compressor 25, and this n-th
A vertical mill hydraulic jack 26 is installed on the upstream side of the stand 20.
A pair of vertical mills 27 (only one is shown in the figure) are provided as edger rolls operated by the hydraulic jack 26, and a jack control signal 17a from the hydraulic jack control section 17 is supplied to the vertical mill hydraulic jack 26. There is.

The level control signal 16a from the leveling device 16 is inputted to the n-th pressure reducer 25, and the n-th leveling detection signal 28a from the n-th leveling detector 28 connected to the n-th pressure reducer 25 is input to the n-th leveling detection signal 28a. The information is input to the n-stand camber rate control device 15, and at both sides of the n-th stand horizontal mill 20, an entry side lateral deviation meter 29 and an exit side lateral deviation meter 30 (forming a position detection device for detecting the position in the width direction) are input. ) are provided.

The input side lateral displacement signal 29a and the output side lateral displacement signal 30a of each of the lateral displacement meters 29, 30 are input to the n-th stand camber calculator 31, and the calculation signal 31a of this n-th stand camber calculator 31 is input to the n-th stand camber calculator 31. is input to the n-th stand camber rate control device 15, and
A second load signal 23a from the load cell 23 is also input to the n-th stand camber rate control device 15.

Next, a case will be described in which camber control is performed using the hot rolling mill configured as described above.

(Example 1) First, when rolling a rolled material 2 consisting of a slab with a temperature difference in the width direction, the high temperature side (DS) is elongated from the low temperature side (WS) as shown in FIG. A camber is generated on the side (WS). However, by moving the rolled material 2 in the width direction by the vertical mill 27, which is an edger roll, the camber can be corrected by the following effect. Advance rates fw, fd, reverse rates gw, gd of the low temperature side (WS) and high temperature side (DS),
The entrance and exit camber, angular velocity, and bar speed are each ρi
, ρ0, ωi, ω0, Vi, V0, and the low temperature side of the inlet (
Assuming that the backward longitudinal forces on the high temperature side (WS) and the high temperature side (DS) are Tw and Td, and the plate width is W, as is well known, the relationship expressed by Equation (1) of Equation 1 is established between the camber and the angular velocity on the entrance and exit sides.

[0019]

[Math 1]

In addition, the following equation (2) is obtained.

[Math 2]

Now, considering the following rolling condition, entry side wedge zero ⇒ hidf = 0, ω0 = 0 entry side camber zero ⇒ ρ
i=0 Tw=Td Temperature difference in the width direction WS<DS From the above-mentioned equation (1), the following equation (4) of Equation 3 is obtained.

[0022]

[Math 3]

Further, from the above-mentioned equation (2) in the rolled state, the following equation (5) of Equation 4 is obtained.

[0024]

[Math 4]

Here, by substituting equation (5) into equation (4), equation (6) of the following equation 5 is obtained.

[0026]

[Math 5]

Therefore, from the above equation (6), the exit side wedge h0d generated due to the difference in deformation resistance due to the temperature difference in the width direction.
A camber ρ0 proportional to f is generated. here h0w
>h0d, the rolling reduction rate γ is γw<γd, the advance rate fw<fd, the reverse rate gw<gd, the camber bends toward the WS side, the entrance side also tilts toward the WS side, and a meandering distance of Δx occurs toward the WS side.

As a method of reducing the camber to zero, a method of changing the mill center and the plate center of the rolled material 2 using an entry edger will be described. First, the edger is placed in an off-center state by Δx toward the DS side with respect to the mill center. At this time, the aforementioned Tw is tension, Td is compression tension, and there exists Δx for which equation (7) of the following number 6 holds,
This allows the exit camber to be zero.

[0029]

[Math 6]

[0030] Furthermore, the off-center on the entry side by the edger is maintained, and in a steady state, the off-center of the roll bite portion becomes Δx. At this time, h0df=ASdf+BΔx+CPdf...(8
) However, Sdf is the screw position difference between WS and DS, and then, from Sdf=0 in equation (8), h0df=BΔx+CPdf=0. That is, by creating the state Δx=(C/B)Pdf, ∂g/∂h0・h0df=0, ∂g/
∂hi·hidf=0, ∂f/∂T·Tdf=0, and rolling can be performed in the state of ρ0=0. In other words, the transition period (Fig. 5
) and steady region (FIG. 8), it is possible to prevent camber and meandering due to the temperature difference in the width direction between WS and DS.

(Embodiment 2) When rolling a rolled material with camber. If the rolled material already has camber, the approach angle of the rolled material being bitten by the rolls changes, and the camber is further promoted on the exit side. However, when the rolled material is moved in the width direction by an edger roll, the camber can be corrected by the following effect.

ρ0 determined by ρi/λ2 in equation (1) is generated. In this case, it was difficult to control the approach angle with a conventional actuator, but it memorizes the value of the camber detected upstream in the longitudinal direction of the bar, and feeds the edger off-center amount by the change in approach angle due to the change in ρi. Forward control. Feedback control of the edger off-center amount is performed using the stand lateral deviation meter so that the roll bite position is constant. Each of the above methods can eliminate the influence of the entrance camber on the exit camber.

(Embodiment 3) When rolling a rolled material in which a plate thickness deviation (wedge) has occurred. When the wedge on the entry side is thick on the DS side as shown in FIG. 11, the rolled material bends and camber occurs on the WS side. Reduction rate γw<γd Advance rate fw<fd Reverse rate gw<gd, and the plate bends toward the WS side, meandering toward the WS side, and
The wedge on the exit side is DS thick. However, if the edger roll is moved in the DS side width direction as shown in FIG. 13, the camber can be corrected by the following effect. Edger Agilost Off-center Δx by width direction control
It is possible to perform control in the fw=fd, gw=gd state by shifting the bar.Also, the above control is possible by controlling the amount of Δx in response to changes in the wedge within the bar. In this case, although it is not possible to correct the raw material wedge on the exit side, the wedge can be controlled with priority given to preventing camber, which is the most impediment to rolling.

(Embodiment 4) A case where there is a deviation (referred to as off-center) between the center of the rolling mill and the width center of the rolled material. If the rolled material is bitten by the rolls with the material held off-center, there will be a difference in the rolling reduction ratio (level) on the left and right sides, and camber will occur. However, by moving the edger roll in the width direction, the camber can be corrected by the following effect. h0df=ASdf+BΔx+CPdf・
(9) Δx of equation (9) h0df occurs, and camber and meandering occur due to changes in the forward rate and reverse rate. In this case, it was difficult to control with the conventional actuator, but by controlling the off-center amount of the edger adjustment so that the off-center Δx = 0 from the leading edge using the lateral deviation meter 29 on the entry side, the exit camber , meandering can be prevented. However, the above-mentioned Pdf becomes Equation (10) of Equation 7.

[0035]

[Math 7]

(Example 5) A case where a friction coefficient occurs between the WS and DS of the work roll. If there was a difference in the coefficient of friction, camber would occur and the rolls would have to be changed. However, when the edger roll is moved in the width direction, the following number 8 (11
) The camber can be corrected by the following formula.

[0037]

[Equation 8] A change h0df in μdf occurs, and camber occurs on the exit side. The camber on the exit side is actually measured by lateral displacement meters 29 and 30 provided on the entrance and exit sides, and the edger adjustment is controlled in the width direction so that ρ0 becomes zero. Several examples have been described above, but in actual operation, these different phenomena occur in combination. Therefore, the most effective control method is to detect and calculate (predict) temperature, camber, wedge, etc., and in addition to the conventional leveling adjustment, move the edger roll using feed-forward control and feedback control to adjust the camber. can be corrected.

[0038]

[Effects of the Invention] Since the camber control method in a hot rolling line according to the present invention is configured as described above, the following effects can be obtained. That is, since the camber ratio, wedge ratio, etc. are calculated and the edger roll is moved in the width direction to adjust the off-center amount, the camber of the rolled material can be effectively corrected. This has made it possible to stably thread the rolled material, eliminate roll errors due to camber, and improve yields and operating rates.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing a hot rolling mill according to the present invention.

FIG. 2 is a plan view showing a non-controlled state.

FIG. 3 is a cross-sectional view of the plate at section A in FIG. 2;

FIG. 4 is a sectional view of the plate at section B in FIG. 2;

FIG. 5 is a plan view showing a control start state.

FIG. 6 is a sectional view of the plate at section A in FIG. 5;

FIG. 7 is a cross-sectional view of the plate at section B in FIG. 5;

FIG. 8 is a plan view showing a steady state.

9 is a sectional view of section A in FIG. 8. FIG.

FIG. 10 is a sectional view of section B in FIG. 8;

FIG. 11 is a plan view showing a control state.

12 is a sectional view of section B in FIG. 11. FIG.

FIG. 13 is a plan view showing a control state.

14 is a sectional view of section A in FIG. 13. FIG.

15 is a sectional view of section B in FIG. 13. FIG.

[Explanation of symbols]

1 First stand 5 Load cell (rolling load measuring means) 6
First screw (roll gap adjustment means) 11
Lateral displacement meter (position detection means) 12 Lateral displacement meter (position detection means) 13 Wedge meter (plate thickness measurement means) 1
4 Thermometer (temperature measurement means) 20 nth stand 27 Vertical mill (edger roll) 50
1st rolling equipment 51 nth rolling equipment

Claims (2)

[Claims] Claims: 1. A first stand (1) provided with at least a rolling load measuring means (5) and a roll gap adjusting means (6); Temperature measuring means (14), plate thickness measuring means (13), and position detecting means (11, 12) for detecting the position of the rolled material in the width direction are provided on the entry and exit sides of the n-1st stand (1). a first rolling equipment (50), and an nth stand (50) provided with at least rolling load measuring means and roll gap adjusting means.
An edger roll (27) for moving the rolled material in the sheet width direction is provided on the entry side of the n-th stand (20), and the n-th stand (20)
In a rolling line equipped with an n-th rolling equipment (51) equipped with position detection means (29, 30) for detecting the position of the rolled material in the width direction on the entry and exit sides of the rolled material, the rolling measured with the first rolling equipment The wedge ratio, camber ratio, and temperature difference in the width direction of the rolled material are calculated from the thickness and temperature of the material, the position in the width direction of the rolled material, the rolling load, and the roll gap, and the camber of the rolled material is corrected using these values. Calculating the camber based on the feed forward control that adjusts the positional relationship between the center of the rolled material in the width direction and the center of the rolling mill using the edger roll, and the position of the rolled material in the width direction on the entrance and exit side of the nth rolling mill, A camber control method in a hot rolling mill, comprising feedback control for adjusting the position of the edger roll so as to correct the camber from this value. 2. The wedge ratio, camber ratio, and temperature difference in the width direction of the rolled material are determined from the thickness and temperature of the rolled material, the position in the width direction of the rolled material, the rolling load, and the roll gap measured in the first rolling equipment. Based on these values, the roll level of the first rolling mill is adjusted to correct the camber of the rolled material, and the positional relationship between the center of the rolled material in the width direction and the center of the n-th rolling mill is adjusted to correct the camber of the rolled material. Feed forward control adjusted by edger roll and nth
The camber is calculated based on the position in the width direction of the rolled material on the entry and exit sides of the rolling mill, and the roll level of the n-th rolling mill is adjusted along with feedback control for adjusting the position of the edger roll to correct the camber based on this value. The camber control method in a hot rolling mill according to claim 1.