JPH0671611B2 - Edge drop control method in strip rolling - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for controlling edge drop of a strip in strip rolling.

(Prior Art) It is desirable that the rolled plate has a small edge drop and has a good shape, that is, the flatness of the plate is uniformly good not only in the plate longitudinal direction but also in the plate width direction. In particular, recently, the requirements for edge drop and shape of a rolled sheet have become more severe.

As one of the methods for controlling the edge drop, there is a method for adjusting the shift in the plate width direction of the work roll in which the roll body end portion is tapered.

For example, in the technique disclosed in Japanese Patent Application Laid-Open No. 58-209402, the shift of the tapered work roll pair in the plate width direction is adjusted according to the plate width. Further, in the technique disclosed in JP-A-60-12213, the edge drop amount measurement value of the steel plate from the plate thickness gauge on the exit side of the final stand and the target edge drop amount set value are compared and calculated, and this comparison is performed. Based on the calculated value, the work roll shift control and the roll bender operation pressure control are performed.

(Problems to be Solved by the Invention) However, in actual rolling, the edge drop amount of the hot rolled sheet changes depending on the conditions of hot rolling. Therefore, the conventional edge drop control cannot sufficiently reduce the edge drop. Further, when the work roll is shifted, the edge portion becomes thick and excessive tension is generated, which may cause ear cracking and the like.

(Means for Solving Problems) An edge drop control method in plate rolling according to the first aspect of the present invention controls a plate edge drop by shifting a work roll having a tapered roll cylinder end in the plate width direction. In the method, the work roll shift amount is adjusted based on the difference between the edge drop of the plate before rolling and its target value and the difference between the edge drop of the plate after rolling and its target value.
The tapered body end portion of the work roll is linearly or curved in a curve such as a sine curve or a circular arc, and contacts the side end portion of the plate. The tapered body end portion is hereinafter referred to as a taper portion.

To control the edge drop, it must be quantified appropriately. Therefore, at the positions at the distances a and b from the plate side edge toward the plate center, respectively, the formula (1)
An edge drop D is defined by two values D ₁ and D ₂ represented by

D ₁ = h _c −h _a D ₂ = h _c −h _b (1) where h _a , h _b and h _c are the distances a, b and c from the plate side edge toward the plate center. The plate thickness at a certain position, and a <b <c. These distances a, b and c are empirically chosen to adequately represent the edge drop D.

Using the edge drop defined as above, the work roll shift amount S _W is generally a function of the edge drop D ₀ of the sheet before rolling and the edge drop D after rolling, S _W = f _s (D ₀ , D) ... (2) _{or, ΔS W = f s (ΔD} 0 as the amount of change, represented by ΔD) ... (3). Here, the work roll shift amount _SW is the distance from the taper start point of the work roll to the plate side end.
The effect of F _W on the edge drop D is generally smaller than that of S _W. Where ΔD ₀ is the difference between the standard edge drop before rolling and the actual edge drop, and ΔD ₀ is
D is the difference between the target edge drop after rolling and the edge drop of the rolled plate.

The above formulas (2) and (3) are obtained in advance by experiments or numerical analysis for an actual machine. Further, the accuracy of these expressions (2) and (3) can be improved by learning.

The edge drop of the plate before or after rolling is measured by, for example, a crown meter arranged immediately before and after the rolling mill, respectively. Work roll shift amount
To set S _W , check the plate side edge position with a width meter etc.,
The work roll is shifted so that the starting point of the roll taper is located at a distance of S _W from the end position on the plate side.

The edge drop control method in strip rolling according to the second aspect of the present invention performs tension control of the edge portion of the strip in addition to the edge drop control of the first aspect of the present invention.

The tension at the plate edge changes according to the change in the Wakuroll shift amount ΔS _W and the change in the work roll bender force ΔF _W , and the change amount in the plate edge tension ΔΛ is generally expressed by the following equation (4). _{= f Λ (ΔS W, ΔF} W) becomes a ... (4). Incidentally. Since the plate tension depends on the plate shape represented by the steepness and the like, ΔΛ may be treated as a plate edge shape instead of the plate edge tension. Formula (4) is also obtained in advance by experiments or numerical analysis for the actual machine.

(Operation) When the edge drop D ₀ of the plate on the rolling mill entrance side or the edge drop D after rolling is large, the work roll shift amount _SW is adjusted so that the contact length of the taper portion of the work roll becomes larger. . As a result, the reduction of the edge of the plate is reduced, and the edge drop D of the rolled plate is reduced.

Further, when the work roll shift S _W is adjusted to reduce the edge drop D of the rolled plate as described above, tension generated in Itatan portion during rolling becomes larger trend. When the work roll shift amount S _W is adjusted as described above, the work roll bender force F _W is adjusted in order to prevent the tension from becoming excessive. As a result, the tension at the edge of the plate is lowered, and the occurrence of ear cracks is prevented.

(Embodiment) Embodiment of the first invention Fig. 1 shows an example of a cold rolling mill in which the present invention is implemented.

The cold rolling mill 5 is a 6-high rolling mill including work rolls 6, intermediate rolls 7 and backup rolls 8. The work roll 6 has a taper portion 6a at the end of the roll body,
It is displaced in the roll axis direction by the work roll shift 13. Also, as a shape control means, the work roll bender 1
1, an intermediate roll shift 14 and a coolant supply device 16 are provided. An edge drop detector 18 that measures the edge drop of the hot-rolled coil 1 to be rolled is provided on the inlet side of the cold rolling mill 5, and an edge drop detector that measures the edge drop of the rolled sheet on the outlet side. 20 are arranged.
As the entrance-side edge drop detector 18 and the exit-side edge drop detector 20, an X-ray type crown meter or a multi-beam type crown meter is used. Further, a load cell for detecting the rolling load P is provided in the reduction device (not shown).
22 are arranged. The cold rolling mill 5 is controlled by a control computer and a controller (neither is shown).

FIG. 2 is a drawing for explaining the definition of edge drop.
In this embodiment, the edge drops D ₁ and D ₂ are defined as follows.

_{D 1 = h 50 -h 15 D} 2 = h 50 -h 25 ... (5) Namely, a = 15 mm in the formula (1), b = 25mm, c =
It is set to 50 mm.

In the edge drop control method of this embodiment, edge drops are detected on the inlet side and the outlet side of the rolling mill.
Then, the work roll shift amount is feedforward-controlled based on the detected entrance side plate edge drop, and the work roll shift amount is feedback controlled based on the exit side plate edge drop.

In the above apparatus, the cooling condition of the work roll 6 by the coolant supply device 16 and the shift amount S of the intermediate roll 7 are preset according to the rolling conditions.

Edge drop variation of entry side delta D and exits the work roll shifting correction amount delta S _W by the change amount D ₀ of edge drop of the side plates is given by the following equation (6).

here, In each of the above formulas, the subscript W represents the work side, D represents the tribe side, − represents the row vector, and ˜ represents the matrix. The coefficient of influence And influence coefficient It is one in which the edge drop variation delta D and delta D ₀ respectively represent the degree of influence on the work roll shift S _W, by experiment for an actual machine, or advance determined by numerical analysis, and stored in the control computer Keep it.

FIG. 3 is a block diagram of the control system of this embodiment.

As shown in FIG. 3, edge drop variation delta D of the rolled plate are determined by the two elements of the change amount delta S _W, and entrance side edge drop amount of change delta D ₀ of the work roll shifting. Influence coefficients shown in these variation delta S _W and delta D ₀ effect on the edge drop variation delta D of plates that are rolled in each of equations (7) and (8) It is represented by.

These influence factors In either case, it is possible to obtain the actual machine in advance by experiments or by numerical analysis.

The characteristics of the detector, regulator and output device in the above block diagram are as follows.

The plate edge drop on the rolling mill entry side precedes rolling by time τ ₁ , and the plate edge drop on the rolling mill exit side is delayed by time τ ₁ between rolling and shape detection.
Each is detected by the crown meter. Based on the detected rolling mill entrance and exit plate edge drop,
The influence coefficient represented by the equations (6e) and (6d) Is used to determine the work roll shift correction amount corresponding to each edge drop. These correction amount is being summed as shown in the equation (6), a work roll shifting correction amount delta S _W is obtained. Work roll shifting correction amount delta S _W obtained by the calculation is output to the work roll shifting through the steady-state deviation compensator and control law. The work roll shift output is feedback-controlled.

Second Embodiment of the Invention In this embodiment, the control of the plate edge tension is further added to the embodiment of the first invention.

Edge drop variation of entry side delta D and exits the work roll shifting correction amount delta S _W by the change amount D ₀ of edge drop of the side plates is given by the equation similar to the embodiment of the first invention (3).

When the work side work roll shift amount is ΔS _WW , the drive side work roll shift amount is ΔS _WD , and the work roll bender force is changed by ΔF _W , the plate edge tension Λ _e is expressed by the following equation (14). It changes by ΔΛ _e as described above.

ΔΛ _e = A _se (ΔS _WW + ΔS _WD ) + A _Fe ΔF _W (14) Here, A _se and A _Fe are influence coefficients, and generally A _mn = α _mn R + β _mn S + γ _mn (14a) α _mn , β _mn , γ _mn : Constants are shown in the form of m = S, F n = 1,2, R is a work roll radius, and S is an intermediate roll shift position. Note that S = 0 when the intermediate roll shift is not used.

In the formula _{(14), ΔΛ e = 0} ( i.e., even if the work roll shifting amount S _W and the work roll bender force F _W is changed, the tension .DELTA..LAMBDA _e of the plate edge to maintain the required value) and put the , ΔF _W = B _F ^T · Δ S _W (15) is obtained. here Is.

FIG. 4 is a block diagram of the control system of this embodiment.

Fourth, as shown in FIG, rolled edge drop variation of the plate was delta D is the amount of change work roll shift delta S _W, the amount of change entry side edge drop delta D ₀ and a work roll bender force variation [Delta] F _W It depends on three factors. Influence coefficients influence on edge drop variation delta D of delta S _W and delta D ₀ is rolled each plate of these variation is shown by the formula (7) and (8) It is represented by. Further, influence coefficients influence the edge drop variation delta D of plates variation [Delta] F _W of the work roll bender force is rolling shown by the following formula (16) It is represented by.

Influence coefficient It is also possible to obtain the actual machine in advance by experiments or by numerical analysis.

The characteristics of the control law and work roll bender system in the above block diagram are as follows.

Control law: Here, the subscript S indicates a work roll shift, and W indicates a work roll bender.

Work roll vendor system: In the above control system, the procedure until the outputs calculated work roll shifting correction amount delta S _W, this in the work roll shifting is the same as the first embodiment. In this embodiment, the correction amount ΔF _W of the work roll bender force is calculated by the above equation (15) based on the output of the work roll shift and is output to the work roll bender. The output of the work roll vendor is feedback controlled.

Here, a specific example of the edge drop of the plate obtained by the method of this embodiment will be described. The rolling equipment was a 6-stand tandem cold rolling mill, and the edge drop was measured on the exit side of the first stand. The specifications of the rolling stand and rolling conditions are as follows.

Work roll diameter: 350mm Body length: 2020mm Intermediate roll diameter: 600mm Body length: 2020mm Backup roll diameter: 1300mm Body length: 2020mm Plate size: Plate thickness 2.7mm → 1.89mm, Plate width 1200mm Rolling ratio: 30% Rolling load: 690ton Tension: Front 13kg / mm ² Rear 3kg / mm ^{2 Under the} above conditions, when the work roll shift is set by the conventional method, the edge drop of the strip on the output side of the rolling mill greatly varies from coil to coil, and it looks like a magnetic steel sheet. Plate breakage occurred frequently in such brittle materials. On the other hand, according to the method of this example, the edge drop of the plate on the delivery side of the rolling mill greatly reduces the variation between the coils, and even if it is a brittle material such as an electromagnetic steel plate, there is no plate breakage. It was

(Effect of the Invention) According to the present invention, the work roll shift amount is adjusted based on the edge drop of the plate before and after rolling, so that the variation in the edge drop between the coils is significantly reduced. Moreover, since the work roll shift amount is adjusted and the work roll bender is also adjusted, no plate breakage occurs.

[Brief description of drawings]

FIG. 1 shows an example of a cold rolling mill in which the present invention is carried out. FIG. 1 is a schematic perspective view of the rolling mill, FIG. 2 is a drawing for explaining the definition of edge drop, and FIGS. 3 and 4 are respectively 1 is a block diagram of a control system, showing an embodiment of the present invention. FIG. 1, 2 ... rolling plate, 6 ... work roll, 6a ... work roll taper part, 7 ... intermediate roll, 8 ... backup roll, 11 ... work roll bender, 13 ... work roll shift, 14 ...... Intermediate roll shift, 16 …… Roll coolant supply device, 18 …… Roll mill entrance side plate edge drop detector, 20 …… Roller exit side plate edge drop detector, 22 …… Load cell.

Claims (2)

[Claims] 1. A method of controlling an edge drop of a plate by shifting a work roll having a taper end portion of a roll in a plate width direction, the difference between the edge drop of the plate before rolling and a target value thereof. And an edge drop control method in sheet rolling, which comprises adjusting a work roll shift amount based on a difference between an edge drop of the sheet after rolling and a target value thereof. 2. A method of controlling an edge drop of a plate by shifting a work roll having a tapered roll cylinder end in the plate width direction, the difference between the edge drop of the plate before rolling and its target value, And the work roll shift amount is adjusted based on the difference between the edge drop of the rolled plate and its target value, and the work roll bender force is adjusted so that the tension at the plate edge becomes an appropriate value. Edge control method for strip rolling.