JP2003326313A - Method for coiling hot-rolled steel strip highly accurately - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a coiling method of a hot-rolled steel strip which is suitable for a period in the state where the hot-rolled steel strip is held with a coiler pinch roll on and after the tail end of the hot-rolled steel strip is passed through a finish rolling mill. <P>SOLUTION: In the coiling method of the hot-rolled steel strip for coiling a steel strip rolled with the finish rolling mill with a coiler, by this highly accurate coiling method of the hot-rolled steel strip, action for opening the gap between the upper and the lower rolls of the pinch roll is performed until the detected load P<SB>0</SB>is not larger than the upper limit PMAX of load in the case that load P<SB>0</SB>detected with a load cell installed between the chock of the lower roll of the pinch roll and a housing for the period that the hot-rolled steel strip is held with the pinch roll installed on the upstream side of the coiler exceeds the upper limit PMAX of load which is preliminarily set. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for winding a rolled steel strip, and more particularly, to a period in which a pinch roll holds the rolled steel strip after the tail end of the rolled steel strip has passed through the finishing mill. In the above, it relates to a high-precision winding method for rolled steel strip.

[0002]

2. Description of the Related Art Conventionally, steel strip is manufactured by so-called hot rolling. FIG. 1 is a diagram showing a typical equipment arrangement of a hot rolling line after a finish rolling mill. As shown in this figure, generally, in this hot rolling line, the rolled steel strip 1
Is finish-rolled by the finish rolling mill 2 and then conveyed through the runout table 4 while being passed through the cooling device 3 installed on the downstream side of the finish rolling mill 2 to cool to a predetermined temperature. While guiding the rolled steel strip 1 to the mechanical center line of the winder by means of the side guide 5 on the winder inlet side, the winder inlet side pinch roll 6 (hereinafter referred to as "pinch roll"), the pinch immediately before the winder A coil 9 is held by a winder mandrel 8 (hereinafter referred to as a mandrel) while being sandwiched by rolls 7 (hereinafter referred to as coiler pinch rolls).
Is being rolled up.

As an example of the mechanical structure of the pinch roll, FIG. 2 shows the arrangement of each device constituting the pinch roll. As shown in this figure, the pinch roll is a lower roll 10 and an upper roll 1 by a gap adjusting device 14 that changes the position of the upper roll 11 installed in the housing 12.
The rolled steel strip 1 is clamped by adjusting the gap between the rolled steel strip 1 and the rolled steel strip 1.
At this time, the load P ₀ detected by the load cell 13 arranged between the chock of the lower roll 10 and the housing 12 becomes the load applied to the rolled steel strip 1. Depending on the state of the rolled steel strip 1, the winding work of the steel strip after finish rolling in such a hot rolling line is performed as shown in FIGS.
And (c) can be classified into three types. Figure 3
In (a), the rolled steel strip 1 is rolled by the finish rolling mill 2,
Moreover, the state in which the most distal end of the rolled steel strip 1 is not wound around the mandrel 8 is shown (hereinafter, referred to as state (a)). Figure 2
In (b), the rolled steel strip 1 is rolled by the finish rolling mill 2,
Moreover, a state in which the steel strip is wound by the mandrel 8 is shown (hereinafter, referred to as a state (b)). Figure 2 (c) shows
The state where the rolled steel strip 1 has been rolled, the tail end has passed through the final stand of the finishing rolling mill 2, and the mandrel 8 has wound the steel strip (hereinafter, state (c) Called). In the states (b) and (c), the pinch roll 6 and the coiler pinch roll 7 sandwich the rolled steel strip 1.

Generally, when the rolled steel strip walks in the width direction, the end faces of the coils are not aligned, the winding shape deteriorates, and quality troubles occur. To prevent such a walk,
By constantly applying tension to the rolled steel strip, the steel strip is stably centered. As the magnitude of this tension is sufficiently large within a range that does not adversely affect the quality, the walk of the rolled steel strip becomes smaller and the winding shape improves. FIG. 4 is a diagram showing the tension applied to the rolled steel strip 1 by each device constituting the winder during the state (c). A tensile force in the traveling direction of the steel strip in which a mandrel is generated in the steel strip: T _MN and a direction opposite to the traveling direction of the steel strip in which a coiler pinch roll, a pinch roll, and a runout table are generated. The tensile force (referred to as T _nPR , T _0PR , and T _HRT , respectively) is applied to perform a stable coil winding. At this time, the coiler pinch roll and the pinch roll that mechanically clamp the steel strip are intentionally strengthened to improve the winding shape of the coil. Strong force against T _MN : T
_{Whereas nPR} and T _0PR can be secured, the runout table in which the _steel strip is not mechanically clamped is T _MN ,
It can exert only weak force as compared with T _{n PR} and T _0PR .

In addition, in the state (c), an operation is carried out in which the speed of the steel strip is rapidly reduced from a high speed during finish rolling to a low speed for improving the winding shape. In particular, the inertial force in the traveling direction: F _BAR acts on the portion of the steel strip 1 that is present on the run-out table. As a result, in the state (c), strong forces in the direction opposite to the traveling direction of the _steel strip 1, T _nPR , T _0PR and F _BAR , act in a direction to _relax the tension of the _steel strip 1. Therefore, in the state (c), the steel strip 1 has
Since only a very weak tension can be applied, the running of the steel strip 5 becomes unstable and the walk in the width direction of the strip becomes large, especially when winding a thin strip of steel strip, etc.
As shown in, there was a frequent occurrence of "plate escape problems after slipping out of the finish butt", which deteriorated the winding shape of the coil.

[0006] In particular, this "plate escape problem after slipping out of the finish tail" is strongly influenced by the magnitude of T _0PR , which has the strongest action of loosening the tension, so in conventional operations, this effect should be reduced. The operator frequently performs manual adjustment of the nip gap between the coiler pinch rolls and the pinch rolls according to the rolling condition at each time, and the operation of searching for the optimum point has been performed. However, due to the fact that the theoretical optimum point is unknown and the occurrence of troubles occurs instantly, the troubles could not be prevented even by performing these manual adjustments.

[0007]

SUMMARY OF THE INVENTION The present invention solves the problems of the prior art as described above, the rolling of the rolled steel strip is completed, and the tail end passes through the final stand of the finishing rolling mill.
And, while the coiler is winding the steel strip, the pinching load of the pinch roll can be controlled so that tension can be constantly applied to the steel strip on the run-out table. The running of the steel strip becomes unstable when winding a thin steel strip, and the walk in the width direction of the strip becomes large, and the winding appearance deteriorates. It is an object of the present invention to provide a high-accuracy winding method for a rolled steel strip, which is improved to significantly reduce quality mismatch and at the same time improve the coil winding shape.

[0008]

The present invention solves the above problems, and the gist of the present invention is the following contents as set forth in the claims. (1) In a winding method of a rolled steel strip in which a steel strip rolled by a finish rolling mill is wound by a coiler, during a period in which a pinch roll installed upstream of the coiler holds the rolled steel strip,
The load P detected by a load cell arranged between the chock of the lower roll of the pinch roll and the housing
_{When 0} exceeds a preset load upper limit P _MAX , the operation of opening the gap between the upper and lower rolls of the pinch roll is carried out until the detected load P ₀ becomes equal to or less than the load upper limit P _MAX. High precision winding method for rolled steel strip.

(2) When viewed from the side with respect to the traveling direction of the steel sheet, the plate thickness 1/2 immediately below the pinch roll bite is taken as the origin, the y axis is taken in the thickness direction, and the steel sheet traveling direction When the x-axis is taken on the basis of the difference 2G between the plate thickness of the rolled steel strip and the gap between the upper and lower pinch rolls and the load P ₀ detected by the load cell, the rolled steel strip at the coordinates (x, y) The stress σ _{x in the} longitudinal direction of the rolled steel strip, the stress σ _{y in the} plate thickness direction, and the shear stress τ _xy that occur in the pinch roll sandwiching part are obtained by the formulas (i) to (vii), and each value is a predetermined value. Upper limit of load P that is a range value
The high-precision winding method for a rolled steel strip according to (1), characterized in that the clearance between the upper and lower rolls of the pinch roll is manipulated in order to obtain _MAX . _{p'= 3 · P 0 / (} 4 · w · L) ··· (i) P 0 = k · 2G ··· (ii) L = √ (G · R-G 2/4) ··· ( iii) Q (x) = − 2 · μ · p ′ / L ² · (x ³ / 3−L ² · x) + 4 · μ · p ′ · L / 3−h · T _out ... (iv) σ _x = −Q (x) / h − ((2 · μ · (−p ′ / L ² ) · (x ² −L ² )) / h) · x + (μ / h) · (2y ² − ^{x 2 -h 2/6) ·} (-2 · p'· x / L 2) _{··· (v) σ y = -} (p'/ L 2) · (x 2 -L 2) + (μ / h) · ((h 2/4) -y 2) · (-2 · p'・ X / L ² ) ・ ・ ・ (Vi) τ _xy = ((2 ・ μ ・ y) / h) ・ (-p '/ L ² ) ・ (x ² -L ² ) ・ ・ ・ (vii) where T _out : pinch External force per unit cross-sectional area in the longitudinal direction acting on the steel strip on the roll exit side , H: plate thickness of rolled steel strip, w: plate width of rolled steel strip, μ: coefficient of friction between rolled steel strip and pinch roll, R: roll radius of pinch roll, P
₀ : Load detected by load cell, 2G: Difference between plate thickness of rolled steel strip and gap between upper and lower pinch rolls, k: Ratio between P ₀ and 2G (P ₀ / 2G)

(3) The value of the upper limit P _MAX of the load is such that the longitudinal stress σ _{x = L} of the part of the part where the steel strip is pinched by the pinch rolls is closest to the pinch side of the pinch roll. The high-precision winding method for a rolled steel strip according to (1) or (2), wherein the external force T _in per unit cross-sectional area in the longitudinal direction acting on the steel strip is set to be equal to or less than the range. (4) Using the external force T _in per unit cross-sectional area in the longitudinal direction acting on the steel strip on the pinch roll entrance side, the value of P _MAX is calculated as h · T _out −μ · p ′ · L · (h ² / (6 · L ² ) −2/3) ≦ h · T _in ... (viii) is set to the maximum P _0, and the method for highly accurate winding of a rolled steel strip according to (1) to (3) is characterized.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION The preferred embodiment of the present invention is as follows.
In the winding method of the rolled steel strip, the formulas (i) to (viii)
According to the above, a computer for _obtaining the value of P _MAX , a load cell mounted between the lower pinch roll chock and the pinch roll housing and capable of detecting the load during clamping of the steel strip, and a device for measuring and opening the gap between the upper and lower pinch rolls , A device for calculating or measuring the acceleration / deceleration rate and weight of the steel strip, a device for calculating or measuring the tension generated by the mandrel, pinch rolls, and the load detected by the load cell, and determining the appropriate roll gap change amount, That is, the winder can be controlled by a device or a computer that can issue a command to the gap opener.

The present invention will be described in detail below with reference to the drawings. FIG. 6 is a layout diagram showing a schematic configuration of a hot rolling line after the finish rolling mill applied to the embodiment according to the present invention. In the actual application of the present invention, in order to reduce the computer load of the device that controls the winder, the plate thickness of the rolled steel strip, the plate width, and the rolling speed / acceleration / deceleration pattern for each of formulas (i) to ( According to vii), the load upper limit P _MAX satisfying the expression (viii) is calculated in advance by the offline computer 15. At this time, the coordinate system of each variable used in the calculation is set as shown in FIG. In addition, the external force per unit cross-sectional area in the longitudinal direction, which acts on the steel strip on the pinch roll exit side, T _out
For the, the deviation between the tension T _{MN applied} to the steel strip during winding by the mandrel and the tension T _nPR generated by the coiler pinch roll is used, and the longitudinal direction acting on the steel strip on the pinch roll entry side is used. External force per unit cross section T _in
For, the acceleration / deceleration rate of the steel strip being wound is dV / dt,
Weight M of moieties present on the run-out table of the steel band, and, from the friction coefficient mu _{HR T} between the steel band and the run-out table rolls, calculated by the following formula (ix). T _in = _μHRT・ MM ・ dV / dt (ix)

Next, in the control device 2 of the winder, the off-line computer 1 sets the load upper limit P _MAX according to the plate thickness, plate width, speed pattern, T _out and T _in of the steel strip. To be done. Then, the control device 16 sequentially calculates the actual values of T _out and T _in during the winding of the steel strip, obtains P _MAX in each case, and arranges them between the pinch roll lower roll and the pinch roll housing. Load detected by the loaded load cell P
Compare ₀ to P _MAX . At this time, P ₀ ≦ P _MAX
Then, keep the roll gap of the pinch roll as it is,
If P ₀ > P _MAX , the operation of issuing a command to the pinch roll roll gap adjusting device 14 to widen the roll gap of the pinch roll until P ₀ ≦ P _MAX ,
The operation is continuously performed until the tail end of the steel strip passes through the pinch roll.

Thus, the value of the load upper limit P _MAX is
The longitudinal stress σ _{x = L of the} part of the part that is pinching the steel strip with the pinch rolls, which is closest to the pinch roll entry side, is the external force per unit cross-sectional area in the longitudinal direction that acts on the steel strip on the pinch roll entry side. By setting the range to be not more than T _in , the Ti existing on the run-out table part of the steel strip must be Ti.
Since tension corresponding to the deviation between n and σ _{x = L} is applied, it is possible to prevent plate escape. Although the present invention has been specifically described above, the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the scope of the invention. For example, it is also within the scope of the present invention that the value α · P _MAX obtained by multiplying the value of the load upper limit P _MAX obtained from the off-line calculation by the adjustment coefficient α is used as the load upper limit in the controller of the winder. .

[0015]

As described above, according to the present invention, the rolling of the rolled steel strip is completed, the tail end has passed through the final stand of the finish rolling mill, and the coiler has wound the steel strip. In the state, it is possible to control the pinching load of the pinch roll so that tension can be constantly applied to the steel strip in the portion existing on the runout table,
Especially when winding a thin steel strip, the running of the steel strip becomes unstable and the walk in the width direction of the strip becomes large, and the winding appearance deteriorates. We were able to greatly improve the quality mismatch, and at the same time improve the coil winding shape.

FIG. 7 shows changes in the plate walk amount of the rolled steel strip before the pinch roll and the pinching load P ₀ of the pinch roll before and after the measures of the present invention. As shown in this figure, before the countermeasure, the clamping load P ₀ becomes higher as the rolled steel strip progresses after the tail end of the steel strip passes through the final stand of the finish rolling mill, and a certain load P _MAX A sharp plate walk occurred at the timing of crossing, and there was a "plate escape trouble after finishing finish slippage" that deteriorates the winding shape, whereas after the countermeasure, the pinch roll clamping load P ₀ is always applied. Since it is stabilized in the region where the upper limit P _MAX is not exceeded, it can be seen that the tension to the steel strip can be properly secured, the plate walk hardly occurs, and the steel strip is stably wound.

In addition, there is a problem of board escape after the finish butt slips out.
Before the measures according to the present invention, the average was 30 cases per month, but after the measures, the average was 2 cases per month, which was 1/10 that of before the measures. Furthermore, it was done conventionally,
Frequent manual adjustments to the pinch roll gap by the operator could be completely eliminated.

[Brief description of drawings]

FIG. 1 is a diagram showing a typical equipment arrangement of a hot rolling line after a finish rolling mill.

FIG. 2 is a diagram showing an outline of a mechanical structure of a coiler pinch roll in a hot rolling line.

[Fig. 3] In the hot rolling line, the winding work of the steel strip after the finish rolling mill is classified into three types according to the positions of the top and tail portions of the steel strip and the positional relationship between the finish rolling mill and the winder. FIG.

FIG. 4 is a schematic diagram showing the tension acting on the steel strip after the tail end of the rolled steel strip has passed through the finishing mill.

[Fig. 5] In carrying out the present invention, a load upper limit P
It is the schematic diagram which shows the xy coordinate system used when calculating _MAX .

FIG. 6 is a block diagram for controlling the pinch roll clearance based on the magnitude relationship between the pinch roll clamping load P ₀ and the load upper limit P _{MAX in} carrying out the present invention.

FIG. 7 is a graph showing changes over time in the amount of steel strip walk on the winding machine entrance side and the pinch roll clamping load P ₀ .

[Explanation of symbols]

1: Rolled steel strip, 2: Finishing mill, 3: Cooling device, 4: Runout table, 5: Side guide, 6: Pinch roll, 7: Coiler pinch roll, 8: Mandrel, 9: coil, 10: lower roll, 11: upper roll, 12: housing, 13: load cell, 14: gap adjusting device, 15: Offline calculator, 16: control device,

Claims (4)

[Claims] 1. A method for winding a rolled steel strip in which a steel strip rolled by a finish rolling mill is wound by a coiler, wherein during the period in which a pinch roll installed upstream of the coiler holds the rolled steel strip, When the load P ₀ detected by the load cell arranged between the chock of the lower roll of the pinch roll and the housing exceeds the preset load upper limit P _{M AX} , the detected load P ₀ is the load. A high-precision winding method for a rolled steel strip, which comprises performing an operation of opening a gap between the upper and lower rolls of the pinch roll until the upper limit P _MAX or less. 2. When viewed from the side with respect to the traveling direction of the steel sheet, the plate thickness 1/2 directly below the pinch roll bite is taken as the origin, the y axis is taken in the thickness direction, and When the x axis is taken, the pinch of the rolled steel strip at coordinates (x, y) is based on the difference 2G between the thickness of the rolled steel strip and the gap between the upper and lower pinch rolls and the load P ₀ detected by the load cell. The stress σ _{x in the} longitudinal direction of the rolled steel strip, the stress σ _{y in the} plate thickness direction, and the shear stress τ _xy that occur at the nip part of the roll are determined by equations (i) to (vii), and each value is within the specified range. The high-precision winding method for a rolled steel strip according to claim 1, wherein an upper limit P _MAX of the load within a range of the value is obtained and the gap between the upper and lower rolls of the pinch roll is manipulated. _{p'= 3 · P 0 / (} 4 · w · L) ··· (i) P 0 = k · 2G ··· (ii) L = √ (G · R-G 2/4) ··· ( iii) Q (x) =-2 · μ · p ′ / L ² · (x ³ / 3−L ² · x) + 4 · μ · p ′ · L / 3−h · T _out ... (iv) σ _x = −Q (x) / h − ((2 · μ · (−p ′ / L ² ) · (x ² −L ² )) / h) · x + (μ / h) · (2y ² − ^{x 2 -h 2/6) ·} (-2 · p'· x / L 2) _{··· (v) σ y = -} (p'/ L 2) · (x 2 -L 2) + (μ / h) · ((h 2/4) -y 2) · (-2 · p'・ X / L ² ) ・ ・ ・ (Vi) τ _xy = ((2 ・ μ ・ y) / h) ・ (-p '/ L ² ) ・ (x ² -L ² ) ・ ・ ・ (vii) where T _out : pinch External force per unit cross-sectional area in the longitudinal direction acting on the steel strip on the roll exit side , H: plate thickness of rolled steel strip, w: plate width of rolled steel strip, μ: coefficient of friction between rolled steel strip and pinch roll, R: roll radius of pinch roll, P
₀ : Load detected by load cell, 2G: Difference between plate thickness of rolled steel strip and gap between upper and lower pinch rolls, k: Ratio between P ₀ and 2G (P ₀ / 2G) 3. The value of the load upper limit P _MAX is such that the longitudinal stress σ _{x = L of the} part of the part where the steel strip is pinched by the pinch rolls is closest to the pinch side of the pinch roll. The high-precision winding method for a rolled steel strip according to claim 1 or 2, wherein the external force T _in per unit cross-sectional area in the longitudinal direction acting on the strip is set to a range not more than T _in . 4. The value of P _MAX is calculated by using the external force T _in per unit cross-sectional area in the longitudinal direction acting on the steel strip on the pinch roll entrance side, h · T _out −μ · p ′ · L · (h ² / (6 · L ² ) −2/3) ≦ h · T _in The maximum P ₀ satisfying (viii) is set, and the method for winding a rolled steel strip with high precision according to any one of claims 1 to 3, wherein