JPH10128438A - Method for coiling continuous hot rolling metal strip - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the probability of occurrence of braking to two pieces on a steel strip just before the inlet side of pinch rolls by setting the drawing- down force of the pinch rolls just before the inlet side of a shear to be equal to the value shown with a specific equation or a larger value than the above in a time of cutting the metal strip. SOLUTION: The drawing-down force of pinch rolls 4 is increased to a specific value P or beyond the P just before cutting a steel strip S with a shear 3. the specific value P is the value of being P=T/μ0 , T is made as the tension of applying ion the steel strip S between the winding coiler K1 and a rolling machine 2, μ0 is made as the coefficient of dynamical friction. Therefore, because the following strip is fed out to the coiler side resisting to the force toward the rolling machine side generated caused by cutting while being pressed with the pinch rolls 4 without slipping, the generation degree of weaving can be made few. As a result, the generation of breaking two pieces just before the inlet side of the pinch rolls 4 can be made few.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a metal strip which has been continuously hot-rolled and has come out of a finishing mill, is cut by a shear at a predetermined length, and the cut preceding and succeeding materials are lined. The present invention relates to a method for winding a continuous hot-rolled metal strip, which is wound alternately by a plurality of coilers arranged in series along a line.

[0002]

2. Description of the Related Art Conventionally, hot rolling of a steel strip has been carried out in batches for each slab and wound up into a single coil. In recent years, however, sheet bars obtained by roughly rolling slabs have been joined together. ,
Continuous hot rolling for continuously finishing and rolling this is being performed. In this continuous hot rolling, the steel strip after finish rolling is cut by a shear at a joining position, and the cut preceding and succeeding materials are alternately coiled by a plurality of coilers arranged along a line into a plurality of coils. Winding is performed.

[0003] In such continuous hot rolling, a tension is applied to a steel strip between a winding coiler and a finish rolling mill, thereby performing stable threading and winding.
Then, as shown in FIG. 4, the steel strip S output from the finishing mill 2 is pinched by the pinch roll 5 immediately before the winding coiler and the pinch roll 4 immediately before the shear entry side, and cut by the shear 3. I have.

Therefore, until immediately before cutting by the shear 3, the steel strip S between the finishing mill 2 and the winding coiler is used.
Is stretched within the elastic limit due to the tension.
, The tension is lost and the following material S ₁
Then, a force returning to the finish rolling mill 2 is generated. Accordingly, it may Uebingu the next strip S ₁ after the strip passing table 7 is generated, the worst case as it is broken two to the next strip S ₁ (broken overlap along the sheet passing direction) occurs Pinch roll 4
If it is wound up as it is, the steel strip may break during winding, and there is a risk that a sheet passing accident may occur.

[0005]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems of the prior art. When cutting with a shear, is it possible to generate waving on the succeeding material cut by the shear? , Even if it occurs, the steel strip is prevented from being broken just before the pinch roll is inserted by preventing the steel strip from being present immediately before the entry of the pinch roll disposed immediately before the shear input side. It is an object to provide a method that can perform

[0006]

In order to solve the above-mentioned problems, the invention according to claim 1 is to wind a metal strip which is continuously hot-rolled and comes out of a finishing mill, to a predetermined length. It is pinched by the pinch roll just before the coiler and the pinch roll just before the shear entry side, cut by the shear, and the cut leading and trailing materials are alternately arranged by a plurality of coilers arranged in series along the line. In the method for winding a continuous hot-rolled metal strip to be wound, at the time of the cutting, the rolling force of the pinch roll immediately before the shear entry side is set to a value equal to or larger than a predetermined value P represented by the following equation (A). To provide a method for winding a continuous hot-rolled metal strip.

P = T / μ ₀ Ａ (A) (where T is the tension applied to the metal band between the winding coiler and the finishing mill just before cutting, and μ ₀
Is the dynamic friction coefficient between the pinch roll and the metal strip immediately before the shear entry side. Before cutting, the pinch roll just before the shear entry side is driven by the metal strip conveyed from the finishing mill and rotates in the direction of sending the metal strip to the coiler side. Generates a force F returning to the finish rolling mill.
To feed the following material to the coiler side against this force F, it is necessary to press the following material with the pinch roll.

Here, the kinetic frictional force f generated between the pinch roll and the trailing material of the cut steel strip is represented by f = μ ₀ · P, but P = T / μ ₀ Then, theoretically, a frictional force having the same magnitude as the tension T immediately before cutting occurs between the following material and the pinch roll at the moment of cutting. Thereby, the following material is sent out to the coiler side against the force F generated by cutting while being pressed down without slipping on the pinch roll, so that the degree of waving can be reduced.

The effect increases as the rolling force at the time of cutting increases. However, if the rolling force is too high, the following material tends to meander, causing poor winding when wound by a coiler. The value at which such winding failure does not occur is defined as the upper limit.

[0010] The invention according to claim 2 is the method of claim 1, wherein at the time of cutting a predetermined value Q _u represented torque of the upper roll of the pinch roll just before Shah entry side in (B ₁₎ the following equation substantially equal or equal to, substantially equal or equal to the predetermined value Q _b represented the torque of the lower roll (B ₂₎ the following equation, is characterized in that each set.

[0011] _{Q u = r u · T /} 2 ‥‥ (B 1) Q b = r b · T / 2 ‥‥ (B 2) ( where, T is, immediately prior to cutting, the take-up coiler and finishing mill is a tension that has been applied to the metal strip between the, r _u
Is the roll radius of said upper roll, r _b is the roll radius of the lower roll. Thus, immediately after the cutting, the following material pinched by the pinch roll immediately before the shear entry side is pulled with the same or substantially the same force as the tension immediately before the cutting, so that waving can be prevented.

According to a third aspect of the present invention, a metal strip which has been continuously hot-rolled and which has exited from a finish rolling mill has a predetermined length and is provided with a pinch roll immediately before a winding coiler and a pinch roll immediately before a shear-in side. In the method of winding a continuous hot-rolled metal strip, the preceding material and the following material that have been cut and cut by the shear are alternately wound by a plurality of coilers arranged in series along the line. At the time of the cutting, the continuous heat characterized by setting the feeding speed of the metal strip by the threading table arranged on the output side of the finishing mill, lower than the moving speed of the metal strip immediately after the output side of the finishing mill. Provided is a method for winding a cold-rolled metal strip.

[0013] The invention according to claim 4 is the invention according to claim 1 or 2.
In the method described in the above, at the time of the cutting, the feeding speed of the metal band by the threading table arranged on the output side of the finishing mill, the speed is set lower than the moving speed of the metal band immediately after the output side of the finishing mill. It is characterized by the following.

Here, the behavior of the metal band on the passing plate table at the time of cutting is analyzed as a longitudinal vibration phenomenon of the elastic band. The vibration equation of the longitudinal wave of the plate is expressed by the following equation (1),

[0015]

(Equation 1) In the equation (1), C _e (force propagation speed) is a sound velocity in the metal band, and is expressed by the following equation (2).

[0016]

(Equation 2) In the equation (2), E is the Young's modulus of the metal band, and ρ is the density of the metal band. The metal band on the threading table at the time of cutting can be represented by a model of one end fixed (finishing mill 2) and the other end free (shear 3) as shown in FIG. ) solving equation displacement u _x in the position x of the fixed end and the starting point is represented by the following expression (3), the stress sigma _x at position x is expressed by the following equation (4).

[0017]

(Equation 3)

[0018]

(Equation 4) In the equations (3) and (4), l is a fixed end-free end distance, here 160 m, t is time, _An is an integration constant, and ω (natural frequency) is expressed by the following equation (5). Is done.

[0019]

(Equation 5) Then, the initial condition [u _{0 at} t = 0 (displacement per unit length at x = 0) = 2 kg / mm ² ] is given by (3),
(4) by substituting determine the integration constant A _n in formula. Using this integration constant _An , from the equations (3) and (4), the time t = 0,
0.023, 0.046, 0.050, 0.068
Displacement u _x and stress σ _{x at} each position X in [sec]
I asked. The result is shown in FIG.

As can be seen from the result, the initial tension is lost from the free end, and a compressive stress is generated from the fixed end.
When the compressive stress exceeds the buckling limit, it is estimated that webbing occurs on the metal strip on the passing plate table. This compressive stress propagates from the fixed end to the free end. That is, the waving is first generated at the portion of the finishing mill 2 which is the fixed end, and propagates to the portion of the shear 3 which is the free end.

In the method according to the third and fourth aspects, at the time of cutting, the feeding speed of the metal strip by the threading table is lower than the moving speed of the metal strip immediately after the exit side of the rolling mill. A force in the direction of the rolling mill is applied to the metal strip on the table. This makes it possible to delay the speed at which the waving generated on the side of the finishing mill propagates to the shear side.

Therefore, the leading end portion of the cut running material can be wound around a coiler without waving. Then, after the leading end portion is wound, tension is generated between the pinch roll just before the winding coiler and the finishing mill, so that the waving generated on the finishing mill side is also eliminated.

In general, the feeding speed of the metal strip by the passing table is set to be the same as the moving speed of the metal strip immediately after the exit side of the finishing mill, so that the metal strip coming out of the finishing mill can be smoothly moved. It is to be conveyed (at the moving speed of the metal strip immediately after the exit side of the rolling mill), and in this method also in the normal state (just before cutting).

[0024]

Embodiments of the present invention will be described below. FIG. 3 is a schematic configuration diagram showing a winding-side facility row of a continuous hot rolling line to which the method of the present invention is applied.

This equipment row is provided with a roughly-rolled sheet bar S
₀Is introduced to join the tail end of the preceding material and the tip end of the following material.
Finish rolling of the joined sheet bar with the joining apparatus 1
Rolling mill (finish rolling mill) 2 and a steel strip (metal
Band) A shear 3 for cutting S at a predetermined length, and the insertion of the shear 3
Along the line with the pinch roll 4 placed just before
No.1 coiler K arranged in series₁And No.2 coiler
K_TwoAnd No.1 coiler K ₁Pin placed just before the entry side of
Tyrol 5 and No.2 coiler K_TwoIs located just before the entrance
And a pinch roll 6. This equipment line
The steel strip S which has been continuously finish-rolled is
No.1 coiler K while being cut to length₁And No.2
Ira K_TwoIs wound up alternately by a plurality of coils.

On the outlet side of the rolling mill 2 on the downstream side, a threading table 7 is arranged. This passing plate table 7,
This is a roller table in which a number of rollers 7a are arranged along a line, and all the rollers 7a are rotated at the same rotation speed. By setting the moving speed of the steel strip S immediately after the exit side to be the same as that of the steel strip S,
Is transported smoothly.

In such continuous hot rolling, the coiler to be wound (here, No. 1 coiler K
_A predetermined tension is applied to the steel strip S between ₁ ) and the rolling mill 2 to perform stable threading and winding. This tension is maintained by setting the winding torque of the coiler to a predetermined value, and the rolling force of the pinch roll 4 normally reduces the steel strip S conveyed from the rolling mill 2 by the shear 3.
It is set to an appropriate value so that it can be introduced smoothly. Further, no torque is applied to the pinch roll 4, and the pinch roll 4 is driven by the steel strip S conveyed from the rolling mill 2 and rotates in a direction of sending the steel strip S to the coiler side.

Then, immediately before the steel strip S is cut by the shear 3, the rolling force of the pinch roll 4 is increased to a predetermined value P. Further, the driving torque applied to each roll of the pinch roll 4, the torque of the upper roll 41 to a predetermined value Q _u, the torque of the lower roll 42 with a predetermined value Q _b. Further, the rotation speed of the roller 7a is set such that the feed speed of the steel strip S by the passing table 7 is lower than the moving speed of the steel strip S immediately after the rolling mill 2 exits.

The predetermined value P is defined as T, the tension applied to the steel strip S between the winding coiler K ₁ and the rolling mill 2 immediately before cutting, and the dynamic friction coefficient between the steel strip S and the pinch roll 4. Is set to μ ₀ , and a value satisfying P = T / μ ₀ is set.

Here, the kinetic frictional force f generated between the pinch roll 4 and the trailing material S ₁ of the cut steel strip is f = μ _0.
It is expressed by P, but by setting P = T / μ ₀ , theoretically, a frictional force having the same magnitude as the tension T immediately before cutting is generated at the moment of cutting, when the following material and the pinch roll Occurs between
As a result, the following material S ₁ is sent out to the coiler side against the force F generated by cutting, while being pressed against the pinch roll 4 without slipping.

[0031] The predetermined value Q _u, due the roll radius r _u of the tension T and the upper roll _{41, Q u = r u ·} T / 2
In represented by a value, the predetermined value Q _b is the the roll radius r _b of the tension T and the lower roll _{42, Q b = r b ·} T /
Let it be the value represented by 2. As a result, immediately after cutting, the following material S ₁ pinched by the pinch roll 4 is pulled by the same force as the tension T immediately before cutting, so that waving does not occur in a portion upstream of the pinch roll 4. be able to. Since the same tension T / 2 acts on the upper and lower surfaces, there is no problem such as deformation.

Since the feed speed of the steel strip S by the passing table 7 is slower than the moving speed of the steel strip S immediately after the rolling mill 2 exits, the rolling speed of the steel strip S on the passing table 7 is reduced. A force in the side direction is applied. Thus, even when waving occurs in the steel strip S on the upstream side of the pinch roll 4, the speed of propagation to the pinch roll 4 side can be slowed down by keeping the steel strip S on the rolling mill 2 side.

Therefore, immediately before the pinch roll 4 enters the steel strip S, the steel strip S is not broken and the coilers K ₁ , K _1
The winding by ₂ is performed stably. In the embodiment, immediately before the steel strip S is cut by the shear 3, the rolling force of the pinch roll 4 is increased to a predetermined value P;
The drive torque is applied to each roll of the pinch roll 4 and the feed speed of the steel strip S by the threading table 7 is made lower than the moving speed of the steel strip S immediately after the rolling mill 2 exits. However, for example, only may be performed.

In this case, the pinch roll 4 and the rolling mill 2
Sufficient for tension does not act, but more likely to Uebingu as compared with the case of performing ~ simultaneously occur, even in such a case, depending on the steel type and plate thickness, the tip portion of the following material S ₁ between the Can be wound around a coiler without waving. Then, after the leading end portion is wound up, tension is generated between the pinch roll 4 and the rolling mill 2, so that the waving generated on the rolling mill 2 side is also eliminated.

The rate at which the feed speed V ₁ of the steel strip S by the threading table 7 is preferably lower than the moving speed V ₂ of the steel strip S immediately after the exit of the rolling mill 2 depends on the type of steel and the like. For example, V ₁ = (0.95
～0.97) is preferably set to V _2.

[0036]

EXAMPLE The continuous hot rolling and the winding and cutting of the rolled steel strip were actually performed by the equipment row shown in FIG. The measures shown in Table 1 below were taken as measures to prevent the occurrence of breakage of two steel sheets when cutting the steel strip. The thickness after rolling is 1 to 2.0 mm
And the case of 2.1 to 5 mm were calculated, and the breakage (average value) rate of two sheets was calculated. The results are shown in Table 1.

Here, the "rate of occurrence of two-sheet breakage" is a value indicating, as a percentage, the ratio of the number of times that two-sheet breakage has occurred to the total number of winding coils for each method. <Measures for Preventing Two Sheets from Breaking> When the steel strip is cut, the rolling force of the pinch roll 4 is reduced to T / μ ₀
Increase.

[0038] at the time of cutting of the steel strip, the torque of the upper roll 41 of the pinch roll 4 to _{(r u · T / 2)} , the torque of the lower roll 42 _{(r b · T / 2)} . When the steel strip is cut, the feed speed of the steel strip S by the threading table 7 is set to 9 times the moving speed of the steel strip S immediately after the exit side of the rolling mill 2.
6%.

[0039]

[Table 1] As can be seen from these results, in No. 6 in which all of the measures (1) to (4) were taken, the occurrence rate of double sheet folding was "0". Also, the combination of No. and No. (No. 4 and No. 5) showed that the double-sheet breakage rate was 20% or less, and the effect was high. In addition, it was found that when the plate thickness was large, the breakage rate of the two sheets could be reduced to 20% only by the above measure.

[0040]

As described above, according to the method of the first aspect, at the time of cutting by the shear, the following material is generated by the cutting while being pressed down without slipping on the pinch roll immediately before the shear entry side. Since it is sent out to the coiler side against the force (force directed to the finish rolling mill side), the degree of occurrence of waving can be reduced. Thus, the probability that two steel sheets are broken immediately before entering the pinch roll can be reduced, so that the winding stability by the coiler is improved.

According to the method of the second aspect, immediately after cutting, the following material pinched by the pinch roll immediately before the shear entry side is pulled with the same or almost the same force as the tension immediately before cutting, so that waving occurs. Can not be. Thus, the probability that two steel sheets are broken immediately before entering the pinch roll can be significantly reduced, so that winding by the coiler can be stably performed.

According to the method of claims 3 and 4, even if waving occurs in the following material at the time of cutting by the shear, the leading end can be wound around the coiler before the waving is propagated to the leading end. Thereafter, tension acts on the following material. Thus, the probability that two steel sheets are broken immediately before entering the pinch roll can be reduced, so that the winding stability by the coiler is improved.

In particular, in the method according to the fourth aspect, it is possible to prevent the waving, which has been unavoidable even by the method according to the first or second aspect, from reaching the pinch roll immediately before the shear entry side. Thus, the probability that two steel sheets are broken immediately before entering the pinch roll can be significantly reduced, so that winding by the coiler can be stably performed.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing a model for analyzing the behavior of a metal strip during cutting.

FIG. 2 is a graph showing a time series calculation result of a displacement and a stress distribution of a metal band by the model of FIG. 1;

FIG. 3 is a schematic configuration diagram showing a winding-side equipment row of a continuous hot rolling line to which the method of the present invention is applied.

FIG. 4 is a schematic view showing a state of cutting a steel strip in a conventional continuous hot rolling line.

[Explanation of symbols]

2 Rolling mill (finishing rolling mill) 3 Shear 4 Pinch roll (Pinch roll just before the shear entry side) 5 Pinch roll (Pinch roll just before the winding coiler) 6 Pinch roll (Pinch roll just before the winding coiler) 7 Passing table K ₁ No.1 coiler K ₂ No.2 coiler S steel strip (metal strip) after S ₁ row material

Claims (4)

[Claims] 1. A metal strip which is continuously hot-rolled and comes out of a finish rolling mill is pinched by a predetermined length between a pinch roll immediately before a winding coiler and a pinch roll immediately before a shear-in side, and is sheared by a shear. In the method for winding a continuous hot-rolled metal strip which is cut and wound by a plurality of coilers arranged in series along a line, the leading material and the following material that have been cut, A method for winding a continuous hot-rolled metal strip, wherein the rolling force of the pinch roll immediately before the side is set to a value equal to or greater than a predetermined value P represented by the following equation (A). P = T / μ ₀ ‥‥ (A) (where T is the tension applied to the metal band between the winding coiler and the finishing mill just before cutting, and μ ₀
Is the dynamic friction coefficient between the pinch roll and the metal strip immediately before the shear entry side. ) Wherein said at cutting, in a substantially equal or equal to the predetermined value Q _u represented torque of the upper roll of the pinch roll just before Shah entry side in (B ₁₎ the following equation, the torque of the lower roll predetermined value substantially equal or equal to Q _b, the winding method of continuous hot rolling metal strip of claim 1, wherein the respectively set to the represented by (B ₂₎ the following equation. _{Q u = r u · T /} 2 ‥‥ (B 1) Q b = r b · T / 2 ‥‥ (B 2) ( however, T is, just before cutting, between the take-up coiler and finishing mill in a tension that has been given to the metal band, r _u
Is the roll radius of said upper roll, r _b is the roll radius of the lower roll. ) 3. A metal strip which is continuously hot-rolled and exits from a finishing mill is pinched by a predetermined length between a pinch roll immediately before a winding coiler and a pinch roll immediately before a shearing-in side, and is then sheared by a shear. In the method of winding a continuous hot-rolled metal strip which is cut and cut by a plurality of coilers arranged in series along a line, the leading material and the succeeding material which have been cut, Continuous hot-rolled metal strip winding, characterized in that the feeding speed of the metal strip by the threading table arranged on the output side of the mill is set lower than the moving speed of the metal strip immediately after the output side of the finishing mill. How to take. 4. The method according to claim 1, wherein at the time of cutting, the feeding speed of the metal strip by the threading table arranged on the output side of the finishing mill is set to be lower than the moving speed of the metal strip immediately after the output side of the finishing mill. The method for winding a continuous hot-rolled metal strip according to claim 1 or 2, wherein: