JP3157721B2 - Manufacturing method of rolled steel sheet by continuous rolling mill equipped with automatic thickness control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a rolled steel sheet by a continuous rolling mill provided with an automatic thickness control device, and more particularly, to correcting a thickness of a rolled steel sheet, a trouble in passing a sheet, or a defective sheet width. The present invention relates to a method for manufacturing a rolled steel sheet, which can be performed quickly within a range in which cracks do not occur.

[0002]

2. Description of the Related Art A continuous rolling mill used for rolling a rolled material as a material for manufacturing a rolled steel sheet by continuously passing between a pair of upper and lower rolling rolls arranged on a plurality of stands is used. If the thickness of each stand is different from the target thickness due to rolling, an automatic gauge control is used to correct this deviation.
Is generally installed. The thickness control method by the automatic thickness control device is mainly classified into a control method based on reduction and a tension control method. In an automatic thickness control device that employs a thickness control method based on reduction, a capacity limit of the reduction device is set as an upper limit of a roll reduction speed, for example, as in a hydraulic reduction device described in JP-A-6-127439. There are many.

[0003]

However, if the capacity limit of the rolling device is set as the upper limit of the rolling speed of the roll, depending on the rolled material, when the rolling speed is reduced near the upper limit of the rolling speed, the sheet speed due to the rolling is reduced. The tension control means (for example, a looper) arranged between the stands may not be able to completely suppress the fluctuation of the tension generated on the entrance side of the stand due to the delay of the rolling operation. There is a possibility that a mis-roll occurs due to an excessively large loop of the material, or conversely, a product defect such as a reduction in a sheet width due to a rolled material located between the stands being pulled too strongly in a longitudinal direction thereof.

Therefore, according to the first aspect of the present invention, according to the plate thickness correction dimension, the plate thickness can be corrected quickly under a high-speed pressure in a range that does not cause a threading trouble or a sheet width defect.
An object of the present invention is to provide a method for producing a rolled steel sheet by a continuous rolling mill having an automatic thickness control device. An object of the invention described in claim 2 is to achieve the object of the present invention even when another rolled material having a different reversal rate during rolling is rolled instead of one rolled material. The invention according to claim 3 is
It is an object of the present invention to achieve the object of the present invention with a simple structure by using a looper having a variable angle arranged between stands as tension control means.

[0005]

In order to achieve the above object, according to the present invention, a plurality of stands are provided with a pair of upper and lower rolling rolls each set at a predetermined rolling position, and a rolled material is provided. It is continuous rolling performed by sequentially passing between these upper and lower rolling rolls, and detects a thickness variation of a rolled material when passing through upper and lower rolling rolls arranged on one stand, and detects this variation in thickness. A corresponding thickness correction command is issued to the thickness control means, and by operating the reduction device based on the command from the thickness control means, the reduction position of the upper and lower rolling rolls is moved to set the target thickness of the rolled material. Correcting the rolling down to the plate thickness, and performing the rolling while suppressing the fluctuation of the tension generated on the entrance side of the stand with the delay of the plate speed due to the rolling down, by controlling the tension control unit interlocked with the plate thickness control unit, In the method for producing a rolled steel sheet by a continuous rolling mill provided with a moving plate thickness control device, a thickness control means is provided with a rolling speed limiter for limiting a rolling speed of a rolling roll, and for one rolled material, various roll reductions are performed. The relationship between the speed and the capacity limit of the tension control means for suppressing the tension generated on the entrance side of the stand accompanying this is obtained in advance, and the tension control means sets the rolling speed at the capacity limit as the upper limit to the rolling speed limiter. By setting, the thickness of the rolled material can be quickly corrected at a high-pressure speed within a range that does not cause a threading trouble or a width failure.

Here, the rolling speed of the rolling roll is shown in FIG.
As shown in (1), it means the time required from the point in time when the plate thickness changes due to the tightening of the rolling-down device corresponding to the plate thickness correction dimension L to the completion thereof. For example, if the thickness correction dimension is 1000
When the time corresponding to the corrected dimension is 2 seconds, the roll reduction speed is 500 μm / sec.

[0007] The invention according to claim 2 is the invention according to claim 1.
As in the case of Ming, tension control means for one rolled material is the capacity limit.
Rolling speed (V₀max) is determined in advance and this rolling speed
(V ₀max) can be used to control the tension in other rolled materials.
Rolling speed (V₁max) is shown below
The rolling speed (V)₁max)
By setting the rolling speed limiter,
Thickness repair of other rolled materials within the range that does not cause
It is characterized in that the correction can be performed quickly at a high pressure.

[0008]

(Equation 2) V ₀ max: the rolling speed at which the tension control means obtained by performing the simulation for one rolled material reaches the capacity limit α ₀ : the reverse movement corresponding to the rolling reduction in one rolled material taking into account the change in sheet thickness Rate of change of rate α ₁ : Rate of change of reverse rate corresponding to the amount of reduction in other rolled materials taking into account the change in sheet thickness β: Constant determined by reduction amount limit and equipment

According to a third aspect of the present invention, an angle-variable looper disposed between stands is used as the tension control means according to the first or second aspect. It is preferable to set the upper limit to the rolling speed limiter.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 has an automatic thickness control means disposed on one of a plurality of stands of a continuous rolling mill used in a production method according to the present invention, and a tension control means disposed on an entrance side of the stand. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic system configuration diagram of an automatic thickness control device, in which 1 is a stand, 2 and 3 are vertical rolling rolls, 4 is a rolled material, 5 is a thickness control means, 6 is a pressing-down device, and 7 is a looper.

The automatic thickness control device of the continuous rolling mill shown in FIG. 1 employs a control method by rolling down, and specifically, passes through upper and lower rolling rolls 2 and 3 arranged on one stand 1a. The thickness variation of the rolled material 4 is detected by a gauge thickness measuring method using a rolling mill as a kind of thickness measuring device using a gauge meter system, and a thickness correction command corresponding to the thickness variation is issued to the thickness control means. 5 and the thickness control means 5
In the normal rolling state in which the thickness variation is relatively small, the rolling position of the upper and lower rolling rolls 2 and 3 is moved to set the thickness of the rolled material 4 to the target thickness in a normal rolling state in which the thickness variation is relatively small. In addition to the reduction in thickness, the variation in tension generated on the entrance side of the stand 1 due to the delay in the plate speed due to the reduction is controlled by the tension control means 7 linked with the thickness control means 5.
It is configured to be suppressed by:

As shown in FIG. 1, as the tension control means, it is preferable to use a looper 7 which is arranged between stands and whose angle can be varied, and indirectly controls the tension by appropriately varying this angle. However, the tension may be controlled using other tension control means, and the tension control means is not particularly limited.

The tension control means 7 is provided with a thickness control means 5.
Specifically, this configuration feeds back a reduction result from the reduction device 6 and a load result from the load cell 8 to the plate thickness control means 5,
The tension control means 7 is linked based on these results (in FIG. 1, the angle θ of the looper 7 is appropriately changed).

Although the thickness variation of the rolled material is detected by the gauge meter method in FIG. 1, it can be detected by, for example, a method using an X-ray thickness gauge or a method using a combination thereof. The thickness control may be performed by feeding back the detected thickness variation to the subsequent stand in addition to the case where the detected thickness variation is fed back to the same stand as shown in FIG.

According to the present invention, the thickness control means 5 is provided with a reduction speed limiter 9 for limiting the reduction speed of the rolling rolls 2 and 3, and for one rolled material 4, various roll reduction speeds and accompanying roll reduction speeds are set. The relationship with the capacity limit of the tension control means for suppressing the tension generated at the entrance side of the stand 1a is determined in advance, and the tension control means sets the rolling speed at the capacity limit as the upper limit to the rolling speed limiter, thereby enabling the communication. It is characterized in that the thickness of the rolled material can be quickly corrected at a high-pressure speed within a range that does not cause a sheet trouble or a sheet width defect.

When the tension control means is the looper 7 as shown in FIG. 1, it is preferable to determine the upper limit of the rolling speed from the relationship with the looper fluctuation angle. FIG.
In addition, when the rolled material 4 of a typical steel type and size was rolled down at a roll reduction speed of 700, 800, 900, 1000 μm / sec., Respectively, it was interlocked to suppress the tension generated on the entry side of the stand 1a. 6 shows an example of a result obtained by simulating the change over time of the angle change of the looper 7.

From this figure, for example, if the fluctuation angle of the looper is to be suppressed to a maximum of 35 °, the upper limit of the rolling speed is set to 800
μm / sec., and this reduction speed may be set in the reduction speed limiter 9.

As described above, if the upper limit of the roll reduction speed is set in the capacity limit of the tension control means 7, even if the roll is reduced at the upper limit of the roll reduction speed, there will be no trouble in threading and defective width. Therefore, let alone the normal rolling state,
In particular, even in an unsteady rolling state where the thickness is changed or a large thickness correction is performed, the thickness can be quickly corrected at a high pressure speed, and the product yield and workability are reduced. improves.

Further, according to the second aspect of the present invention, by executing the above-described simulation, the rolling speed (V ₀ m
If ax) is obtained in advance, the rolling speed (V ₁ max) at which the tension control means becomes the capacity limit by the following equation (4) can be determined for another rolled material without newly performing a simulation. Can be calculated.

The process of deriving equation (4) will be described below. Assuming that the amount of tightening of the rolling position of the upper and lower rolling rolls 2 and 3 of one stand 1a is ΔS, and the amount of change in the sheet speed caused by the tightening is ΔV, ΔV = − {b / {h.} h / ∂S · ΔS (1) where b is the reverse speed and h is the plate thickness. Where α = −∂
Assuming that b / ∂h · ∂h / ∂S, the equation (1) becomes ΔV = αΔS (2).

Assuming that the amount of change in the plate speed when the reduction is performed by ΔS ₀ with the simulation material is ΔV ₀ , ΔV ₀ = α ₀ ΔS ₀ . Similarly, assuming that the amount of change in the sheet speed when the reduction is performed by ΔS ₁ with another rolled material is ΔV ₁ , ΔV ₁ = α ₁ ΔS ₁
Becomes In order to make the amount of change in the plate speed the same during the rolling operation, it is necessary to satisfy the relationship of ΔV ₀ = ΔV ₁ ,
That is, it is necessary to satisfy the relationship α ₀ ΔS ₀ = α ₁ ΔS ₁ . Dividing both sides by ΔT gives

(Equation 3) here

[Outside 1] Is a rolling operation amount per unit time, that is, a rolling speed. Therefore

(Equation 4) That _{α 0 V 0max = α 1 V} 1max becomes, therefore, a _{V 1max = (α 0 / α} 1) V 0max ----- (3).

However, the equation (3) does not take into account parameters other than the rolling speed, that is, parameters due to the influence of the rolling amount limit and the equipment, and is actually nonlinear. not good. Therefore, accounts for the parameter due to influence of reduction rate limit and equipment wherein inventors have conducted extensive studies results, the α ₀ / α ₁ ratio, reduction ratio limits and constants β uniquely determined by the equipment It has been found that the power is a good match with the actual machine. Therefore, V _1max is _actually calculated from the following equation.

(Equation 5) The value of the constant β is, for example, 1. in a hot finishing mill.
It is preferred to be in the range of 5 to 2.0.

Next, V ₁ max of the other rolled material is calculated by this formula, and this is set as a rolling speed limiter.
Rolling was performed on an actual machine, and the thickness was corrected at a high pressure under a final stand of a finishing mill. For example, in the material of 3.5 mm thickness × 1505 mm width ultra low carbon steel, V ₀ max a 800 [mu] m / sec, the α ₀ -42.65, the alpha ₁ and -46.27, variation angle θ looper is 30deg at maximum . Using this value, V actually obtained by equation (4)
_{When 1} max was set as the rolling speed limiter, the rolling pressure of the other rolled material could be quickly corrected at the rolling speed within a range that would not cause a threading trouble or a strip width defect.

From the results of the examples, there was no occurrence of a trouble of passing a sheet or a defect of a sheet width even though the sheet pressure was corrected at a high-pressure speed.

Thus, tension control in one rolled material
Rolling speed (V ₀max)
In other words, the tension control means in other rolled materials may be at the capacity limit.
The rolling speed (V₁max) is obtained by equation (4).
Reduction speed (V₁max) is set to the reduction speed limiter.
Setting eliminates the possibility of threading troubles and
The thickness of other rolled materials quickly at high pressure
The rolling speed (V₁max)
There is no need to perform simulations to determine
And product yields are improved.

The above is merely an example of the embodiment of the present invention, and various changes can be made within the scope of the claims. For example, as long as the rolling mill is provided with an automatic thickness control device of a control method by reduction, it can be applied regardless of the type of the hot rolling mill or the cold rolling mill.

[0027]

According to the first aspect of the present invention, the upper limit of the roll reduction speed can be set optimally in accordance with the sheet thickness correction dimension within a range in which there is no trouble in threading or defective sheet width. In particular, a remarkable effect is exhibited when the roll reduction speed needs to be increased, such as when the plate thickness correction dimension is large and the large plate thickness correction dimension is corrected quickly in a short time.

Further, since there is almost no passing trouble, the execution rate of the automatic thickness control is improved, and the occurrence rate of the defective thickness is greatly reduced as compared with the related art.

In addition, since the mass flow is not disturbed, the operator can temporarily stop the automatic thickness control device or reduce the pressure (manual adjustment of the pressure reduction) in order to ensure the sheet passing property. This eliminates the necessity of performing, and thus improves the thickness accuracy and the workability.

Further, according to the present invention, even when another rolled material is rolled in place of one rolled material, if the optimum roll reduction speed for one rolled material is known, another rolled material can be rolled. The optimum roll reduction speed for the rolled material can be easily calculated from the above equation (4). This is because it is necessary to determine the optimum roll reduction speed for each rolled material by performing a new simulation. Is eliminated, workability is improved, and product cost is reduced.

According to a third aspect of the present invention, the effect of the first or second aspect of the present invention is reduced by using a simple structure by using an angle-variable looper disposed between stands as tension control means. Can be achieved.

[Brief description of the drawings]

FIG. 1 is a schematic system diagram of an automatic thickness control device of a continuous rolling mill used in a manufacturing method according to the present invention.

FIG. 2 is a diagram for explaining a rolling speed of a rolling roll.

FIG. 3 shows the change over time of the change angle of the looper that can suppress the tension generated on the entrance side of the stand when the rolled material of a typical steel type or size is reduced at various roll reduction speeds. It is a figure showing an example of the result of simulation.

[Explanation of symbols]

 1 Stand 2 Upper rolling roll 3 Lower rolling roll 4 Rolled material 5 Sheet thickness control means 6 Rolling-down device 7 Looper 8 Load cell 9 Rolling-down speed limiter 10 Feeding direction

Claims (3)

(57) [Claims] 1. A continuous rolling process in which a pair of stands are provided with a pair of upper and lower rolling rolls each set at a predetermined rolling position, and a rolled material is sequentially passed between the upper and lower rolling rolls. A thickness variation of a rolled material that has passed through upper and lower rolling rolls disposed on one stand is detected, and a thickness correction command corresponding to the thickness variation is issued to the thickness control means, and a command from the thickness control means is issued. By moving the rolling position of the upper and lower rolling rolls to correct the thickness of the rolled material to the target thickness by operating the drafting device based on the In the method for producing a rolled steel sheet by a continuous rolling mill equipped with an automatic thickness control device, the above-described rolling is performed while suppressing the fluctuation of the tension generated on the side by the tension control means linked with the thickness control means. In the sheet thickness control means, a rolling speed limiter for limiting the rolling speed of the rolling roll is provided, and for one rolled material, various roll rolling speeds and the tension generated on the entrance side of the stand due to the roll rolling speed are suppressed. By previously obtaining the relationship with the capacity limit of the tension control means, and by setting the tension control means to the rolling speed limiter with the rolling speed at the capacity limit as an upper limit, in a range in which a threading trouble or a sheet width defect does not occur, A method for producing a rolled steel sheet by a continuous rolling mill provided with an automatic thickness control device, wherein the thickness of the rolled material can be quickly corrected at a high-pressure speed. 2. A continuous rolling process in which a pair of upper and lower rolling rolls each set at a predetermined rolling position are arranged on a plurality of stands, and a rolled material is sequentially passed between the upper and lower rolling rolls. A thickness variation of a rolled material that has passed through upper and lower rolling rolls disposed on one stand is detected, and a thickness correction command corresponding to the thickness variation is issued to the thickness control means, and a command from the thickness control means is issued. By moving the rolling position of the upper and lower rolling rolls to correct the thickness of the rolled material to the target thickness by operating the drafting device based on the In the method for producing a rolled steel sheet by a continuous rolling mill equipped with an automatic thickness control device, the above-mentioned rolling is performed while suppressing the fluctuation of the tension generated on the side by a tension control device linked with the thickness control device. If the thickness control means is provided with a rolling speed limiter for limiting the rolling speed of the rolling roll, and if the rolling speed (V ₀ max) at which the tension control means of one rolled material is at the capacity limit is determined in advance, the other factors can be obtained. speed reduction of the tension control means of the rolled material is the ability limit (V ₁ max) is determined by the formula shown below, the obtained reduction rate (V ₁ max)
By setting the rolling speed limiter, the thickness of the other rolled material can be quickly corrected at the high rolling speed within a range that does not cause a threading trouble or a defective width.
A method for producing a rolled steel sheet by a continuous rolling mill having an automatic thickness control device. (Equation 1) V ₀ max: the rolling speed at which the tension control means obtained by performing the simulation for one rolled material reaches the capacity limit α ₀ : the reverse movement corresponding to the rolling reduction in one rolled material taking into account the change in sheet thickness Rate of change of rate α ₁ : Rate of change of reverse rate corresponding to the amount of reduction in other rolled materials taking into account the change in sheet thickness β: Constant determined by reduction amount limit and equipment 3. The tension control means is a looper disposed between stands and capable of varying the angle, and the upper limit of the reduction speed is set to a reduction speed limiter based on a relationship with the variation angle of the looper. The method for producing a rolled steel sheet according to the above.