JP6922873B2 - Temperable rolling method, temper rolling equipment and steel sheet manufacturing method - Google Patents

Description

The present invention relates to a temper rolling method, a temper rolling apparatus, and a method for manufacturing a steel sheet.

Generally, steel sheets used for automobiles, beverage cans, etc. are continuously cast, hot-rolled, and cold-rolled, and after undergoing annealing and plating processes, they are processed according to their respective shapes. Further, after the hot rolling step and the cold rolling step, a temper rolling step is carried out in which the quality of the material is adjusted by applying a slight rolling reduction to the steel sheet according to the demand of the product.

Flatness is one of the qualities controlled in the temper rolling process described above. This flatness is evaluated by the elongation difference rate Δε [%] in the width direction of the steel sheet. Also, differential expansion rate [Delta] [epsilon] based on the differential expansion .DELTA.l the width direction of the steel sheet at a constant interval l, that is indicated by "Δε = Δl / l", the value obtained by multiplying the 10 ⁵ to the "I-Unit" It is called in units.

Poor flatness of the steel sheet occurs because the elongation rates of the steel sheet in the width direction are not uniform during the rolling process, and when the flatness is large, the steel sheet undulates by the difference in elongation in the width direction. Such a steel sheet causes defects in a subsequent press or the like, and also causes uneven plating in the plating process. Further, if the flatness cannot be controlled well in the rolling process, a phenomenon called "narrowing down" occurs in which the steel plates are folded into the rolling stand.

Here, as a general method of controlling the flatness of the steel sheet, for example, an output side flatness measuring device for measuring the flatness of the steel sheet after rolling is provided, and the flatness measured by the measuring device is fed back to the rolling stand. Feedback control for operating the actuator (work roll bender) is performed (for example, Patent Document 1).

Further, especially in the case of low pressure lowering rate after hot rolling, changes in shape (flatness) in the hot rolling process, cooling process and winding process are predicted, and the shape after temper rolling is optimized. A rolling control method for determining a set value has also been proposed (for example, Patent Documents 2 and 3).

Japanese Patent No. 2964887 Japanese Patent No. 5971292 Japanese Patent No. 5971293

However, for example, the method of Patent Document 1 does not assume a case where the flatness of the steel sheet before rolling is very poor (large), although the rolling is performed for the purpose of controlling the flatness after rolling. Further, although the methods of Patent Documents 2 and 3 assume the shape before temper rolling, the control is performed only from the viewpoint of shape control, and the control is not performed from the viewpoint of narrowing down suppression.

The present invention has been made in view of the above, and is a temper rolling method capable of suppressing the occurrence of narrowing down even when the flatness of the steel sheet before rolling is poor in the temper rolling step. It is an object of the present invention to provide a temper rolling apparatus and a method for manufacturing a steel sheet.

In order to solve the above-mentioned problems and achieve the object, the temper rolling method according to the present invention is a temper rolling method in which a steel sheet is temper-rolled by a pair of upper and lower work rolls. It is characterized in that the flatness at a longitudinal position is measured, and a set value of an actuator that controls the shape of the steel plate is determined according to the flatness corresponding to the position of the steel plate directly under the work roll.

Further, the temper rolling method according to the present invention is characterized in that, in the above invention, the actuator is a work roll bender, and the set value F of the actuator is determined so as to satisfy the following equation (1). ..

Further, in the tempering rolling method according to the present invention, in the above invention, the actuator so as to satisfy the equation (1) only when the maximum elongation difference ratio in the width direction of the inlet steel sheet exceeds a preset threshold value. It is characterized in that the set value F of is determined.

In order to solve the above-mentioned problems and achieve the object, the temper rolling apparatus according to the present invention is provided with a pair of upper and lower work rolls for temper rolling the steel sheet and the work rolls to control the shape of the steel sheet. The actuator to be used, an entry-side flatness measuring device provided on the upstream side in the transport direction of the work roll and measuring the flatness of the steel sheet at each longitudinal position before rolling in advance, and the entry-side flatness measuring device. Further, it is characterized by including a control device for determining a set value of the actuator according to the flatness corresponding to the position of the steel plate immediately below the work roll.

Further, in the tempering rolling apparatus according to the present invention, in the above invention, the actuator is a work roll bender, and the control device determines a set value F of the actuator so as to satisfy the following equation (1). It is characterized by that.

In order to solve the above-mentioned problems and achieve the object, the method for producing a steel sheet according to the present invention is to perform temper rolling on a steel sheet after hot rolling by the temper rolling method according to the above invention. It is a feature.

According to the present invention, by determining the set value of the actuator that controls the shape of the steel sheet according to the flatness of the steel sheet before rolling, even if the flatness of the steel sheet before rolling is poor, the narrowing down can be performed. The occurrence can be suppressed.

FIG. 1 is a graph showing the relationship between the flatness of the output steel sheet and the presence or absence of narrowing down in the temper rolling process. FIG. 2 is a graph showing the relationship between the flatness of the inlet steel sheet and the presence or absence of narrowing down in the temper rolling process. FIG. 3 is a schematic view schematically showing the configuration of a temper rolling mill according to an embodiment of the present invention.

The temper rolling method, the temper rolling apparatus, and the method for manufacturing a steel sheet according to the present invention will be described with reference to the drawings. The present invention is not limited to the following embodiments. In addition, the components in the following embodiments include those that can be easily replaced by those skilled in the art, or those that are substantially the same.

The present invention relates to a rolling technique for suppressing narrowing down such as double biting that occurs in a steel sheet in a temper rolling process for producing a steel sheet (metal plate, metal strip). The temper rolling performed after hot rolling or cold rolling is performed for the purpose of removing the yield point behavior of the steel sheet, controlling the flatness of the steel sheet, adjusting the surface roughness of the steel sheet, and the like. On the other hand, as described above, in the rolling process including the temper rolling process, when the steel sheet is introduced into the rolling mill in a bent state, narrowing down may occur in which the steel sheet is rolled in a double-bite state. It has been an issue from the past.

Here, it has been conventionally known that when the flatness of the steel sheet immediately after the rolling stand is very poor (large), narrowing occurs at the rolling stand. In addition to the quality of the steel sheet, such narrowing may cause the steel sheet to break if it occurs during high-speed operation, resulting in a large production loss such as a stoppage of the production line.

As shown in FIG. 1, the inventors have conducted various investigations and studies, and as shown in FIG. We found that narrowing down may occur even within the range. In the figure, the vertical axis represents the flatness of the protruding steel plate, and the horizontal axis represents the vendor power of the work roll vendor.

Further, as shown in FIG. 2, the inventors have stated that the flatness of the steel plate on the entrance side (before temper rolling) of the rolling stand (hereinafter referred to as “entry side steel plate”) has a great influence on the occurrence of narrowing down. I found it. In the figure, the vertical axis represents the flatness of the inlet steel plate, and the horizontal axis represents the presence / absence of narrowing down.

The results of FIGS. 1 and 2 show that even if the flatness of the rolled steel sheet is properly controlled, narrowing may occur due to the influence of the flatness of the inlet steel sheet. Based on these findings, the inventors have come up with a method of suppressing the occurrence of narrowing down by considering the flatness of the inlet steel plate in addition to the flatness of the outlet steel plate.

[Turning rolling equipment and temper rolling method]
Hereinafter, the configuration of the temper rolling apparatus according to the embodiment of the present invention and the temper rolling method using the temper rolling apparatus will be described with reference to FIG. The temper rolling apparatus according to the present embodiment includes a rolling mill 1 and a control device 2. Further, the rolling mill 1 includes a rolling stand 11, an entry-side flatness measuring device 12, an exit-side flatness measuring device 13, bridle rolls 14 and 15, a payoff reel 16, and a coiler 17. .. In the temper rolling apparatus (conditioning rolling line) shown in the figure, the payoff reel 16, the bridle roll 14, the inlet flatness measuring device 12, the rolling stand 11, and the output are from the upstream side to the downstream side in the transport direction. The side flatness measuring device 13, the bridle roll 15, and the coiler 17 are arranged in this order.

The rolling stand 11 includes a pair of upper and lower backup rolls 111a and 111b, a pair of upper and lower work rolls 112a and 112b, and a pair of upper and lower work roll benders 113a and 113b.

The backup rolls 111a and 111b are arranged so as to face each other with the pair of work rolls 112a and 112b interposed therebetween. The upper backup roll 111a comes into contact with the outer peripheral surface of the upper work roll 112a from above and presses the work roll 112a downward. As a result, the backup roll 111a applies the load required for rolling the steel sheet S to the work roll 112a. Further, the lower backup roll 111b comes into contact with the outer peripheral surface of the lower work roll 112b from below and presses the work roll 112b upward. As a result, the backup roll 111b applies the load required for rolling the steel sheet S to the work roll 112b.

The work rolls 112a and 112b are arranged so as to face each other in the plate thickness direction of the steel plate S with a transport path for transporting the steel plate S in the transport direction (longitudinal direction). The work rolls 112a and 112b rotate (rotate) the steel plates S that are sequentially transported along the transport path while sandwiching them in the plate thickness direction, thereby continuously rolling (tempering rolling) the steel plates S.

The work roll benders 113a and 113b are actuators for controlling the shape of the steel plate S. The work roll benders 113a and 113b are provided on the work rolls 112a and 112b, respectively. Specifically, the work roll benders 113a and 113b perform a roll bending operation of bending the work rolls 112a and 112b in the plate thickness direction of the steel plate S for the purpose of controlling the shape of the steel plate S, respectively.

The magnitude of the bending force applied to the work rolls 112a and 112b by the work roll benders 113a and 113b is determined by the "actuator set value" described later. The operation of the work roll benders 113a and 113b is controlled by the control device 2 described later based on the set value of this actuator. The "actuator set value" specifically indicates the set value of the bender force of the work roll benders 113a and 113b.

The entry-side flatness measuring device 12 is provided on the upstream side of the work rolls 112a and 112b in the transport direction. The entry-side flatness measuring device 12 measures the flatness at each longitudinal position of the steel sheet S before rolling (before temper rolling) in advance on the entry side of the rolling stand 11. Then, the entry-side flatness measuring device 12 outputs the measured flatness and the position information (coordinates of the position where the flatness is measured) of the steel plate S corresponding to the flatness to the control device 2.

The exit side flatness measuring device 13 is provided on the downstream side of the work rolls 112a and 112b in the transport direction. The output side flatness measuring device 13 measures the flatness at each longitudinal position of the steel sheet S after rolling (after temper rolling) on the output side of the rolling stand 11. Then, the output side flatness measuring device 13 outputs the measured flatness and the position information (coordinates of the position where the flatness is measured) of the steel plate S corresponding to the flatness to the control device 2.

The "longitudinal position" of the steel sheet S for which the output side flatness measuring device 13 measures the flatness differs depending on the timing at which the flatness of the steel sheet S before rolling is measured. For example, as described above, when the flatness of the steel sheet S before temper rolling is measured by the entry-side flatness measuring device 12 in the temper-rolling step, the “each longitudinal position” of the entry-side flatness measuring device 12 Is "each longitudinal position" of the exit side flatness measuring device 13. On the other hand, as will be described later, when the flatness of the steel sheet S before temper rolling is measured in the hot rolling process, which is the pre-process of the temper rolling process, the total length of the steel sheet S is before the start of temper rolling. The position where the lengths cut off due to defects or the like are converted and combined is referred to as "each longitudinal position" of the output side flatness measuring device 13.

The bridle rolls 14 and 15 are devices for applying a predetermined tension to the steel plate S. The payoff reel 16 is a device that pays out and conveys the coiled steel plate S toward the rolling stand 11. The coiler 17 is a device for winding the rolled steel sheet S into a coil.

The control device 2 is specifically realized by a general-purpose information processing device such as a personal computer or a workstation, and has, for example, a CPU, a ROM, a RAM, or the like as main components. The control device 2 is an actuator (work roll benders 113a, 113b) that controls the shape of the steel plate S according to the flatness corresponding to the position of the steel plate directly below the work rolls 112a, 112b measured by the entry side flatness measuring device 12. ) Is determined. The above-mentioned "flatness corresponding to the position of the steel plate directly under the work rolls 112a and 112b" is the flatness input from the input side flatness measuring device 12 and the position information of the steel plate S corresponding to the flatness. Identify based on.

Specifically, the control device 2 determines the set value F of the actuator so as to satisfy the following equation (1). The coefficient k in the following formula (1) can be experimentally obtained based on, for example, the reduction rate of the steel sheet S.

Here, the control device 2 determines the set value F of the actuator so as to satisfy the above equation (1) only when the maximum elongation difference ratio in the width direction of the inlet steel plate exceeds a preset threshold value. You may.

In this case, the control device 2 assumes that the occurrence rate of narrowing down is low as a result of the flatness measurement by the entry-side flatness measuring device 12, that is, the flatness of the entry-side steel plate is less than a predetermined threshold value. , The set value F of the actuator is determined by the feedback control by the output side flatness measuring device 13 as in the conventional case. That is, the control device 2 determines the set value F of the actuator according to the following equation (2).

On the other hand, when it is assumed that the occurrence rate of narrowing down is high as a result of the flatness measurement by the entry-side flatness measuring device 12, that is, when the flatness of the entry-side steel plate exceeds a predetermined threshold, the control device 2 is described as described above. As shown in the equation (1), the correction value determined by the flatness (maximum elongation difference rate) measured by the entry side flatness measuring device 12 with respect to the value of the feedback control by the exit side flatness measuring device 13. (Δε _max ) is added to calculate the set value F of the actuator. As a result, the occurrence of narrowing down is avoided.

Here, the threshold value when the control device 2 determines the set value F of the actuator can be set to 250 [I-unit] based on, for example, the result of FIG.

[Manufacturing method of steel sheet]
The present invention can also be carried out as a method for manufacturing a steel sheet S, for example, by performing temper rolling on the steel sheet S after hot rolling by the temper rolling method according to the above-described embodiment.

According to the temper rolling method, the temper rolling apparatus, and the method for manufacturing the steel plate S according to the present embodiment as described above, the actuator that controls the shape of the steel plate S according to the flatness of the steel plate S before rolling. By determining the set value (the set value of the bender force of the work roll benders 113a and 113b), it is possible to suppress the occurrence of narrowing down even when the flatness of the steel sheet S before rolling is poor.

Hereinafter, the present invention will be described in more detail with reference to examples. In this embodiment, as in FIG. 1, Comparative Examples 1 and 2 in which only feedback control (FB control) based on the flatness of the output side is performed using a temper rolling apparatus provided with one rolling stand, and the output side. The presence or absence of narrowing down was compared with the invention example in which feedback control based on flatness and feedforward control (FF control) based on entry-side flatness were performed. In the examples of the invention and Comparative Examples 1 and 2, a steel plate having a thickness of 1.2 mm and a width of 1250 mm was used, and the tension on the inlet side was set to 1.6 tonf and the tension on the outlet side was set to 7.6 tonf.

Further, in the invention example, the flatness of the input side steel sheet is measured in advance in a previous process (for example, a hot rolling process), and the bender force at the rolling position is changed according to the maximum elongation difference ratio in the width direction of the input side steel sheet. While rolling. Then, at the time of rolling, when the maximum elongation difference ratio in the width direction of the input side steel sheet exceeds 250 [I-unit], the coefficient k = 0.1 is set, and the bender force is changed according to the above formula (1). Controlled. On the other hand, in Comparative Examples 1 and 2, the condition of passing through a steel plate having poor entry-side flatness under the condition of normal bender force was cited. Table 1 shows the conditions for temper rolling and the determination results for narrowing down in Invention Examples and Comparative Examples 1 and 2.

In Table 1, the flatness on the entrance side and the flatness on the exit side were evaluated at the point where the maximum elongation difference ratio in the width direction was the largest in the steel sheet. Further, in the determination of flatness on the exit side, the case where the maximum elongation difference rate exceeds 35 is evaluated as x, and the case where the maximum elongation difference rate does not exceed 35 is evaluated as ◯. Further, in the narrowing down judgment, the one in which the narrowing down occurred was marked with x, and the one in which the narrowing down did not occur was marked with ◯.

When the maximum elongation difference ratio of the inlet steel sheet was small (less than 250) as in Comparative Example 1, narrowing down did not occur. On the other hand, when the maximum elongation difference ratio of the inlet steel sheet is large (250 or more) as in Comparative Example 2, narrowing occurs at a large portion of the inlet steel sheet, and the steel sheet according to Comparative Example 2 is scrap.

On the other hand, in the example of the invention, although the maximum elongation difference ratio of the inlet steel sheet is large (250 or more), it is narrowed down by using the feedback control based on the flatness on the exit side and the feedforward control based on the flatness on the inlet side in combination. Was avoided, and the flatness could be kept good. This proved the effectiveness of the present invention.

Although the temper rolling method, the temper rolling apparatus, and the method for manufacturing a steel sheet according to the present invention have been specifically described above with reference to embodiments and examples for carrying out the invention, the gist of the present invention is limited to these descriptions. It must be broadly interpreted based on the description of the scope of claims. Needless to say, various changes, modifications, etc. based on these descriptions are also included in the gist of the present invention.

For example, the flatness (maximum elongation) of the inlet steel sheet used in the above formula (1) shall be the one measured by the inlet flatness measuring device 12 installed in the temper rolling apparatus (conditioning rolling line). Is most desirable, but the value measured in the pre-process of the temper rolling process may be used. For example, when the pre-process of the tempering rolling process is a hot rolling process, the wave height of the steel sheet is measured with a laser distance meter after hot rolling in the hot rolling process, and the input side steel sheet is measured in the subsequent tempering rolling process. It may be used as the flatness of. In this case, since it is not necessary to provide the inlet-side flatness measuring device 12 in the temper rolling apparatus, the apparatus configuration can be simplified and the cost can be reduced.

1 Rolling machine 11 Rolling stand 111a, 111b Backup roll 112a, 112b Work roll 113a, 113b Work roll bender (actuator)
12 Input side flatness measuring device 13 Outing side flatness measuring device 14,15 Bridle roll 16 Payoff reel 17 Coiler 2 Control device S Steel plate

Claims (6)

In the temper rolling method of temper rolling a steel sheet with a pair of upper and lower work rolls,
The flatness at each longitudinal position of the steel sheet before rolling is measured in advance, and the set value of the actuator that controls the shape of the steel sheet is determined according to the flatness corresponding to the position of the steel sheet directly under the work roll .
A correction value determined based on the flatness at each longitudinal position of the steel sheet before rolling with respect to the set value of the actuator by feedback, which is determined based on the flatness at each longitudinal position of the steel sheet after rolling. A temper rolling method characterized by determining a set value of the actuator by adding the actuator. The actuator is a work roll bender and
The temper rolling method according to claim 1, wherein the set value F of the actuator is determined so as to satisfy the following formula (1).

2. The temper rolling method described. A pair of upper and lower work rolls for temper rolling of steel sheets,
An actuator provided on the work roll and controlling the shape of the steel plate,
An entry-side flatness measuring device provided on the upstream side of the work roll in the transport direction and measuring the flatness of the steel sheet at each longitudinal position before rolling in advance.
An output side flatness measuring device provided on the downstream side in the transport direction of the work roll and measuring the flatness at each longitudinal position of the steel sheet after rolling.
A control device that determines a set value of the actuator according to the flatness corresponding to the position of the steel plate directly below the work roll as measured by the entry-side flatness measuring device.
Equipped with a,
The control device is based on the flatness measured by the entry-side flatness measuring device with respect to the set value of the actuator by feedback, which is determined based on the flatness measured by the exit-side flatness measuring device. The temper rolling apparatus, characterized in that the set value of the actuator is determined by adding the correction value determined in the above. The actuator is a work roll bender and
The tempering rolling apparatus according to claim 4, wherein the control device determines a set value F of the actuator so as to satisfy the following formula (1).

A method for producing a steel sheet, which comprises performing temper rolling on a steel sheet after hot rolling by the temper rolling method according to any one of claims 1 to 3.

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