JPH1058020A - Method for setting roll gap of continuous rolling mill - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the manual adjustment by an operator by taking roll gap difference between adjacent stands as the target roll gap difference and securing the target roll gap difference for setting the roll gap of each stand. SOLUTION: A slab is made into a coiled product by heating the slab to a prescribed temp. in a heating furnace, executing rough rolling it into a rough bar with a roughing mill and rolling it into a prescribed band steel with a finishing mill. The pass schedule of the finishing mill and target roll gap difference are preliminarily stored from results. The roll gap difference between the adjacent stands at the time of rolling a prescribed product is stored from the results about the specification of every kind. When the pass schedule thickness is decided, the roll gap is calculated, the roll gap difference between the adjacent stands is determined and the deviation from the target roll gap difference is determined. When the deviation is over the allowance, by correcting the pass schedule thickness till the deviation becomes not more than the allowance, calculation is executed. Thereby, the target roll gap difference is secured, so the manual adjustment by the operator is reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for setting a roll gap of a continuous rolling mill.

[0002]

2. Description of the Related Art Generally, when a hot strip is processed by a continuous rolling mill, a reasonable roll gap,
It is necessary to determine operation setting values such as the rolling speed in advance. Conventionally, these setups have been automatically set by a computer based on a rolling model based on a known rolling theory.

However, if rolling is performed using the set value automatically set by the computer as it is, it is not possible to obtain a product with a predetermined accuracy, and at present, the operator performs rolling with some correction. Was. However, the manual intervention by the operator in automatic control rolling requires extremely high skill, requires instantaneous judgment, and has individual differences, making it difficult to ensure stable operation and stable accuracy. Was.

In view of the above, various automatic correction methods have been conventionally proposed to minimize the manual intervention of the operator. For example, in the device disclosed in Japanese Patent Publication No. 50-29708, the exit side thickness is changed based on the deviation between the calculated rolling load and the standard rolling load. Also,
Japanese Unexamined Patent Application Publication No. 3-99710 has determined an optimal pass schedule so as to minimize an evaluation function constituted by a rolling load.

[0005]

However, even with the use of various conventional techniques, it has been difficult to eliminate manual intervention by an operator. The reason is that the determination of the path schedule contains many vague elements that cannot be determined only by theoretical formulas, and it is almost impossible to construct a prediction formula or inference that incorporates all of these vague elements. This is because, ultimately, the intuition of the operator must be relied on.

[0006] However, there is a need for further reduction of manual intervention work by operators due to a decrease in the number of skilled workers and a demand for a reduction in operation costs. In view of the above, an object of the present invention is to provide a method of setting a roll gap of a continuous rolling mill in which manual intervention by an operator is reduced as much as possible under such a current situation.

[0007]

SUMMARY OF THE INVENTION The present inventors have conducted intensive studies on measures for further reducing the manual intervention of the operator, and as a result, the difference in roll gap between adjacent stands has been found.
It was found that it had an important effect on product accuracy. The present invention has been made based on this finding, and the feature thereof is that, in a method of setting a roll gap of each stand of a continuous rolling mill, a roll gap difference between adjacent stands (hereinafter simply referred to as “roll gap difference”). The roll gap difference) is set in advance as a target roll gap difference, and when setting the roll gap of each stand, the roll gap of each stand is set so that the target roll gap difference can be secured.

[0008] The setting of the roll gap of each stand is to calculate the roll gap of each stand based on a predetermined pass schedule plate thickness to calculate the roll gap of each stand. Can be secured by modifying the pass schedule plate thickness. The pass schedule plate thickness correction calculates the roll gap of each stand, obtains the roll gap difference between adjacent stands from the obtained roll gap, and permits the difference between the obtained roll gap difference and the target roll gap difference. When the value is greater than or equal to, it can be performed.

The target roll gap difference is determined for each type of material to be rolled, sheet width, sheet thickness, and strength. It is preferable that the rolling is applied to finish rolling of a hot strip.

[0010]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic configuration diagram of a continuous rolling mill facility to which the method of the present invention is applied. In the figure, a slab heated to a predetermined temperature in a heating furnace 1 is roughly rolled by a rough mill 2 to be formed into a rough bar, and the rough bar is further continuously processed by a finishing mill 3 to a predetermined width and thickness. It is rolled into a strip and wound up by the coiler 4 to obtain a product. The finishing mill 3 is constituted by a continuous rolling mill in which a first stand (F1) to a seventh stand (F7) are arranged in series.

FIG. 2 shows a flowchart of the setup of the finishing mill 3. In the present invention, the pass schedule plate thickness and the target roll gap difference are set in advance and stored in the storage unit. That is, based on past results, each stand (F1 to F
The exit side plate thickness of 7) is collected as the actual value. Based on the actual values, the exit side thickness of each stand when rolling a product having a predetermined thickness is tabulated in the form of a thickness table and stored in a memory in advance.

Similarly, from the past results, the difference in roll gap between adjacent stands when rolling a predetermined product is collected as actual values as shown in FIG. Based on this actual value, the roll gap difference when rolling a predetermined product is tabulated in the form of a target roll gap difference table for each type of material to be rolled, sheet width, sheet thickness, and strength, and stored in memory. It is stored in advance.

Under such preconditions, first, the pass schedule plate thickness is determined. This pass schedule sheet thickness is determined by calling a predetermined sheet thickness table stored in the memory that matches the product specification to be rolled this time, thereby obtaining the pass schedule sheet thickness, that is, each stand. Is determined. Similarly, the target roll gap difference is determined by calling a predetermined roll gap difference table from the target roll gap difference table stored in the memory that matches the product specifications to be rolled this time.

Next, a roll gap setting calculation is performed based on the pass schedule sheet thickness determined in this way. This setting calculation is performed by predetermined advance rate calculation, roll speed calculation, temperature prediction calculation, and rolling load prediction calculation. Then, the roll gap difference between the adjacent stands is obtained from the roll gap of each stand thus obtained.

Next, a deviation between the determined roll gap difference and the determined target roll gap difference is determined. Next, it is determined whether the deviation is equal to or less than an allowable value. If the value is equal to or less than the allowable value, the roll gap difference based on the roll gap obtained by the setting calculation is within the range of the target roll gap difference, so it is determined that the setting is the optimal setting, and the roll gap value is set to the set value. Is determined.

If the deviation exceeds the allowable value, the target roll gap difference cannot be secured by using the roll gap obtained by the setting calculation, so that it is determined that the setting is not optimal, and the setting calculation is repeated. Do. This recalculation is performed by correcting the pass schedule plate thickness. The thickness correction is performed according to the following equation (1).

[0017]

H = h ′ + α · Δds (1) Δds = ds′−dsh: current calculation plate thickness h ′: previous calculation plate thickness α: distribution coefficient ds ′: target roll gap difference ds: calculation roll Gap difference That is, the deviation is distributed to each stand to calculate the outlet thickness correction amount of each stand, and the correction amount is added to the pass schedule thickness to correct the pass schedule thickness, and again. Repeat the same setting calculation.
Then, the above correction is repeated until the deviation between the roll gap difference and the target roll gap difference becomes equal to or smaller than the allowable value.

Preferably, a determinant is used as the distribution coefficient. That is, since the finishing mill is a tandem mill, changing the thickness of a certain stand changes the roll gap between the front and rear stands. Therefore, using the equation (2) showing the relationship between the sheet thickness and the roll gap, the determinant of the equation (3) using the matrix J considering all the stands, and the equation (4) using the inverse determinant thereof It is preferable to correct the plate thickness.

[0019]

ΔS _i = (1 / M _i ) · (∂P _i / ∂h _i ) · Δh _i (2) ΔS = JΔh (3) h = h ′ + J ⁻¹ · Δds (4) where, ΔS: roll gap change amount M: mill constant ∂P / ∂h: plasticity coefficient Δh: stand exit side plate thickness change i: stand number Δds = ds'-dsh: current calculated plate thickness h ': Previous calculated thickness ds': target roll gap difference ds: calculated roll gap difference

[0020]

EXAMPLE A simulation was performed under the following conditions to determine the difference between the method of the present invention for making the roll gap difference constant and the conventional method of making the pass schedule plate thickness constant. Assuming a plate thickness of 1.2 mm, a plate width of 1200 mm, steel grade XH1805K, and a rough mill exit side temperature of 1150 ° C,
The exit temperature of the finishing mill was varied between 800 and 840C at 10C intervals.

The simulation results are shown in FIGS. From this simulation result, it can be said that the rolling according to the method of the present invention for making the roll gap difference constant is a rolling in which the change in the plate deformation from the front coil is smaller than the rolling for making the pass schedule plate thickness constant. In other words, according to the conventional calculation method, when a material having the same conditions such as plate thickness, plate width, and steel type is rolled, the exit temperature of the finishing mill is changed from 840 ° C. to 800 ° C.
The load applied to the first stand to the fifth stand varies evenly, whereas the load applied to the seventh stand varies greatly. That is, 840 ° C
When the 7th stand exit side plate shape is good, 800 ° C
Then, it becomes an ear wave, and conversely, 840 when it is good at 800 ° C
It means that when it changes to ° C, it becomes longer.

As described above, in the conventional method, since the plate shape is deteriorated, the operator manually intervenes and corrects the pass schedule.
The yield was worsening. In the method of the present invention, plate thickness, plate width,
Even if the finish mill outlet temperature changes from 840 ° C. to 800 ° C. when rolling the same material such as steel type, the first
Since the load applied from the stand to the seventh stand is evenly changed, when the exit side plate shape of the seventh stand is good at 840 ° C., the exit side plate shape is good even at 800 ° C. Conversely, when the temperature changes from 800 ° C. to 840 ° C., the plate shape becomes good.

From this, it can be seen that since the variation in the temperature change between the front and rear coils greatly affects the load balance, it is preferable to perform rolling while ensuring a difference in roll gap.

[0024]

According to the present invention, when the roll gap is set, the roll gap is automatically set so that the target roll gap difference can be ensured. Therefore, the operator does not need to worry about the roll gap difference. Manual intervention is reduced.

[Brief description of the drawings]

FIG. 1 is a layout view of a continuous rolling mill to which the method of the present invention is applied.

FIG. 2 is a flowchart of the method of the present invention.

FIG. 3 is a diagram illustrating an example of a target roll gap difference.

FIG. 4 is a graph showing a load balance according to a conventional calculation method.

FIG. 5 is a graph showing the load balance according to the method of the present invention.

[Explanation of symbols]

 3 Finishing mill (continuous rolling mill)

Claims (5)

[Claims] 1. A method of setting a roll gap of each stand of a continuous rolling mill, comprising: setting a roll gap difference between adjacent stands in advance as a target roll gap difference; A roll gap setting method for a continuous rolling mill, wherein a roll gap of each stand is set so that a target roll gap difference can be secured. 2. The setting of the roll gap of each stand is as follows.
The roll gap of each stand is obtained by performing a predetermined setting calculation based on a pass schedule plate thickness given in advance, and the target roll gap difference is secured by correcting the pass schedule plate thickness. The method for setting a roll gap of a continuous rolling mill according to claim 1, wherein 3. A roll gap of each stand is determined, a roll gap difference between adjacent stands is determined from the determined roll gap, and a difference between the determined roll gap difference and a target roll gap difference is equal to or more than an allowable value. 3. The method according to claim 2, wherein the thickness of the pass schedule is corrected.
The roll gap setting method of the continuous rolling mill as described in the above. 4. The continuous rolling mill according to claim 1, wherein the target roll gap difference is determined for each type of material to be rolled, sheet width, sheet thickness, and strength. Roll gap setting method. 5. The method for setting a roll gap of a continuous rolling mill according to claim 1, wherein the rolling is hot finish rolling of a steel strip.