JP4218119B2 - Shape control method and apparatus for cross rolling mill - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a shape control method and apparatus for controlling the shape of a material to be rolled by controlling the profile of a work roll in a cross rolling mill for rolling the material to be rolled such as a hot-rolled steel strip.
[0002]
[Prior art]
In a hot finish rolling mill that rolls a material to be rolled as a hot-rolled steel strip, a contact portion of the work roll of the rolling mill with the material to be rolled is worn with rolling. In particular, when several rolls of the same width are rolled, this work roll wears significantly, and the work roll profile has a shape as shown in FIG. Here, a step is generated in the portions corresponding to both end portions of the contact portion with the material to be rolled (hereinafter referred to as a step portion).
[0003]
On the other hand, since it is hot rolling, the work roll receives heat input from the material to be rolled, and a profile change due to thermal expansion occurs as shown in FIG. 6B (hereinafter referred to as a thermal crown).
The actual work roll has a profile in which the above-described stepped portion and the thermal crown are superimposed (FIG. 6C).
[0004]
Here, when rolling the next material wider than the material to be rolled so far with the work roll of the profile shown in FIG. 6 (c), the profile is transferred to the material to be rolled, and the material to be rolled is The profile is poor.
For this reason, conventionally, the rolling order of the material to be rolled is scheduled to be rolled from a wide one to a narrow one, and the work roll is exchanged after the rolling of the narrow material is completed. It was.
[0005]
Also, as shown in FIG. 6 (d), rolling is performed while grinding the step portion with an on-line grinder installed in the rolling mill, and the wide portion can be rolled after the narrow-width material rolling by removing the step portion. There have been attempts to do so.
Further, in JP-A-55-94717, JP-A-60-158909, JP-A-63-5814, JP-A-63-171210, etc., the thermal crown in the work roll is controlled. For this purpose, a technique for adjusting the amount of roll cooling water in the axial direction of the work roll (that is, the width direction of the material to be rolled) and controlling the shape of the material to be rolled is already known.
[0006]
[Problems to be solved by the invention]
On the other hand, in recent years, in a hot finishing rolling mill, a cross rolling mill is being adopted in which an angle is provided between roll axes of upper and lower work rolls, that is, rolling is performed by crossing the upper and lower work rolls.
The cross rolling machine can control the shape of the material to be rolled by controlling the cross angle by utilizing the fact that the gap between the upper and lower work rolls differs between the roll center and both ends when the upper and lower work rolls are crossed. Rolling mill.
[0007]
When rolling with a work roll having a thermal crown using this cross rolling mill, there are the following problems.
First, the roll gap of a work roll having a thermal crown in a cross rolling mill will be described.
The broken line in FIG. 7A shows the initial roll profile before the occurrence of the thermal crown. And a thermal crown as shown to a continuous line generate | occur | produces by rolling hot. However, the initial roll profile is finished in advance in a predetermined curve (hereinafter referred to as initial crown) in consideration of roll deflection during rolling.
[0008]
Here, the roll profile, which was in the shape of a broken line before rolling, becomes a shape like a solid line after rolling, for example, 50 workpieces having a width of 1000 mm, and a thermal crown as shown is formed.
7 (b) to 7 (d) respectively show the upper and lower directions in the case of a cross angle of 0 ° ((b) diagram), a cross angle of 1.0 ° ((c) diagram), and a cross angle of 1.6 ° ((d) diagram). The work roll interval (in the case of having a thermal crown, the vertical axis is set so that the roll interval at the narrowest vertical roll interval is 0 μm) is shown. In each case, the broken line is the calculated value in the case of the initial crown, and the solid line is the calculated value in the case of having the thermal crown.
[0009]
As is apparent from the figure, when the thermal crown is provided, a protrusion (hereinafter also referred to as a high spot) is generated at a position corresponding to the end portion of the plate width. When a rolled material having a width wider than the position of the protrusion is passed through the work roll having the illustrated roll gap and rolled, the protrusion is transferred to the material to be rolled, resulting in a poor plate profile. .
[0010]
Here, in order to eliminate the protruding portion, the roll may be ground by an online grinder in the same manner as already described with reference to FIG. 6D to eliminate the thermal crown.
However, grinding the portion corresponding to the thermal crown online requires a long grinding time, and during that time, it is necessary to stop the rolling, so that the rolling efficiency is greatly reduced. In addition, the roll basic unit is also greatly reduced.
[0011]
Further, as shown in JP 55-94717, JP 60-158909, JP 63-5814, JP 63-171210, rolls in the axial direction of the work roll Even when adjusting the amount of cooling water, since the change of the gap between the upper and lower work rolls due to the change of the cross angle is not taken into account, roll cooling that properly eliminates the protrusions can be performed. There wasn't.
[0012]
For this reason, in the cross rolling mill, the so-called width return rolling in which the thermal crown is eliminated and the wide-width material is continuously rolled after the narrow-width material rolling cannot be performed freely.
The present invention provides a shape control method and apparatus capable of freely performing this width return rolling in a cross rolling mill.
[0013]
[Means for Solving the Problems]
The present invention relates to a shape control method in a cross rolling machine that rolls a material to be rolled by crossing upper and lower work rolls, and a plurality of work pieces arranged in the axial direction of the work roll and capable of adjusting the amount of cooling water independently. Set the amount of cooling water for each roll water cooling means based on the predicted value or measured value of the work roll profile and the cross angle of the work roll, and control the shape of the material to be rolled by controlling the cooling of the work roll surface. The above problems have been solved by the shape control method in the cross rolling mill characterized by the above.
[0014]
Further, it is a shape control device for a cross rolling machine that rolls a material to be rolled by crossing the upper and lower work rolls, and a plurality of work roll water cooling devices that are arranged in the axial direction of the work roll and can independently adjust the cooling water amount. Adjusting means of the work roll water cooling means based on the means, the work roll profile predicting means or measuring means, the cross angle setting means for setting the cross angle of the work roll, and the cross angle of the work roll profile and the work roll. The above-mentioned problem has been solved by applying a shape control device in a cross rolling mill composed of a cooling water amount adjusting means.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 1 shows an example of a shape control apparatus of the present invention. 1A shows a side view of only the last two stands (F6, F7) of the continuous finishing mill composed of seven stands, and FIG. 1B shows a plan view of the F6 stand.
[0016]
Each stand has an upper work roll 2a, a lower work roll 2b, an upper backup roll 3a, a lower backup roll 3b, and a cross angle adjusting device 6 for changing the cross angle of the upper and lower work rolls. A cross angle setting value is sent from the shape control device 5 to the cross angle adjusting device 6.
The shape control device of the present invention has a plurality of water cooling nozzles 4a arranged along the work roll 2a and a plurality of water cooling nozzles 4b arranged along the axial direction of the work roll 2b. Cooling water is supplied from the water pipe 10. In the present embodiment, ten water-cooling nozzles 4a and 4b are provided for the upper and lower work rolls, respectively. The water piping to each water cooling nozzle has flow rate adjusting valves 8a and 8b as cooling water amount adjusting means. The flow rate adjusting valves 8a and 8b are adjusted in opening degree by the shape control device 5.
[0017]
The F6 stand is equipped with an online profile meter 7a that measures the roll profile of the upper work roll online and an online profile meter 7b that measures the roll profile of the lower work roll online. The roll profile measurement data is sent to the shape control device 5.
[0018]
Next, the work roll cooling method of the present invention using the work roll cooling apparatus shown in FIG. 1 will be described.
In the shape control device 5, the amount of cooling water ejected from the water cooling nozzles 4a and 4b is determined according to the flow shown in FIG.
The host computer (not shown) stores the actual usage (rolling conditions, cooling conditions) of each work roll currently incorporated, and the shape control device during the rolling interval (during the waiting time until the next rolled material bites into the rolling mill) Use result data is output to 5. At the same time, the rolling conditions of the next rolled material (the target thickness value and the target crown value on the stand exit side) are output to the roll shape control device 5. In FIG. 1, the sixth stand F6 is provided with online profile meters 7a and 7b capable of measuring the work roll profile online. With respect to the stand on which the online profilometer is installed, measurement data based on the stand is sent to the shape control device 5.
[0019]
In the shape control device 5, first, the roll profile of the current work roll is calculated based on the usage record data of the work roll sent from the host computer or the roll profile measurement data by the online profilometer (step 110). Then, the optimum cross angle of each stand is determined based on the roll profile calculation value and the rolling condition of the next rolled material (plate thickness target value, plate crown target value, etc. on each stand exit side) (step 120). Next, the width direction distribution of the gap between the upper and lower work rolls when each stand is rolled as the cross angle determined in step 120 is predicted (step 130). Based on the distribution in the width direction, the amount of cooling water at each position in the width direction is calculated to determine the opening degree of each flow rate adjusting valve 8 (step 140).
[0020]
3 (a) and 3 (b) show the upper and lower workpieces when the work rolls during rolling are cooled with the same amount of cooling water in the width direction when the cross angle is 0 ° and 1.6 °, respectively. A roll gap (broken line in the figure) and an upper and lower work roll gap (solid line in the figure) targeted in the work roll cooling method according to the present invention are shown. In the present invention, in step 140, a cooling water amount distribution that can reduce the height of the protrusion is obtained. That is, the cooling water amount distribution is determined so that the gap between the upper and lower work rolls is as shown by the solid line in the figure.
[0021]
4A and 4B show examples of calculation results of the roll cooling water amount at each position in the width direction when the cross angle is 0 ° and 1.6 °, respectively. Comparing the case where the cross angle is 0 ° and the case where the cross angle is 1.6 °, the amount of cooling water in the vicinity of the protrusion is different. Looking at the right side of the line center (0 mm position) in the figure, the amount of cooling water at -800 to -600 mm position is 200 l / min · m when the cross angle is 0 °, whereas it is 1.6 ° when the cross angle is 1.6 °. Then, it is set to 150 l / min · m. The amount of cooling water at the position of −400 to −200 mm is 200 l / min · m when the cross angle is 0 °, whereas it is 180 l / min · m when the cross angle is 1.6 °. In this way, the amount of cooling water at each position in the width direction for smoothing the protrusions is changed according to the cross angle, so that the upper and lower workpieces can be adjusted regardless of the cross angle. The distribution in the width direction of the gap between the rolls can be made smooth.
[0022]
In the work roll cooling device shown in the above embodiment, ten water cooling nozzles are arranged in the width direction to provide cooling at each position in the width direction, but the present invention is not limited to this. In addition, the number of water-cooled nozzles can be freely determined according to the required work roll profile. Further, it is desirable that the cooling water amount and the like have an appropriate equipment capacity depending on rolling conditions such as rolling temperature, and it is needless to say that the cooling water amount is not limited to the above.
[0023]
Moreover, in the said embodiment, although the example which applied this invention to the last 2 stands of a hot finish rolling mill was shown, it cannot be overemphasized that this invention is not limited to this but can apply to another stand.
[0024]
【Example】
An embodiment to which the shape control of the present invention is applied will be described.
Rolling was performed for each of the present invention example to which the present invention shown in FIG. 1 was applied and a conventional example in which shape control was not performed, and the shape comparison in the sheet width direction of the material to be rolled was performed.
First, a low carbon steel strip having a width of 1000 mm and a low carbon steel strip having a width of 1200 mm were prepared as the material to be rolled, and the rolling was performed alternately. Next, the conventional rolling is performed in the same manner.
[0025]
The result is shown in FIG. FIG. 5 shows the measured width direction profile after rolling the material to be rolled.
Here, in the 49th example of the conventional example, protrusions called edge buildup are prominently appearing at both ends in the plate width direction of the 1000 mm wide material. In the 50th 1200 mm wide material, edge buildup appears at both ends, and a high spot having a height of 40 μm is generated at a position corresponding to the width of 1000 mm.
[0026]
On the other hand, in the example of the present invention, the edge buildup at the 49th line is relatively small, and the high spot recognized at the 50th line is 5 μm in height and is suppressed to a level that does not cause a problem.
[0027]
【The invention's effect】
By applying the present invention, optimum work roll water cooling according to the cross angle of the cross rolling mill is possible, and the shape control in the width direction of the material to be rolled in the cross rolling mill can be optimized.
According to the present invention, width return rolling can be performed freely without worrying about the rolling schedule. Therefore, the regulation of rolling order can be greatly relaxed, which can greatly contribute to productivity improvement.
[Brief description of the drawings]
FIG. 1 is a configuration diagram showing a shape control device of the present invention, in which (a) is a side view and (b) is a plan view.
FIG. 2 is a block diagram illustrating shape control of the present invention.
FIG. 3 is a diagram showing an upper and lower roll gap in a roll axis direction.
FIG. 4 is a graph showing an example of a cooling water amount pattern in shape control of the present invention.
FIG. 5 is a graph showing a width direction profile of a material to be rolled.
FIG. 6 is a graph for explaining a conventional method for eliminating a step portion due to wear of a work roll.
FIG. 7 is a graph showing a roll profile of a work roll and a vertical roll gap for each cross angle.
[Explanation of symbols]
2a, 2b work roll
3a, 3b Backup roll
4a, 4b Water cooling nozzle (work roll water cooling means)
5 Shape control device 6 Cross angle adjusting device (cross angle setting means)
7, 7a, 7b Profilometer (Profiling means)
8a, 8b valves (cooling water volume adjustment means)
10 Water piping
11 Water pump

Claims (2)

It is a shape control method in a cross rolling mill that rolls the material to be rolled by crossing the upper and lower work rolls, and a plurality of work roll water cooling means that are arranged in the axial direction of the work roll and can independently adjust the cooling water amount. Each cooling water amount is set based on the predicted value or actual measurement value of the work roll profile and the cross angle of the work roll, and the shape of the material to be rolled is controlled by controlling the cooling of the work roll surface. Shape control method in a cross rolling mill. It is a shape control device in a cross rolling machine that rolls the material to be rolled by crossing the upper and lower work rolls, and a plurality of work roll water cooling means that are arranged in the axial direction of the work roll and can independently adjust the cooling water amount; , Work roll profile prediction means or measurement means, cross angle setting means for setting the cross angle of the work roll, and cooling for adjusting the respective cooling water amounts of the work roll water cooling means based on the cross angle of the work roll profile and the work roll A shape control device in a cross rolling mill comprising water amount adjusting means.

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