JP3464378B2 - Strip crown control method and apparatus - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plate crown control method and apparatus in a hot rolling process which is a manufacturing process of metal plate products such as steel, aluminum and copper.

[0002]

[Related Background Art] One of the important factors that determines the quality of metal plate products such as steel, aluminum and copper is the plate thickness accuracy. With the recent sophistication of quality requirements, the plate thickness accuracy has come to be required not only in the longitudinal direction of the rolled plate material but also in the width direction. That is, it has become necessary to reduce not only the variation in the plate thickness in the longitudinal direction of the plate material but also the variation in the plate thickness in the width direction.

The plate thickness distribution in the width direction of such a plate material is generally called a plate crown, and the maximum value of this plate thickness variation is called a plate crown amount. The plate crown amount at the final product stage is almost determined by the plate crown in the hot rolling process. Thus, since the plate crown in the hot rolling process has a close relationship with the plate crown amount of the final product, various control methods and devices for controlling the plate crown in the hot rolling process have been developed, Has been introduced.

Examples of such a control method include an initial crown type work roll bender type cross roll type backup roll type with sleeve shift roll type heat crown type and the like. The initial crown method is a method of controlling a plate crown by using a work roll provided with an appropriate roll crown during polishing.

The work roll bender system is a system in which the work roll bearing box is pressed by a hydraulic jack to change the roll deflection to control the plate crown. The cross roll method is a method of controlling the plate crown by giving a variable crossing angle to the upper and lower work rolls and geometrically changing the roll gap. The sleeve-equipped backup roll method is a method of controlling the plate crown by deforming the surface shape of the sleeve-equipped backup roll by hydraulic pressure or the like.

The shift roll system controls the plate crown by giving a special asymmetric crown or a single taper to the upper and lower work rolls and shifting them in opposite directions to geometrically change the roll gap. It is a method to do. The heat crown method is to spray a cooling spray onto a work roll while forming a pattern of strength in the width direction of the roll, and to cool the work roll unevenly in the width direction.
This is a method of controlling the distribution of the amount of thermal expansion of the work rolls and thereby controlling the plate crown.

The above method has been effective in controlling the plate crown when the ratio of the plate width of the rolled material to the roll surface length is sufficiently large.

[0008]

In order to improve the productivity of rolled materials and reduce the equipment cost of rolling mills, it is necessary to produce rolled materials having various strip widths with a large rolling mill. When it is attempted to produce a narrow strip with a large rolling mill, the strip width of the strip is ½ or less, or ⅓ or less of the strip width with which the rolling mill can appropriately control the strip crown according to the above method. It may be the board width.

Since all of the above-described various plate crown control methods work effectively when the strip width of the rolled material is sufficient, when the strip width of the rolled material becomes extremely narrow in this way, The crown may not be properly controlled. On the other hand, if it is possible to effectively control the strip crown even if the strip width of the rolled material is narrow, it is necessary to always effectively control the strip crown regardless of the strip width. It becomes very complicated. Further, control unnecessary for the plate crown control of the rolled material having a normal plate width will be performed. Further, if it is attempted to effectively control the plate crown only in the case of a narrow plate material, it is possible that the control of the plate crown becomes unstable during the rolling of the wide plate material.

Further, a local and abrupt plate crown change called edge drop may occur at the edge of the plate material. In order to correct such edge drop and obtain a plate crown having an ideal shape. Requires a very large crown variation in a locally limited range. Therefore, it is very difficult and wasteful to correct only the local edge drop by using the method for controlling the plate crown over the entire plate width as described above.

In particular, in the rolling having a large plate thickness and a large reduction amount, which is represented by hot rolling of a thick plate, the lateral flow of the material (3
Dimensional deformation) is likely to occur. Therefore, in such a rolling process, the edge drop amount of the plate material becomes large, and it is difficult to reduce the plate crown amount. On the other hand, in order to avoid the above inconvenience, a plurality of plate crown control mechanisms are installed for each width of the plate material passing between the work rolls, or the work rolls are replaced according to the width of the plate material. hand,
It is possible to control the strip crown appropriately for strips of any width, but in order to take such measures, the equipment cost of the rolling mill and the productivity of the strip are increased. It is not preferable because it causes a decrease.

The object of the present invention is to provide a sheet crown in a hot rolling process which is a process for producing metal plate products such as steel, aluminum and copper, especially when a narrow plate material is rolled using a wide rolling mill. It is to provide a method and apparatus for effectively controlling the above.

[0013]

In order to achieve the above-mentioned object, a plate crown control method and a plate crown control apparatus according to the present invention are provided in a hot rolling of a metal plate, at least during the final rolling step of the rolled material. By cooling / heating the sheet in the sheet width direction, the temperature distribution in the sheet width direction is changed, and the rolled material is controlled so as to approach the target sheet crown.

During the final pass rolling in which the plate crown of the rolled material is almost determined, the temperature distribution in the plate width direction of the rolled material is changed, so that the temperature at the plate edge is particularly lower than that at the central part. By doing so, the deformation resistance of the plate end becomes high, and the plate end becomes difficult to deform. As a result, the lateral flow of the material is suppressed, so that the edge drop can be suppressed and a rolled plate with a small crown amount can be obtained.

The strip crown control method and strip crown control apparatus according to the present onset Ming, assuming the temperature of the plate width direction of the rolled material is as homogeneous, it predicts the strip crown of the rolled material, predicted strip crown And the deviation from the target plate crown, and in order to bring the predicted plate crown close to the target plate crown, the necessary temperature change amount for the plate center part at the plate edge is estimated based on the deviation. The rolled material is then cooled / heated in the strip width direction based on this estimated value.

Since the predicted strip crown and the targeted strip crown can be compared accurately, it is possible to estimate an accurate required temperature change amount for bringing the rolled material close to the targeted strip crown, and the rolled material strip can be estimated. Crown control can be performed more accurately.

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of a plate crown control method and apparatus according to the present invention will be described below with reference to the drawings. As shown in FIGS. 1 and 2, a strip crown control device 1 according to the present invention includes a reversible rolling mill 10, and cooling devices 21 arranged on the sheet material loading and unloading sides of the rolling mill 10.
22, the rolling mill 10 and the cooling devices 21 and 22 are controlled,
The control device 30 and the like effectively control the plate crown of the plate material.

The reversible rolling mill 10 includes rolling rolls 11 and 1.
2. The rolling plate transport table 40 and the like are provided. The rolling rolls 11 and 12 include a pair of upper and lower work rolls 11a and 12a and backup rolls 11b and 12b having a diameter larger than that of the work rolls 11a and 12a.
The work rolls 11a and 12a sandwich the rolled material of the work between the two rolls and roll the work rolls. The work rolls 11a and 12a are reversibly driven to rotate as shown by solid and wavy arrows in FIG.

The rolling load of the work rolls 11a and 12a is applied by the backup rolls 11b and 12b. A hydraulic pressure reducing device 13 is arranged below the lower backup roll 12b. As shown in FIG.
As shown in, the reduction hydraulic control circuit 13a is connected,
Hydraulic oil is supplied to the pressure reducing device 13 from the pressure reduction hydraulic control circuit 13a, and a rolling load is applied to the roll shaft of the lower backup roll 12b by the pressure reducing device 13.

The reduction hydraulic control circuit 13a includes a control device 3
0 is connected to the reduction control device 30a, and the reduction control device 30a controls the hydraulic pressure control circuit 13a for reduction based on a predetermined pass schedule, and through the hydraulic reduction device 13, each pass of the rolled material. Rolling rolls 11 and 12
To reduce. Work roll benders 14 are disposed at both ends of the work rolls 11a and 12a, as indicated by a chain double-dashed line in FIG. Work roll vendor 14
2, as shown in FIG. 2, the bender hydraulic control circuit 14a
It is controlled by the rolling-down control device 30a via. This work roll vendor 14 makes the work roll 11
A and 12a are bent to correct the shape of the rolled material.

Before and after the work rolls 11a and 12a,
Spray devices 15 and 16 for directly injecting a coolant are arranged on the work rolls 11a and 12a. Each of the spray devices 15 and 16 has a large number of nozzles 15a and 16a arranged facing the rolls at predetermined intervals in the axial direction of the work rolls 11a and 12a, and heat crown solenoid valves 15b and 16b corresponding to the nozzles. It has and. As shown in FIG. 2, the heat crown solenoid valves 15b and 16b are connected to the pressure reduction control device 30a, and the pressure reduction control device 30a operates the spray devices 15 and 16 in accordance with a predetermined pass schedule. Can be made.

The rolling plate conveying table 40 is for supporting the rolled material that is carried in and out between the work rolls in the forward and reverse directions. The cooling devices 21 and 22 are composed of four cooling devices 21u, 21d, 22u and 22d, and are arranged on both sides of the work rolls 11a and 12a so as to face each other so as to be located above and below the rolled material. And the cooling device 2
1u, 21d, 22u, 22d are composed of a plurality of zones that can be cooled at different temperatures in the plate width direction,
These zones are arranged side by side at least in the width direction of the rolled material. More specifically, this zone includes, for example, a plurality of coolant sprays (nozzles) 21 arranged in a matrix at intervals of 100 mm to 200 mm.
a, 21b, 22a, 22b and control valves 21c, 21d, 2 arranged corresponding to the coolant sprays, respectively.
2c and 22d.

The cooling / heating controller 30b shown in FIG.
The solenoid valves 21c, 21d, 22c, 22d are driven to inject the cooling water uniformly from the solenoid valves 21c, 21d, 22c, 22d in the plate width direction, or the cooling water is non-uniformly ejected in the plate width direction. This is for effectively controlling the plate crown by causing a change in temperature distribution in the width direction. The cooling / heating control device 30b increases the injection amount of the coolant spray in the vicinity of the plate edge, thereby locally cooling the edge (plate edge) of the rolled material of any plate width. You can

When an electric heater, which will be described later, is provided in parallel with the coolant spray, the cooling / heating control device 30b.
It is also possible to control the electric heater to heat the plate material non-uniformly in the plate width direction. Further, the coolant sprayers 21a, 21b, 22a, 22b only need to be able to change the cooling amount in the plate width direction, so that they are not necessarily arranged in a matrix, and a plurality of coolant sprayers are arranged in at least one row in the plate width direction. It should be provided.

Next, the control of the plate crown will be described in detail with reference to the flow charts shown in FIGS. First, the control device 30 executes a normal path schedule setting calculation routine (step 1). This routine is calculated without considering the temperature difference in the plate width direction.
Specifically, the dimensions of the material, the material temperature, the deformation resistance, etc. are input to the reduction control device 30a, and the initial pass schedule calculation, the reduction pattern, the rolling speed, the sheet width direction are calculated based on the theoretical formula and the empirical formula which are determined in advance. To determine a uniform cooling rate.
Various methods for distributing the reduction amount of each pass in the pass schedule have been proposed in Japanese Patent Laid-Open No. 62-259605.

Next, based on the pass schedule, rolling speed, and cooling amount determined in step 1, the temperature of the central portion in the width direction of the sheet material during the final pass (hereinafter referred to as "N pass") rolling, And the deformation resistance in the N path is predicted (step 2). In addition, generally, in this N-pass rolling, a plate crown of a normal plate material is determined. Next, the rolling load and bending crown of the N pass are calculated (step 3), the thermal crown of the rolling roll of the N pass is predicted and calculated (step 4), and the edge drop amount due to the three-dimensional deformation of the plate end portion of the N pass is calculated. Is calculated (step 5). The prediction calculation in steps 3 to 5 can be calculated by inputting the calculated value obtained in step 2 into a table based on the experimental result.

Next, the N-pass plate crown shape is predicted and calculated based on the calculation results obtained in steps 3 to 5 (step 6). This prediction calculation is performed by a calculation formula in which the above calculation result is modeled by a finite element method or a table based on an experimental result. An example of the plate thickness distribution (crown shape) in the plate width direction obtained by this prediction calculation is the distribution shown by the dotted line in FIG. or,
The target plate crown shape is the shape shown by the solid line in FIG.

Further, the deviation between the plate crown predicted in step 6 and the target plate crown is obtained, and the correction operation amount of the plate crown correcting actuator is calculated from this deviation (step 7). The plate crown correcting actuator is, for example, a work roll bender, roll shift, roll cross, or the like. Next, it is determined whether or not the correction operation amount obtained in step 7 is within the correction operation amount limit of the actuator (step 8). If it is within the correction operation amount limit, only the correction operation of the correction actuator is performed. It is determined that the target plate crown can be corrected, and the examination of the width direction temperature control amount of the plate material is finished (step 8A).

When it is determined in step 8 that the correction amount exceeds the correction operation amount limit of the actuator and the correction cannot be performed to the target plate crown only by the correction operation of the correction actuator, the target plate crown is corrected. The required plate crown correction amount at the plate edge is obtained from the deviation from the shape (step 9). Subsequently, the coefficient of influence on the bending crown due to the decrease in the plate edge temperature is calculated (step 10
A), the coefficient of influence on the edge drop amount due to the plate edge temperature decrease is calculated (step 10B). This can be obtained using a table based on experimental results and the like using the calculated value obtained in step 6.

Then, based on the results obtained in steps 9 to 10B, the temperature decrease amount at the plate end portion necessary to correct the target plate crown is calculated (step 10).
C). Next, the temperature distribution in the strip width direction during N-pass rolling is predicted based on the normal cooling pattern under the initial calculation conditions obtained in step 1 (step 11). In this case, the temperature distribution in the plate width direction at this time is the distribution as shown by the dotted line in FIG.
The necessary (target) temperature reduction amount in the plate width direction obtained in C has the temperature distribution shown by the solid line in FIG. From the difference between the two,
The amount of temperature decrease (hatched portion) to be corrected is obtained.

Then, the difference in the required cooling amount between the plate central portion and the plate end portion is calculated (step 12). This cooling amount corresponds to the corrected temperature decrease amount obtained by the comparison in FIG. 6, and specifically, the cooling water temperature, the flow rate, the number of nozzles to be operated, the cooling time, etc. are calculated. Through the above steps, the required widthwise temperature control amount is determined as the cooling amount (step 13).

Then, returning to step 2, step 10
Assuming that the temperature distribution calculated in C is obtained, the predicted plate crown is calculated again, and steps 10A and 10 are performed.
It is confirmed that the target plate crown can be corrected by repeating steps 3 to 7 by adding the influence of the temperature decrease of the plate end obtained in B. After the required cooling amount is obtained by the above steps, hot rolling is actually started.

The hot rolling is performed according to the following procedure.
First of all, based on the pass schedule determined by the control device 30, the rolling control device 1 is operated by the reduction control device.
First, 1 and 12 are set to the first rolling position, and the work rolls 11a and 12a are set in the forward rotation direction (the solid arrow direction in FIG. 1).
Then, the rolling plate transport table 40 is driven to roll the rolling material by the set rolling amount, and the rolling material is pulled out to the opposite side of the rolling mill 1.

Next, the rolling rolls 11 and 12 are set to the second rolling position, and the work rolls 11a and 12a and the rolling plate transport table 40 are driven in the reverse rotation direction (the direction of the dotted arrow in FIG. 1), Rolling is performed in the same manner as described above, and the rolling mill 1 is pulled out to the material carrying-in side, and such rolling is repeated a number of times (N times) determined by the pass schedule.

The work rolls 11a and 12a are rolled down by operating the hydraulic roll-down device 13 via the hydraulic control circuit 13a, and during rolling, the work roll bender 14 works the work rolls 11a and 12a based on a predetermined pass schedule. The work rolls 11a, 1 with the cooling nozzles 15a, 16a for heat crown.
Cool 2a.

If it is determined in step 8 that the target plate crown can be corrected by only the correction actuator, the temperature control in the plate width direction is not performed. That is, the cooling device 2
By 1 and 22, constant cooling water is supplied in the plate width direction in all pass schedules. However, when the cooling amount is calculated to be zero in step 1, the cooling water is not supplied. On the other hand, when it is determined in step 8 that the target plate crown cannot be corrected, the temperature control in the plate width direction is performed as follows.

Up to the N-1th pass, the cooling water corresponding to the cooling amount obtained in the above step 1 is sprayed uniformly by the cooling devices 21 and 22 in the width direction of the plate material. However, step 1
If it is calculated that the cooling amount is zero, the cooling water is not supplied. In the N pass, in addition to this cooling water, cooling water corresponding to the cooling amount obtained in the above step 12 is further added and supplied to the vicinity of the plate end by coolant spray. When supplying this cooling water, cooling / cooling is performed based on the plate width input in advance during the initial pass schedule calculation.
The heating control device 30b selects the coolant spray located near the plate end, and the control valves 21c, 21 corresponding to this are selected.
This is performed by driving d, 22c and 22d. or,
This cooling water may be supplied from both the cooling devices 21 and 22, or may be supplied from either one of the cooling devices.

In this way, by making the temperature of the plate end lower than that of the central part, the deformation resistance of the plate end can be increased and the lateral flow of the material can be suppressed. As a result,
It is possible to reduce the deformation at the plate end portion and suppress the edge drop, and it is possible to obtain a rolled plate having a small crown amount. According to the plate crown control method of the present invention,
The temperature difference between the plate central portion and the plate end portion is positively controlled within the target range, which may cause precipitation of different metal structures in the width direction. However, by using an alloy composition that is unlikely to affect the mechanical properties as a material, or by appropriately selecting the rolling temperature band during rolling, defects due to the precipitation of different metal structures, that is, the mechanical properties of the plate material It is possible to prevent the occurrence of unevenness and the occurrence of strain after cutting due to residual stress. Further, even if unevenness in mechanical properties of the plate material, residual stress, etc. occur, it can be easily corrected by heat treatment or straightening after rolling.

In the above-described embodiment, the plate end portion is cooled more than the plate central portion. However, depending on the pass schedule, the plate thickness, the cooling mode, etc., it is appropriate without temperature control particularly in the plate width direction. The plate edge portion may be excessively cooled by exceeding the temperature difference in the plate width direction. In such a case, a heating device such as an electric heater may be provided near the cooling device to locally heat the plate end portion. This heating device is also controlled by the cooling / heating control device, as shown in FIG.
This, on the contrary, promotes three-dimensional deformation of the plate edge,
A target plate crown can be obtained.

Further, in the above-described embodiment, the temperature control in the strip width direction is performed in the N pass which is the final pass. However, when the rising strip thickness (final strip thickness of the rolling process) is thin or When the plate material is wide and the plate material is hard to deform, etc., the upstream paths before the N path are also considered as paths that affect the plate crown determination, and this upstream path also has the same plate width direction temperature as described above. It is preferable to perform control.

In such a case, even if an attempt is made to greatly change the plate crown with only N passes, since the lateral flow of the material is actually restricted, a large proportion of the change component is the change in strain in the longitudinal direction . Will be converted to. For this reason,
Although the desired plate crown change cannot be obtained and the flatness of the plate material deteriorates, such problems can be prevented by performing plate crown control in multiple passes including the upstream pass. You can

In the above embodiment, the hot reversible rolling mill, which is a typical thick plate mill, has been described, but it goes without saying that the present invention can be applied to other mill forms such as a tandem mill. Yes. In this case, regarding the pass schedule, it may be considered that the above-mentioned "pass" is read as "stand", the pass proceeds sequentially at each stand, and at least the stand corresponding to the final pass performs the above-described plate crown control.

[0043]

As described above, the plate crown control method and the plate crown control device according to the present invention, in the hot rolling of a metal plate, the rolled material is rolled in the plate width direction at least during the final rolling step. It is characterized in that the temperature distribution in the strip width direction is changed by cooling / heating and the rolled material is controlled so as to approach the target strip crown.

At the time of the final pass rolling in which the strip crown of the rolled material is almost determined, the temperature distribution in the sheet width direction of the rolled material is changed so that the temperature at the edge of the sheet is lower than that at the center. By doing so, the deformation resistance of the plate end becomes high, and the plate end becomes difficult to deform. As a result, the lateral flow of the material is suppressed, so that the edge drop can be suppressed and a rolled plate with a small crown amount can be obtained.

Further, since it is not necessary to install a plurality of mechanisms for controlling the plate crown for each width of the rolled plate or replace work rolls for each change in plate width, it is possible to reduce equipment costs and productivity. Can be improved. In particular, the above-mentioned effect becomes remarkable when rolling a narrow material using a wide rolling mill.

The strip crown control method and strip crown control apparatus according to the present onset Ming, assuming the temperature of the plate width direction of the rolled material is as homogeneous, it predicts the strip crown of the rolled material, predicted strip crown And the deviation from the target plate crown, and in order to bring the predicted plate crown close to the target plate crown, the necessary temperature change amount for the plate center part at the plate edge is estimated based on the deviation. The rolled material is then cooled / heated in the strip width direction based on this estimated value.

Since the predicted strip crown and the target strip crown can be compared accurately, the amount of temperature change required for bringing the rolled material closer to the target strip crown can be estimated, and the strip crown control of the rolled material can be performed. It can be done more accurately.

[Brief description of drawings]

FIG. 1 is a diagram schematically showing a plate crown control device according to an embodiment of the present invention.

FIG. 2 is a functional block diagram for explaining a plate crown control method and device according to an embodiment of the present invention.

FIG. 3 is a flowchart showing a plate crown control method according to an embodiment of the present invention.

FIG. 4 is a flowchart showing a method for controlling the plate crown, which is subsequent to the flowchart in FIG.

FIG. 5 shows a case where a temperature control in the width direction according to the present invention is performed.
It is a figure which shows the board thickness distribution of the rolling material at the time of the last pass in comparison with the prior art example.

FIG. 6 shows a case where the temperature control in the width direction according to the present invention is performed,
It is a figure which compares with the prior art example the board temperature distribution of the board width direction of the rolling material at the time of the last pass.

[Explanation of symbols]

1 Plate crown controller 10 rolling mill 11 rolling rolls 11a Work roll 11b backup roll 12 rolling rolls 12a work roll 12b backup roll 21 Cooling device 21a, 21b Coolant spray 21c, 21d Solenoid valve 22 Cooling device 22a, 22b Coolant spray 22c, 22d solenoid valve 40 Rolled plate transport table

Claims (2)

(57) [Claims] 1. A method for controlling a plate crown in hot rolling of a metal plate, which is performed on the assumption that the temperature of the rolled material in the plate width direction is uniform.
Predict the plate crown of the timber and compare the predicted plate crown with the targeted plate crown.
To find the deviation and bring the predicted plate crown closer to the target plate crown
In addition, based on the deviation, it is necessary to adjust the plate edge to the plate center.
Estimate the amount of temperature change, and based on this estimated value , cool / roll the rolled material in the strip width direction at least during the final rolling process.
By heating, change the temperature distribution in the plate width direction,
A plate crown control method comprising controlling a rolled material so as to approach a target plate crown. 2. At least in the hot rolling of a metal plate.
A plate crown control device for the final rolling step, wherein at least a hot rolling mill that rolls the sheet material and a rolled material loading side or unloading side of the hot rolling mill are used.
Rolling material cooling / heating means provided on either side of the rolling material is assumed to have a uniform temperature in the plate width direction.
Predict the plate crown of the timber and compare the predicted plate crown with the targeted plate crown.
It is necessary to obtain the deviation and eliminate it from the center of the plate at the edge of the plate.
Estimate the required temperature change amount and control the rolling material cooling / heating means based on the estimated value
Then, change the temperature distribution in the width direction of the rolled material to
And a control means for approaching the target plate crown
A plate crown control device characterized by the above.