JPH0352705A - Control of sectional profile of rolled stock in hot continuous rolling line - Google Patents

Abstract

PURPOSE:To improve accuracy of total crown by measuring sectional wedge quantity of sheet bar on the inlet side of finishing mills, converting into press- down leveling quantity of the stand of each finishing mill and setting the difference in opening of roll on the driving side and the operation side. CONSTITUTION:The thickness of both end parts of a sheet bar 1 which is rolled with a group 7 of roughing mills is measured with a measuring instrument 8 for wedge and leveling quantity is calculated with an operation device 14 and is reflected and set as the difference in opening of mill roll on the driving side and the operation side of the group 10 of finishing mills. The thickness is measured with laser transmitters 5A, 5A' and receivers 5B, 5B' of the measuring instrument 8 and, because the instrument is movable with rollers 4, 4', the thickness on the optional position of the sheet bar 1 can be measured. By pressing down and correcting the non-symmetric sectional profile in the broadwise direction that is generated on the sheet bar with leveling control of the group of the finishing mills 10, the hot strip of high-accuracy of total crown can be manufactured.

Description

[Detailed description of the invention] [Industrial application field]

The present invention relates to a method for controlling the cross-sectional profile of a rolled material (product coil) in a continuous hot rolling line.

[Conventional technology]

In conventional continuous hot rolling lines, 6-eye iHC minors, Pair-Cross minors, etc. are used as means to control the plate cross-sectional profile.
In combination with a work roll pending device, the profile of the plate cross section is controlled. However, these rolling means only control a symmetrical cross-sectional profile as shown in FIG. If 30μm is given,
Assuming a symmetrical cross-sectional profile, while satisfying the exit shape of each stand, the sum of the inevitable roll initial crown, thermal crown, mechanical roll deflection crown, and controllable roll pending crown is achieved. The cross-sectional shape is controlled by controlling the amount of plate crown transferred onto the material using the previously controllable roll pending amount.

[Problem to be solved by the invention]

However, the actual cross-section of the plate is not necessarily symmetrical, and as shown in comparison with FIGS. 5 and 6, the cross-sectional profile is formed by overlapping the plate wedge and the crown. The problem with the crown of the product (rolled material) is the total amount of crown, which includes the wedge and the pure crown portion, and it is not possible to control the asymmetrical total crown simply by controlling the bender alone. The factors that cause wedges are considered to be factors that occur during the rough mill rolling stage and factors that occur during the finishing mill rolling stage. Possible causes include asymmetry on the driving and operating sides, such as differences in constants, sheet passing position, sheet temperature distribution, and mechanical play in the mill. Once a wedge occurs at the stage of
It is extremely difficult to control this manually on the finishing mill side. In other words, a sheet bar with a wedge deteriorates the threading performance of the finishing mill, the leading end causes the guide between the stands to be misaligned, and the rear end creates a guide restriction, but for the operator, it is difficult to level the plate during rolling. The best way to maintain sheet threading is to appropriately control the difference in the amount of reduction between the drive side and the operating side. This is because it is very difficult to go so far as to do so. The present invention was made in order to solve these problems, and it is an object of the present invention to appropriately correct the asymmetric cross-sectional profile in the width direction and obtain a good cross-sectional profile in continuous hot rolling. The object is to provide a method for controlling the cross-sectional profile of a rolled material. [Means for Solving the Problems] As summarized in FIG. 1, the present invention provides a method for controlling the cross-sectional profile of a rolled material in a continuous hot rolling line. A procedure for measuring the amount of wedge at the input side of the finishing mill, a procedure for converting the measured wedge amount into the rolling reduction leveling amount of each finishing mill stand, and a procedure for converting the measured wedge amount into the rolling reduction leveling amount of each finishing mill stand, and the drive side of the finishing mill's rolling reduction control device based on the converted rolling reduction leveling amount. , and a procedure for setting the roll opening difference on the operation side, thereby achieving the above object.

[Effect]

In the present invention, the wedge amount of the sheet bar is measured using, for example, a laser distance meter on the entry side of the finishing mill, and this wedge amount is transferred to a calculation device and converted into the reduction leveling amount of each finishing mill stand. The reduction leveling amount converted by the arithmetic device is set and reflected by the reduction control device as the difference in the opening degree of the left and right mill rolls, and during this time the sheet bar is rolled by each finishing mill roll set to the degree difference. As a result, even if a wedge occurs on the sheet bar on the exit side of the rough mill, this can be corrected during the rolling stage in the finishing mill, and the non-uniformity of the cross-sectional profile of the product (rolled material) can be corrected. Ru.

【Example】

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 2 shows the configuration of a continuous hot rolling line in which the present invention is implemented. The slab extracted from the heating furnace 6 is rolled in a rough mill group (rough rolling mill group) 7, and is usually 3Qn+ called a sheet bar.
It is rolled to an intermediate material with a thickness of m to 60 mm. Thereafter, it is sent to a finishing mill group 10 via a delay table 9, where finishing rolling is performed. The finish-rolled product passes through a sprayer 11 and a coiler 12
After being wound up by the coil conveyor 13, it is carried out. The method of determining the target thickness of the sheet bar 1 (how to set the rolling opening of each stand of the rough mill) is determined by a table method, rather than using a strict thickness calculation (so-called finishing mill setup calculation). Regarding the mill elongation of each stand, the draft (rolling opening degree) is generally given in a corrected form, and this target sheet bar thickness is used as the initial value for calculating the rolling opening degree of the finishing mill group 10. However, this The wedge amount of the sheet bar 1 is determined by the mill constant difference between the driving side and the operating side of the coarse mill group 7,
This occurs due to the passing position of each rough mill group 7 of the slab, the temperature distribution in the width direction of the slab, the mechanical play of the rolling device, etc., and this has a significant effect on the cross-sectional profile of the product. In the past, even if such a sheet bar wedge occurred, it was rolled in the finishing mill group 10 without knowing the whole, and the symmetrical crown was controlled with a bender, etc., but the asymmetric component of the wedge could not be controlled. Met. In this example, the wedge of the sheet bar is measured, and in addition to the rolling opening of the finishing reduction mill (same distance between left and right), the leveling opening (difference between left and right opening) is also calculated.These calculated leveling openings Finishing mill group 10 with reduction opening including degree
The opening degree shall be set as follows. For example, if the sheet bar wedge is 200 μm, and the 45 mm sheet bar thickness is rolled to 2.3 mm by a finishing mill, 200X2.3/45 = 10.2 μm, and the target crown material is 30 μm. Then, 1
7% is occupied by wedges, which shows the importance of controlling the cross-sectional profile with seat bar wedges in mind. In general, radiation methods (for example, X-ray or gamma ray scanning in the width direction) are considered to be the mainstream method for measuring plate thickness because they can be measured with high accuracy. Techniques for measuring the thickness of a plate in the width direction using this measurement principle include JP-A-58-707 and JP-A-58-10604;
58-44306, 59-65709, etc., but due to the attenuation of radiation, thick materials have a large radiation projection area, making local measurement difficult, so they are used only for thin materials. On the other hand, since the seat bar 1 usually has a thickness of 30 to 60 mm, it is difficult to measure the seat bar wedge using the radiation described above. Therefore, in this embodiment, a laser distance meter 8 is used to measure the wedge amount. What is a laser distance meter?
43507, the distance from the reference value of the top and bottom surfaces of the sheet par 1 is measured, and the sheet bar thickness that exists in the middle is measured from both values. be. In this case, by moving the laser distance meter 8 in the width direction and measuring the thickness of both ends of the seat bar 1, the amount of seat bar wedge can be determined from this difference. The crown can also be determined from the plate thickness at several points in the width direction (see Figures 5 and 6). FIG. 3 shows the wedge measuring device (laser distance meter) 8.
This shows the structure of As shown in the figure, laser transmitters 5A, 5A' and receivers 5B15B- are provided on the upper and lower surfaces of the seat bar 1, respectively, within U-shaped frames 2 and 21. With respect to changes in the width of the sheet bar 1, it is movable by rollers 4, 4', etc. provided on the track 3, and regardless of the width of the sheet bar 1, both ends of the sheet bar 1 are included. It is possible to measure the plate thickness at any position, and to determine the amount of wedge and crown. This laser measurement is applied to the sheet bar immediately after rolling in the roughing mill, and the leveling opening degree on the continuous finishing mill side is adjusted based on the sheet bar wedge amount obtained as a result. FIG. 4 shows the configuration of the wedge amount calculation section of the calculation device 14. A wedge amount calculation section (not shown) of the calculation device 14 calculates the data from the receivers 5B and 5B of the laser distance meter 8 shown in FIG. The height of the bar is determined, the plate thickness at both ends is measured from this value, and the seat bar wedge ΔW is measured from the plate thickness at both ends. The seat bar wedge ΔW measured in this way is
This is absorbed by the difference in rolling leveling between the driving side and the operating side of the finishing mill. In a normal continuous hot rolling line, when the tip of sheet par 1 comes out of the rough mill group 7, mill cooling water is used to reach the target temperature, plate thickness, and width crown on the finishing exit side of the finishing mill group 10 for rolling the next material. Setup control is implemented to calculate the roll-down opening, bender, roll shift, and per-stand speed. A typical example of this setup control is published in "Theory and Practice of Plate Rolling" by the Japan Iron and Steel Institute, page 289. Note that the reduction setting value determined here is the same setting value on the driving side and the operating side. If an attempt is made to eliminate the seat bar wedge ΔW on the entry side in the three upstream stands of the finishing mill group 10, it is sufficient to find ΔW1 to ΔW3 that satisfy equation (1). ΔW1×mouth 3/H1+ΔW 2 X H s/mouth 2+
ΔWs=ΔW×Port 3/Port 0 (1) Port 0: Seat bar center thick mouth i: 1 stand exit side thickness <<i=1 to 3) Δwi: Wedge amount to be eliminated by i stand After appropriately distributing these ΔW1 to ΔW3 to each stand, the predicted rolling load for each stand and the individual mill constants for each stand driving side and operating side are determined by setup control, so leveling is performed using equation (2). Determine the amount. ΔAi=ΔW+ − { (1/2)・Pi +Qi
}* (1 / K i op - 1 / K
i o R)・・・・・・・・・(2) −1 1 − Δj2i : Leveling amount pi of i stand: Predicted load Qi of i stand: Roll pending force KioR of i stand:!
Slope constant Kiop on the driving side of the stand: Mill constant on the operating side of the stand This calculation is performed by the arithmetic unit 14, and the calculated leveling amount is converted to the leveling amount on the driving side and operating side by the mill reduction control equipment (not shown). It is reflected and set as the mill opening difference. In this way, the seat bar wedge amount ΔW is accurately measured by the laser distance meter 8 on the entry side of the finishing mill group 10, and the measured wedge amount ΔW is transferred to the calculation device 14 to be transmitted to each finishing mill stand. The rolling leveling amount calculated by the calculation device 14 is reflected as the difference in the opening degree of the left and right mill rolls by the rolling control device. Since rolling is performed in each finishing mill mouth roll based on the difference, non-uniformity of the cross section of the sheet bar on the finishing mill entrance side is corrected.As for the symmetrical crown component, as before,
Fixed by roll pending.

【Effect of the invention】

As described above, according to the present invention, a hot strip with high total crown accuracy can be manufactured by correcting the asymmetric cross-sectional profile (wedge) in the width direction generated in the sheet bar by the leveling control of the finishing mill. You can get the excellent effect of being able to do it.

[Brief explanation of drawings]

FIG. 1 is a flowchart showing the gist of the present invention, FIG. 2 is a schematic front view of an automatic control device for a continuous hot rolling line in which the present invention is implemented, and FIG. 3 is a wedge measuring device ( laser distance meter)
Fig. 4 is a block diagram showing the signal flow from the laser distance meter; Fig. 5 is a rolled material plate with a symmetrical plate cross-sectional profile, which is the premise of conventional crown control. Thickness Profile Diagram FIG. 6 is a plate thickness profile diagram of a rolled material having an actual asymmetric plate cross-sectional profile. 1... Seat bar 2... Frame, 3...
・Trajectory, 4...Roller 5...Sensor 6...Heating furnace, 7...Rough mill group, 8...Laser distance meter (wedge measuring device) 9...
Delay table, 10... Finishing mill group, 11... Spray 12... Coiler, 13... Coil conveyor, 14... Arithmetic device.

Claims (1)

[Claims] (1) In the method of controlling the cross-sectional profile of rolled material in a continuous hot rolling line, there is a procedure for measuring the cross-sectional wedge amount of the sheet bar at the entry side of the finishing mill, and the measured wedge amount is used as the rolling leveling amount of each finishing mill stand. A continuous hot rolling line characterized by comprising: a step of converting the leveling amount into a rolling reduction; and a step of setting a roll opening difference between the driving side and the operating side of a rolling reduction control device of a finishing mill based on the converted rolling reduction leveling amount. A method for controlling the cross-sectional profile of rolled material.