JP2010274289A - Setup method of roll gap in reverse rolling - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a setup method of a roll gap in reverse rolling, for setting up the roll gap so that the thickness of a steel plate on a bitten side end is accurately matched with the target plate thickness. <P>SOLUTION: In the setup method of the roll gap at a bitten end of a steel plate 1 when conducting the reverse rolling of the steel plate 1 by using AGC (Automatic Gauge Control) in a rolling mill, the thickness difference ΔH<SB>a</SB>is obtained from the thickness at the bite-releasing side end and the thickness of a regular portion of the steel plate 1 rolled by the previous rolling pass, and the roll gap changing amount ΔS at the bitten side end in the present rolling pass is obtained from expression ΔH<SB>a</SB>(1+K/M) (wherein K is the deformation resistance of the regular portion of the steel plate; and M is a mill constant). The roll gap G<SB>a</SB>at the bitten side end in the present rolling pass is determined by correcting the roll gap G at the regular portion in the present pass with the obtained roll gap changing amount ΔS. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a method for setting up a roll gap at a biting tip of a steel sheet when the steel sheet is reverse-rolled by a rolling mill.

  In general, when a slab is hot-rolled into a thick steel plate with a rolling mill, the mill elongation is obtained from the roll gap of the rolling mill and the measured rolling load, and the exit side plate thickness calculated from this mill elongation becomes the target plate thickness. Thus, a plate thickness control method (FB-AGC: Feed Back Automatic Gauge Control) for adjusting the roll gap is performed. Since this FB-AGC usually starts at a position advanced by about 80 mm after the steel sheet is caught in the roll, the tip of about 80 mm is a dead zone and is not controlled.

Further, the biting end portion of the steel plate tends to be in a supercooled state, and the biting end portion tends to be thicker by about 1 mm than the steady portion (steel plate intermediate portion) due to an increase in deformation resistance due to supercooling. In general AGC, the load in the thickened area is detected, and tightening of the roll gap by AGC starts based on this load, but the thickened area is an extremely short area (about 800 mm from biting). There is also a problem in that a region where the AGC control cannot catch up with the rolling speed and consequently is not thick is tightened, and a region where the plate thickness is conversely thinner than the target plate thickness occurs.
Therefore, the roll gap before biting the steel plate is adjusted to tighten more than expected within the range where the lower limit plate thickness of the product custom dimension is not cut in the region where the plate thickness is thin, but sufficient plate thickness control is performed. Not done.

  In order to solve such a problem, in Patent Document 1, when adjusting the position of the reduction cylinder before the steel sheet is caught in the roll, the amount of increase in the reduction cylinder when the steel sheet is caught in the roll is rolled. A steel plate thickness control method has been proposed in which the roll gap is tightened in accordance with the predicted rolling load calculated from the deformation resistance of the material, rolling conditions, etc. The amount of rise of the reduction cylinder due to the impact at the time of biting into the roll is calculated from the predicted rolling load, and the reduction cylinder is adjusted to the tightening side of the roll gap according to this amount of rise, thereby A sheet thickness control method for reducing the sheet thickness deviation is also disclosed.

Japanese Patent Laid-Open No. 11-207405

  However, the plate thickness control method of the steel sheet according to Patent Document 1 described above is to set up the roll gap of the biting side end from the predicted load of the tip, and it is difficult to accurately predict the load, The roll gap cannot be controlled properly, and it is difficult to control the thickness of the biting end of the steel plate, and a portion thicker than the target thickness may remain or the thickness may be reduced.

  Therefore, the present invention solves the above-mentioned problems that could not be controlled only by load prediction, and sets up the roll gap so that the thickness of the biting side end of the steel plate matches the target plate thickness with high accuracy. It is an object of the present invention to provide a roll gap setup method in reverse rolling.

In order to solve the above-mentioned problem, the roll gap setup method in reverse rolling according to the first configuration of the present invention is the roll gap at the biting end of the steel sheet when the steel sheet is reverse rolled using AGC in a rolling mill. in the setup, the rolled steel plate in the previous rolling pass, determine the thickness H _m of the thickness H _h and the constant part of噛抜end, Searching for the thickness deviation [Delta] H _a from the two plate thickness, now calculated roll gap change amount ΔS in clipping position end at the next rolling pass by the following formula (1), the roll gap G _a, Imatsugi path constant region roll gap at the clipping position end at Imatsugi rolling pass It is determined by correcting from G the above-obtained roll gap change amount ΔS.

但し、Ｋ：鋼板定常部変形抵抗、Ｍ：ミル定数
この第１の構成により、鋼板の噛込端部の板厚を定常部の板厚と略同等にすることが可能となり、鋼板長手方向で板厚偏差の小さい鋼板とすることができる。

However, K: Steel plate steady portion deformation resistance, M: Mill constant This first configuration makes it possible to make the plate thickness of the biting end of the steel plate substantially equal to the plate thickness of the steady portion, and in the longitudinal direction of the steel plate. A steel plate having a small thickness deviation can be obtained.

Also, how to set up the roll gap in the reverse rolling according to the second configuration of the present invention is characterized by obtaining the thickness variation [Delta] H _a of the first configuration by the following formula (2).

However, G _h:噛抜side roll gap, F _h:噛抜side rolling load G _m: constant section roll gap, F _m: a constant section rolling load the second configuration, the plate thickness of the rolling load and roll gap Deviation can be calculated and productivity is not affected when calculating thickness deviation.

  Moreover, the roll gap setup method in the reverse rolling according to the third configuration of the present invention uses the following formula (3) instead of the formula (1) for the roll gap change amount ΔS according to the first or second configuration. It is characterized by seeking.

However, F _AVE ^n-1 : Rolling load of the stationary part in the previous rolling pass,
F _MAX ^n-1 : Maximum rolling load at the end of the biting side in the previous rolling pass,
K ^n: Imatsugi rolling pass deformation resistance,
K ^n-1 : Pre-rolling path deformation resistance,
ΔH ⁿ : Set rolling amount of the current rolling pass,
H _h : Plate thickness of the end portion on the biting side of the pre-rolling pass,
H ⁿ : The set thickness of the next rolling pass.
With this third configuration, even when the front end of the steel plate becomes supercooled and hardened, a high-grade steel plate with a smaller thickness deviation can be obtained.

  In the present invention, when reverse rolling a steel sheet using AGC in a rolling mill, it is possible to make the thickness of the biting end of the steel sheet substantially equal to the thickness of the steady part, and the thickness in the longitudinal direction of the steel sheet. Steel sheets with small deviation can be obtained, and the effects in this field are great, such as improvement of yield and saving of labor for steel sheet maintenance.

It is a control system block diagram for enforcing the edge part plate | board thickness control method of the steel plate which concerns on this invention. It is a control block diagram for enforcing the edge part plate | board thickness control method of the steel plate which concerns on this invention.

  The present inventor indicates that the biting side of the pre-rolling pass (hereinafter sometimes simply referred to as “previous pass”), which is a feature of reverse rolling, is referred to as the current rolling pass (hereinafter simply referred to as “present pass”). The part to be rolled is the same and the time from the biting to the biting is short, and the steel plate temperature difference is small, so the rolling performance of the previous rolling pass is It has been found that the thickness of the biting side end can be controlled with high accuracy by using it for setting up the roll gap at the biting side end in this rolling pass.

Generally, the end portions of the steel plate (the biting side end portion and the biting side end portion) are easier to cool than the steady portion, and in particular, the biting side end portion of the steel plate is an AGC dead zone. Therefore, it tends to be thicker than the plate thickness of the stationary part.
For this reason, it is necessary to narrow the roll gap at the biting side end portion by an amount corresponding to the increase in the plate thickness (narrow the roll gap) as compared with the roll gap at the stationary portion.
For this purpose, first, the plate thickness H _m of the steady portion and the plate thickness H _h of the biting side end, which are the rolling results of the pre-rolling pass, are obtained, respectively, and the plate thickness deviation ΔH _a, which is the difference between these plate thicknesses. (= H _h −H _m ) needs to be obtained.
The thickness at the end of the biting side is the average thickness in the range from the end of the biting side to 800 mm in the direction of the steady portion in consideration of the AGC dead zone of 80 mm and the subsequent response. Further, the plate thickness H _m of the steady portion is the average plate thickness in the region excluding the end portions on the biting side and the biting side. Further, the end on the biting side or the biting side is a range from the end of the biting or biting steel plate to the center portion 800 mm in the longitudinal direction of the steel plate.

Then, the roll gap G _a of bite end of Imatsugi rolling pass is corrected preset roll gap G constant region in the thickness deviation [Delta] H _a in該今next rolling pass (e.g., setting a roll gap of the constant region with thickness deviation [Delta] H _a subtraction) value from G, it is an small steel plate thickness deviation.
In addition, the roll gap G of the stationary part in this rolling pass is determined from the rolling schedule.
However, since the end portion on the biting side is the dead zone of AGC as described above, in order to perform more accurate plate thickness control, the plate thickness deviation ΔH is simply determined from the set roll gap G of the steady portion. _{In addition} to correcting a, the sheet thickness deviation ΔH _a is calculated by using a sheet thickness influence coefficient (1 + K / M) including a mill constant M that affects the roll gap and a deformation resistance K of the steady portion of the target steel sheet. The roll gap change amount ΔS for reliably correcting the above is obtained by the above equation (1).
The calculated value obtained by subtracting the roll gap change amount ΔS from the set roll gap G of the stationary part in the current rolling pass as shown in the following equation (4) is the roll at the end on the biting side of the current rolling pass. _Let it be a gap Ga.

The deformation resistance K of the stationary part is preferably obtained in advance by an offline test from the temperature of the stationary part and the carbon equivalent _Ceq .

  In addition, the method for determining the plate thickness of the stationary part and the biting side end in the pre-rolling pass is measured by a measuring instrument such as a laser plate thickness gauge, and a gauge meter thickness calculation method calculated from the rolling load and roll gap. However, since the bite side plate thickness of the current pass uses the plate thickness of the bite side in the pre-rolling pass, it is up to the instrument to obtain the plate thickness without affecting productivity. It is preferable to adopt a gauge meter plate thickness calculation method that calculates from the rolling load and the roll gap instead of actual measurement.

In this case, the plate thickness H _m of the steady portion is expressed by the following equation (5) based on the roll gap G _m when rolling the steady portion, the rolling load F _{m at} that time, and the mill constant M. Ask for.

The above, and the roll gap G _m of constant section, with an average roll gap during which rolling a constant region, and in the average load when that rolling the constant region and the rolling force F _m is there.
Further, in the same manner, the thickness H _h of the biting side end in the pre-rolling pass is the roll gap G _h when the biting side end is rolled, the rolling load F _{h at} that time, and the mill Based on the constant M, the following equation (6) is used.

The roll gap G _h and the rolling load F _h at the biting side end are the average roll gap when rolling the biting side end region, and are the average load at that time.
Therefore, the thickness deviation [Delta] H _a constant region and噛抜end can be obtained by the following equation (7). This is the same as the formula (2).

Then, set by substituting the [Delta] H _a, determine the roll gap change amount [Delta] S, the steady portion in the Imatsugi rolling passes in this roll gap change amount [Delta] S in the formula the obtained thickness deviation ΔH _a (1) The roll gap G is corrected (G−ΔS = G−ΔH _a × (1 + K / M)) to obtain a roll gap G _{a at} the time of setting up the biting side end of the current rolling pass.

Further, for example, when descaling is strengthened to obtain a high-quality surface-shaped steel plate, the tip of the steel plate may be warped, and in this case, the tip is supercooled and hardened. Therefore, it is preferable to obtain the hardness at the end of the steel plate and set the roll gap value of the setup at the biting side end of the current rolling pass based on the obtained hardness.
This hardness is predicted from the maximum load at the end portion on the biting side of the previous pass, the average load at the stationary portion, the deformation resistance K of the previous pass and the current pass.

The method for obtaining this hardness will be specifically described below.
First, the rolling load (F _AVE ^n-1 ) of the stationary part in the previous pass, the maximum rolling load (F _MAX ^n-1 ) of the end on the biting side, the predicted temperature and the carbon equivalent of the biting side end of the current pass Deformation resistance (K ⁿ ) at the biting side end of the current pass obtained from C _eq , Deformation resistance at the biting side end of the previous pass obtained from the temperature and carbon equivalent C _{eq of the} biting side end of the previous pass ( Based on the ratio of K ^n-1 ), the hardness (HD) at the biting side end portion in the current pass is obtained by the following equation (8).

  The predicted temperature at the biting side end of the next pass is obtained by heat transfer analysis by FEM (Finite Element Method) in the thickness direction and the rolling length direction, and the temperature of the previous pass is the temperature It is preferable to obtain by actual measurement with a meter.

Said a hardness HD of steel tip obtained, obtains a predicted reduction amount [Delta] H _p ⁿ of bite end of the now following the path by the following equation (9) from the set reduction ratio [Delta] H ⁿ of Imatsugi path.

The bite-side end of the front plate thickness H _h of噛抜end in the path, thickness deviation [Delta] H _a and now set thickness H ⁿ follows path and the predicted reduction amount [Delta] H from the _p ⁿ now following rolling pass The roll gap change amount ΔS is obtained from the following equation (10).

That is, the above equation (3) is obtained by the above equations (9) to (10), and a value obtained by subtracting the roll gap change amount ΔS of the equation (3) from the set roll gap G of the stationary part in the current rolling pass is obtained. The roll gap G _a at the time of setup of the biting side end of the current rolling pass is set. This makes it possible to roll the steel plate biting end to a plate thickness equivalent to that of the steady portion.

An embodiment of a sheet thickness control method in hot rolling of a steel sheet according to the present invention will be specifically described with reference to FIGS. 1 and 2.
In FIG. 1, WR is a work roll for rolling the steel plate 1, BR is a backup roll, 2 is a load measuring device (for example, a load cell) for measuring a rolling load, and 3 is a reduction screw position for detecting the screw position of the reduction screw 4. Detector 4 is a reduction screw that adjusts the roll gap of the upper and lower work rolls WR, 5 is a roll gap calculation control device that calculates and adjusts the roll gap, and 6 is an AGC cylinder that detects the cylinder position of the AGC cylinder 7 during rolling. A position detector, 8 is a mill constant M of the rolling mill, and a host computer that stores the rolling schedule of the steel sheet 1 to be rolled, 9 is a reduction screw controller for controlling the position of the reduction screw 4, and 10 is a cylinder position of the AGC cylinder 7. AGC cylinder controller to be controlled, T is provided on the exit side of the work roll WR, A thermometer for measuring the surface temperature of the plate.

  The roll gap setting of the work roll WR and the backup roll BR is determined by the reduction screw position and the AGC cylinder position. The reduction screw control device 9 is based on the set plate thickness of the current pass from the rolling schedule stored in the host computer 8. Then, the determined reduction screw position is input, and the reduction screw 4 is driven based on the input reduction screw position information to set the steady portion roll gap G. Further, the roll gap is adjusted via the AGC cylinder 7 by the AGC cylinder controller 10 based on the roll gap change amount ΔS from the roll gap calculation unit 5. This adjustment is because the rolling screw 4 cannot be moved during rolling, and the AGC cylinder 7 that can be controlled during rolling is moved to set the correction amount (ΔS) of the roll gap.

First, the calculation / control example 1 of the roll gap calculation control device 5 corresponding to the first configuration and the second configuration of the present invention will be specifically described with reference to FIG.
The roll gap calculation control device 5 includes a rolling position calculation unit 5a, a roll gap calculation unit 5b, a plate thickness calculation unit 5c, a plate thickness deviation calculation unit 5d, a roll gap change amount calculation unit 5e, and a deformation resistance calculation unit 5f. ing.

  And this rolling position calculating part 5a is measured with the load measuring device 2, and when the rolling load F exceeding the preset reference value is inputted, it is judged that rolling has started, and the length of the steel sheet to be rolled is determined from the host computer 8. Enter the rolling speed. Then, the rolling position in the longitudinal direction of the steel sheet 1 being rolled is calculated from the input information, and the calculated current rolling position is sequentially output to the roll gap calculation unit 5b.

  The roll gap calculation unit 5b receives the input rolling position information, the screw position information of the reduction screw 4 measured by the reduction screw position detector 3, the position of the AGC cylinder measured by the AGC cylinder position detector 6, and the load measurement. The rolling load F measured with the vessel 2 is input, and the roll gap G between the upper and lower work rolls WR at each position in the longitudinal direction of the steel sheet is calculated.

  In addition, each information of the said rolling load F, a screw position, and an AGC cylinder position is taken in sequentially, for example at an interval of every 16 ms, and it calculates and outputs each at the timing taken in.

The plate thickness calculation unit 5c inputs the roll gap G sequentially input from the roll gap calculation unit 5b and the mill constant M from the high-order computer 8, and calculates the plate thickness of the steady portion excluding the 800 mm at the front and rear ends of the steel plate. The average value H _m is calculated from the equation (5), and the plate thickness of the rear end portion of the biting side (the range from the biting end to the 800 mm steady portion side) is further calculated by the above formula (6). The average value H _h is calculated and output to the plate thickness deviation calculating section 5d. The average plate thickness (hereinafter also referred to simply as end plate thickness) H _h, the average plate thickness (hereinafter also simply referred to as steady portion plate thickness) H _m , the rolling load F _h , and the roll gap G _h. Is also transmitted to the host computer 8.

Then, the plate thickness deviation calculating section 5d calculates a plate thickness deviation ΔH _a which is a difference (H _h −H _m ) from the input end plate thickness H _h and the steady portion plate thickness H _m , and changes the roll gap. The quantity calculation part 5e outputs.

Further, the deformation resistance calculation unit 5f is a steel plate temperature measured by a thermometer T provided on the exit side of the rolling mill (the average temperature of the steady portion is preferable, but a length set in advance from the steel plate tip, for example, about 1500 mm, The temperature at the position on the rear end side of the steel plate may be used.) And the carbon equivalent C _eq of the target steel plate is input from the host computer 8. Based on this, for example, the deformation resistance K is calculated from the table shown in Table 1 showing the relationship between the preset temperature, the carbon equivalent C _eq , and the deformation resistance K, and output to the roll gap change amount calculation unit 5e. .

The roll gap change amount calculation unit 5e rolls according to (ΔH _a × (1 + K · M)) on the right side of the equation (4) based on the inputted sheet thickness deviation ΔH _a , deformation resistance K and the mill constant M inputted from the host computer 8. The gap change amount ΔS is calculated and output to the AGC cylinder control device 10.

Next, a second embodiment of calculation / control of the roll gap calculation control device 5 corresponding to the third configuration of the present invention will be specifically described with reference to FIG.
The roll gap calculation control device 5 includes a rolling position calculation unit 5a, a roll gap calculation unit 5b, a plate thickness calculation unit 5c, a plate thickness deviation calculation unit 5d, a roll gap change amount calculation unit 5e, and a deformation resistance calculation according to the first embodiment. In addition to the part 5f, it comprises a hardness calculation part 5g and a reduction amount calculation part 5h.

Note that the rolling position calculation unit 5a, the roll gap calculation unit 5b, the plate thickness calculation unit 5c, and the plate thickness deviation calculation unit 5d are the same as those in the first embodiment, and a description thereof is omitted here.
The hardness calculation unit 5g sequentially inputs the current rolling position P in the longitudinal direction of the steel sheet from the rolling position calculation unit 5a in the same manner as described above, and also sequentially inputs the rolling load F from the load detector 2 to the average load F the _AVE ^n-1 and the maximum load F _MAX ^n-1 of噛抜end calculates, further, deformation resistance K ⁿ from deformation resistance calculating unit 5f and the deformation resistance K ^n-1 before path now follows path And the hardness HD of the biting side end in the current pass is calculated according to the equation (8).

The reduction amount calculation unit 5h calculates the hardness HD of the biting side end in the above-mentioned current pass calculated by the hardness calculation unit 5g and the set reduction amount ΔH of the biting side end of the current pass input from the host computer 8. calculates a predicted reduction amount [Delta] H _p ⁿ of bite end of the now following a path from the equation (9) from the ^n.

Roll gap change amount calculation unit 5e reduction amount prediction rolling reduction [Delta] H _p ⁿ of bite end of Imatsugi path entered from the operation unit 5h, thickness deviation [Delta] H _a and before input from the thickness deviation computing unit 5d thickness H _h of噛抜end of the path, the roll gap change amount ΔS of bite end of Imatsugi path equation (10) by setting thickness H ⁿ of Imatsugi path entered from the host computer 8 Calculate and output to the AGC cylinder controller 10.

WR Work roll BR Backup roll 1 Steel plate 2 Load measuring device 3 Rolling screw position detector 4 Rolling screw 5 Roll gap calculation control device 5a Rolling position calculation unit 5b Roll gap calculation unit 5c Plate thickness calculation unit 5d Plate thickness deviation calculation unit 5e Roll Gap change amount calculation unit 5f Deformation resistance calculation unit 5g Hardness calculation unit 5h Rolling amount calculation unit 6 AGC cylinder position detector 7 AGC cylinder 8 Host computer 9 Rolling screw control device 10 AGC cylinder control device

Claims (3)

In the roll gap setup method at the biting end of the steel plate when reverse rolling the steel plate using AGC in a rolling mill, the thickness of the biting side end and the steady portion of the steel plate rolled in the pre-rolling pass calculated plate thickness, obtains the thickness deviation [Delta] H _a from the two plate thickness, obtains the roll gap change amount ΔS in clipping position end at Imatsugi rolling passes by formula (1), in Imatsugi rolling passes the roll gap setting up in the reverse rolling and determining by the roll gap G _a, is corrected by the roll gap change amount ΔS determined from said Imatsugi path constant region roll gap G in the clipping position end .

However, K: Steel plate steady part deformation resistance, M: Mill constant. Up method of adjusting a roll gap in the reverse rolling according to claim 1, characterized in that determining the thickness deviation [Delta] H _a in the following formula (2).

However, _{G h:}噛抜side of the roll gap, _{F h:}噛抜side rolling load,
G _m : Stationary part roll gap, F _m : Stationary part rolling load. 3. The roll gap setup adjustment method in reverse rolling according to claim 1 or 2, wherein the roll gap change amount [Delta] S is obtained by the following equation (3) instead of the equation (1).

However, F _AVE ^n-1 : Rolling load of the stationary part in the previous rolling pass,
F _MAX ^n-1 : Maximum rolling load at the end of the biting side in the previous rolling pass,
K ^n: Imatsugi rolling pass deformation resistance,
K ^n-1 : Pre-rolling pass deformation resistance,
ΔH ⁿ : Set rolling amount of the current rolling pass,
H _h : Plate thickness of the end portion on the biting side of the pre-rolling pass,
H ⁿ : The set thickness of the next rolling pass.

Images