CN112439791B - Thickness control method in finish rolling threading process - Google Patents
Thickness control method in finish rolling threading process Download PDFInfo
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Abstract
A thickness control method in the process of finish rolling threading belongs to the control field. The method comprises the steps of rolling force measured value and data processing; calculating actual performance rolling force and set deviation; judging the set deviation directivity; calculating a directional rolling force adjustment coefficient; redistributing the load of the rear rack based on the actual performance of the front rack; correcting the rotating speed of each rack based on inter-rack second flow balance cascade; and arranging the adjusted new control parameters, and sending the set values to the L1 for control execution. The method dynamically identifies preset deviation by using actual performance rolling force measurement data of the front 3 frames in the finish rolling threading process, predicts the strip steel outlet thickness deviation, and resets control parameters of all the finish rolling frames by adopting a full-line reduction load redistribution, rolling mill rotation speed and roll gap dynamic recalculation mode, so as to correct the thickness abnormal condition caused by the precomputed integral deviation as much as possible in the subsequent passes, thereby obviously improving the hot rolling thickness control precision. The method can be widely applied to the field of control of the thickness of the strip steel in finish rolling.
Description
Technical Field
The invention belongs to the field of control, and particularly relates to a method for controlling the thickness of a strip steel head in a steel rolling process.
Background
In the process of finish rolling of strip steel (or called as a working section), the strip steel is continuously rolled for multiple times, the thickness of the strip steel is detected at a finish rolling outlet through a thickness measuring device, the thickness deviation is determined by an Automatic Gain Control (AGC) according to the actual performance thickness of the strip steel and the target thickness of the strip steel, and the roll gap of a final frame is adjusted to a certain degree so as to correct the thickness of the strip steel.
A typical finish thickness control system is shown in FIG. 1. In the figure, F1 to F7 are the numbers of the stands of the finishing area from front to back (according to the convention in the industry, the stands F1 to F3 are generally called front stands; F5 to F7 are generally called back stands; and the convention of directly using F1 to F7 to represent the first to seventh stands is also used, the same applies below).
The thickness measuring instrument is generally arranged at a position about 10 meters away from a finish rolling outlet, so that AGC is intervened and adjusted at a position 10 meters behind the strip steel, and the thickness precision of the strip body can be effectively controlled.
The roll gap correction method in the process of passing through the strip is applied to a few production lines, but the rolling stability is not considered, and the large-amplitude thickness correction cannot be realized.
Obviously, in the prior art, the thickness of a finish rolling outlet is often greatly deviated due to the reasons of inaccurate information of finish rolling incoming materials or inaccurate setting of an L2 (process control computer or process control level) control model and the like.
Meanwhile, in general, the hot finish rolling has a gauge after the F7 rolling mill. After general thickness measurement, the thickness is fed back to an L1 (basic automation computer or basic automation layer) monitoring AGC control system, deviation identification is carried out, the deviation identification is used for roll gap dynamic adjustment, and monitoring AGC control can be formally started and executed about 1 second after threading. Therefore, the problem of the thickness deviation of the strip body of the strip steel can be solved, and the abnormal thickness of the head of the strip steel is difficult to improve.
The invention discloses a method for adaptively correcting a roll gap of a hot rolling finishing mill group by utilizing threading in a Chinese patent with an authorization notice date of 201 year 02, month 06 and an authorization notice number of CN 102233358B, which comprises the following steps of firstly, determining the rolling force deviation of 1 st to 3 rd stands, and secondly, determining parameters influencing set deformation resistance; determining four deformation resistance adjustment strategies, and selecting a corresponding adjustment strategy according to a deviation mode; step four, calculating to obtain the deformation resistance adjustment quantity of the 1 st to 3 rd frames according to the measured actual rolling force of the 1 st to 3 rd frames, and obtaining the deformation resistance adjustment quantity of the 4 th to 7 th frames through the deformation resistance adjustment quantity of the 1 st to 3 rd frames; and step five, finally, calculating according to a thickness increment equation to obtain the roll gap adjustment quantity of the 4 th to 7 th frames.
The technical scheme adopts the deviation information of actually measured and set rolling force of the first three racks to judge the adjustment type of the deformation resistance, calculates the adjustment quantity of the deformation resistance according to different types, finally calculates the roll gap adjustment quantity of the subsequent racks and dynamically sets the roll gap adjustment quantity, thereby improving the control precision of the head thickness of the strip steel. However, the method does not balance the flow per second between the racks, nor redistributes the pressing load of the rear rack, and cannot well realize large-amplitude thickness correction.
Disclosure of Invention
The invention aims to solve the technical problem of providing a thickness control method in the finish rolling threading process. The method dynamically identifies the preset deviation by using the actual performance rolling force measurement data of the first 3 frames in the process of finish rolling threading, predicts the thickness deviation of a strip steel outlet, and resets the control parameters of all the frames in finish rolling by adopting the modes of full-line reduction load redistribution, rolling mill rotation speed and roll gap dynamic recalculation, so as to correct the thickness abnormal condition caused by the precomputation integral deviation as much as possible in the subsequent passes, thereby obviously improving the control precision of the hot rolling thickness.
The technical scheme of the invention is as follows: the thickness control method in the finish rolling threading process is characterized by comprising the following steps of:
1) Processing the measured value and data of the rolling force;
2) Calculating the deviation between the actual performance rolling force and the set value;
3) And (3) judging the set deviation directivity: if no integral deviation exists, executing the step 8; if the integrity deviation exists, executing the next step;
4) Calculating the adjustment coefficient of the directional rolling force;
5) Redistributing the load of the rear rack based on the actual performance of the front rack;
6) Correcting the rotating speed of each rack based on inter-rack second flow balance cascade;
7) Arranging the adjusted new control parameters: the rotating speed of each frame, the roll gap of each frame and the like, and the set values are issued to the L1 for control execution;
8) And finishing the thickness control of the finish rolling threading process.
The processing of the rolling force actual measurement value and the data in the step 1) comprises the steps of actually measuring actual performance rolling force data of the head of the strip steel after the strip threading of the finish rolling pass is completed, sending the actual performance rolling force data from L1 to L2, carrying out basic processing on the measured data by L2, judging whether the data is valid, and carrying out filtering processing on abnormal data.
And calculating the actual performance rolling force and the set deviation in the step 2), wherein the calculation comprises the steps of comparing the actual performance rolling force of the first three stands with the set rolling force and calculating the actual performance deviation proportion of the F1-F3 stands.
The judgment of the deviation directionality set in the step 3) comprises the step of judging whether the deviation direction has the directional deviation characteristic or not according to the actual performance deviation proportion of the first three racks.
The calculation of the directional rolling force adjustment coefficient in the step 4) comprises the step of calculating the directional adjustment coefficient by calculating the rolling force according to the deviation direction and the deviation amplitude.
And the step 5) of redistributing the load of the rear rack based on the actual performance of the front rack comprises the steps of calculating the expected deviation of the F4 rack according to the deviation coefficient, and further calculating the roll gap difference of the F4 rack to obtain the inlet thickness of the F5 rack. And (4) combining the finish rolling target thickness, and redistributing the load of the F5, F6 and F7 frames.
And 6) correcting the rotating speed of each frame in a cascading manner based on the flow balance between frames in the step 6), wherein the steps of correcting the rotation speed of the roller in a cascading manner by the F1-F4 frames according to the new outlet thickness of each frame are included.
Further, the set directionality of deviation is determined in the following manner:
pass actual performance rolling force F of single stand sj And a set rolling force F set Ratio, calculating the deviation coefficient f corr And judging actual performance deviation:
in the formula, F sj Collecting actual performance rolling force for the L1 when the rack is threaded; f set Presetting rolling force for the frame model; f. of corr Setting a proportion coefficient of the actual rolling force and the set rolling force;
respectively calculating the rolling force coefficients of the three frames F1, F2 and F3, identifying the deviation direction, and then combining the frames to comprehensively judge the overall set deviation;
when the deviation directions of the F1, the F2 and the F3 are the same, judging that the set rolling force has integral direction deviation; otherwise, when the F2 and the F3 are in the same direction and the deviation coefficients are both larger than 6%, judging that the set rolling force has integral deviation; otherwise, when the F1 and the F3 are in the same direction and the deviation coefficient is larger than 6 percent, judging that the set rolling force has integral deviation.
Further, the calculation of the adjustment coefficient of the directional rolling force is performed in the following manner:
calculating the directivity adjustment coefficient delta f when the rolling force integral directivity deviation is provided corr For re-optimizing the calculated roll force of the rear frame;
adjustment coefficient of integral directional rolling force Deltaf corr The calculation method is as follows:
Δf corr ＝f1 corr *c1+f2 corr *c2+f3 corr *c3
in the formula,. DELTA.f corr For the overall directional rolling force coefficient, f1 corr Is F1 roll force deviation coefficient of the stand, F2 corr Is the roll force deviation coefficient of F2 stand, F3 corr The rolling force deviation coefficient of the F3 frame is obtained, c1 is the weight of the F1 frame, c2 is the weight of the F2 frame, and c3 is the weight of the F3 frame;
because the directivity deviation has the possibility of misjudgment, in order to prevent overshoot, amplitude limiting and attenuation operations are added during the calculation of the directivity coefficient;
and (3) correcting the directivity coefficient:
Δf corr ＝1±abs(Δf corr -1)*alpha
in the formula,. DELTA.f corr For adjusting the coefficient, alpha is the attenuation coefficient, when Δ f corr >In the 0-hour formula, plus or minus is positive, Δ f corr <The negative sign is taken when 1 is reached.
Further, before the redistribution of the load of the rear frame based on the actual result of the front frame, calculating the bounce deviation caused by the deviation of the rolling force from F1 to F4;
calculating the bounce deviation caused by the rolling force deviation of F1-F4, and calculating the thickness deviation caused by the bounce according to a bounce equation:
when calculating the bounce deviation, since F4 has no actual rolling force, the set rolling force is multiplied by the directional correction coefficient to replace the directional correction coefficient;
wherein Δ Gap (i) is a bounce deviation amount, F (i) sj To achieve rolling force, F (i) set To set the rolling force, stiffness (i) is the mill Stiffness, and i is the stand number (1, 2, 3, 4).
Further, the redistribution of the rear rack load based on the actual performance of the front rack is carried out according to the following formula:
eps(i)＝h(i-1)-h(i)/h(i-1)
in the formula, eps (i) is the new reduction rate of each rack, h (i) is the outlet thickness of each rack, h (i-1) is the inlet thickness of each rack, and i is the number of the rack.
Further, the cascade correction of the rotating speed of each rack based on the second flow balance among the racks further comprises recalculation of roll gap setting of the rear racks F5-F7, namely, recalculating the rolling force and the roll gap of the racks F5, F6 and F7 according to a precomputation flow on the basis of not changing the preset water and strip threading speed of the racks.
Specifically, the rolling force is calculated by the following formula:
F＝k m ·w·l d ·Q p ·K F
in the formula, F is rolling force, w is width, l d Crush contact arc length, k m Resistance to deformation of the material, Q p Coefficient of influence of external friction, K F -rolling force learning factor.
Specifically, the roll gap is calculated by adopting the following formula:
S SET ＝h+S Z -S M +S OIL +S B +S WRS +S WRC -S RW +S RH +S ZSET
in the formula, S SET Calculated for the roll gap, h is the target exit thickness of the frame, S Z Roll gap at zero adjustment of rolling force, S M For bouncing by rolling forces, S OIL Is the deviation of oil film thickness, S B For bouncing due to roll bending forces, S WRS Amount of position compensation for roll shifting, S WRC For compensation of the original crown of the working roll, S RW For wear of the working rolls, S RH For working roll thermal expansion deviation, S ZSET The roll gap setting value is zero adjustment.
Furthermore, the rotation speed of each frame is corrected in a cascade mode based on the flow balance between frames per second, and the calculation comprises the calculation of the thickness of a new outlet of each frame from F1 to F4 and the calculation of the rotation speed of a new roller of each frame from F1 to F4.
Specifically, the thickness calculation of the new outlet of each frame from F1 to F4 is carried out according to the following formula:
H(i) new ＝H(i) old +ΔGap(i)
in the formula, H (i) new For each rack new exit thickness, H (i) old And presetting outlet thickness for each rack, wherein delta Gap (i) is the bounce deviation of each rack, and i is the number of the rack.
Specifically, the rotating speed calculation of the new roller of each frame F1-F4 is carried out according to the following formula:
V(i) new ＝V(i) old *H(i) old /H(i) new
in the formula, V (i) new For each frame new speed, V (i) old Presetting the rotation speed for each frame H (i) old Presetting the outlet thickness for each frame, H (i) new And i is the new outlet thickness of each rack, and is the number of the rack.
Compared with the prior art, the invention has the advantages that:
1. according to the technical scheme, the rolling force data obtained by three times of measurement before finish rolling of the strip steel are fully utilized, the direction and the amplitude of the set overall deviation are judged, the dynamic control of the head thickness of the strip steel in the finish rolling threading process is realized by recalculating and setting control parameters, the abnormal phenomenon of the head thickness control caused by the set overall deviation of the finish rolling is solved, and the accuracy of the head thickness control index is effectively improved;
2. according to the technical scheme, two key factors of the outlet thickness of each stand and the speed of the rolling mill are covered in the aspect of readjustment of control parameters, and the blocking amount caused by abnormal thickness of the head of the strip steel is reduced by 60% in practical application in 1780 hot rolling;
3. on the basis of the traditional control principle, the technical scheme of the invention adds the functions of dynamically resetting various control quantities in the finish rolling threading process: after the three previous frames are threaded and actual performance rolling force measurement data are acquired, the deviation conditions of the three frames are integrated, the deviation direction of the three frames and the actual performance is further judged and set, the thickness of a finish rolling target is combined, the thickness load of the frames which are not threaded is redistributed, flow balance and speed cascade adjustment are carried out on a finish rolling whole line on the basis of new load distribution, and the phenomenon that the thickness deviation of the head of the strip steel is large due to the fact that the whole deviation is set is well solved.
Drawings
FIG. 1 is a schematic view of a conventional finish rolling thickness control system;
FIG. 2 is a schematic view of the construction of a thickness dynamic control system in the finish rolling threading of the present invention;
FIG. 3 is a block diagram of the dynamic control process of the thickness during the finish rolling threading of the invention.
In the drawing, F1 to F7 are the numbers of the respective stands of the finish rolling area from the front to the rear.
Detailed Description
The invention is further described below with reference to the following figures and examples.
In fig. 2, the technical scheme of the application identifies the setting deviation of the full-length rolling force of the strip steel by using the rolling force data measured by the head actual performance during the threading of the strips through F1, F2 and F3, predicts the thickness deviation of the head of the strip steel, and develops the control and regulation technology in the strip steel finish rolling threading process, thereby solving the problem of abnormal head thickness of the strip steel caused by the whole deviation of the setting of the rolling force of the strip steel.
The technical scheme of this application, on the basis of traditional control principle, has increased the multiple controlled variable developments of finish rolling threading in-process and has reset the function: after the three previous frames are threaded and actual performance rolling force measurement data are acquired, the deviation conditions of the three frames are integrated, the deviation direction of the three frames and the actual performance is further judged and set, the thickness of a finish rolling target is combined, the thickness load of the frames which are not threaded is redistributed, flow balance and speed cascade adjustment are carried out on a finish rolling whole line on the basis of new load distribution, and the phenomenon that the thickness deviation of the head of the strip steel is large due to the fact that the whole deviation is set is well solved.
Specifically, the technical scheme of the invention is detailed as follows:
1. the technical principle is as follows:
the L2 thickness control is set to solve the thickness deviation of the head of the strip steel, and the thickness unevenness in the full length direction is not considered. According to the technical scheme, the actual performance rolling force data of the head of the strip steel obtained by measuring the front frame is fully utilized, the direction and the amplitude of the integral deviation are judged and set, and the dynamic control of the thickness of the head of the strip steel in the finish rolling threading process is realized by recalculating and setting control parameters. The model principle is as follows:
(1) Judging the direction of the rolling force deviation:
single stand pass actual performance rolling force F sj And a set rolling force F set Ratio, calculating the deviation coefficient f corr And judging actual performance deviation:
in the formula, F sj Collecting actual performance rolling force for the L1 when the rack is threaded; f set Presetting rolling force for the frame model; f. of corr The actual rolling force and the set rolling force proportion coefficient are used.
Respectively calculating the rolling force coefficients of three frames F1, F2 and F3 (namely the first frame, the second frame, the third frame and the same below), identifying deviation directions, combining the three frames to comprehensively judge the overall set deviation, and judging that the overall direction deviation exists in the set rolling force when the deviation directions of the F1, the F2 and the F3 are the same; otherwise, when the F2 and the F3 are in the same direction and the deviation coefficients are both larger than 6 percent, judging that the set rolling force has integral deviation; otherwise, when the F1 and the F3 are in the same direction and the deviation coefficients are both larger than 6%, judging that the set rolling force has integral deviation.
(2) Calculating a directional rolling force adjustment coefficient:
calculating the directivity adjustment coefficient delta f when the rolling force integral directivity deviation is provided corr And the method is used for calculating the rolling force of the rear frame in a re-optimization mode.
Adjustment coefficient of integral directional rolling force Deltaf corr The calculation method is as follows:
Δf corr ＝f1 corr *c1+f2 corr *c2+f3 corr *c3 (2)
in the formula,. DELTA.f corr For the overall directional rolling force coefficient, f1 corr Is the roll force deviation coefficient of F1 stand, F2 corr Is the roll force deviation coefficient of F2 stand, F3 corr And c1 is the rolling force deviation coefficient of the F3 stand, c1 is the weight of the F1 stand, c2 is the weight of the F2 stand, and c3 is the weight of the F3 stand.
Since there is a possibility of misjudgment of the directivity deviation, in order to prevent overshoot, clipping and attenuation operations are added at the time of directivity coefficient calculation.
And (3) correcting the directivity coefficient:
Δf corr ＝1±abs(Δf corr -1)*alpha (3)
in the formula,. DELTA.f corr For adjusting the coefficient, alpha is the attenuation coefficient, when Δ f corr >In the 0-hour formula, plus or minus is positive, Δ f corr <The negative sign is taken when 1 is reached.
(3) Calculating the bounce deviation caused by the F1-F4 rolling force deviation:
since the actual rolling force does not match the set value and the amount of bounce during rolling of the roll fluctuates, it is necessary to calculate the thickness deviation caused by the bounce by using a bounce equation based on the deviation amount of the rolling force.
When calculating the bounce deviation, since the F4 stand does not have the actual rolling force, the set rolling force is multiplied by the directional correction coefficient instead.
Wherein Δ Gap (i) is a bound deviation amount F (i) sj To achieve rolling force, F (i) set To set the rolling force, stiffness (i) is the mill Stiffness, and i is the stand number (1, 2, 3, 4).
(4) And (3) redistribution of the pressing load of the rear frame:
the rear frames refer to frames F5, F6 and F7 (namely the fifth to seventh frames, the same applies below), and due to the fact that the roll difference exists in the frame F4 to cause bounce deviation, all the rear frames have changed inlet thickness, and the reloading distribution is needed to be carried out to offset the influence caused by the inlet thickness difference.
eps(i)＝h(i-1)-h(i)/h(i-1) (5)
In the formula, eps (i) is the new reduction rate of each rack, h (i) is the outlet thickness of each rack, h (i-1) is the inlet thickness of each rack, and i is the rack number.
(5) And (3) setting and recalculating roll gaps of the rear frames F5-F7:
the rolling force and the roll gap of the F5, F6 and F7 frames are recalculated according to the precomputation flow on the basis of not changing the preset frame water and strip threading speed.
The rolling force is calculated by the following formula:
F＝k m ·w·l d ·Q p ·K F (6)
wherein F-rolling force, w-width, l d Flattened contact arc length, k m Resistance to deformation of the material, Q p Coefficient of influence of external friction, K F -rolling force learning factor.
The roll gap is calculated by the following formula:
S SET ＝h+S Z -S M +S OIL +S B +S WRS +S WRC -S RW +S RH +S ZSET (7)
in the formula, S SET Calculated for the roll gap, h is the target exit thickness of the frame, S Z Roll gap at zero adjustment of rolling force, S M For bouncing by rolling forces, S OIL Deviation of oil film thickness, S B For bouncing due to roll bending forces, S WRS Amount of position compensation for roll shifting, S WRC For compensation of the original crown of the working roll, S RW For wear of the working rolls, S RH Deviation of working roll thermal expansion, S ZSET The roll gap setting value is zero adjustment.
(6) And (3) correcting flow balance among racks:
due to the fact that the thicknesses of the inlet and the outlet of each rack are changed, flow imbalance among the racks is caused, the flow imbalance condition does not exist when the F5, F6 and F7 racks are subjected to load distribution again, but the F1-F4 racks need to correct roller rotation in a cascading mode according to the thickness of the new outlet of each rack.
Calculating the thickness of the new outlet of each frame from F1 to F4:
H(i) new ＝H(i) old +ΔGap(i) (8)
in the formula, H (i) new For each rack new exit thickness, H (i) old The exit thickness is predetermined for each frame, Δ Gap (i) isAnd (4) bounce deviation of each rack, wherein i is the number of the rack.
Calculating the rotating speed of the new roller of each frame from F1 to F4:
V(i) new ＝V(i) old *H(i) old /H(i) new (9)
in the formula, V (i) new For each frame new speed, V (i) old Presetting the rotation speed for each frame H (i) old Presetting the outlet thickness for each frame, H (i) new And i is the thickness of a new outlet of each rack, and is the number of the rack.
2. The technical scheme is as follows:
as shown in fig. 3, the present patent utilizes the actual performance data of the head rolling force measured by the frames F1, F2 and F3 to identify the deviation range between the strip steel setting and the actual performance, and develops the control parameter resetting technology in the strip steel threading process, thereby solving the problem of large thickness deviation caused by the preset integral deviation of the strip steel.
The specific technical steps are as follows:
2.1 measured value and data processing of rolling force:
after the threading of the finish rolling pass is finished, actually measured actual performance rolling force data of the head of the strip steel are sent to L2 from L1, the L2 carries out basic processing on the measured data, judges whether the data are effective or not, and carries out filtering processing on abnormal data.
L1, actual performance data acquisition:
2.2 calculating the deviation between the actual performance rolling force and the set value:
and comparing the actual performance values of the first three stands with the set rolling force distribution, and calculating actual performance deviation proportions of the F1-F3 stands.
2.3 deviation directivity judgment set:
and judging whether the directional deviation characteristic and the deviation direction are provided or not according to the actual performance deviation proportion of the first three racks.
2.4 calculation of the adjustment coefficient of the directional rolling force:
and calculating the rolling force according to the deviation direction and the deviation amplitude to calculate the directional adjustment coefficient.
2.5 redistribution of rear rack loads based on the actual performance of the front rack:
and calculating the expected deviation of the F4 frame according to the deviation coefficient, and further calculating the roll gap difference of the F4 frame to obtain the inlet thickness of the F5 frame. And (4) combining the finish rolling target thickness, and redistributing the load of the F5, F6 and F7 frames.
2.6 correcting the rotating speed of each rack in a cascade mode based on the second flow balance among the racks:
the step of correcting the rotating speed of each rack based on the second flow balance among the racks comprises recalculation of roll gap setting of the rear racks F5-F7, namely, recalculating the rolling force and the roll gap of the racks F5, F6 and F7 according to a precomputation flow on the basis of not changing the water and the strip threading speed of the preset racks.
2.7 new control parameters after adjustment are sorted: the rotating speed of each frame, the roll gap of each frame and the like, and the set values are issued to the L1 for control execution:
entry correction data structure:
example (b):
inlet thickness: 45.71mm
Speed of threading the strip steel: 11m/s
Target width: 1265mm Cold State
Target thickness: 3.53mm cold state
Presetting data:
1. and (3) actual measured value and data processing of rolling force:
and requiring the L1 to collect the actual performance value of the rolling force of the head part for 0.2s, eliminating 2 actual performance points of the head part, removing the maximum and minimum values, and calculating the average rolling force of the remaining points.
The actual performance rolling forces of the L1 return F1, F2, F3 stands are 19038.3KN, 17488.8KN, 17178.5KN, respectively.
2. Calculating the actual performance deviation proportion of the rolling force:
calculating actual performance rolling force deviation proportions of the F1, F2 and F3 frames:
the actual performance rolling force deviation ratios of the three frames F1-F3 are-0.21, -0.09826, -0.08166 respectively.
3. Judging the directionality of the rolling force deviation:
the actual performance rolling forces of the three frames are all smaller than 0, the deviation directions are consistent, and the absolute values of deviation proportions are all larger than 6%, so that the directional deviation of the rolling forces is judged.
4. Calculating the adjustment coefficient of the directional rolling force:
the weight coefficient c1 is set to 0.2, c2 is set to 0.3, c3 is set to 0.4, and the attenuation coefficient alpha takes a value of 0.63.
Δf corr ＝1+(-0.21*0.2-0.09826*0.3-0.08166*0.4)*0.6＝0.934
The adjustment coefficient of the directionality of the rolling force was calculated by weighting the rolling force deviations of the F1, F2, and F3 stands to obtain 0.934.
5. Calculating the bounce deviation caused by the rolling force deviation of the F1-F4 frames:
prediction F (4) sj ＝0.934*16008.3＝14951.7
Bounce deviation:
the calculation results of the bounce deviation of the frames F1 to F4 before finish rolling are respectively as follows: -0.8448, -0.3176, -0.2046, -0.1921, units mm.
6. Correcting the inlet thickness of the F5 frame to obtain the pressed load redistribution of the F5-F7 frame:
taking the outlet thickness of the F4 frame as input, the finish rolling target thickness as output, redistributing the reduction rate:
and recalculating the rolling forces of the rear frames F5, F6 and F7 through the rolling force model to obtain the rolling force under the new load:
F(5)＝12559(KN)
F(6)＝9191(KN)
F(7)＝7825(KN)
multiplying by using the rolling force adjustment coefficient:
F(5) adj ＝12559*0.934＝11730(KN)
F(6) adj ＝9191*0.934＝8584(KN)
F(7) adj ＝7825*0.934＝7309(KN)
at this point, the post-stand load distribution and rolling force calculation is completed.
7. And (3) setting and recalculating roll gaps of the rear frames F5-F7:
and recalculating roll gaps of the rear frames F5, F6 and F7 through the roll gap model by using the corrected roll force:
Gap(5) adj ＝2.972(mm)
Gap(6) adj ＝2.337(mm)
Gap(7) adj ＝2.055(mm)
and then, the roll gap calculation of the rear frame is completed, and the roll gap value is adjusted along with the load distribution change.
8. Based on the second flow balance among the frames, the rotating speed of each frame is corrected in a cascade mode:
and calculating the actual flow thickness by the F1, F2 and F3 frames according to the bounce deviation delta Gap corresponding to the actual rolling force:
eps(5)＝0.2632
eps(6)＝0.18967
eps(7)＝0.13737
H(1) new ＝24.919+(-0.8448)＝24.0742(mm)
H(2) new ＝15.1798+(-0.3176)＝14.8622(mm)
H(3) new ＝9.95581+(-0.2546)＝9.7012(mm)
and F4, calculating the flow thickness by the frame according to the predicted bounce deviation delta Gap (4):
H(4) new ＝7.02141+(-0.1921)＝6.829(mm)
and F5, F6 and F7 frames set the flow thickness according to the reloading distribution:
H(5) new ＝5.17339(mm)
H(6) new ＝4.19214(mm)
H(7) new ＝3.61626(mm)
and calculating the rotating speed (linear speed) of the F1-F4 rack according to the flow balance by using the principle that the speed of the strip steel at the outlet is not changed:
V(1) new ＝1.44011*24.919/20.791＝1.491(m/s)
V(2) new ＝2.38645*15.1798/14.8622＝2.437(m/s)
V(3) new ＝3.67312*9.95581/9.70123＝3.77(m/s)
V(4) new ＝5.24077*7.02141/6.86075＝5.388(m/s)
and the rotating speeds of the F5-F7 frames are adjusted and calculated according to the load distribution, and output is as follows:
V(5) new ＝7.191(m/s)
V(6) new ＝8.989(m/s)
V(7) new ＝10.474(m/s)
and at this moment, according to the second flow balance principle between the racks, the rotating speeds of all the racks are corrected again.
9. Arranging the adjusted new control parameters, and sending the new control parameters to the L1 for control and execution:
so far, all calculations of tape threading process thickness control model are accomplished, have following control data to issue to L1 and carry out: finish rolling all the machine frames at a rotating speed; rolling force, outlet thickness, roll gap of the rear frames F5-F7.
10. And (4) conclusion:
the existing online control model only performs micro roll gap adjustment on an F7 frame, and is difficult to effectively control in thickness control. The model among this application technical scheme carries out flow balance based on the finish rolling full line, and through carrying out thickness deviation correction to 3 frame F5 of rear portion, F6 and F7, correction range is big, and the adjustment ability is strong.
In this embodiment, after the tape threading thickness control model is corrected, the actual performance rolling force of the F4-F7 head is as follows:
F sj (4)＝15149(KN)
F sj (5)＝11260(KN)
F sj (6)＝8465(KN)
F sj (7)＝7453(KN)
the actual performance outlet thickness is 3.633 (mm), the thickness correction is not carried out by using the technical scheme, the actual performance rolling force deviation is calculated according to the correction coefficient of 0.934, and the rolling force deviation amount is as follows:
ΔF(7)＝F set (7)*(1-Δf corr )＝7999.61*(1-0.934)＝528(KN)
at the F7 stand, the 528KN rolling force difference causes about 0.1mm bounce deviation, and the steel strip in the case is thinner by about 0.1mm.
According to the technical scheme, the pre-set deviation is dynamically identified by utilizing the actual performance rolling force measurement data of the first 3 frames in the finish rolling threading process, the thickness deviation of the strip steel outlet is predicted, and the method of re-setting the control parameters of all the finish rolling frames by adopting the modes of full-line reduction load redistribution, rolling mill rotation speed and roll gap dynamic re-calculation is adopted to correct the thickness abnormal condition caused by the pre-calculated integral deviation as much as possible in the subsequent passes, so that the hot rolling thickness control precision is obviously improved.
The invention can be widely applied to the field of strip steel thickness control of a finish rolling section.
Claims (10)
1. A thickness control method in a finish rolling threading process is characterized by comprising the following steps:
1) And (3) actual measured value and data processing of rolling force:
after finishing pass threading of finish rolling, actually measuring actual performance rolling force data of the head of the strip steel from L1 to L2, processing the measured data by the L2, judging whether the data is effective, and filtering abnormal data;
2) Calculating the deviation between the actual performance rolling force and the set rolling force:
the method comprises the steps of comparing the actual performance values of the first three racks with the distribution of set rolling force, and calculating the actual performance deviation proportion of the F1-F3 racks;
3) And (3) judging the set deviation directivity: if no integral deviation exists, executing the step 8); if the integrity deviation exists, executing the next step;
the set deviation directionality judgment comprises the steps of judging whether the set deviation directionality has the directional deviation characteristic and the deviation direction according to the actual performance deviation proportion of the first three racks;
the judgment of the set deviation directivity is carried out according to the following modes:
pass actual performance rolling force F of single stand sj And a set rolling force F set Ratio, calculating the deviation coefficient f corr And judging actual performance deviation:
in the formula, F sj The actual performance rolling force is acquired by the L1 when the rack is threaded; f set Setting rolling force for the frame model; f. of corr Is a deviation coefficient;
respectively calculating the deviation coefficients of the rolling forces of the three frames F1, F2 and F3, identifying the deviation direction, and then combining the frames to comprehensively judge the deviation of the whole direction;
4) Calculating a directional rolling force adjustment coefficient:
calculating a directional rolling force adjustment coefficient according to the deviation direction and the deviation amplitude;
the calculation of the adjustment coefficient of the directional rolling force is carried out according to the following modes:
calculating the directional rolling force adjustment coefficient delta f when the rolling force overall direction deviation is provided corr For re-optimizing the calculated stand rolling force;
the directional rolling force adjustment coefficient Deltaf corr The calculation method of (2) is as follows:
Δf corr ＝f1 corr *c1+f2 corr *c2+f3 corr *c3
in the formula,. DELTA.f corr Adjustment coefficient for directional rolling force, f1 corr Is the coefficient of variation of the rolling force of the F1 stand, F2 corr Is the coefficient of variation of the rolling force of the F2 stand, F3 corr The deviation coefficient of the rolling force of the F3 frame is shown, c1 is the weight of the F1 frame, c2 is the weight of the F2 frame, and c3 is the weight of the F3 frame;
5) Redistributing the load of the rear rack based on the actual performance of the front rack:
calculating the expected deviation of the F4 rack according to the deviation coefficient, and further calculating the roll gap difference of the F4 rack to obtain the inlet thickness of the F5 rack; the load redistribution is carried out on the F5, F6 and F7 racks by combining the finish rolling target thickness;
6) Based on the second flow balance among the frames, the rotating speed of each frame is corrected in a cascade mode:
the method comprises the following steps that F1-F4 frames are used for correcting the rotating speed of a roller in a cascading manner according to the new outlet thickness of each frame;
7) And (4) arranging the adjusted new control parameters:
control parameters including the rotating speed of each frame and the roll gap of each frame, and a set value is issued to the L1 for control execution;
8) Finishing the thickness control of the finish rolling threading process;
the thickness control method in the finish rolling threading process dynamically identifies preset deviation by using actual performance rolling force measurement data of the first 3 racks in the finish rolling threading process, predicts strip steel outlet thickness deviation, adopts a method of full-line reduction load redistribution, rolling mill rotation speed and roll gap dynamic recalculation, and resets control parameters of all the racks in finish rolling, corrects the thickness abnormal condition caused by the precomputation of the whole deviation in subsequent passes, thereby improving the hot rolling thickness control precision.
2. The method of controlling the thickness in the finish rolling threading process according to claim 1, wherein when the directions of deviations F1, F2, and F3 are the same, it is judged that there is an overall direction deviation of the set rolling force;
otherwise, when the deviation directions of the F2 and the F3 are the same and the deviation coefficients are both larger than 6%, judging that the set rolling force has integral direction deviation;
otherwise, when the deviation directions of the F1 and the F3 are the same and the deviation coefficients are both larger than 6%, judging that the set rolling force has integral direction deviation.
3. The method of claim 1, wherein a bounce deviation caused by an F1-F4 rolling force deviation is calculated before the redistribution of the after-stand load based on the pre-stand performance;
calculating the bounce deviation caused by the rolling force deviation of F1-F4, and calculating the thickness deviation caused by the bounce according to a bounce equation:
when calculating the bounce deviation, the actual performance rolling force of the F4 is replaced by the set rolling force multiplied by the directional rolling force adjusting coefficient because the F4 has no actual performance rolling force;
wherein Δ Gap (i) is a bound deviation amount F (i) sj To achieve rolling force, F (i) set To set the rolling force, stiffness (i) is the mill Stiffness, i is the stand number 1, 2, 3, 4.
4. The finish rolling threading thickness control method of claim 1, wherein the post-stand load redistribution based on pre-stand performance is performed according to the following formula:
in the formula, eps (i) is the new reduction rate of each rack, h (i) is the outlet thickness of each rack, h (i-1) is the inlet thickness of each rack, and i is the rack number.
5. The finish rolling threading thickness control method as recited in claim 1, wherein the rotating speed of each stand is corrected in cascade based on the flow balance between the stands per second, and further comprising recalculating the roll gap settings of the rear stands F5 to F7, i.e., recalculating the rolling forces and roll gaps of F5, F6, and F7 according to a precalculation flow without changing the preset stand threading speed.
6. The method of controlling the thickness in the finish rolling threading as recited in claim 5, wherein the rolling forces of F5, F6, and F7 are calculated by using the following equations:
F＝k m ·w·l d ·Q p ·K F
in the formula, F is rolling force, w is width, l d Crush contact arc length, k m Resistance to deformation of the material, Q p Coefficient of influence of external friction, K F -rolling force learning coefficient;
then, the directional rolling force adjustment coefficient is used for multiplication, and the rear rack load distribution and the rolling force calculation are completed.
7. The finish rolling threading thickness control method as recited in claim 5, wherein the roll gap is calculated using the following formula:
S SET ＝h+S Z -S M +S OIL +S B +S WRS +S WRC -S RW +S RH +S ZSET
in the formula, S SET Calculated for the roll gap, h is the target exit thickness of the frame, S Z Roll gap at zero adjusted rolling force, S M For bouncing by rolling forces, S OIL Is the deviation of oil film thickness, S B For bouncing due to roll bending forces, S WRS Amount of position compensation for roll shifting, S WRC For compensation of the original crown of the working roll, S RW For wear of the working rolls, S RH Deviation of working roll thermal expansion, S ZSET The roll gap setting value is zero adjustment.
8. The method of controlling the thickness in the finish rolling threading process as recited in claim 1, wherein the rotating speeds of the stands are corrected in cascade based on the inter-stand second flow balance, and the calculation of the new exit thicknesses of the stands F1 to F4 and the calculation of the rotating speeds of the rolls of the stands F1 to F4 are included.
9. The finish rolling threading thickness control method as recited in claim 8, wherein the calculation of the new exit thickness of each of the F1 to F4 stands is performed according to the following formula:
H(i) new ＝H(i) old +ΔGap(i)
in the formula, H (i) new For each rack new exit thickness, H (i) old Presetting outlet thickness for each rack, wherein i is a rack number, and delta Gap (i) is the bounce deviation of each rack, and the specific calculation formula is as follows:
wherein, F (i) sj To realize the rolling force, F (i) set To set the rolling force, stiffness (i) is the mill Stiffness, i is the stand number 1, 2, 3, 4.
10. The finish rolling threading thickness control method according to claim 8, wherein the calculation of the new roll rotation speed of each of the stands F1 to F4 is performed according to the following formula:
V(i) new ＝V(i) old *H(i) old /H(i) new
in the formula, V (i) new For each frame new speed, V (i) old Presetting the rotation speed for each frame H (i) old Presetting the outlet thickness for each frame, H (i) new And i is the thickness of a new outlet of each rack, and is the number of the rack.
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| CN113680828A (en) * | 2021-08-23 | 2021-11-23 | 北京北科麦思科自动化工程技术有限公司 | Automatic thickness control method used in plate strip production process |
| CN114130833A (en) * | 2021-11-11 | 2022-03-04 | 武钢集团昆明钢铁股份有限公司 | On-line automatic control system and method for dimension of rolled product of rod and wire rolling mill |
| CN114406015B (en) * | 2022-01-26 | 2023-09-01 | 北京首钢股份有限公司 | Load distribution method and device for finishing mill frame, electronic equipment and medium |
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