CN109226280B - Method for controlling double-edge wave shape and medium-wave shape of five-stand cold continuous rolling high-strength steel plate strip - Google Patents

Method for controlling double-edge wave shape and medium-wave shape of five-stand cold continuous rolling high-strength steel plate strip Download PDF

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CN109226280B
CN109226280B CN201811233342.2A CN201811233342A CN109226280B CN 109226280 B CN109226280 B CN 109226280B CN 201811233342 A CN201811233342 A CN 201811233342A CN 109226280 B CN109226280 B CN 109226280B
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CN109226280A (en
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李长生
金鑫
王煜
彭良贵
武志成
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Northeastern University China
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    • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
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Abstract

The invention provides a method for controlling double-edge wave and medium-wave plate shapes of a five-stand cold continuous rolling high-strength steel plate strip, and relates to the technical field of cold continuous rolling steel plate shape control. The method comprises the steps of firstly, providing a precondition for controlling the shapes of double-edge waves and medium waves by adopting the method, then setting a last rack as an ith rack, and calculating the shape value of the double-edge waves or the medium waves at the outlet of the ith-1 rack; comparing the calculated value of the double-side wave or middle wave plate shape at the outlet of the ith rack with the measured value, and repeatedly calculating until the calculated value meets the quality requirement of the finished plate shape; and then calculating the corrected value of the bending force of the working roll and the intermediate roll of the i-1 th frame, and if the corrected value does not meet the requirement, calculating the corrected value of the bending force of the working roll and the intermediate roll of the i-2 th frame until the deviation of the shape of the double side waves or the middle waves at the outlet of the i-th frame reaches the requirement of the quality of the finished product shape. The control method provided by the invention improves the control precision of the double-side wave or middle wave plate shape of the front machine frame, reduces the regulation and control pressure of the last machine frame and improves the plate shape quality of products.

Description

Method for controlling double-edge wave shape and medium-wave shape of five-stand cold continuous rolling high-strength steel plate strip
Technical Field
The invention relates to the technical field of strip shape control of five-stand cold continuous rolling strip steel, in particular to a method for controlling double-edge wave and medium-wave shape of a five-stand cold continuous rolling high-strength strip steel.
Background
The cold-rolled strip steel is widely applied to various fields of national economy, and along with the improvement of the quality of the cold-rolled strip steel, the requirements of users on the shape quality are gradually improved. Good sheet quality plays a crucial role in improving the product quality and yield of downstream processes.
The shape, the thickness and the width of the strip steel are the same, the strip steel is an important index for measuring the geometric dimension precision of the strip steel, the warping degree of the strip steel is visualized, and the distribution of the residual stress in the strip steel after rolling along the width direction of the strip steel is substantial. Common defects of plate shapes are mainly divided into edge waves, middle waves, 1/4 waves, mixed waves and the like.
The patent application No. 201510006441.7 proposes a cold rolling process for preventing the edge breaking and wave defect of an extremely thin strip steel. The method achieves the purpose of controlling the double-side waves of the ultrathin strip by the matched setting of the tension and the rolling force. However, the process parameters such as tension, rolling force and the like in the method are made based on a common strength grade material less than 600MPa, and are not suitable for the production of high-strength automobile plate strip steel.
The 200510028316.2 patent teaches a rolling process that overcomes the composite wave shape. The method achieves the purpose of controlling the defects of medium waves, double waves and other composite wave shapes by optimizing the roll shape of the working roll. However, this method is proposed based on a CVC rolling mill in which work rolls are axially movable, and is not applicable to a HC rolling mill and a UCM rolling mill in which widely used work rolls are not axially movable.
The high-strength steel for the automobile has higher deformation resistance, generally between 600MPa and 1200 MPa. In the rolling process, the elastic deformation of the roller system is increased due to larger rolling force, so that the control difficulty of the plate shape is increased. At present, the control of the double-side wave and the middle wave plate shape of the cold rolling unit mainly depends on the feedback control of the last rack, namely the plate shape measuring roller at the outlet of the last rack obtains the values of the double-side wave and the middle wave plate shape at the outlet, and then the values are fed back to an executing mechanism of the last rack to eliminate the plate shape deviation of the double-side wave and the middle wave. The middle frame is not provided with a plate shape measuring roller, so that the set value of the plate shape actuating mechanism can be determined only according to the plate shape of the incoming material and assuming the plate shape of the inlet of each frame. When the strength of cold-rolled incoming materials is high, the deviation between the assumed value and the actual value is large, accurate plate shape control cannot be achieved, the plate shape at the inlet of the last rack is poor, and even if the plate shape execution mechanism of the last rack reaches the limit value, the defects of double-side waves and medium waves caused by the front rack cannot be eliminated.
According to the traditional control method for the cold continuous rolling double-side-wave and medium-wave plate shapes, the plate shapes of 1-4 frames are assumed according to the hot rolling incoming material plate shape, and when the rolling mill produces high-strength-level strip steel, the assumed values have larger deviation with the actual values of the frames. Therefore, the regulation and control capability of the double-side wave and middle wave plate shape defects of the middle machine frame is reduced, and the pressure of the final machine frame for eliminating the plate shape defects is increased.
Disclosure of Invention
The invention aims to solve the technical problem of the prior art, and provides a method for controlling the defects of double-edge waves and medium-edge waves of a five-stand cold continuous rolling high-strength steel plate strip, so that the defects of the double-edge waves and the medium-edge waves of high-strength steel for automobiles are controlled.
In order to solve the technical problems, the technical scheme adopted by the invention is as follows: a method for controlling the defects of double-edge wave shape and medium-wave shape of a five-stand cold continuous rolling high-strength steel plate strip comprises the following steps:
a method for controlling the shape of double-edge waves and medium waves of a five-stand cold continuous rolling high-strength steel plate strip comprises the following steps:
step 1, judging whether the roll bending force of a working roll and a middle roll of a last frame simultaneously reaches or exceeds 90% of a limit value, and whether the deviation of a double-edge wave shape or a middle-edge wave shape exceeds the requirement range of the quality of a finished product shape, if so, executing a step 2, otherwise, executing a step 5;
step 2, setting the last machine frame as an ith machine frame, and calculating the shape value of the outlet double-edged wave or the central wave plate of the ith machine frame based on an influence function method according to the actually measured value of the shape value of the outlet double-edged wave or the central wave plate of the ith machine frame and the actually measured value of the roller bending force;
step 2.1, supposing that the shape value of the outlet double-edge wave or the middle corrugated plate of the i-1 th rack is flati-1；
Step 2.2, calculating the value of double-edge wave or medium-wave plate shape at the outlet of the ith rack according to the measured value of the bending force of the ith rack by an influence function methodiThe specific method comprises the following steps:
step 2.2.1, according to the outlet bilateral wave or middle wave plate shape value flight of the i-1 th racki-1Calculating the profile of the exit profile of the i-1 th racki-1As shown in the following formula
Figure GDA0002208361110000021
Wherein, profilei-1Is distributed at the outlet section of the i-1 th rack, HjIs the thickness of the jth point of the i-1 th rack inlet, HcIs the center thickness of the entrance of the (i-1) th rack,
Figure GDA0002208361110000022
is the average thickness of the entrance of the (i-1) th rack,
Figure GDA0002208361110000023
is the average thickness of the exit of the ith-1 rack;
step 2.2.2, calculating the rolling force distribution P of the ith rack by using a Bradled-Ford-Hill equation;
step 2.2.3, calculating the pressure distribution between the rollers of the ith rack by actually measuring the distribution of the bending force and the rolling force of the ith rack, wherein the pressure distribution is shown by the following two formulas:
QWI＝P+FW/Lw_cy×Δx (2)
QIB＝QWI+FI/Li_cy×Δx (3)
wherein Q isWIThe pressure between the working roll and the intermediate roll of the ith frame, QIBThe pressure between the middle roll and the back-up roll of the ith frame, FWIs the bending force of the i-th frame work roll, FIThe bending force of the ith frame intermediate roll is Lw _ cy, the hydraulic cylinder center distance of the ith frame working roll is Lw _ cy, the hydraulic cylinder center distance of the ith frame intermediate roll is Li _ cy, and delta x is the unit width of the ith frame roller;
step 2.2.4, calculating the elastic deformation of the roller of the ith frame by using an influence function method, thereby determining the distribution of the rolled section of the ith frame, wherein the distribution is shown in the following formula:
YW＝GW(QWI-P)-GFWFW(4)
YI＝GI(QIB-QWI)-GFIFI(5)
YB＝GBQIB(6)
YWI＝YWI0+YI-YW-MI-MW(7)
YIB＝YIB0+YB-YI-MB-MI(8)
YWS＝GWSP (9)
profilei＝H0+(YWS-YWS0)+(MW-YW) (10)
wherein, P is the rolling force of the ith frame; y isW、YI、YBThe elastic bending of the working roll, the middle roll and the supporting roll of the ith frame respectively; gW、GI、GBRespectively the elastic bending influence functions of the working roll, the intermediate roll and the supporting roll of the ith frame, GFW、GFIRespectively are the influence functions of the bending force of the working roll and the bending force of the intermediate roll of the ith machine frame; y isWI、YIBThe coordinated deformation of the working roll and the middle roll of the ith frame and the coordinated deformation of the middle roll and the supporting roll of the ith frame are respectively carried out; y isWI0、YIB0The flattening amount of the surface centers of the working roll and the middle roll of the ith frame and the roll of the supporting roll is respectively; mW、MI、MBConvexity vectors of an ith frame working roll, a middle roll and a supporting roll are respectively; y isWSFlattening the working roll caused by the rolling force of the ith frame; y isWS0The flattening amount of the working roll caused by the rolling force at the center of the ith frame plate; gWSIs the flattening influence function of the ith machine frame; profileiThe rolled sections of the ith frame are distributed; h0Is half of the central thickness of the rolled strip steel of the ith frame;
step 2.2.5, utilizing the calculated i-th frame after-rolling section distribution profileiCalculating the shape value of the double-side wave or the middle corrugated plate of the rolled strip steel of the ith frameiThe following formula shows:
Figure GDA0002208361110000031
wherein E issIs the modulus of elasticity, v, of the strip steelsThe poisson ratio of the strip steel is shown;
step 3, calculating the calculated value of the double-edge wave or middle-wave plate shape of the exit of the ith rackiMeasured value of double-edge wave or middle wave plate shape of ith rack outleti *Comparing, if the error exceeds the set value epsilon, iteratively correcting the assumed outlet double wave or middle wave plate shape value of the i-1 th rack by adopting an exponential smoothing method, re-executing the step 2.2, and re-calculating the flightiUntil the ith frame outlet is provided with a double wave or a middle wave plate shape value flightiOutputting the shape value of the outlet bilateral wave or the middle corrugated plate of the i-1 th rack until the convergence precision is met;
the assumed values of the outlet double-edge waves or the middle corrugated plates of the i-1 th rack are iteratively corrected by adopting an exponential smoothing method, and the following formula is shown:
Figure GDA0002208361110000041
wherein the content of the first and second substances,
Figure GDA0002208361110000042
is the nth iteration value of the i-1 th rack;
Figure GDA0002208361110000043
is the iteration value of the (n-1) th rack of the (i-1) th rack; λ is a smoothing constant;
Figure GDA0002208361110000044
the calculated value of the nth time of the ith-1 rack;
step 4, comparing the value of the shape of the double-edge wave or the middle-edge wave at the outlet of the i-1 rack calculated in the step 3 with the target shape of the outlet of the i-1 rack, calculating the correction quantity after the roll bending force of the i-1 rack is corrected, reducing the deviation of the shape of the double-edge wave or the middle-edge wave of the i-1 rack, and improving the shape quality of the i-1 rack, wherein the specific method comprises the following steps:
when the i-1 th machine frame bending force correction quantity is calculated, the following objective function is defined:
Figure GDA0002208361110000045
wherein, Delta epsilonkThe shape error of the kth shape measurement section of the i-1 th rack is obtained; k is the plate shape measuring section of the i-1 th rack, k is 1, … and N, and N is the plate shape measuring dividing unit number; gwbThe roll bending regulation coefficient of the working roll of the i-1 th frame is set; gibThe roll bending control coefficient of the intermediate roll of the i-1 th frame is obtained; m iswbThe correction quantity of the roll bending of the working roll of the i-1 th frame is obtained; m isibThe correction quantity of the bending roll of the middle roll of the i-1 th frame is obtained; calculating the partial derivative of the formula (13), so that the objective function f (m) takes the minimum value, and eliminating the plate shape error, wherein the formula is as follows:
Figure GDA0002208361110000046
mt＝mwbor mib(14)
Further, a correction amount m of the roll bending force of the i-1 st frame when the objective function f (m) takes the minimum value is obtainedt；
Step 5, if the corrected correction value of the bending force of the working roll and the middle roll of the (i-1) th frame exceeds 90% of the limit value at the same time, and the deviation of the double-edge wave or middle wave plate shape still does not meet the requirement of the quality of the finished product plate shape, re-executing the step 2-4, and calculating the corrected correction value of the bending roll of the (i-2) th frame until the deviation of the double-edge wave or middle wave plate shape of the outlet plate shape of the (i) th frame meets the requirement of the quality of the finished product plate;
and 6, ending.
Adopt the produced beneficial effect of above-mentioned technical scheme to lie in: according to the method for controlling the shape of the double-edge waves and the middle-edge waves of the five-rack cold continuous rolling high-strength steel plate strip, the shape of the double-edge waves and the middle-edge waves at the inlet of the front rack is calculated by an influence function method with high calculation precision and high speed according to the actually measured shape values of the double-edge waves and the middle-edge waves of the frame plate-shaped roller of the last rack and the actual values of the bending roller force of each rack.
Drawings
Fig. 1 is a flowchart of a method for controlling double-edge wave and medium-wave plate shapes of a five-stand cold continuous rolling high-strength steel plate strip according to an embodiment of the invention;
fig. 2 is a diagram of an ith rack exit double-edge wave or middle-wave plate shape flight provided by the embodiment of the inventioniA calculation flowchart of (1);
FIG. 3 is a diagram of an i-1 th rack exit double-edge wave or middle-wave shape flight according to an embodiment of the present inventioni-1Iteratively revising the flow chart;
fig. 4 is a schematic diagram illustrating the strip shape of a finished product strip before controlling the double-edge wave and middle-wave shape of a five-stand cold continuous rolled high-strength steel strip according to the first embodiment of the present invention;
fig. 5 is a schematic diagram illustrating the strip shape of a finished product strip after the method for controlling the double-edge wave and medium-wave shape of a five-stand cold continuous rolled high-strength steel strip according to the first embodiment of the present invention is adopted;
fig. 6 is a schematic diagram illustrating the strip shape of a finished plate strip before controlling the double-edge wave and middle-wave shapes of a five-stand cold continuous rolled high-strength steel plate strip according to a second embodiment of the present invention;
fig. 7 is a schematic diagram illustrating the strip shape of a finished product strip after the method for controlling the double-edge wave and medium-wave shape of a five-stand cold continuous rolled high-strength steel strip according to the second embodiment of the invention is adopted;
fig. 8 is a schematic diagram illustrating the strip shape of a finished plate strip before controlling the double-edge wave and middle-wave shapes of a five-stand cold continuous rolled high-strength steel plate strip according to a third embodiment of the present invention;
fig. 9 is a schematic diagram of the strip shape of a finished product strip after the method for controlling the double-edge wave and medium-wave shape of a five-stand cold continuous rolled high-strength steel strip provided by the third embodiment of the invention is adopted.
Detailed Description
The following detailed description of embodiments of the present invention is provided in connection with the accompanying drawings and examples. The following examples are intended to illustrate the invention but are not intended to limit the scope of the invention.
In the embodiment of the invention, a 1740mm six-roller five-rack cold continuous rolling unit is taken as an example, and the double-edge wave shape or the middle wave shape of the rolling mill is controlled by using the double-edge wave shape and middle wave shape control method for the five-rack cold continuous rolling of the high-strength steel plate strip.
In this embodiment, the basic parameters of the rolling mill are as follows: diameter of the working roll: 430-480 mm; diameter of the intermediate roll: 510-580 mm; diameter of the supporting roller: 1315-1465 mm; roll inclination: -1mm to +1 mm; bending force of the working roll: 2400KN to 2400 KN; intermediate roll bending force: -2700KN to 2700 KN; transversely moving the intermediate roller: -125mm to +125 mm.
A method for controlling the shape of double-edge waves and medium waves of a five-stand cold continuous rolling high-strength steel plate strip is shown in figure 1 and comprises the following steps:
step 1, judging whether the roll bending force of a working roll and a middle roll of a last frame simultaneously reaches or exceeds 90% of a limit value, and whether the deviation of a double-edge wave shape or a middle-edge wave shape exceeds the requirement range of the quality of a finished product shape, if so, executing a step 2, otherwise, executing a step 5;
step 2, setting the last machine frame as an ith machine frame, and calculating the shape value of the outlet double-edged wave or the central wave plate of the ith machine frame based on an influence function method according to the actually measured value of the shape value of the outlet double-edged wave or the central wave plate of the ith machine frame and the actually measured value of the roller bending force;
step 2.1, supposing that the shape value of the outlet double-edge wave or the middle corrugated plate of the i-1 th rack is flati-1；
Step 2.2, calculating the value of double-edge wave or medium-wave plate shape at the outlet of the ith rack according to the measured value of the bending force of the ith rack by an influence function methodiAs shown in fig. 2, the specific method is as follows:
step 2.2.1, according to the outlet bilateral wave or middle wave plate shape value flight of the i-1 th racki-lCalculating the profile of the exit profile of the i-1 th racki-1As shown in the following formula
Figure GDA0002208361110000061
Wherein, profilei-1Is distributed at the outlet section of the i-1 th rack, HjIs the thickness of the jth point of the i-1 th rack inlet, HcIs the center thickness of the entrance of the (i-1) th rack,
Figure GDA0002208361110000062
is the average thickness of the entrance of the (i-1) th rack,
Figure GDA0002208361110000063
is the average thickness of the exit of the ith-1 rack;
step 2.2.2, calculating the rolling force distribution P of the ith rack by using a Bradled-Ford-Hill equation;
step 2.2.3, calculating the pressure distribution between the rollers of the ith rack by actually measuring the distribution of the bending force and the rolling force of the ith rack, wherein the pressure distribution is shown by the following two formulas:
QWI＝P+FW/Lw_cy×Δx (2)
QIB＝QWI+FI/Li_cy×Δx (3)
wherein Q isWIThe pressure between the working roll and the intermediate roll of the ith frame, QIBThe pressure between the middle roll and the back-up roll of the ith frame, FWIs the bending force of the i-th frame work roll, FIThe bending force of the ith frame intermediate roll is Lw _ cy, the hydraulic cylinder center distance of the ith frame working roll is Lw _ cy, the hydraulic cylinder center distance of the ith frame intermediate roll is Li _ cy, and delta x is the unit width of the ith frame roller;
step 2.2.4, calculating the elastic deformation of the roller of the ith frame by using an influence function method, thereby determining the distribution of the rolled section of the ith frame, wherein the distribution is shown in the following formula:
YW＝GW(QWI-P)-GFWFW(4)
YI＝GI(QIB-QWI)-GFIFI(5)
YB＝GBQIB(6)
YWI＝YWI0+YI-FW-MI-MW(7)
YIB＝YIB0+YB-YI-MB-MI(8)
YWS＝GWSP (9)
profilei＝H0+(YWS-YWS0)+(MW-YW) (10)
wherein, P is the rolling force of the ith frame; y isW、YI、YBThe elastic bending of the working roll, the middle roll and the supporting roll of the ith frame respectively; gW、GI、GBRespectively the elastic bending influence functions of the working roll, the intermediate roll and the supporting roll of the ith frame, GFW、GFiRespectively are the influence functions of the bending force of the working roll and the bending force of the intermediate roll of the ith machine frame; y isWI、YIBThe coordinated deformation of the working roll and the middle roll of the ith frame and the coordinated deformation of the middle roll and the supporting roll of the ith frame are respectively carried out; y isWI0、YIB0Are respectively the ith frame working rollFlattening the surface centers of the middle roller, the middle roller and the supporting roller; mW、MI、MBConvexity vectors of an ith frame working roll, a middle roll and a supporting roll are respectively; y isWSFlattening the working roll caused by the rolling force of the ith frame; y isWS0The flattening amount of the working roll caused by the rolling force at the center of the ith frame plate; gWSIs the flattening influence function of the ith machine frame; profileiThe rolled sections of the ith frame are distributed; h0Is half of the central thickness of the rolled strip steel of the ith frame;
step 2.2.5, utilizing the calculated i-th frame after-rolling section distribution profileiCalculating the shape value of the double-side wave or the middle corrugated plate of the rolled strip steel of the ith frameiThe following formula shows:
Figure GDA0002208361110000071
wherein E issIs the modulus of elasticity, v, of the stripsThe poisson ratio of the strip steel is shown;
step 3, calculating the calculated value of the double-edge wave or middle-wave plate shape of the exit of the ith rackiMeasured value of double-edge wave or middle wave plate shape of ith rack outleti *Comparing, if the error exceeds the set value epsilon, iteratively correcting the assumed outlet double wave or middle wave plate shape value of the i-1 th rack by adopting an exponential smoothing method, re-executing the step 2.2, and re-calculating the flightiUntil the ith frame outlet is provided with a double wave or a middle wave plate shape value flightiOutputting the shape value of the outlet bilateral wave or the middle corrugated plate of the i-1 th rack until the convergence precision requirement is met;
the assumed outlet bilateral wave or median wave shape value of the i-1 th rack is iteratively corrected by adopting an exponential smoothing method, as shown in fig. 3, the following formula is shown:
Figure GDA0002208361110000072
wherein the content of the first and second substances,
Figure GDA0002208361110000073
is the nth iteration value of the i-1 th rack;
Figure GDA0002208361110000074
is the iteration value of the (n-1) th rack of the (i-1) th rack; λ is a smoothing constant;
Figure GDA0002208361110000075
the calculated value of the nth time of the ith-1 rack;
step 4, comparing the value of the shape of the double-edge wave or the middle-edge wave at the outlet of the i-1 rack calculated in the step 3 with the target shape of the outlet of the i-1 rack, calculating the correction quantity after the roll bending force of the i-1 rack is corrected, reducing the deviation of the shape of the double-edge wave or the middle-edge wave of the i-1 rack, and improving the shape quality of the i-1 rack, wherein the specific method comprises the following steps:
when the i-1 th machine frame bending force correction quantity is calculated, the following objective function is defined:
Figure GDA0002208361110000081
wherein, Delta epsilonkThe shape error of the kth shape measurement section of the i-1 th rack is obtained; k is the plate shape measuring section of the i-1 th rack, k is 1, … and N, and N is the plate shape measuring dividing unit number; gwbThe roll bending regulation coefficient of the working roll of the i-1 th frame is set; gibThe roll bending control coefficient of the intermediate roll of the i-1 th frame is obtained; m iswbThe correction quantity of the roll bending of the working roll of the i-1 th frame is obtained; m isibThe correction quantity of the bending roll of the middle roll of the i-1 th frame is obtained;
calculating the partial derivative of the formula (13), so that the objective function f (m) takes the minimum value, and eliminating the plate shape error, wherein the formula is as follows:
Figure GDA0002208361110000082
mt＝mwbor mib(14)
Further, a correction amount m of the roll bending force of the i-1 st frame when the objective function f (m) takes the minimum value is obtainedt；
Step 5, if the corrected correction value of the bending force of the working roll and the middle roll of the (i-1) th frame exceeds 90% of the limit value at the same time, and the deviation of the double-edge wave or middle wave plate shape still does not meet the requirement of the quality of the finished product plate shape, re-executing the step 2-4, and calculating the corrected correction value of the bending roll of the (i-2) th frame until the deviation of the double-edge wave or middle wave plate shape of the outlet plate shape of the (i) th frame meets the requirement of the quality of the finished product plate;
and 6, ending.
The first embodiment is as follows:
preparing a QP980 automobile dual-phase steel plate strip with the thickness of 2.75mm and the width of 1250mm, rolling the double-phase steel plate strip into a plate strip with the thickness of 0.7mm after five-pass cold continuous rolling, and before and after controlling by adopting the method for controlling the double-edge wave shape and the middle-wave shape of the five-rack cold continuous rolling high-strength steel plate strip, wherein the roll bending force parameters of each rack are shown in a table 1:
TABLE 1 roll bending force parameters of each frame before and after the method of the invention is applied
Figure GDA0002208361110000083
As can be seen from Table 1, the bending force of the fifth frame is close to the limit value before the method of the present invention is applied, and the bending force of the front frames has a margin. FIG. 4 shows the strip shape of the finished plate before the method of the present invention is applied, and it can be seen from the figure that the quality of the plate shape is poor, and the two sides of the plate strip present obvious double edge wave defects. After the method is put into use, as shown in figure 5, the actual values of the bending force of each frame tend to be balanced, and the quality of the finished plate shape is obviously improved.
Example two:
preparing a DP980 automobile dual-phase steel plate strip with the thickness of 3.5mm and the width of 1160mm, rolling the steel plate strip into a plate strip with the thickness of 1.2mm after five-pass cold continuous rolling, and controlling the parameters of the roll bending force of each stand as shown in a table 2 before and after the control by adopting the method for controlling the double-edge wave shape and the middle-wave shape of the five-stand cold continuous rolling high-strength steel plate strip disclosed by the invention:
TABLE 2 roll bending force parameters of each frame before and after the method of the present invention is applied
Figure GDA0002208361110000091
As can be seen from Table 2, the bending force of the fifth frame is close to the limit value before the method of the present invention is applied, and the bending force of the front frames has a margin. FIG. 6 shows the strip shape of the finished plate before the method of the present invention is applied, and it can be seen from the figure that the quality of the plate shape is poor, and the two sides of the plate strip present obvious double edge wave defects. After the method is put into use, as shown in fig. 7, the actual values of the bending force of each frame tend to be balanced, and the quality of the finished plate shape is obviously improved.
Example three:
preparing a DP780 automobile dual-phase steel plate strip with the thickness of 3.5mm and the width of 1200mm, rolling the steel plate strip into a plate strip with the thickness of 0.9mm after five-pass cold continuous rolling, and controlling the parameters of the plate shape bending roll force of each stand as shown in Table 3 before and after the control by adopting the method for controlling the double-edge wave shape and the middle-wave shape of the five-stand cold continuous rolling high-strength steel plate strip of the invention:
TABLE 3 roll bending force parameters of each frame before and after the method of the invention is applied
Figure GDA0002208361110000092
As can be seen from Table 3, the bending force of the fifth frame is close to the limit value before the method of the present invention is applied, and the bending force of the front frames has a margin. FIG. 8 shows the strip shape of the finished plate before the method of the present invention is applied, and it can be seen from the figure that the quality of the plate shape is poor, and the two sides of the plate strip present obvious double edge wave defects. After the method is put into use, as shown in fig. 9, the actual values of the bending force of each frame tend to be balanced, and the quality of the finished plate shape is obviously improved.
Finally, it should be noted that: the above embodiments are only used to illustrate the technical solution of the present invention, and not to limit the same; while the invention has been described in detail and with reference to the foregoing embodiments, it will be understood by those skilled in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some or all of the technical features may be equivalently replaced; such modifications and substitutions do not depart from the spirit of the corresponding technical solutions and scope of the present invention as defined in the appended claims.

Claims (4)

1. A method for controlling the shape of double-edge waves and medium waves of a five-stand cold continuous rolling high-strength steel plate strip is characterized by comprising the following steps of: the method comprises the following steps:
step 1, judging whether the roll bending force of a working roll and a middle roll of a last frame simultaneously reaches or exceeds 90% of a limit value, and whether the deviation of a double-edge wave shape or a middle-edge wave shape exceeds the requirement range of the quality of a finished product shape, if so, executing a step 2, otherwise, executing a step 5;
step 2, setting the last machine frame as an ith machine frame, and calculating the shape value of the outlet double-edged wave or the central wave plate of the ith machine frame based on an influence function method according to the actually measured value of the shape value of the outlet double-edged wave or the central wave plate of the ith machine frame and the actually measured value of the roller bending force;
step 2.1, supposing that the shape value of the outlet double-edge wave or the middle corrugated plate of the i-1 th rack is flati-1；
Step 2.2, calculating the value of double-edge wave or medium-wave plate shape at the outlet of the ith rack according to the measured value of the bending force of the ith rack by an influence function methodi；
Step 3, calculating the calculated value of the double-edge wave or middle-wave plate shape of the exit of the ith rackiMeasured value of double-edge wave or middle wave plate shape of ith rack outleti *Comparing, if the error exceeds the set value epsilon, iteratively correcting the assumed outlet double wave or middle wave plate shape value of the i-1 th rack by adopting an exponential smoothing method, re-executing the step 2.2, and re-calculating the flightiUntil the ith frame outlet is provided with a double wave or a middle wave plate shape value flightiOutputting the shape value of the outlet bilateral wave or the middle corrugated plate of the i-1 th rack until the convergence precision requirement is met;
step 4, comparing the value of the shape of the double-edge wave or the middle-edge wave at the outlet of the i-1 rack calculated in the step 3 with the target shape of the outlet of the i-1 rack, calculating the correction amount after the roll bending force of the i-1 rack is corrected, reducing the deviation of the shape of the double-edge wave or the middle-edge wave of the i-1 rack, and improving the shape quality of the i-1 rack;
step 5, if the corrected correction value of the bending force of the working roll and the middle roll of the (i-1) th frame exceeds 90% of the limit value at the same time, and the deviation of the double-edge wave or middle wave plate shape still does not meet the requirement of the quality of the finished product plate shape, re-executing the step 2-4, and calculating the corrected correction value of the bending roll of the (i-2) th frame until the deviation of the double-edge wave or middle wave plate shape of the outlet plate shape of the (i) th frame meets the requirement of the quality of the finished product plate;
and 6, ending.
2. The method for controlling the shape of the double edge waves and the middle wave of the five-stand cold continuous rolled high-strength steel plate strip according to claim 1, characterized by comprising the following steps: the specific method of the step 2.2 comprises the following steps:
step 2.2.1, according to the outlet bilateral wave or middle wave plate shape value flight of the i-1 th racki-1Calculating the profile of the exit profile of the i-1 th racki-1As shown in the following formula
Figure FDA0002208361100000011
Wherein, profilei-1Is distributed at the outlet section of the i-1 th rack, HjIs the thickness of the jth point of the i-1 th rack inlet, HcIs the center thickness of the entrance of the (i-1) th rack,
Figure FDA0002208361100000012
is the average thickness of the entrance of the (i-1) th rack,
Figure FDA0002208361100000013
is the average thickness of the exit of the ith-1 rack;
step 2.2.2, calculating the rolling force distribution P of the ith rack by using a Bradled-Ford-Hill equation;
step 2.2.3, calculating the pressure distribution between the rollers of the ith rack by actually measuring the distribution of the bending force and the rolling force of the ith rack, wherein the pressure distribution is shown by the following two formulas:
QWI＝P+FW/Lw_cy×Δx (2)
QIB＝QWI+FI/Li_cy×Δx (3)
wherein Q isWIThe roll being the working roll and the intermediate roll of the ith frameIntermediate pressure, QIBThe pressure between the middle roll and the back-up roll of the ith frame, FWIs the bending force of the i-th frame work roll, FIThe bending force of the ith frame intermediate roll is Lw _ cy, the hydraulic cylinder center distance of the ith frame working roll is Lw _ cy, the hydraulic cylinder center distance of the ith frame intermediate roll is Li _ cy, and delta x is the unit width of the ith frame roller;
step 2.2.4, calculating the elastic deformation of the roller of the ith frame by using an influence function method, thereby determining the distribution of the rolled section of the ith frame, wherein the distribution is shown in the following formula:
YW＝GW(QWI-P)-GFWFW(4)
YI＝GI(QIB-QWI)-GFIFI(5)
YB＝GBQIB(6)
YWI＝YWI0+YI-YW-MI-MW(7)
YIB＝YIB0+YB-YI-MB-MI(8)
YWS＝GWSP (9)
profilei＝H0+(YWS-YWS0)+(MW-YW) (10)
wherein, P is the rolling force of the ith frame; y isW、YI、YBThe elastic bending of the working roll, the middle roll and the supporting roll of the ith frame respectively; gW、GI、GBRespectively the elastic bending influence functions of the working roll, the intermediate roll and the supporting roll of the ith frame, GFW、GFIRespectively are the influence functions of the bending force of the working roll and the bending force of the intermediate roll of the ith machine frame; y isWI、YIBThe coordinated deformation of the working roll and the middle roll of the ith frame and the coordinated deformation of the middle roll and the supporting roll of the ith frame are respectively carried out; y isWI0、YIB0The flattening amount of the surface centers of the working roll and the middle roll of the ith frame and the roll of the supporting roll is respectively; mW、MI、MBRespectively an ith frame working roll, a middle roll,A crown vector of the support roll; y isWSFlattening the working roll caused by the rolling force of the ith frame; y isWS0The flattening amount of the working roll caused by the rolling force at the center of the ith frame plate; gWSIs the flattening influence function of the ith machine frame; profileiThe rolled sections of the ith frame are distributed; h0Is half of the central thickness of the rolled strip steel of the ith frame;
step 2.2.5, utilizing the calculated i-th frame after-rolling section distribution profileiCalculating the shape value of the double-side wave or the middle corrugated plate of the rolled strip steel of the ith frameiThe following formula shows:
Figure FDA0002208361100000031
wherein E issIs the modulus of elasticity, v, of the strip steelsThe poisson ratio of the strip steel.
3. The method for controlling the shape of the double edge waves and the middle wave of the five-stand cold continuous rolled high-strength steel plate strip according to claim 2, characterized by comprising the following steps: and 3, iteratively correcting the assumed outlet double-edge wave or middle wave plate shape value of the i-1 th rack by adopting an exponential smoothing method, wherein the formula is as follows:
Figure FDA0002208361100000032
wherein the content of the first and second substances,
Figure FDA0002208361100000033
is the nth iteration value of the i-1 th rack;
Figure FDA0002208361100000034
is the iteration value of the (n-1) th rack of the (i-1) th rack; λ is a smoothing constant;
Figure FDA0002208361100000035
the calculated value of the nth time of the ith-1 rack.
4. The method for controlling the double-edge wave shape and the medium-wave shape of the five-stand cold continuous rolling high-strength steel plate strip according to claim 3, characterized by comprising the following steps: the specific method of the step 4 comprises the following steps:
when the i-1 th machine frame bending force correction quantity is calculated, the following objective function is defined:
Figure FDA0002208361100000036
wherein, Delta epsilonkThe shape error of the kth shape measurement section of the i-1 th rack is obtained; k is the plate shape measuring section of the i-1 th rack, k is 1, … and N, and N is the plate shape measuring dividing unit number; gwbThe roll bending regulation coefficient of the working roll of the i-1 th frame is set; gibThe roll bending control coefficient of the intermediate roll of the i-1 th frame is obtained; m iswbThe correction quantity of the roll bending of the working roll of the i-1 th frame is obtained; m isibThe correction quantity of the bending roll of the middle roll of the i-1 th frame is obtained; calculating the partial derivative of the formula (13), so that the objective function f (m) takes the minimum value, and eliminating the plate shape error, wherein the formula is as follows:
Figure FDA0002208361100000037
further, a correction amount m of the roll bending force of the i-1 st frame when the objective function f (m) takes the minimum value is obtainedt。
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