A cold rolling method for reducing the transverse thickness difference and improving the sheet shape

Abstract

The application discloses a cold rolling method for reducing transverse thickness difference and improving plate shape, which comprises the following steps: step one, detecting the transverse thickness difference of raw material; step two, detecting the cold rolling plate shape; step three, increasing the reduction rate to increase the elongation coefficient; step four, reducing the rolling pressure gradually; step five, reducing the transverse thickness difference by a small amplitude through the first two passes; and step six, improving the plate shape through the last three passes. The application provides a guarantee for the feedforward control for reducing the transverse thickness difference by detecting the transverse thickness difference of the raw material through a crown meter before the first rolling mill; the transverse thickness difference is reduced by a small amplitude and gradually through the first and second rolling mills when the plasticity of the rolled piece is large, and the plate shape is adjusted from the third rolling mill, so that the target of reducing the transverse thickness difference of the cold rolling strip steel and obtaining a good plate shape is realized; a first plate shape meter is arranged at the outlet of the second rolling mill, so as to provide a guarantee for the feedforward control of the plate shape by the third and fourth rolling mills.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of cold rolling technology, and particularly relates to a cold rolling method for reducing transverse thickness difference and improving plate shape. BACKGROUND

[0002] The transverse thickness difference is the thickness deviation in the width direction of the plate strip, and the plate shape is whether and how much waves are generated in each part in the width direction of the plate strip. The hot-rolled strip steel has a large transverse thickness difference and different degrees of wave shape as the cold rolling raw material. If good plate shape is obtained, it is difficult to reduce the transverse thickness difference, and if the transverse thickness difference is reduced, it is difficult to obtain good plate shape.

[0003] The prior art generally only sets a plate shape instrument at the outlet of the fifth rolling mill, and only implements feedback control on the fifth rolling mill. The plate shape control ability is weak, time lag is long, and the transverse thickness difference of any hot-rolled material can only be reduced but cannot be completely eliminated through cold rolling. A large reduction in the transverse thickness difference will generate serious wave shape, produce unqualified products, and even cause the strip to break, resulting in that the rolling cannot be carried out. SUMMARY

[0004] The present application aims to provide a cold rolling method for reducing transverse thickness difference and improving plate shape to solve the problems in the background.

[0005] To achieve the above-mentioned purpose, the present application provides the following technical scheme: a cold rolling method for reducing transverse thickness difference and improving plate shape, comprising the following steps: step one, detecting the transverse thickness difference of the raw material; step two, detecting the cold rolling plate shape; step three, increasing the reduction rate to increase the elongation coefficient; step four, reducing the rolling pressure by each pass; step five, reducing the transverse thickness difference by a small amplitude through the first two passes; and step six, improving the plate shape through the last three passes.

[0006] In the step one, the roll gap shape of the rolling mill is set according to the transverse thickness difference of the hot-rolled material detected by the crown instrument, so as to reduce the cold rolling transverse thickness difference.

[0007] In the step two, the roll gap shape is adjusted according to the cold rolling process or outlet plate shape detected by the plate shape instrument, so as to obtain good plate shape.

[0008] In the above step three, the reduction is the percentage of the difference between the pre-rolling thickness and the post-rolling thickness, and the extension coefficient is the ratio of the pre-rolling thickness to the post-rolling thickness. According to the formula: reduction ε = (H - h) ÷ H x 100%. ε - reduction; H - pre-rolling thickness; h - post-rolling thickness; extension coefficient λ = H ÷ h. λ - extension coefficient; H - pre-rolling thickness; h - post-rolling thickness; under the condition of uniform extension: λ = H ÷ h = ΔH ÷ Δh. ΔH - transverse thickness difference before cold rolling; Δh - transverse thickness difference after cold rolling; it is obtained that Δh = ΔH ÷ λ and λ = 1 ÷ (1 - ε), that is, the greater the reduction ε, the greater the extension coefficient λ, and the smaller the transverse thickness difference Δh after rolling; that is, by increasing the reduction to improve the extension coefficient, the transverse thickness difference of the cold-rolled strip can be reduced;

[0009] In the above step four, under the principle of uniform deformation, if the transverse thickness difference Δh of the next pass satisfies Δh < ΔH, the roll deflection of the next pass must be smaller than that of the previous pass, which needs to be achieved by gradually reducing the rolling pressure to gradually reduce the elastic bending deformation of the roll; under the condition of the same roll stiffness: ΔH - Δh = (Pfront - Pback) ÷ K or Δh = ΔH - (Pfront - Pback) ÷ K; Pfront - rolling force of the previous pass; Pback - rolling force of the next pass; K - roll stiffness coefficient N / mm; according to the above formula, the rolling force of the next pass is smaller than that of the previous pass, which is a necessary condition to obtain good plate shape and reduce the transverse thickness difference of the cold-rolled strip;

[0010] In the above step five, the first two passes of the five-pass tandem cold rolling mill adopt the method of non-uniform extension when the plasticity of the rolled piece is high, and the reduction is relatively large at the places where the thickness of the strip is large in the width direction, so as to reduce the transverse thickness difference by a small amount.

[0011] In the above step six, the third and fourth passes of the mill adopt the method of uniform extension to adjust the plate shape when the hardening degree of the rolled piece is not high, and the fifth pass adopts the method of uniform extension to make a slight adjustment to the plate shape of the strip.

[0012] Preferably, in the step one, a crown instrument is arranged in front of the first pass, and the inclination, bending force and axial movement position of the intermediate roll of the first and second passes are controlled by feedforward control according to the thickness difference of the incoming material detected by the crown instrument, Figure 1 : 1 - inclination control of the first and second passes; 2 - roll shifting and bending control of the upper roll of the intermediate roll of the first and second passes; 3 - bending control of the upper work roll of the first and second passes; 4 - bending control of the lower work roll of the first and second passes; 5 - roll shifting and bending control of the lower roll of the intermediate roll of the first and second passes, and the roll shifting of the intermediate roll is used to offset the harmful torque that can cause bending deformation of the work roll transmitted by the backup roll.

[0013] Preferably, in the step two, two plate shape instruments are arranged, the first plate shape instrument is arranged at the outlet of the second rolling mill, the third and fourth rolling mills are controlled by the feedforward control according to the plate shape of the outlet of the second rolling mill detected by the first plate shape instrument, including the inclination control of the upper support roll, the roll shifting and bending control of the intermediate roll, the bending control of the work roll, the second plate shape instrument is arranged at the outlet of the fifth rolling mill, the fifth rolling mill is controlled by the feedback control, including the inclination control of the upper support roll, the roll shifting and bending control of the intermediate roll, the bending control of the work roll, the segmented cooling control of the work roll, 6-the segmented cooling control of the upper work roll, 7-the segmented cooling control of the lower work roll. The segmented cooling is used to improve the rib wave of the strip, and the emulsion is sprayed to the corresponding position of the work roll according to the position where the rib wave is generated, so that the local thermal crown of the work roll is reduced.

[0014] Preferably, in the step three, the total reduction rate is the percentage of the ratio of the thickness of the hot-rolled material minus the thickness of the strip after being rolled by the fifth rolling mill to the thickness of the hot-rolled material, the greater the reduction rate ε, the greater the elongation coefficient λ, and the smaller the transverse thickness difference Δh after rolling, and the total reduction rate is increased by increasing the thickness of the material under the condition that the rolling thickness is unchanged; the following is an example that the transverse thickness difference of the material is 0.02 mm and the rolling thickness is 1.0 mm:

[0015] When H=2 mm, the reduction rate ε=50%, the elongation coefficient λ=2, and the transverse thickness difference Δh after cold rolling is 0.01 mm;

[0016] When H=2.22 mm, the reduction rate ε=55%, the elongation coefficient λ=2.22, and the transverse thickness difference Δh after cold rolling is 0.009 mm;

[0017] When H=2.5 mm, the reduction rate ε=60%, the elongation coefficient λ=2.5, and the transverse thickness difference Δh after cold rolling is 0.008 mm;

[0018] When H=2.857 mm, the reduction rate ε=65%, the elongation coefficient λ=2.857, and the transverse thickness difference Δh after cold rolling is 0.007 mm;

[0019] When H=3.33 mm, the reduction rate ε=70%, the elongation coefficient λ=3.33, and the transverse thickness difference Δh after cold rolling is 0.006 mm;

[0020] When H=4.0 mm, the reduction rate ε=75%, the elongation coefficient λ=4, and the transverse thickness difference Δh after cold rolling is 0.005 mm;

[0021] When H=5.0 mm, the reduction rate ε=80%, the elongation coefficient λ=5, and the transverse thickness difference Δh after cold rolling is 0.004 mm;

[0022] When H = 6.67 mm, the reduction ratio ε = 85%, the elongation coefficient λ = 6.67, and the difference Δh after cold rolling in the transverse direction = 0.0029 mm;

[0023] As shown in the above example, the total reduction ratio is increased by 5%, and the transverse thickness difference after cold rolling is reduced by 0.001 mm (1 μm); in fact, by increasing the reduction ratio, the transverse thickness difference after cold rolling cannot be reduced to the expected value; when the reduction ratio is 80%, the transverse thickness difference after cold rolling can only be reduced to 0.009-0.01, because in the actual rolling process, the strip steel is not uniformly elongated in the width direction, or the original thick part is elongated less, or the original thin part is elongated more, resulting in an increase in H2-h2, and the transverse thickness difference Δh after cold rolling cannot be reduced to the expected value; the thickness difference before rolling ΔH = H1-h1; the thickness difference after rolling Δh = H2-h2; λ = (H1-h1) ÷ (H2-h2); therefore, by increasing the total reduction ratio of cold rolling, the cold rolling thickness difference can be reduced to a certain extent, but it cannot be completely reduced in proportion to the elongation coefficient, and merely increasing the total reduction ratio of cold rolling is not enough to reduce the transverse thickness difference after cold rolling.

[0024] Preferably, in the fourth step, the rolling pressure of the second rolling mill is 11% lower than that of the first rolling mill; the rolling pressure of the third rolling mill is 11% lower than that of the second rolling mill; the rolling pressure of the fourth rolling mill is 12% lower than that of the third rolling mill; and the rolling pressure of the fifth rolling mill is 20% lower than that of the fourth rolling mill; if the rolling force of the first rolling mill is 90000 KN, the rolling force of the second rolling mill is 80100 KN, the rolling force of the third rolling mill is 71289 KN, the rolling force of the fourth rolling mill is 62734 KN, and the rolling force of the fifth rolling mill is 56467 KN. According to the formula ΔH-Δh = (Pfront-Pback) ÷ K and Δh = ΔH-(Pfront-Pback) ÷ K, the rolling force of the cold continuous rolling is reduced by each rolling mill, which not only enhances the uniform elongation, but also provides a guarantee for reducing the transverse thickness difference.

[0025] Preferably, in step five, (1) a straightening roller with a diameter of 150 mm is added at the entrance of the second rolling mill, and the strip steel is pressed down by 5 mm during rolling, which functions to straighten and suppress the wave shape of the strip steel at the exit of the first rolling mill, so that the second rolling mill can smoothly bite into the rolled piece; (2) a straightening roller with a diameter of 150 mm is added at the entrance of the third rolling mill, and the strip steel is pressed down by 5 mm during rolling, which functions to straighten and suppress the wave shape of the strip steel at the exit of the second rolling mill, so that the third rolling mill can smoothly bite into the rolled piece; (3) for wedge-shaped incoming material, the actual roll gap shape of the first rolling mill is set to be wedge-shaped through PC1, and the side with greater thickness in the width direction of the strip steel is pressed in by 0.001-0.002 mm than the side with smaller thickness, in order to reduce the transverse thickness difference, the first rolling mill adopts non-uniform deformation, and the side with greater thickness is pressed down relatively more; after the strip steel passes through the first rolling mill, the side with greater thickness will appear a wave shape, and after the strip steel passes through the straightening roller in front of the second rolling mill, the wave shape is improved and suppressed under the action of the inter-stand tension and the straightening roller, and the strip steel smoothly enters the second rolling mill; the actual roll gap shape of the second rolling mill is set to be wedge-shaped through PC1, and the side with greater thickness in the width direction of the strip steel is pressed in by 0.001-0.0015 mm than the side with smaller thickness, in order to reduce the transverse thickness difference, the second rolling mill still adopts non-uniform deformation, and the side with greater thickness is pressed down relatively less than the first rolling mill, which is conducive to reducing the degree of wave shape; after the strip steel passes through the second rolling mill, the side with greater thickness will appear a wave shape, and after the strip steel passes through the straightening roller in front of the third rolling mill, the wave shape is improved and suppressed under the action of the inter-stand tension and the straightening roller, and the strip steel smoothly enters the third rolling mill; the third, fourth and fifth rolling mills are responsible for adjusting the single-sided wave shape; (4) for convex-shaped incoming material, the actual roll gap shape of the first rolling mill is set to be concave-shaped through PC1, and the middle part with greater thickness in the width direction of the strip steel is pressed in by 0.001-0.002 mm than the two sides with smaller thickness, in order to reduce the transverse thickness difference, the first rolling mill adopts non-uniform deformation, and the middle part with greater thickness is pressed down relatively more; after the strip steel passes through the first rolling mill, the middle part with greater thickness will appear a wave shape, and after the strip steel passes through the straightening roller in front of the second rolling mill, the wave shape is improved and suppressed under the action of the inter-stand tension and the straightening roller, and the strip steel smoothly enters the second rolling mill; the actual roll gap shape of the second rolling mill is set to be concave-shaped through PC1, and the middle part with greater thickness in the width direction of the strip steel is pressed in by 0.001-0.0015 mm than the two sides with smaller thickness; in order to reduce the transverse thickness difference, the second rolling mill still adopts non-uniform deformation, and the middle part with greater thickness is pressed down relatively less than the first rolling mill, which is conducive to reducing the degree of wave shape; after the strip steel passes through the second rolling mill, the middle part with greater thickness will appear a wave shape, and after the strip steel passes through the straightening roller in front of the third rolling mill, the wave shape is improved and suppressed under the action of the inter-stand tension and the straightening roller, and the strip steel smoothly enters the third rolling mill; the third, fourth and fifth rolling mills are responsible for adjusting the double-sided wave shape.

[0026] Preferably, in step six, (1) the plate shape meter at the outlet of the second rolling mill feeds forward the third and fourth rolling mills according to the detected wave shape and degree; (2) according to the total adjustment amount calculated by the computer PC2, the third rolling mill is responsible for 2 / 3 of the total adjustment amount, and the fourth rolling mill is responsible for 1 / 3 of the total adjustment amount; (3) for single-side wave shape, the second and third rolling mills adjust through the inclination value of the rolling mill, and the adjustment direction is that the roll gap of the side with larger thickness of the strip steel is larger; (4) for double-side wave shape, the second and third rolling mills adjust through the bending roll force and the intermediate roll shifting, and the adjustment direction is that the roll gap of the middle part of the rolling mill is larger; (5) the plate shape meter at the outlet of the fifth rolling mill feeds back the fifth rolling mill according to the detected wave shape and degree; (6) according to the total adjustment amount calculated by the computer PC3, the fifth rolling mill is responsible for 100% of the total adjustment amount of the plate shape at the outlet of the fifth rolling mill; (7) for single-side wave shape, the fifth rolling mill adjusts through the inclination value of the rolling mill, and the adjustment direction is that the roll gap of the side with larger thickness of the strip steel is larger; (8) for double-side wave shape, the fifth rolling mill adjusts through the bending roll force and the intermediate roll shifting, and the adjustment direction is that the roll gap of the middle part of the rolling mill is larger; (9) for the rib wave shape in the width direction of the strip steel, the fifth rolling mill adjusts through the emulsion to cool the rib of the working roll body of the fifth rolling mill.

[0027] Compared with the prior art, the present application has the following advantages:

[0028] The present application provides guarantee for the feedforward control of reducing the transverse thickness difference by detecting the transverse thickness difference of the incoming material through the crown meter before the first rolling mill; the transverse thickness difference is reduced by the first and second rolling mills through small-amplitude gradual non-uniform extension when the plasticity of the rolled piece is large, and the target of reducing the transverse thickness difference of the cold-rolled strip steel and obtaining good plate shape is achieved in combination with the plate shape adjustment starting from the third rolling mill; the prior art generally only sets one plate shape meter at the outlet of the fifth rolling mill, and only implements feedback control on the fifth rolling mill, so the plate shape control ability is weak and time-lagged; the first plate shape meter is set at the outlet of the second rolling mill, which provides guarantee for the feedforward control of the third and fourth rolling mills on the plate shape; the third and fourth rolling mills in the intermediate section of the cold continuous rolling mill control the plate shape when the hardening degree of the rolled piece is not very high, so the plate shape adjustment ability is improved; the straightening roll is set at the inlet of the second and third rolling mills, which provides reliable guarantee for the non-uniform extension of the first and second rolling mills to reduce the transverse thickness difference and the smooth entry of the rolled piece into the second and third rolling mills; the transverse thickness difference of the cold-rolled strip steel is reduced to 5-7 μm, and good plate shape is obtained. BRIEF DESCRIPTION OF DRAWINGS

[0029] Figure 1 The rolling mill distribution diagram of the present application;

[0030] Figure 2 The plate shape transverse thickness difference diagram of the present application;

[0031] Figure 3 The flow chart of the present application. DETAILED DESCRIPTION

[0032] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work fall within the scope of protection of the present application.

[0033] In the description of the present application, it should be noted that the terms "upper", "lower", "inner", "outer", "front end", "rear end", "two ends", "one end", "the other end" and the like indicate the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the present application. In addition, the terms "first", "second" are only for descriptive purposes and cannot be understood as indicating or implying relative importance.

[0034] In the description of the present application, it should be noted that unless otherwise explicitly specified and limited, the terms "mounting", "provided with", "connection" and the like should be broadly understood, for example, "connection" can be fixed connection, can also be detachable connection, or integrally connected; can be mechanical connection, can also be electrical connection; can be directly connected, can also be indirectly connected through an intermediate medium, can be the communication inside two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0035] Please refer to Figures 1-3 The present application provides an embodiment:

[0036] Embodiment 1

[0037] To achieve the above object, the present application provides the following technical scheme: a cold rolling method for reducing the transverse thickness difference and improving the plate shape, comprising the following steps: step one, detecting the transverse thickness difference of the raw material; step two, detecting the cold rolling plate shape; step three, increasing the reduction rate to increase the elongation coefficient; step four, reducing the rolling pressure by each pass; step five, reducing the transverse thickness difference by the first two passes; step six, improving the plate shape by the last three passes.

[0038] In the above step one, the roll gap shape of the rolling mill is set according to the transverse thickness difference of the hot rolling material detected by the crown meter to reduce the cold rolling transverse thickness difference, and the transverse thickness difference of the incoming material is detected by the crown meter before the first rolling mill to provide a guarantee for the feedforward control before the transverse thickness difference is reduced.

[0039] In the above step two, according to the detection of the cold rolling process or the exit strip shape by the strip shape meter, the roll gap shape is adjusted to obtain a good strip shape, and the first and second stands are used to implement small amplitude gradual reduction non-uniform elongation to reduce the transverse thickness difference when the plasticity of the rolled piece is large, and the strip shape is adjusted from the third stand, so that the target of obtaining a good strip shape while reducing the transverse thickness difference of the cold rolled strip is achieved;

[0040] In the above step three, the reduction is the percentage of the pre-rolling thickness minus the post-rolling thickness, and the ratio of the pre-rolling thickness, and the elongation coefficient is the ratio of the pre-rolling thickness and the post-rolling thickness. According to the formula: reduction ε = (H - h) ÷ H × 100%. ε - reduction; H - pre-rolling thickness; h - post-rolling thickness; elongation coefficient λ = H ÷ h. λ - elongation coefficient; H - pre-rolling thickness; h - post-rolling thickness; under uniform elongation conditions: λ = H ÷ h = ΔH ÷ Δh. ΔH - transverse thickness difference before cold rolling; Δh - transverse thickness difference after cold rolling; it is obtained that Δh = ΔH ÷ λ and λ = 1 ÷ (1 - ε), that is, the larger the reduction ε is, the larger the elongation coefficient λ is, and the smaller the post-rolling transverse difference Δh is; that is, by increasing the reduction to improve the elongation coefficient, the transverse thickness difference of the cold rolled strip can be reduced, and the first strip shape meter is arranged at the exit of the second stand, which provides a guarantee for the feedforward control of the strip shape by the third and fourth stands;

[0041] In the above step four, under the principle of uniform deformation, if the transverse thickness difference Δh of the next pass is less than the transverse thickness difference ΔH of the previous pass, the roll deflection of the next pass must be less than that of the previous pass, which requires that the rolling pressure be gradually reduced to gradually reduce the elastic bending deformation of the rolls; under the condition that the roll stiffness is the same: ΔH - Δh = (Pfront - Pback) ÷ K or Δh = ΔH - (Pfront - Pback) ÷ K; Pfront - rolling force of the previous pass; Pback - rolling force of the next pass; K - roll stiffness coefficient N / mm; according to the above formula, the rolling force of the next pass is less than that of the previous pass, which is a necessary condition for obtaining a good strip shape and reducing the transverse cold rolling thickness difference, and the third and fourth stands of the intermediate section of the cold continuous rolling mill are used to control the strip shape when the hardening degree of the rolled piece is not very high, which improves the strip shape adjustment capability;

[0042] In the above step five, for any transverse thickness difference of the hot rolled material, the transverse thickness difference can only be reduced by cold rolling, but cannot be completely eliminated, and a large reduction in the transverse thickness difference will result in serious wave shape and produce unqualified products, and even cause the strip to break, leading to the failure of rolling. The first and second stands of the five-stand cold continuous rolling mill are used to implement non-uniform elongation when the plasticity of the rolled piece is high, so that the reduction amount is relatively large at the places where the strip thickness in the width direction is large, and the transverse thickness difference is reduced in a small amplitude, and straightening rolls are arranged at the entrances of the second and third stands, which provide reliable guarantee for the non-uniform elongation of the first and second stands to reduce the transverse thickness difference and the smooth entry of the rolled piece into the second and third stands.

[0043] In the above step six, after the first two rolling mills adopt the non-uniform extension method, the first rolling mill and the second rolling mill outlet will appear waves. For the waves of the second rolling mill outlet, the third and fourth rolling mills adopt the uniform extension method to adjust the strip shape when the hardening degree of the rolled piece is not very high, and then the fifth rolling mill adopts the uniform extension method to make micro-adjustment to the strip shape, so as to reduce the transverse thickness difference of the cold-rolled strip to 5-7 μm and obtain good strip shape.

[0044] Example 2

[0045] Step one, detect the transverse thickness difference of the raw material, arrange a crown meter in front of the first rolling mill, according to the incoming material thickness difference detected by the crown meter, feed forward control the inclination, bending force and axial movement position of the intermediate roller of the first and second rolling mills, Figure 1 : 1- inclination control of the first and second rolling mills; 2- roll shifting and bending control of the upper intermediate roller of the first and second rolling mills; 3- bending control of the upper work roller of the first and second rolling mills; 4- bending control of the lower work roller of the first and second rolling mills; 5- roll shifting and bending control of the lower intermediate roller of the first and second rolling mills, the roll shifting of the intermediate roller is to offset the harmful torque that the support roller transmits to the work roller to cause bending deformation;

[0046] Step two, detect the cold-rolled strip shape, two strip shape meters, the first strip shape meter is arranged at the outlet of the second rolling mill, according to the outlet strip shape of the second rolling mill detected by the first strip shape meter, feed forward control the third and fourth rolling mills, including inclination control of the upper support roller; roll shifting and bending control of the intermediate roller; bending control of the work roller; the second strip shape meter is arranged at the outlet of the fifth rolling mill, and feedback control is performed on the fifth rolling mill, including inclination control of the upper support roller; roll shifting and bending control of the intermediate roller; bending control of the work roller; segmented cooling control of the work roller, 6- segmented cooling control of the upper work roller; 7- segmented cooling control of the lower work roller. The segmented cooling is to improve the rib wave shape of the strip, according to the position where the rib wave shape is generated, the emulsion is sprayed to the corresponding position of the work roller to reduce the local thermal crown of the work roller;

[0047] Step three, increase the reduction rate to increase the extension coefficient, the total reduction rate is the percentage of the thickness of the hot-rolled incoming material minus the thickness of the strip after being rolled by the fifth rolling mill, and then compared with the thickness of the hot-rolled incoming material; according to the formula Δh = ΔH ÷ λ and λ = 1 ÷ (1 - ε), the greater the reduction rate ε, the greater the extension coefficient λ, and the smaller the transverse thickness difference Δh after rolling. In the case of constant rolling thickness, the total reduction rate is increased by increasing the incoming material thickness; the following takes the incoming material transverse thickness difference of 0.02 mm and the rolling thickness of 1.0 mm as an example:

[0048] When H=2.5mm, reduction ε=60%, elongation coefficient λ=2.5, and the difference in the transverse direction after cold rolling Δh=0.008mm;

[0049] When H=2.5mm, reduction ε=60%, elongation coefficient λ=2.5, and the difference in the transverse direction after cold rolling Δh=0.008mm;

[0050] When H=2.5mm, reduction ε=60%, elongation coefficient λ=2.5, and the difference in the transverse direction after cold rolling Δh=0.008mm;

[0051] When H=2.5mm, reduction ε=60%, elongation coefficient λ=2.5, and the difference in the transverse direction after cold rolling Δh=0.008mm;

[0052] When H=2.5mm, reduction ε=60%, elongation coefficient λ=2.5, and the difference in the transverse direction after cold rolling Δh=0.008mm;

[0053] When H=2.5mm, reduction ε=60%, elongation coefficient λ=2.5, and the difference in the transverse direction after cold rolling Δh=0.008mm;

[0054] When H=2.5mm, reduction ε=60%, elongation coefficient λ=2.5, and the difference in the transverse direction after cold rolling Δh=0.008mm;

[0055] When H=2.5mm, reduction ε=60%, elongation coefficient λ=2.5, and the difference in the transverse direction after cold rolling Δh=0.008mm;

[0056] From the above example, it can be seen that the total reduction is increased by 5%, and the transverse thickness difference after cold rolling is reduced by 0.001mm (1μm); in fact, by increasing the reduction, the transverse thickness difference after cold rolling cannot be reduced to the expected value; when the reduction is 80%, the transverse thickness difference after cold rolling can only be reduced to 0.009-0.01, because in the actual rolling process, the width of the strip is not completely uniformly stretched, or the thickness of the original large place is stretched small, or the thickness of the original small place is stretched large, resulting in H2-h2 increasing, and the transverse thickness difference Δh after cold rolling is reduced to the expected value; the thickness difference before rolling ΔH=H1-h1; the thickness difference after rolling Δh=H2-h2; λ=(H1-h1)÷(H2-h2); therefore, increasing the total reduction of cold rolling can reduce the thickness difference of cold rolling to a certain extent, but it cannot be completely reduced in proportion to the elongation coefficient, and simply reducing the transverse thickness difference after cold rolling by increasing the total reduction of cold rolling is not enough.

[0057] Step four, reduce the rolling pressure by each stand; the rolling pressure of the second stand is 11% lower than that of the first stand; the rolling pressure of the third stand is 11% lower than that of the second stand; the rolling pressure of the fourth stand is 12% lower than that of the third stand; the rolling pressure of the fifth stand is 20% lower than that of the fourth stand; if the rolling force of the first stand is 90000KN, then the rolling force of the second stand is 80100KN, the rolling force of the third stand is 71289KN, the rolling force of the fourth stand is 62734KN, and the rolling force of the fifth stand is 56467KN. According to the formula ΔH-Δh=(Pfront-Pback)÷K and Δh=ΔH-(Pfront-Pback)÷K, the rolling force of the continuous rolling is reduced by each stand, which not only enhances the uniform extension, but also provides a guarantee for reducing the transverse thickness difference.

[0058] Step five, small amplitude reduction of transverse thickness difference through the first two passes, (1) add straightening roll at the entrance of the second mill, diameter 150mm, during rolling, the strip is pressed down by 5mm, the effect is to straighten and suppress the wave shape of the strip at the exit of the first mill, so that the second mill bites into the rolled piece smoothly; (2) add straightening roll at the entrance of the third mill, diameter 150mm, during rolling, the strip is pressed down by 5mm, the effect is to straighten and suppress the wave shape of the strip at the exit of the second mill, so that the third mill bites into the rolled piece smoothly; (3) for wedge-shaped incoming material, through PC1, the actual roll gap shape of the first mill is set to be wedge-shaped, the side with larger thickness in the width direction of the strip is pressed in by 0.001-0.002mm than the side with smaller thickness, in order to reduce the transverse thickness difference, the first mill adopts non-uniform deformation, the side with larger thickness is pressed down relatively more; after the strip passes through the first mill, the side with larger thickness will appear wave shape, after the strip passes through the straightening roll in front of the second mill, under the action of interstand tension and straightening roll, the wave shape is improved and suppressed and smoothly enters the second mill; through PC1, the actual roll gap shape of the second mill is set to be wedge-shaped, the side with larger thickness in the width direction of the strip is pressed in by 0.001-0.0015mm than the side with smaller thickness, in order to reduce the transverse thickness difference, the second mill still adopts non-uniform deformation, the side with larger thickness is pressed down relatively less than the first mill, which is conducive to reducing the degree of wave shape; after the strip passes through the second mill, the side with larger thickness will appear wave shape, after the strip passes through the straightening roll in front of the third mill, under the action of interstand tension and straightening roll, the wave shape is improved and suppressed and smoothly enters the third mill; the third, fourth and fifth mills are responsible for adjusting single-sided wave shape; (4) for convex-shaped incoming material, through PC1, the actual roll gap shape of the first mill is set to be concave-shaped, the middle part with larger thickness in the width direction of the strip is pressed in by 0.001-0.002mm than the two sides with smaller thickness, in order to reduce the transverse thickness difference, the first mill adopts non-uniform deformation, the middle part with larger thickness is pressed down relatively more; after the strip passes through the first mill, the middle part with larger thickness will appear wave shape, after the strip passes through the straightening roll in front of the second mill, under the action of interstand tension and straightening roll, the wave shape is improved and suppressed and smoothly enters the second mill; through PC1, the actual roll gap shape of the second mill is set to be concave-shaped, the middle part with larger thickness in the width direction of the strip is pressed in by 0.001-0.0015mm than the two sides with smaller thickness; in order to reduce the transverse thickness difference, the second mill still adopts non-uniform deformation, the middle part with larger thickness is pressed down relatively less than the first mill, which is conducive to reducing the degree of wave shape; after the strip passes through the second mill, the middle part with larger thickness will appear wave shape, after the strip passes through the straightening roll in front of the third mill, under the action of interstand tension and straightening roll, the wave shape is improved and suppressed and smoothly enters the third mill; the third, fourth and fifth mills are responsible for adjusting double-sided wave shape.

[0059] Step six, improve the shape of the plate by the last three passes, (1) the shape of the plate instrument at the exit of the second mill according to the detected wave shape and degree, feedforward control of the third and fourth mill; (2) according to the total adjustment amount calculated by the computer PC2, the third mill is responsible for 2 / 3 of the total adjustment amount; the fourth mill is responsible for 1 / 3 of the total adjustment amount; (3) for single-sided wave shape, the second and third mills adjust through the inclination value of the mill, and the adjustment direction is that the roll gap of the side with larger thickness of the strip steel is larger; (4) for double-sided wave shape, the second and third mills adjust through the bending roll force and the intermediate roll shifting, and the adjustment direction is that the roll gap of the middle part of the roll is larger; (5) the shape of the plate instrument at the exit of the fifth mill according to the detected wave shape and degree, feedback control of the fifth mill; (6) according to the total adjustment amount calculated by the computer PC3, the fifth mill is responsible for 100% of the total adjustment amount of the plate shape at the exit of the fifth mill; (7) for single-sided wave shape, the fifth mill adjusts through the inclination value of the mill, and the adjustment direction is that the roll gap of the side with larger thickness of the strip steel is larger; (8) for double-sided wave shape, the fifth mill adjusts through the bending roll force and the intermediate roll shifting, and the adjustment direction is that the roll gap of the middle part of the roll is larger; (9) for the rib wave shape in the width direction of the strip steel, the fifth mill adjusts through the emulsion cooling rib of the working roll body of the fifth mill.

[0060] The parts not described in the present application are the known technology of those skilled in the art.

[0061] Finally, it should be pointed out that the above specific embodiments are only used to illustrate the technical solutions of the present application and are not limiting. Although the present application has been described in detail with reference to the embodiments, those skilled in the art should understand that the technical solutions of the present application can be modified and replaced equivalently without departing from the spirit and scope of the technical solutions of the present application, and they should be covered in the scope of the claims of the present application.

Claims

1. A cold rolling method for reducing the transverse thickness difference and improving the shape of the plate, comprising the steps of: step one, detecting the transverse thickness difference of the raw material; step two, detecting the shape of the cold rolled plate; step three, increasing the reduction rate to increase the elongation coefficient; step four, reducing the rolling pressure by rack; step five, reducing the transverse thickness difference by the first two passes; step six, improving the shape of the plate by the last three passes; characterized in that: in the above step one, the roll gap shape of the rolling mill is set according to the transverse thickness difference of the hot rolled material detected by the crown meter to reduce the transverse thickness difference of the cold rolled plate; in the above step two, the roll gap shape is adjusted according to the shape of the cold rolling process or the outlet plate shape detected by the shape meter to obtain a good plate shape; in the above step three, the reduction rate is the percentage of the difference between the pre-rolling thickness and the post-rolling thickness compared to the pre-rolling thickness, and the elongation coefficient is the ratio of the pre-rolling thickness to the post-rolling thickness, according to the formula: reduction rate ε = (H - h) ÷ H × 100%, ε - reduction rate; H - pre-rolling thickness; h - post-rolling thickness; elongation coefficient λ = H ÷ h, λ - elongation coefficient; H - pre-rolling thickness; h - post-rolling thickness; under the condition of uniform elongation: λ = H ÷ h = ΔH ÷ Δh, ΔH - transverse thickness difference before cold rolling; Δh - transverse thickness difference after cold rolling; Δh = ΔH ÷ λ and λ = 1 ÷ (1 - ε) are obtained, that is, the greater the reduction rate ε, the greater the elongation coefficient λ, and the smaller the transverse thickness difference Δh after rolling; that is, by increasing the reduction rate to increase the elongation coefficient, the transverse thickness difference of the cold rolled strip is reduced; in the above step four, under the principle of uniform deformation, if the transverse thickness difference Δh of the next pass is less than the transverse thickness difference ΔH of the previous pass, the deflection of the rolling roller of the next pass must be less than that of the previous pass, which requires reducing the rolling pressure by rack to reduce the elastic bending deformation of the rolling roller by rack; under the condition of the same rolling stiffness: ΔH - Δh = (Pfront - Pback) ÷ K or Δh = ΔH - (Pfront - Pback) ÷ K; Pfront is the rolling force of the previous pass; Pback is the rolling force of the next pass, K is the rolling stiffness coefficient N / mm; in the above step five, the first two passes of the five-pass cold continuous rolling mill adopt the method of non-uniform elongation when the plasticity of the rolled piece is high; in the above step six, after the first two passes of the rolling mill adopt the method of non-uniform elongation, the first pass and the second pass outlet will appear wave shape, for the wave shape of the second pass outlet, the third and fourth passes of the rolling mill adopt the method of uniform elongation to adjust the shape of the strip when the hardening degree of the rolled piece is not very high, and then the fifth pass adopts the method of uniform elongation to adjust the shape of the strip. In the above step one, a crown meter is arranged in front of the first pass rolling mill, and the inclination, bending force and axial movement position of the intermediate roller of the first and second passes are controlled by feedforward control according to the thickness difference of the incoming material detected by the crown meter. In the above step two, two shape meters are arranged, The first shape meter is arranged at the outlet of the second pass rolling mill, and the inclination control of the upper support roller, the roll shifting and bending control of the intermediate roller, and the bending control of the work roller of the third and fourth passes are controlled by feedforward control according to the outlet shape of the second pass detected by the first shape meter. ​ ​ ​ 2. A cold rolling method for reducing the transverse thickness difference and improving the sheet shape according to claim 1, characterized in that: ​ 3. A cold rolling method for reducing the cross-thickness difference and improving the sheet shape according to claim 1, characterized in that: ​ ​ The second plate-shaped instrument is arranged at the outlet of the fifth rolling mill, and is used for feedback control of the fifth rolling mill, including inclination control of the upper supporting roller, roll shifting and bending control of the intermediate roller, bending control of the working roller, and segmented cooling control of the working roller.

4. A cold rolling method for reducing the cross-thickness difference and improving the sheet shape according to claim 1, characterized in that: In step three, the total reduction ratio is the percentage of the ratio of the thickness of the hot-rolled material to the thickness of the strip after being rolled by the fifth rolling mill; according to the formula Δh=ΔH÷λ and λ=1÷(1-ε), the greater the reduction ratio ε, the greater the elongation coefficient λ, and the smaller the transverse thickness difference Δh after rolling; in the case of constant rolling thickness, the total reduction ratio is increased by increasing the thickness of the material.

5. A cold rolling method for reducing the cross-thickness difference and improving the sheet shape according to claim 1, characterized in that: In step four, the rolling pressure of the second rolling mill is 11% lower than that of the first rolling mill; the rolling pressure of the third rolling mill is 11% lower than that of the second rolling mill; the rolling pressure of the fourth rolling mill is 12% lower than that of the third rolling mill; and the rolling pressure of the fifth rolling mill is 20% lower than that of the fourth rolling mill, according to the formula ΔH-Δh=(Pfront-Pback)÷K and Δh=ΔH-(Pfront-Pback)÷K.

6. A cold rolling method for reducing the cross-thickness difference and improving the sheet shape according to claim 1, characterized in that: In the step five, (1), a straightening roller with a diameter of 150 mm is added at the entrance of the second rolling mill, and the strip steel is pressed down by 5 mm during rolling, which is used to straighten and suppress the wave shape of the strip steel at the exit of the first rolling mill, so that the second rolling mill can smoothly bite into the rolling piece; (2), a straightening roller with a diameter of 150 mm is added at the entrance of the third rolling mill, and the strip steel is pressed down by 5 mm during rolling, which is used to straighten and suppress the wave shape of the strip steel at the exit of the second rolling mill, so that the third rolling mill can smoothly bite into the rolling piece; (3), for the wedge-shaped incoming material, the actual roll gap shape of the first rolling mill is set to be wedge-shaped through the computer PC1, and the side with larger thickness in the width direction of the strip steel is pressed in by 0.001-0.002 mm than the side with smaller thickness, in order to reduce the transverse thickness difference, the first rolling mill adopts non-uniform deformation, and the side with larger thickness is pressed down relatively more; after the strip steel passes through the first rolling mill, the side with larger thickness will appear wave shape, and after the strip steel passes through the straightening roller in front of the second rolling mill, the wave shape is improved and suppressed under the action of the inter-stand tension and the straightening roller, and the strip steel smoothly enters the second rolling mill; the actual roll gap shape of the second rolling mill is set to be wedge-shaped through the computer PC1, and the side with larger thickness in the width direction of the strip steel is pressed in by 0.001-0.0015 mm than the side with smaller thickness, in order to reduce the transverse thickness difference, the second rolling mill still adopts non-uniform deformation, and the side with larger thickness is pressed down relatively less than the first rolling mill, which is conducive to reducing the degree of wave shape; after the strip steel passes through the second rolling mill, the side with larger thickness will appear wave shape, and after the strip steel passes through the straightening roller in front of the third rolling mill, the wave shape is improved and suppressed under the action of the inter-stand tension and the straightening roller, and the strip steel smoothly enters the third rolling mill; the third, fourth and fifth rolling mills are responsible for adjusting the single-sided wave shape; (4), for the convex-shaped incoming material, the actual roll gap shape of the first rolling mill is set to be concave-shaped through the controller, and the middle part with larger thickness in the width direction of the strip steel is pressed in by 0.001-0.002 mm than the two sides with smaller thickness, in order to reduce the transverse thickness difference, the first rolling mill adopts non-uniform deformation, and the middle part with larger thickness is pressed down relatively more; after the strip steel passes through the first rolling mill, the middle part with larger thickness will appear wave shape, and after the strip steel passes through the straightening roller in front of the second rolling mill, the wave shape is improved and suppressed under the action of the inter-stand tension and the straightening roller, and the strip steel smoothly enters the second rolling mill; the actual roll gap shape of the second rolling mill is set to be concave-shaped through the computer PC1, and the middle part with larger thickness in the width direction of the strip steel is pressed in by 0.001-0.0015 mm than the two sides with smaller thickness; in order to reduce the transverse thickness difference, the second rolling mill still adopts non-uniform deformation, and the middle part with larger thickness is pressed down relatively less than the first rolling mill, which is conducive to reducing the degree of wave shape; after the strip steel passes through the second rolling mill, the middle part with larger thickness will appear wave shape, and after the strip steel passes through the straightening roller in front of the third rolling mill, the wave shape is improved and suppressed under the action of the inter-stand tension and the straightening roller, and the strip steel smoothly enters the third rolling mill; the third, fourth and fifth rolling mills are responsible for adjusting the double-sided wave shape.

7. A cold rolling method for reducing the cross-thickness difference and improving the sheet shape according to claim 6, characterized in that: In step six, (1) the plate shape meter at the exit of the second rolling mill feeds forward the third and fourth rolling mills according to the detected wave shape and degree; (2) according to the total adjustment amount calculated by the computer PC2, the third rolling mill is responsible for 2 / 3 of the total adjustment amount, and the fourth rolling mill is responsible for 1 / 3 of the total adjustment amount; (3) for single-side wave shape, the second and third rolling mills are adjusted by the inclination value of the rolling mill; (4) for double-side wave shape, the second and third rolling mills are adjusted by the bending force of the rolling mill and the shifting of the intermediate roller; (5) the plate shape meter at the exit of the fifth rolling mill feeds back the fifth rolling mill according to the detected wave shape and degree; (6) according to the total adjustment amount calculated by the computer PC3, the fifth rolling mill is responsible for 100% of the total adjustment amount of the plate shape at the exit of the fifth rolling mill; (7) for single-side wave shape, the fifth rolling mill is adjusted by the inclination value of the rolling mill; (8) for double-side wave shape, the fifth rolling mill is adjusted by the bending force of the rolling mill and the shifting of the intermediate roller; (9) for rib wave shape in the width direction of the strip, the fifth rolling mill adjusts the ribs of the working roller body of the fifth rolling mill by emulsion cooling.

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