Method for increasing same-plate difference by rolling silicon steel through CVC roller

Abstract

The invention discloses a method for increasing the same-plate difference by rolling silicon steel through a CVC roller, and belongs to the technical field of steel rolling processes. The method is mainly characterized in that on the basis of the original CVC roll shape, the roll shape and the convexity adjustment range of a hot rolling roll and a cold rolling roll are optimized, a segmented cooling control mode is adopted for the roll, a tension adjusting roll is additionally arranged in front of a cold rolling coiler to conduct tension compensation on strip steel, and the same-plate difference of the strip steel is smaller than or equal to 5 micrometers and can reach 86% or above by adopting the measures.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of steel rolling process, and particularly relates to a method for improving the same-plate difference of silicon steel rolled by a CVC roll. BACKGROUND

[0002] In recent years, silicon steel products have gradually matured, and the manufacturing end of products such as motors and transformers has reached a completely automatic level, and the uniformity of the thickness of the whole roll of raw material silicon steel, that is, the same-plate difference, is particularly strict. The whole roll same-plate difference (including the horizontal and vertical same-plate difference) is required to be less than or equal to 5 microns, and more stringent users require it to be less than or equal to 3 microns. The control level of the silicon steel same-plate difference of domestic major steel plants is uneven. Single-stand production of silicon steel is adopted for cold rolling, or the Mitsubishi UCMM model is adopted for continuous rolling mills, and the same-plate difference control is better. However, the same-plate difference control level of the CVC model rolling mill is poor, and the average value reaches 8 microns to 12 microns, which affects the grade and market share of the product.

[0003] The same-plate difference of silicon steel products is inversely proportional to the edge cutting amount, and the larger the edge cutting amount, the better the same-plate difference. However, the amount of edge cutting directly affects the yield, that is, the manufacturing cost, so under the premise of meeting the same-plate difference requirements of users, the use of the minimum edge cutting amount is the most economical approach. Due to the form of the rack, the elastic flattening deformation of the roll on both sides of the traditional CVC roll shape rolling mill is greater than the middle part, which leads to a 25 mm to 40 mm reduction of the edge part of the strip steel by 40 microns to 50 microns. The economic mode of the minimum edge cutting amount of one-time edge cutting cannot completely remove the edge thinning area, and the edge thinning is the main factor leading to the large same-plate difference of the silicon steel finished product. Therefore, based on the existing CVC roll shape, the roll shape curve corresponding to the strip thinning area is changed to compensate for the thinning amount, so as to achieve the purpose of improving the same-plate difference.

[0004] Chinese patent application No. CN 115815340 A discloses a method for improving the same-plate difference of silicon steel. The patent only gives the roll shape insertion amount of the work roll and the intermediate roll shifting value, and does not point out the specific roll shape and how to apply it to high-order roll shapes or multi-segment line roll shapes, while the roll shape is an important factor in the field production. The present patent gives a specific optimization scheme for the CVC roll shape, which has guiding significance for field production.

[0005] Chinese patent application No. CN 113351652 A discloses a method and device for controlling the horizontal same-plate difference of cold-rolled silicon steel. The influencing factors of the horizontal same-plate difference of the cold-rolled steel plate include the thermal crown of the roll and the symmetry of the finished edge cutting amount, which will affect the same-plate difference. The present patent considers the above influencing factors and contains a method for improving the vertical same-plate difference of the strip steel. SUMMARY

[0006] The application aims to provide a method for improving the same-plate difference of CVC roll-rolled silicon steel, which optimizes the roll shape and crown adjustment range of the roll on the basis of the original CVC roll shape, adopts the control mode of segmented cooling for the roll, and additionally sets a tension adjustment roll before the cold rolling coiler to compensate the tension of the strip.

[0007] To solve the above technical problems, the application adopts the following technical scheme:

[0008] The application is a method for improving the same-plate difference of CVC roll-rolled silicon steel, which comprises the following steps.

[0009] 1) The CVC roll shapes of the work rolls and the backup rolls of the first and second stands before hot rolling are respectively optimized, the CVC roll shapes of the work rolls and the backup rolls are both 10th power, the stress distribution state of the roll is changed, the wear of the local part of the roll caused by stress concentration is reduced, and thus the cross-sectional profile of the raw steel coil is improved.

[0010] 2) The taper is set at the two ends of the work rolls of the first and second stands before cold rolling, the taper height and length value are determined according to the edge thinning position and thickness of the hot-rolled raw material, and the edge thinning amount of the strip is compensated through the distribution of the two stands.

[0011] 3) The crown adjustment range of the rolling mill is optimized, the roll gap equivalent adjustment range of the roll shape is set as [-0.30mm, 1.0mm], the crown of the hot-rolled plate and the wedge value are controlled to be greater than or equal to 2, the target crown is 25μm-30μm, and the wedge value is controlled to be within ±12μm.

[0012] 4) The wear of the offline hot-rolling roll and the measured offline roll temperature are checked, the thermal expansion coefficient is checked, the cooling mode of the roll cooling nozzle is controlled by the water amount, the crown value is fed back according to the plate shape instrument, the cooling intensity of each nozzle corresponding position is controlled in real time, the roll produces appropriate temperature distribution along the width direction of the plate strip, and thus the reasonable platform-shaped thermal crown is formed.

[0013] 5) The heating temperature difference of the slab whole coil is less than or equal to 20℃, the rigidity of each stand rolling mill is kept greater than or equal to 80%, the thickness difference of the hot-rolled whole coil is less than or equal to 0.03mm, and the hardness value deviation of the whole coil is less than 5%.

[0014] 6) The roll of the last stand of the cold continuous rolling adopts the partition cooling, and the working roll temperature difference is less than or equal to 3℃ through the PID control of the cooling liquid flow.

[0015] 7) The micro-tension adjustment roll is additionally set before the cold rolling coiler to compensate the tension of the strip, and the transverse stress difference of the strip is less than or equal to 15MPa.

[0016] Further, the taper height of the two ends of the roll ranges from 20μm to 50μm, and the taper length ranges from 60mm to 120mm.

[0017] Further, the hot rolling raw material width is 1260mm, and the finished product width is 1200mm.

[0018] Further, the S1 and S2 cold rolling rack working rolls are provided with taper at both ends, the S1 and S2 taper heights are 35μm and 25μm respectively, and the taper lengths are 120mm and 100mm respectively.

[0019] Further, the S5 rolling roll of the cold continuous rolling final rack is cooled in 11 areas.

[0020] Further, the strip steel same plate difference is less than 5μm through the method.

[0021] Further, the same plate difference can reach 90% through the method.

[0022] Compared with the prior art, the beneficial technical effects of the present application are:

[0023] Through optimizing the hot rolling roll curve, the stress distribution between the rolls is more uniform, the strip steel cross section profile is improved, the appropriate roll gap equivalent adjustment domain is set, and the crown control is more efficient; through the cooling mode of the roll cooling nozzle controlling the water amount by roll, the strip steel edge thinning caused by the excessive roll thermal crown in the edge thinning area is avoided; the above technical scheme can obtain the hot rolling raw material roll with ideal crown and smooth cross section without local high points. The control of the hot coil crown and the wedge ratio is greater than or equal to 2, the target crown is 25μm-30μm, and the wedge value is controlled within ±12μm, so as to prevent the rib (convex rib) defect caused by unreasonable control of the crown wedge ratio when rolling 0.3mm-0.5mm thin specification silicon steel products.

[0024] By setting appropriate taper at both ends of the cold rolling roll, the edge reduction of the hot rolling raw material roll is compensated, so as to achieve the target of the finished steel coil transverse same plate difference; by controlling the whole roll thickness difference and hardness deviation of the hot rolling raw material roll, the longitudinal same plate difference of the finished steel coil is guaranteed to reach the target requirement. Through the above technical scheme, the strip steel same plate difference of less than 5μm is increased from less than 50% before implementation to more than 86% after implementation. BRIEF DESCRIPTION OF DRAWINGS

[0025] The present application will be further described below in combination with the description of the drawings.

[0026] Figure 1 is the original 3rd power roll shape and 10th power roll curve;

[0027] Figure 2 is the off-line roll wear condition;

[0028] Figure 3 is the off-line roll temperature;

[0029] Figure 4 is the setting diagram of the taper setting at both ends of the cold rolling S1 and S2 rack working rolls. DETAILED DESCRIPTION

[0030] The application will be further described in connection with specific embodiments.

[0031] A method for improving the same-plate difference of a CVC roll-rolling silicon steel, comprising:

[0032] 1. The CVC of the work rolls and backup rolls of hot rolling F1 and F2 racks is a 10th power roll curve, and the formula is as follows:

[0033] Rh(x) = A0 + A1x + A2x2 + A3x3 + A4x4 + A5x5 + A6x6 + A7x7 + A8x8 + A9x9 + A10x10

[0034] The roll shape coefficients and values are as shown in the following table:

[0035]

[0036]

[0037] The original 3rd power roll shape and the 10th power roll curve are as shown in Figure 1 .

[0038] 2. The roll gap equivalent adjustment domain of the hot rolling roll shape is set to [-0.30mm, 1.0mm]; the hot coil plate crown is controlled between 25μm~30μm, the wedge is controlled within ±12μm, and the crown to wedge ratio is ≥2.

[0039] 3. The hot rolling roll wear is checked, and the measured hot rolling roll temperature is checked, as shown in Figure 2 and Figure 3 The thermal expansion coefficient is checked, one pair of roll cooling nozzles is set every 40mm in the roll body length of 2000mm, the nozzle water quantity is controlled by PID control mode, the cooling intensity of each nozzle corresponding position is adjusted according to the crown value fed back by the plate shape instrument.

[0040] 4. The rolling mill rigidity of each rack is kept ≥80% before rolling, the slab whole coil heating temperature difference is ≤20℃, the hot coil whole coil thickness difference is ≤0.03mm, and the whole coil hardness value deviation is <5%.

[0041] 5. The hot rolling raw material width is 1260mm, and the finished product width is 1200mm. The work rolls of cold rolling S1 and S2 racks are set with taper at both ends, the taper heights of S1 and S2 are 35μm and 25μm respectively, and the taper lengths are 120mm and 100mm respectively, as shown in Figure 4 .

[0042] 6. The roll of the last rack S5 of cold continuous rolling adopts 11-zone cooling, and the working roll temperature difference is ≤3℃ by PID control of the cooling liquid flow.

[0043] 7. A micro tension adjusting roller is arranged in front of a cold rolling coiler to compensate the tension of the strip, and the transverse stress difference of the strip is less than or equal to 15 MPa.

[0044] Through the implementation of the above technical scheme, the strip same plate difference is less than or equal to 5 μm, and the strip same plate difference can reach 90%.

[0045] The above-described embodiments are only used to describe the preferred modes of the present application, and are not used to limit the scope of the present application. Without departing from the design spirit of the present application, various modifications and improvements of the technical scheme of the present application made by those skilled in the art shall fall within the protection scope determined by the claims of the present application.

Claims

1. A method for improving the strip difference of CVC rolled silicon steel characterized by, Comprise: 1) Respectively optimize the CVC roll shape curve of the work roll and backup roll of the two stands before hot rolling, the CVC roll shape curve of the work roll and backup roll is 10 times, change the stress distribution state of the roll, reduce the wear caused by stress concentration to the local roll, so as to improve the cross section profile of the raw steel coil; 2) Set the taper at both ends of the work roll of the two stands before cold rolling, the taper height and length value is determined according to the edge thinning position and thickness of the hot rolled raw material, and the edge thinning amount is made up through the distribution of the two stands; 3) Optimize the crown adjustment range of the rolling mill, set the roll gap equivalent adjustment range of the roll shape to [-0.30mm, 1.0mm]; Control the crown and wedge ratio of the hot coil plate ≥2, the target crown is 25μm~30μm, and the wedge value is controlled within ±12μm; 4) Verify the wear of the offline hot rolling roll, measure the temperature of the offline roll, check the thermal expansion coefficient, adopt the cooling mode of the roll cooling nozzle controlling the water quantity of each roll, according to the crown value feedback by the shape meter, control the cooling intensity of each nozzle corresponding position in real time, make the roll produce appropriate temperature distribution along the width direction of the strip, so as to form reasonable platform-shaped hot crown; 5) The heating temperature difference of the slab whole coil is ≤20℃, the rigidity of each stand rolling mill is kept ≥80%, the thickness difference of the hot coil whole coil is ≤0.03mm, and the hardness value deviation of the whole coil is <5%; 6) The last stand roll of the cold continuous rolling adopts partition cooling, and the working roll temperature difference is ≤3℃ through PID control of the cooling liquid flow. 7) A micro tension adjusting roller is additionally arranged in front of the cold rolling coiler to compensate the tension of the strip, and the transverse stress difference of the strip is ≤15MPa.

2. The method of claim 1, wherein the CVC roll rolled silicon steel improves the strip difference, and The taper height of the roll two ends is in the range of 20μm~50μm, and the taper length is in the range of 60mm~120mm.

3. The method of claim 1, wherein the CVC roll rolled silicon steel improves the strip difference, and The width of the hot rolling raw material is 1260mm, and the width of the finished product is 1200mm.

4. The method of claim 3, wherein the CVC roll rolled silicon steel improves the strip difference, and The taper is set at both ends of the work roll of the S1 and S2 stands of the cold rolling, the taper height of S1 and S2 is 35μm and 25μm respectively, and the taper length is 120mm and 100mm respectively.

5. The method of claim 1, wherein the CVC roll rolled silicon steel improves the strip difference, and The S5 roll of the last stand of the cold continuous rolling adopts 11-zone cooling.

6. The method of claim 3, wherein the CVC roll rolled silicon steel improves the strip difference, and Through the method, the strip same plate difference is ≤5μm.

7. The method of claim 3, wherein the CVC roll rolled silicon steel improves the strip difference, and Through the method, the same plate difference can reach 90%.

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