A control method for transverse thickness difference of non-oriented silicon steel for six-high cold continuous rolling mill

Abstract

The application discloses a kind of suitable for six-roller cold continuous rolling mill non-oriented silicon steel transverse thickness difference control method, belong to cold-rolled plate rolling technical field.The method includes: design optimization six-roller cold continuous rolling mill S1-S3 rack's edge drop control work roll new roll shape curve;Build cold continuous rolling mill finite element simulation model and verify;Through finite element model simulation analysis edge drop control work roll shape under the influence law of rolling process parameters to transverse thickness difference;With the shape control characteristics of edge drop control work roll shape, propose six-roller cold continuous rolling mill work roll and intermediate roll bending force control strategy.The application can effectively reduce non-oriented silicon steel transverse thickness difference by work roll shape optimization and bending force collaborative control, improve cold-rolled silicon steel product quality and production stability, suitable for six-roller cold continuous rolling mill non-oriented silicon steel batch production.

Description

Technical Field

[0001] This invention belongs to the field of metallurgical rolling automation control, and specifically relates to a method for controlling the transverse thickness difference of non-oriented silicon steel in a six-roll cold continuous rolling mill. Background Technology

[0002] Non-oriented silicon steel is a core soft magnetic material for high-end equipment such as drive motors for new energy vehicles and high-efficiency energy-saving transformers. With the explosive growth of the global new energy industry, the market demand for high-grade non-oriented silicon steel continues to rise, especially with increasingly stringent requirements for its dimensional accuracy (transverse thickness difference). Currently, the six-roll UCM cold continuous rolling mill is the mainstream cold-rolled non-oriented silicon steel production equipment in China. However, most traditional control schemes use a single work roll shape, which cannot adapt to the rolling needs of multiple width specifications. This results in large fluctuations in strip edge drop. Moreover, existing control relies heavily on on-site experience for debugging and lacks scientific simulation analysis methods. The optimization cycle of process parameters is long and the trial and error cost is high. It is difficult to balance the stability of mass production and product accuracy, which has become one of the key technical bottlenecks for the localization of high-end non-oriented silicon steel.

[0003] From the perspective of the shape control mechanism of the six-roll cold continuous rolling mill, the existing technologies mostly use single control methods such as bending roll force and roll shifting in isolation, without establishing a coordinated control mechanism between roll shape characteristics and process parameters, resulting in low efficiency in controlling transverse thickness difference. For example, patent (CN 119870149 A) ​​discloses a method for reducing the transverse thickness difference of silicon steel products. This method reduces the thickness difference of the strip by adjusting parameters such as the amount of roll shifting, the bending force, and the reduction rate of the cold continuous rolling mill. Patent (CN 115815340 A) discloses a method for improving the thickness difference of silicon steel. This method improves the thickness difference of silicon steel by establishing a coupled model to iteratively calibrate the rolling force and inputting the hot rolling crown and the target thickness difference into the model. Patent (CN 120502588 A) discloses a work roll and working method for reducing the transverse thickness difference of cold-rolled strip steel. This method effectively reduces the transverse thickness difference of cold-rolled strip steel by setting the intermediate roll crown and the small diameter areas on both sides of the work roll body. Patent (CN 109465297 A) discloses a method and device for improving the transverse thickness difference of high-grade non-oriented silicon steel. By preset the target crown value compensation value and compensation position, the rolling process is controlled to improve the control level of the transverse thickness difference of high-grade non-oriented silicon steel.

[0004] The existing solution does not design differentiated roll shapes for the rolling characteristics of each stand and ignores the pre-control role of the upstream stand on edge drop, resulting in a sharp increase in the adjustment pressure of the subsequent stands and ultimately causing the transverse thickness difference of the finished strip to exceed the standard. Summary of the Invention

[0005] To address the shortcomings of existing technologies, the present invention aims to provide a method for controlling the transverse thickness difference of non-oriented silicon steel in a six-roll cold continuous rolling mill. By integrating roll shape design, simulation analysis, and dynamic control, this method solves the problem of controlling the transverse thickness difference of non-oriented silicon steel, effectively reducing the transverse thickness difference and improving the product quality and production stability of cold-rolled silicon steel.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] A method for controlling transverse thickness difference of non-oriented silicon steel applicable to a six-roll cold continuous rolling mill, the specific steps of which are as follows:

[0008] The edge drop control work rolls of the S1-S3 stands of the six-roll cold continuous rolling mill adopt a single-taper edge drop control work roll shape structure. The mathematical expression of the roll shape curve of the single-taper edge drop control work roll structure is as follows:

[0009]

[0010] in, W The width of the strip is in mm; L The length of the roll is in mm; Non-contact arc length, mm; Contact arc length, mm; R Where the radius of the roller is in mm; h The effective height of the roller shape, used to evaluate the adaptability of the roller shape, is measured in mm.

[0011] Based on the actual equipment parameters of the six-roll cold continuous rolling mill, a finite element simulation model was established that includes the support roll, intermediate roll, work roll and strip integrated contact, and the finite element simulation model was verified.

[0012] By sequentially setting the bending force of the work roll in the finite element simulation model The bending force of the working roll The range is -150kN to 250kN, with each 50kN interval representing a bending force of the intermediate roller. The bending force of the intermediate roller The range is 0~220kN, with each 50kN interval. Thickness data of at least 11 measuring points on the cross-section of the strip are extracted, and the distribution curve of the transverse thickness of the strip is obtained by fitting. The dominant influencing factors of key process parameter variables on the transverse thickness difference are determined.

[0013] To achieve optimal shape quality of rolled non-oriented silicon steel sheets, a multi-objective optimization objective function is constructed. The minimum value of this objective function is obtained through iterative deformation of the rolling mill roll system, yielding the optimal combination of bending forces between the work roll and intermediate roll. The objective function is:

[0014]

[0015] in, The crown of the rolled strip, in mm; Target convexity, mm; To set an upper limit for allowable convexity fluctuations; For export-side devaluation, mm; The maximum allowable edge drop limit is in mm; Rolling as the first i Stepped plate components, , , These are the weighting coefficients.

[0016] Furthermore, the actual production line produces non-oriented silicon steel with a bandwidth range of 1000~1400mm; 1000~1150 mm is the narrow bandwidth group; 1150~1280mm is the medium bandwidth group; and 1280~1400mm is the wide strip group.

[0017] Furthermore, the six-roll cold continuous rolling mill S1 and S2 stands are respectively equipped with single-taper edge drop control work rolls with corresponding taper parameters under the narrow-width strip group, the medium-width strip group and the wide strip group to achieve width adaptability matching.

[0018] Furthermore, the S3 stand of the six-roll cold continuous rolling mill uniformly adopts the edge drop control of the work roll shape with optimal taper parameters under the narrow strip group, the medium strip group and the wide strip group.

[0019] Furthermore, the strip material in the finite element simulation model is non-oriented silicon steel. A bilinear kinematic hardening elastoplastic constitutive model is adopted, with the actual stress-strain curve as input and the work roll, intermediate roll, and support roll as elastic bodies, to assign the Young's modulus, Poisson's ratio, and density to the non-oriented silicon steel.

[0020] Furthermore, in the finite element simulation model, a friction model is used between the rolls and the strip, and the contact between the rolls is set as elastic contact.

[0021] Furthermore, in the finite element simulation model, the strip is subjected to full constraints on displacement and rotation in the X, Y, and Z directions, and the rolls are only allowed to be displaced in the Y direction and rotated in the X direction; the rolling force is applied to the center of the journal of the support roll, and the bending force of each roll is applied to the center of its own journal.

[0022] Furthermore, the finite element simulation model is meshed, and the reduced integral C3D8R element type is selected to balance computational accuracy and efficiency. Local mesh refinement is performed in the contact area between the strip and the work roll and in the tapered transition area at the edge of the work roll, with the minimum element size controlled at 1 mm.

[0023] Furthermore, the process parameter variables include the bending force of the work roll. (-150kN~250kN), intermediate roll bending force (0~220kN), rolling force, intermediate roll displacement.

[0024] Furthermore, the objective function constraints include:

[0025]

[0026] The beneficial effects of this invention are as follows: Addressing the industry pain points of large transverse thickness differences and high strip shape control difficulties in the production of non-oriented silicon steel using a six-roll cold continuous rolling mill, this invention provides a method for controlling the transverse thickness difference of non-oriented silicon steel produced in a six-roll cold continuous rolling mill, possessing significant technical advantages and engineering application value. By optimizing the design of the new roll shape for the edge drop control work rolls of the S1-S3 stands, the problem of strip edge thinning can be precisely improved. The constructed finite element simulation model provides an accurate and low-cost verification tool for process parameter analysis, significantly reducing on-site trial and error time and material costs. Simulation clarifies the influence of rolling process parameters on the transverse thickness difference, and the work roll and intermediate roll bending force control strategy, combined with roll shape characteristics, achieves coordinated adaptation between roll shape and process. This method can stably control the transverse thickness difference of non-oriented silicon steel within 7μm, effectively reducing the risk of strip breakage and scrap rate, enhancing the stability of batch production, meeting the high-precision requirements of non-oriented silicon steel for high-end motors, and helping enterprises improve product competitiveness and economic benefits. Attached Figure Description

[0027] Appendix Figure 1 This is a flowchart of the method for controlling the transverse thickness difference of non-oriented silicon steel in a six-roll cold continuous rolling mill, according to the present invention.

[0028] Appendix Figure 2 A schematic diagram of the single taper edge drop control work roll profile curve of the S1-S3 stands of a six-roll cold continuous rolling mill provided in an embodiment of the present invention;

[0029] Appendix Figure 3 A schematic diagram of the finite element simulation model of a six-roll cold continuous rolling mill provided in an embodiment of the present invention;

[0030] Figure 4(a) is a schematic diagram of the shape control capability of the work roll bending force of the six-roll cold continuous rolling mill provided in the embodiment of the present invention;

[0031] Figure 4(b) is a schematic diagram of the shape control capability of the intermediate roll bending force of the six-roll cold continuous rolling mill provided in the embodiment of the present invention;

[0032] Appendix Figure 5 A flowchart for optimizing the bending force of the work roll and intermediate roll of a six-roll cold continuous rolling mill provided in an embodiment of the present invention;

[0033] Appendix Figure 6 A schematic diagram showing the effect of the method for controlling the transverse thickness difference of non-oriented silicon steel in a six-roll cold continuous rolling mill provided in this embodiment of the invention before and after application. Detailed Implementation

[0034] The present invention will now be further described with reference to the accompanying drawings and specific embodiments:

[0035] The method for controlling the transverse thickness difference of non-oriented silicon steel in a six-roll cold rolling mill, as described in this embodiment, was applied to a large industrial 1550 six-roll cold rolling mill. Figure 1 The diagram shown is a flowchart illustrating a specific implementation of the present invention, which includes the following steps:

[0036] S1: Based on the analysis of the causes of transverse thickness difference defects in non-oriented silicon steel strip during the six-roll cold continuous rolling process, and combined with the evaluation of the compatibility between the existing work roll shape and different strip widths, a new roll shape curve for the edge drop control work roll of the S1-S3 stand of the six-roll cold continuous rolling mill is designed and optimized.

[0037] In this embodiment, the edge drop control work rolls of the six-roll cold continuous rolling mill S1-S3 stands adopt a single-taper edge drop control work roll shape structure. The mathematical expression of the roll shape curve of the single-taper edge drop control work roll structure is as follows:

[0038]

[0039] in, W The width of the strip is in mm; L The length of the roll is in mm; Non-contact arc length, mm; Contact arc length, mm; R Where the radius of the roller is in mm; h The effective height of the roller shape, used to evaluate the adaptability of the roller shape, is measured in mm.

[0040] Specifically, the obtained rolling width range of the six-roll cold continuous rolling mill was divided into width groups. Stands S1 and S2 were adapted to different taper single-taper side-drop roll profiles according to their groups, while stand S3 adopted a single taper roll profile. After experimental verification, the work roll profile parameters for stands S1-S3 were obtained as shown in Table 1, and the roll profile curves are as follows: Figure 2 As shown.

[0041] Table 1. Roll profile parameters of work rolls for frames S1-S3

[0042]

[0043] S2: Based on the actual equipment parameters of the six-roll cold continuous rolling mill, a finite element simulation model is established that includes the support roll, intermediate roll, work roll and strip integrated contact, and the finite element simulation model is verified.

[0044] In this embodiment, the process of establishing the finite element simulation model in S1 above is as follows:

[0045] Based on the basic parameters of the rolling mill site (as shown in Table 2), a geometric model of a six-roll cold continuous rolling mill is constructed.

[0046] Table 2 Basic Simulation Conditions

[0047]

[0048] The material properties of non-oriented silicon steel, work roll, intermediate roll, and support roll are set, with the density ρ set to 7850 kg / m³. 3 The elastic modulus E = 1.9 × 10⁻⁶ 5 MPa, Poisson's ratio μ=0.3;

[0049] The interaction relationships of the model are defined as follows: the Coulomb friction model is adopted between the rolls and the strip, the friction coefficient is taken in the range of 0.05~0.15, the contact between each roll is set as elastic contact, the normal penalty algorithm is adopted, and the tangential penalty function coefficient is set to 0.1;

[0050] By setting boundary conditions for the model and meshing it, a finite element simulation model of the six-roll cold rolling mill was obtained, as shown in Figure 4. The accuracy of the finite element simulation model was verified using field-measured transverse thickness difference data of non-oriented silicon steel. The maximum error between the measured transverse thickness difference trend and the simulated transverse thickness difference was 8.39%, which is within the allowable error range, indicating that the finite element model can simulate the actual rolling process of the six-roll cold rolling mill.

[0051] S3: By sequentially setting the bending force of the work roll in the finite element simulation model. The bending force of the working roll The range is -150kN to 250kN, with each 50kN interval representing a bending force of the intermediate roller. The bending force of the intermediate roller The range is 0~220kN, with each 50kN interval. Thickness data of at least 11 measuring points on the cross-section of the strip are extracted, and the distribution curve of the transverse thickness of the strip is obtained by fitting. The dominant influencing factors of key process parameter variables on the transverse thickness difference are determined.

[0052] As shown in Figure 4(a), the influence of the work roll bending force changing from -150kN to 250kN on the strip shape was analyzed. It was found that both the secondary and quaternary strip shape components showed a good linear growth trend as the work roll bending force gradually increased. Specifically, the secondary strip shape component changed from -90.4MPa to 3.1MPa, indicating that the strip shape underwent a transformation from edge waviness to a straight state, and then from a straight state to a medium waviness. Figure 4(b) shows that within the range of 0-220kN, both the secondary and quaternary strip shape components showed linear growth, but the quaternary component showed a relatively smaller change, indicating that the intermediate roll bending force has a strong controllability over secondary strip shape defects. The results indicate that, under the condition of fixed roll shape parameters, the bending forces of the work roll and intermediate roll are a direct and effective means to achieve precise control of transverse thickness differences.

[0053] S4: To achieve optimal shape quality of the rolled non-oriented silicon steel sheet, a multi-objective optimization objective function is constructed. The minimum value of this objective function is obtained through iterative deformation of the rolling mill roll system, yielding the optimal combination of bending forces between the work roll and intermediate roll. The objective function is:

[0054]

[0055] in, The crown of the rolled strip, in mm; Target convexity, mm; To set an upper limit for allowable convexity fluctuations; For export-side devaluation, mm; The maximum allowable edge drop limit is in mm; Rolling as the first i Stepped plate components, , , These are the weighting coefficients.

[0056] Based on the shape control characteristics of the designed edge-drop control work roll, the optimization objective is to meet the high-precision flatness requirements of the rolled non-oriented silicon steel sheet. Simultaneously, the intermediate roll shifting amount for stands S1-S4 is set to 30mm, and for stand S5, it is set to 40mm. The bending force range for the work rolls in stands S1-S3 is set to -120kN to 160kN, and for the intermediate rolls in stands S1-S3, it is set to 50kN to 350kN. Through multi-round iterative calculations of the rolling roll system deformation, the optimal bending force matching parameters for the work rolls and intermediate rolls are obtained. The calculation process is as follows: Figure 5 Ultimately, a bending roll force setting strategy adapted to the shape of the work roll for edge drop control was formed (as shown in Table 3), and it was applied to the automatic bending roll force setting module of the six-roll cold continuous rolling mill to achieve precise control of the rolling process.

[0057] Table 3 Bending force settings for work rolls and intermediate rolls on S1-S3 stands

[0058]

[0059] This invention provides a method for controlling the transverse thickness difference of non-oriented silicon steel in a six-roll cold continuous rolling mill. By collecting and analyzing rolling data during stable production and combining it with continuous detection feedback, the method significantly improves the shape quality of high-precision exported silicon steel. The thickness difference of the non-oriented silicon steel at 10mm from the edge is stably controlled within 7μm. Specifically, the proportion of high-precision thickness differences ≤7μm in the five-stand cold rolling mill increases from 47.62% to 93.33% (e.g., ...). Figure 6 As shown in the figure, it has reached the advanced level in the industry, significantly reduced the risk of customer complaints and product returns caused by plate shape defects, and provided an innovative solution and practical path for solving the ultra-high plate shape quality requirements of wide silicon steel in the new generation of high-tech cold continuous rolling mills.

[0060] In summary, the transverse thickness difference control method for non-oriented silicon steel proposed in this embodiment achieves a significant improvement in the high-precision transverse thickness difference control effect at the exit of cold-rolled silicon steel without affecting production and with minimal equipment modification.

[0061] Furthermore, it should be noted that, in this document, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or terminal device that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or terminal device. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or terminal device that includes said element.

[0062] Finally, it should be noted that the above description represents a preferred embodiment of the present invention. It should be pointed out that although preferred embodiments have been described, those skilled in the art, once they understand the basic inventive concept of the present invention, can make various improvements and modifications without departing from the principles described herein. These improvements and modifications should also be considered within the scope of protection of the present invention. Therefore, the appended claims are intended to be interpreted as including both the preferred embodiments and all changes and modifications falling within the scope of the embodiments of the present invention.

[0063] For those skilled in the art, various other corresponding changes and modifications can be made based on the technical solutions and concepts described above, and all such changes and modifications should fall within the protection scope of the claims of this invention.

Claims

1. A method for controlling transverse thickness difference of non-oriented silicon steel in a six-roll cold continuous rolling mill, characterized in that, The specific steps are as follows: The edge drop control work rolls of the S1-S3 stands of the six-roll cold continuous rolling mill adopt a single-taper edge drop control work roll shape structure. The mathematical expression of the roll shape curve of the single-taper edge drop control work roll structure is as follows: in, W The width of the strip is in mm; L The length of the roll is in mm; Non-contact arc length, mm; Contact arc length, mm; R Where the radius of the roller is in mm; h The effective height of the roller shape, used to evaluate the adaptability of the roller shape, is measured in mm. Based on the actual equipment parameters of the six-roll cold continuous rolling mill, a finite element simulation model was established that includes the support roll, intermediate roll, work roll and strip integrated contact, and the finite element simulation model was verified. By sequentially setting the bending force of the work roll in the finite element simulation model The bending force of the working roll The range is -150kN to 250kN, with each 50kN interval representing a bending force of the intermediate roller. The bending force of the intermediate roller The range is 0~220kN, with each 50kN interval. Thickness data of at least 11 measuring points on the cross-section of the strip are extracted, and the distribution curve of the transverse thickness of the strip is obtained by fitting. The dominant influencing factors of key process parameter variables on the transverse thickness difference are determined. To achieve optimal shape quality of rolled non-oriented silicon steel sheets, a multi-objective optimization objective function is constructed. The minimum value of this objective function is obtained through iterative deformation of the rolling mill roll system, yielding the optimal combination of bending forces between the work roll and intermediate roll. The objective function is: in, The crown of the rolled strip, in mm; Target convexity, mm; To set an upper limit for allowable convexity fluctuations; For export-side devaluation, mm; The maximum allowable edge drop limit is in mm; Rolling as the first i Stepped plate components, , , These are the weighting coefficients.

2. The method for controlling transverse thickness difference of non-oriented silicon steel in a six-roll cold continuous rolling mill as described in claim 1, characterized in that, Also includes: The actual production line produces non-oriented silicon steel with a bandwidth range of 1000~1400mm; 1000~1150mm is the narrow bandwidth group; 1150~1280mm is the medium bandwidth group; and 1280~1400mm is the wide bandwidth group.

3. The method for controlling transverse thickness difference of non-oriented silicon steel in a six-roll cold continuous rolling mill as described in claim 2, characterized in that, The six-roll cold continuous rolling mill S1 and S2 stands are respectively equipped with single-taper edge drop control work rolls with corresponding taper parameters under the narrow width strip group, the medium width strip group and the wide strip group to achieve width adaptability matching.

4. The method for controlling transverse thickness difference of non-oriented silicon steel in a six-roll cold continuous rolling mill as described in claim 2, characterized in that, The S3 stand of the six-roll cold continuous rolling mill uniformly adopts the edge drop control of the work roll shape with optimal taper parameters under the narrow strip group, the medium strip group and the wide strip group.

5. The method for controlling transverse thickness difference of non-oriented silicon steel in a six-roll cold continuous rolling mill as described in claim 1, characterized in that, The strip material in the finite element simulation model is non-oriented silicon steel. A bilinear kinematic hardening elastoplastic constitutive model is adopted, with the actual stress-strain curve as input and the work roll, intermediate roll and support roll as elastic bodies, to assign the Young's modulus, Poisson's ratio and density to the non-oriented silicon steel.

6. The method for controlling transverse thickness difference of non-oriented silicon steel in a six-roll cold continuous rolling mill as described in claim 5, characterized in that, In the finite element simulation model, a friction model is used between the rolls and the strip, and the contact between the rolls is set as elastic contact.

7. The method for controlling transverse thickness difference of non-oriented silicon steel in a six-roll cold continuous rolling mill as described in claim 5, characterized in that, In the finite element simulation model, the strip is subject to full constraints on displacement and rotation in the X, Y, and Z directions, while the rolls are only allowed to move in the Y direction and rotate in the X direction. The rolling force is applied to the center of the journal of the support roll, and the bending force of each roll is applied to the center of its own journal.

8. The method for controlling transverse thickness difference of non-oriented silicon steel in a six-roll cold continuous rolling mill as described in claim 5, characterized in that, The finite element simulation model was meshed, and the reduced integral C3D8R element type was selected to balance computational accuracy and efficiency. Local mesh refinement was performed in the contact area between the strip and the work roll and in the tapered transition area at the edge of the work roll, with the minimum element size controlled at 1 mm.

9. The method for controlling transverse thickness difference of non-oriented silicon steel in a six-roll cold continuous rolling mill as described in claim 1, characterized in that, The rolling process parameters include the bending force of the work rolls. Intermediate roll bending force Rolling force and intermediate roll displacement.

10. The method for controlling transverse thickness difference of non-oriented silicon steel in a six-roll cold continuous rolling mill as described in claim 1, characterized in that, The objective function constraints include:

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