Intelligent rolling method suitable for wide-specification high-grade surface quality strip steel

Abstract

The invention provides an intelligent rolling method suitable for wide-specification high-grade surface quality strip steel, and belongs to the technical field of industrial control. The method comprises the steps that in the hot rolling process, the strip steel temperature is adjusted in a sectional mode, and hot rolling of strip steel is completed; in the cold rolling process, cold rolling rack control parameters are obtained based on the cold rolling rack control model; and controlling each cold rolling rack to finish cold rolling of the strip steel through the secondary control system based on the control parameters. According to the method, the surface quality of the strip steel is improved by analyzing the mechanism of the edge scratch defect and reducing the wave shape of the edge of the strip steel; based on the performance uniformity of hot rolling raw materials, the roll shape of a working roll, inter-frame tension and various technological parameters of rolling lubrication, intelligent control over the edge surface quality of the wide-specification high-grade surface strip steel can be completed without other auxiliary equipment and large-scale transformation.

Description

Technical Field

[0001] The present invention relates to the technical field of industrial control, and particularly to an intelligent rolling method applicable to wide - specification high - grade surface quality strip steel. Background Art

[0002] During the production process of wide - specification high - grade surface cold - rolled strip steel, due to the increase in strip width, it is more sensitive to the uniformity of raw material properties, work roll profile, inter - stand tension, and lubrication state during the rolling process, and defects such as edge waviness that affect the edge quality are extremely likely to occur.

[0003] Traditional methods adjust for a single surface process and cannot meet the production requirements of products with extreme width specifications. At the same time, with the upgrade of coating processes by downstream users, higher requirements for surface quality in the width direction are needed, and there is an urgent need to improve the edge surface quality of wide - specification strip steel.

[0004] Therefore, there is a need for a method that synergistically optimizes multiple factors for the edge surface quality of wide - specification high - grade surface products, suppresses strip edge waviness defects, realizes the uniform control of lubrication state in the width direction, and improves the edge surface quality of wide - specification strip steel. Summary of the Invention

[0005] In view of this, the present invention provides an intelligent rolling method applicable to wide - specification high - grade surface quality strip steel. According to the hot - rolling parameters and strip - steel specification parameters of the strip steel, the inter - stand tension of the cold - rolling mill is controlled; the parameters in the steel - rolling process are quantitatively controlled to completely remove the edge waviness defects of wide - specification high - surface - grade cold - rolled strip steel; thereby improving the overall quality of wide - specification high - surface - grade cold - rolled strip steel.

[0006] To this end, the present invention provides the following technical solutions:

[0007] An intelligent rolling method applicable to wide - specification high - grade surface quality strip steel, comprising:

[0008] In the hot - rolling process, the strip - steel temperature is adjusted in sections to complete the hot - rolling of the strip steel;

[0009] In the cold - rolling process, based on the cold - rolling mill control model, the cold - rolling mill control parameters are obtained;

[0010] The secondary control system controls each cold - rolling mill to complete the cold - rolling of the strip steel based on the control parameters.

[0011] Further, the cold - rolling mill control model includes:

[0012] F 3-4 = 15 + k 3-4 ·(w - 1200),

[0013] F 4-5= 20 + k 4-5 ·(w - 1200);

[0014] where k is the preset width influence coefficient; w is the strip width; F 3-4 represents the tension between the third stand and the fourth stand; F 4-5 represents the inter-stand tension between the fourth stand and the fifth stand.

[0015] Furthermore, the segmented regulation of the strip temperature includes:

[0016] In the hot rolling stage, heat compensation is performed on the strip edges.

[0017] In the laminar cooling stage, the spraying area of the strip is determined according to the strip specification parameters.

[0018] Furthermore, determining the spraying area of the strip according to the strip specification parameters includes:

[0019] If the strip width is greater than or equal to 1200 mm and less than 1400 mm, the side spraying and reverse spraying are turned off, and the middle width of 1100 mm is reserved for spray cooling.

[0020] If the strip width is greater than 1400 mm and less than or equal to 1600 mm, the side spraying and reverse spraying are turned off, and the middle width of 1300 mm is reserved for spray cooling.

[0021] If the strip width is greater than 1600 mm, the side spraying and reverse spraying are turned off, and the middle width of 1500 mm is reserved for spray cooling.

[0022] Furthermore, controlling the cold rolling of the strip by each cold rolling stand based on the control parameters by the secondary control system includes:

[0023] Construct an inter-stand tension database; input the inter-stand tension database into the secondary control system;

[0024] The secondary control system calculates the inter-stand tension according to the received strip specification parameters and transmits it to the primary control system for intelligent control of the inter-stand tension.

[0025] Furthermore, the control parameters also include:

[0026] The load distribution ratio of each stand, the emulsion temperature, and the emulsion flow rate.

[0027] Furthermore, determining and setting the emulsion temperature and the emulsion flow rate according to the strip specification parameters includes:

[0028] If the strip width is greater than or equal to 1200 mm and less than 1400 mm, the emulsion flow rate from the first stand to the fourth stand is 5000 - 5200 L / min, and the emulsion temperature is 50 - 52 °C;

[0029] If the strip width is greater than 1400 mm and less than or equal to 1600 mm, the emulsion flow rate from the first stand to the fourth stand is 5200 - 5400 L / min, and the emulsion temperature is 52 - 54 °C;

[0030] If the strip width is greater than 1600 mm, the emulsion flow rate from the first stand to the fourth stand is 5400 - 5600 L / min, and the emulsion temperature is 54 - 56 °C.

[0031] Advantages and positive effects of the present invention:

[0032] 1) Through the mechanism analysis of the edge scratch defect, the design idea of effectively controlling the edge rolling lubrication state by adjusting the strip edge waviness is clarified in the method of the present invention. Based on process parameters such as the performance uniformity of hot-rolled raw materials, the work roll profile, the inter-stand tension, and rolling lubrication, the intelligent control of the edge surface quality of wide-specification high-grade surface cold-rolled strip can be completed without other auxiliary equipment and a large number of modifications.

[0033] 2) The wide-specification high-surface-grade cold-rolled strip obtained by the method of the present invention has good edge surface quality. While there are no obvious defects on the edge, the strip shape quality is also effectively improved, meeting the usage requirements of downstream users. The proposed multi-factor collaborative control design concept and specific process parameter requirements can be directly applied to industrial production lines, achieving the simplification of the production process and the improvement of production efficiency. Description of the Drawings

[0034] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the drawings in the following description are some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0035] Figure 1 It is a flow chart of the intelligent rolling method applicable to wide-specification high-grade surface quality strip in the embodiment of the present invention. Detailed Embodiments

[0036] To enable those skilled in the art to better understand the solution of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0037] It should be noted that the terms "first", "second", etc. in the specification and claims of the present invention and the above-mentioned drawings are used to distinguish similar objects, and do not necessarily need to be used to describe a specific order or sequence. It should be understood that such data can be interchanged under appropriate circumstances so that the embodiments of the present invention described here can be implemented in an order other than those illustrated or described here. In addition, the terms "comprising" and "having" and any variations thereof are intended to cover non-exclusive inclusion. For example, a process, method, system, product or device comprising a series of steps or units does not necessarily have to be limited to those steps or units clearly listed, but may include other steps or units not clearly listed or inherent to these processes, methods, products or devices.

[0038] The present invention provides an intelligent rolling method applicable to wide-specification high-grade surface-quality strip steel. By analyzing the generation mechanism of edge scratches in the cold rolling process, the design idea of effectively controlling the edge rolling lubrication state by adjusting the strip edge waviness is clarified. Based on process parameters such as the uniformity of hot-rolled raw material properties, work roll profile, inter-stand tension, and rolling lubrication, the strip edge uniformity and process lubrication state are finely controlled throughout the process, achieving a significant improvement in the surface quality of the edges of wide-specification high-grade cold-rolled strip steel.

[0039] Combined with Figure 1 , the method of the present invention is further described as follows:

[0040] S1. Determine the stage temperature control strategy for the hot rolling process to ensure strip uniformity and thus improve the surface quality of the final strip edges. The specific steps include:

[0041] S1.1 In the high-pressure descaling stage, at the entrance of rough rolling and the entrance of finish rolling, multiple groups of high-pressure descaling water are turned on; preferably, the descaling water pressure ≥ 18 MPa;

[0042] S1.2 Perform heating compensation on the strip edges during the hot rolling stage;

[0043] Preferably, after rough rolling or before finish rolling, the temperature of the 50-mm area at the strip edges is raised by 30 - 50 °C;

[0044] S1.3 In the laminar cooling stage;

[0045] Adjust the spray area of the strip according to the strip specification parameters;

[0046] Preferably, for strips with a width of 1200 - 1400 mm, turn off the side spraying and reverse spraying at the edges, and retain the spray cooling with a width of 1100 mm in the middle;

[0047] For strips with a width of 1400 - 1600 mm, turn off the side spraying and reverse spraying at the edges, and retain the spray cooling with a width of 1300 mm in the middle;

[0048] For strips with a width greater than 1600 mm, turn off the side spraying and reverse spraying at the edges, and retain the spray cooling with a width of 1500 mm in the middle.

[0049] S2. Based on the analysis of the edge scratching defects of cold-rolled strips, determine the control strategy for the cold rolling process;

[0050] Analyze the generation mechanism of cold-rolled edge scratching defects: Currently, the edge surface defects of wide-specification high-grade surface cold-rolled strips are mainly caused by the fluctuation of the lubrication state during the rolling process; the edge waviness during the rolling process affects the lubrication state of the strip edge, causing it to change from critical lubrication to dry friction, and then generating edge scratching defects that affect the edge surface quality. For wide-specification cold-rolled products, the change in tension affects the thermal crown of the roll, especially the back tension has a greater impact. Therefore, adjusting the tension is one of the means to control the edge wave; the tension affects the rolling pressure. According to rolling theory, due to the change in tension, especially the change in back tension, it has a great impact on the rolling pressure. The change in rolling pressure will inevitably lead to a change in the elastic deformation of the roll, so it will inevitably affect the formation of the edge wave; when the tension is unevenly distributed transversely, it will cause obvious transverse flow of the metal, even in the case of sheet rolling that macroscopically seems to be nearly plane deformation. Under a certain high-directional deformation, the result of the transverse flow will inevitably change the transverse extension distribution, and thus inevitably change the strip shape. By cooperating with the increase of the intermediate roll bending force, the effective control of the transverse tension distribution can be achieved. The adjustment direction of the load distribution takes into account that on the premise of the existence of micro-edge waves in the raw material, the work-hardening of the strip in the front stand is smaller and the deformation ability is stronger. A higher load distribution is beneficial to the control of the edge shape and is not likely to cause the rupture of the process lubricating oil film. Therefore, on the premise of ensuring the rolling stability, design the following cold rolling process control strategy.

[0051] Therefore, the influence of the edge waviness defect of wide-specification products on the lubrication state is the main factor that differentiates from the surface quality control of conventional-specification products. It is necessary to re-design and consider the multi-factor collaborative control from aspects such as the uniformity control of the raw material along the width direction, the work roll profile design, the optimization of the interstand tension, and the lubrication process to meet the continuously improving surface quality requirements of downstream users.

[0052] S2.1 Use the cold rolling interstand tension model to determine the interstand tension according to the strip specification parameters;

[0053] According to the strip specifications, the tension F between the third and fourth stands is obtained through the inter-stand tension model of the cold rolling mill 3-4 , and the inter-stand tensions F between the fourth and fifth stands 4-5 :

[0054] F 3-4 = 15 + k 3-4 ·(w - 1200),

[0055] F 4-5 = 20 + k 4-5 ·(w - 1200);

[0056] In the formula, k is the width influence coefficient; w is the strip width, with the unit of mm

[0057] Construct a data set of strip parameters and corresponding inter-stand tensions, and input the strip specifications and the corresponding inter-stand tension data set into the secondary control system; the secondary control system calculates the inter-stand tension according to the strip specifications and transmits it to the primary control system to achieve intelligent control of the inter-stand tension

[0058] S2.2 Design the rolling load distribution plan

[0059] 1) The coiling tension is 40 KN or more

[0060] 2) The bending rolls of the second, third, and fourth stands are 100%

[0061] 3) In this embodiment, the rolling reduction ratio is designed as shown in Table 1

[0062] Table 1

[0063] Frame First Frame Second Frame Third Frame Fourth Frame Fifth Frame Load Distribution (%) 25-27 21-23 12-13 6-8 0.5-1.0

[0064] S2.3 Design the control strategy of the cold rolling rolls according to the analysis of the influence of the roll curve shape on the strip edge wave

[0065] The influence of changing the roll curve shape on the strip edge wave is reflected in the following two aspects: the geometric dimensions of the cold rolling rolls will cause changes in the shape of the bearing roll gap; the change in the roll profile of the work roll will bring about changes in the roll gap and elasticity, thus causing changes in the loaded roll gap. Since the roll profile of the work roll directly affects the roll gap shape, a certain convexity design is carried out on the work roll, which can not only change the shape of the mill's no-load roll gap, but also effectively improve the distribution of the contact pressure between the work roll and the intermediate roll, and has a significant effect on improving the edge wave shape and the edge rolling lubrication state. Therefore, on the premise of ensuring rolling stability, the following cold rolling roll control scheme is designed

[0066] The roll curve of the work roll of the fourth stand is set to 0.08 mm

[0067] The curves of the backup rolls of the second stand, the third stand and the fourth stand are set to 0.5 mm.

[0068] S2.4 Select the parameters of the cold rolling emulsion;

[0069] The emulsion parameters are the key factors affecting rolling lubrication. With the adjustment of the emulsion parameters, its cooling effect will be improved, and the temperature in the deformation zone will be reduced accordingly. The reduction of the temperature in the deformation zone will increase the dynamic viscosity of the lubricating oil, and the oil film thickness will increase, which also plays a role in improving the lubrication effect and reducing the friction coefficient. When the friction coefficient decreases, the rolling pressure decreases, resulting in a decrease in the dynamic viscosity. In this way, a closed loop is formed among the dynamic viscosity of the lubricating oil, the oil film thickness, the friction coefficient and the rolling pressure, and finally a balance is achieved. Therefore, select the emulsion parameters according to the strip specifications:

[0070] For strips with a width of 1200 - 1400 mm, the emulsion flow rate from the first stand to the fourth stand is 5000 - 5200 L / min, and the emulsion temperature is 50 - 52 °C;

[0071] For strips with a width of 1400 - 1600 mm, the emulsion flow rate from the first stand to the fourth stand is 5200 - 5400 L / min, and the emulsion temperature is 52 - 54 °C;

[0072] For strips with a width greater than 1600 mm, the emulsion flow rate from the first stand to the fourth stand is 5400 - 5600 L / min, and the emulsion temperature is 54 - 56 °C.

[0073] Taking specific application examples to further illustrate the method of the present invention:

[0074] In this application example, six strips with different specification parameters are selected respectively, and the rolling control methods corresponding to the strips with each specification parameter are determined by the method of the present invention, and products without wavy defects at the strip edges are obtained.

[0075] 1. According to the hot rolling uniformity control method in the present invention, the hot rolling process control scheme in this embodiment is shown in Table 2:

[0076] Table 2

[0077] Serial Number Strip Width (mm) Middle Spraying Width (mm) 1 1435 1300 2 1350 1100 3 1200 1100 4 1435 1300 5 1620 1500 6 1481 1300

[0078] 2. According to the cold rolling rolling load distribution method in the present invention, the cold rolling rolling load distribution scheme in this embodiment is shown in Table 3:

[0079] Table 3

[0080]

[0081] 3. According to the cold rolling inter-stand tension control method in the present invention, the cold rolling inter-stand tension in this embodiment is shown in Table 4:

[0082] Table 4

[0083]

[0084] 4. According to the emulsion parameter selection method in the present invention, the emulsion parameters in this embodiment are shown in Table 5.

[0085] Table 5

[0086]

[0087] Combining the hot rolling process control scheme, cold rolling rolling load distribution, cold rolling process parameters, and the selection of emulsion parameters in this application embodiment to obtain the technical solution, the results of the rolled strip are shown in Table 6.

[0088] Table 6

[0089] Serial Number Number of Strip Edge Waviness Defects 1 0 2 0 3 0 4 0 5 0 6 0

[0090] It can be seen from the application embodiment that by using the method for controlling the edge surface quality of wide-specification high-grade surface cold-rolled strip in the present invention, the edge surface quality of the wide-specification high-grade surface cold-rolled strip is good. And the effective control of the edge surface quality of the wide-specification high-grade surface cold-rolled strip can be completed without other auxiliary equipment and a large number of modifications, simplifying the production process and reducing the production cost. At the same time, with the continuous development of automatic control technology, intelligent production with high efficiency and high stability is an effective means for steel enterprises to further achieve cost reduction and efficiency improvement. Therefore, the method of the present invention is of great significance for the high-efficiency production of strip steel products and adapting to the technological upgrading of downstream users.

[0091] Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements on some or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. An intelligent rolling method for wide-spec high-quality strip steel, characterized in that: include: In the hot rolling process, the strip temperature is adjusted in stages to complete the hot rolling of the strip; In the cold rolling process, based on the cold rolling stand control model, the cold rolling stand control parameters are obtained; The secondary control system controls each cold rolling stand based on the control parameters to complete the cold rolling of the steel strip.

2. According to claim 1, an intelligent rolling method for wide-spec high-quality strip steel is characterized in that: The cold rolling mill stand control model comprises: F 3-4 =15+k 3-4 ·(w-1200), F 4-5 =20+k 4-5 ·(w-1200); Where, k is the preset width influence coefficient; w is the strip width; F 3-4 Indicates the tension between the third and fourth racks; F 4-5 Indicates the inter-rack tension between the fourth rack and the fifth rack.

3. The intelligent rolling method for wide-spec high-quality strip steel according to claim 1, characterized in that: The stepwise adjustment of the strip temperature comprises: During the hot rolling stage, the edges of the strip are heated for compensation; During the laminar cooling stage, the spraying area of ​​the strip is determined according to the strip specification parameters.

4. The intelligent rolling method for wide-spec high-quality strip steel according to claim 3, characterized in that: Determining the spraying area of ​​the steel strip according to the steel strip specification parameters includes: If the strip width is greater than or equal to 1200mm and less than 1400mm, turn off the side water spray and reverse water spray, and keep the middle width of 1100mm spray cooling; If the strip width is greater than 1400mm and less than or equal to 1600mm, turn off the edge water spray and reverse water spray, and keep the middle width of 1300mm spray cooling; If the strip width is greater than 1600mm, turn off the edge water spray and reverse water spray, and retain the middle width of 1500mm for spray cooling.

5. The intelligent rolling method for wide-spec high-quality strip steel according to claim 2, characterized in that: The method of controlling each cold rolling stand to complete the cold rolling of the steel strip based on the control parameters through the secondary control system includes: Construct an inter-rack tension database; input the inter-rack tension database into the secondary control system; The secondary control system calculates the inter-rack tension based on the received strip steel specification parameters and transmits it to the primary control system for intelligent control of the inter-rack tension.

6. The intelligent rolling method for wide-spec high-quality strip steel according to claim 1, characterized in that: The control parameters also include: Load distribution ratio of each rack, emulsion temperature and emulsion flow rate.

7. The intelligent rolling method for wide-spec high-quality strip steel according to claim 6, characterized in that: Determining and setting the emulsion temperature and emulsion flow rate according to the strip steel specification parameters includes: If the strip width is greater than or equal to 1200mm and less than 1400mm, the emulsion flow rate of the first to fourth racks is 5000-5200L / min, and the emulsion temperature is 50-52℃; If the strip width is greater than 1400mm and less than or equal to 1600mm, the emulsion flow rate of the first to fourth racks is 5200-5400L / min, and the emulsion temperature is 52-54℃; If the strip width is greater than 1600mm, the emulsion flow rate from the first to the fourth rack is 5400-5600L / min, and the emulsion temperature is 54-56℃.

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