A method for starting a thin gauge ultra-high grade non-oriented silicon steel continuous rolling process

Abstract

The present application relates to the field of metal rolling, a kind of thin gauge ultra-high grade non-oriented silicon steel continuous rolling process original plate starting method, comprising the following steps: step one, adjusting S1-S4 rack rolling pressure preset;Step two, adjusting S5 rack rolling pressure preset;Step three, adjusting the bending force of each rack working roll and the bending force of intermediate roll;Step four, tension deviation adjustment in the process of starting;Step five, bending force recovery in the process of starting;Step six, cut the roll shear.The present application realizes the true sense of high-grade silicon steel continuous rolling, greatly improves the production efficiency of unit;Solve the problem of process cost increase caused by the empty winding roll second online rescue due to the high-grade silicon steel strip cannot start.

Description

Technical Field

[0001] This invention relates to the field of metal rolling, and more particularly to a method for starting the rolling mill of thin-gauge, ultra-high grade non-oriented silicon steel in continuous rolling processes. Background Technology

[0002] Conventional large-diameter acid rolling mills are specifically designed for the production of silicon steel with a silicon content of less than 2.1%. Based on urgent market demand and equipment capabilities, Taiyuan Iron & Steel's 1450 acid rolling mill has gradually developed a continuous rolling process for high-grade silicon steel with a silicon content of more than 2.8%. However, due to the characteristics of silicon steel, when the silicon content of silicon steel exceeds 2.5%, the brittleness of the base material increases sharply. Compared with medium and low grade silicon steel, high grade silicon steel has a much higher incidence of abnormalities such as strip breakage during continuous rolling production. After production is interrupted due to strip breakage or equipment failure, it is extremely difficult to resume production smoothly.

[0003] Process flow: The acid rolling mill is equipped with two uncoilers at the inlet. When producing high-grade silicon steel, the mill uses one uncoiler for single-line production, while the other uncoiler is used to keep spare coils (Q235 or other low-silicon grades) to deal with emergencies. If the production of high-grade silicon steel is interrupted due to strip breakage or equipment failure, the spare coil is quickly uncoiled and welded. Then, the high-grade silicon steel coil in the acid tank on the production line is wound loosely. The strip head of the spare coil is wound onto the coiler, which can quickly start the machine and resume production. The tail of the spare coil can be welded with high-grade silicon steel again to resume the production of high-grade silicon steel.

[0004] Problems: When the silicon steel content exceeds 2.5%, the brittleness of the base material increases significantly. When starting the rolling mill of ultra-high grade silicon steel slabs, the brittleness of the raw material hinders the success rate of starting the rolling mill of the slabs. At present, ultra-high grade silicon steel adopts a single uncoiler uncoiling process, which makes it difficult for the production line to maintain high-speed production. This limits the pickling and continuous rolling speeds, resulting in a decrease in unit capacity and an increase in various energy consumption indicators. Furthermore, high grade silicon steel coils that are unwound due to production interruptions need to be transferred to other units for salvage production.

[0005]

[0006] This invention standardizes the rolling pressure correction coefficient, work roll bending force correction coefficient, and intermediate roll bending force correction coefficient during the start-up process of ultra-high grade silicon steel slabs. At the same time, it creatively invented the S5 stand constant rolling pressure start-up mode, which improves the success rate of start-up of ultra-high grade silicon steel slabs, frees up the second uncoiling channel at the entrance, realizes double uncoiling production, greatly improves the production efficiency of ultra-high grade silicon steel slabs, and reduces the energy consumption per ton of ultra-high grade silicon steel produced. Summary of the Invention

[0007] The purpose of this invention is to address the above-mentioned problems by providing a method for starting the rolling mill of thin-gauge, ultra-high grade non-oriented silicon steel in a continuous rolling process.

[0008] The objective of this invention is achieved as follows: a method for starting the rolling mill of thin-gauge, ultra-high grade non-oriented silicon steel in a continuous rolling process, comprising the following steps: Step 1, adjusting the preset rolling pressure of stands S1 to S4: The preset formula for the starting rolling pressure is: F x = F Sx *(1+a x In the formula: S x :S x Rack, x=1, 2, 3, 4, F x :S x Actual rolling pressure of the stand, t, F Sx Sx stand setting rolling pressure, t, a x : Rolling pressure correction factor, a x =0.05~0.15, x=1, 2, 3, 4; Step 2, Adjust the preset rolling pressure of S5 stand: Fix the rolling pressure of S5 stand at 900~1000t; Step 3, Adjust the bending force of the work rolls and intermediate rolls of each stand: Preset formula for the bending force of the work rolls at startup: W x = W Sx *(1- b x In the formula: S x :S x Rack, x=1, 2, 3, 4, 5, W x :S x Actual bending force of the working roll on the frame, t, W Sx :Sx frame setting work roll bending force, t, b x : Correction coefficient for bending force of work roll, b x =0.1~0.3, x=1, 2, 3, 4, 5; Preset formula for the bending force of the intermediate roller during startup: I x = I Sx *(1-c x In the formula: S x :S x Rack, x=1, 2, 3, 4, 5, I x :S x Actual bending force of the working roll on the frame, t, I Sx :Sx frame setting work roll bending force, t, c x : Correction coefficient for bending force of intermediate roll, c x=0.05~0.25, x=1, 2, 3, 4, 5; Step 4, Tension deviation adjustment during startup: Maintain the tension deviation value within the range of -0.3t~0.3t during startup; Step 5, Bending roll force recovery during startup: As the original plate is started, the strip thickness of each stand will gradually be compressed to the corresponding set thickness value. When the actual strip thickness value deviates from the set thickness value within the range of 0~150μm, increase the bending roll of the corresponding stand to gradually restore it to the set bending roll force. The S5 stand adjusts the bending roll according to the actual exit strip shape value; Step 6, Slitting and shearing: When the thickness of each stand reaches the corresponding set thickness value, and the exit strip shape value of the S5 stand is within 15I, shearing and slitting can be performed, and the original plate startup is completed.

[0009] In step five, the S5 frame adjusts the bending rollers according to the actual exit plate shape value as follows: if the plate shape is a medium wave, reduce the bending of the work roller or intermediate roller; if the plate shape is an edge wave, increase the bending of the work roller or intermediate roller to ensure that the plate shape value is within 15I.

[0010] The beneficial effects of this invention are: 1. It realizes true continuous rolling of high-grade silicon steel, greatly improving the production efficiency of the unit; 2. It solves the problem of increased process costs caused by the inability to start the machine due to strip breakage of high-grade silicon steel, resulting in the need for secondary online recovery of empty coils; 3. It shortens the production cycle of high-grade silicon steel and improves the internal logistics and transportation of materials. Implementation

[0011] This invention proposes a method for starting the rolling mill of thin-gauge ultra-high grade non-oriented silicon steel in continuous rolling processes. By setting correction coefficients for rolling pressure, work roll bending force, and intermediate roll bending force, and using formulas to adjust the preset values ​​of rolling pressure and bending force before starting the rolling mill, and matching a specific tension deviation control range, the entire starting process of the thin-gauge strip is maintained in a high rolling pressure, low bending roll mode. This ensures micro-double-sided wavy rolling between stands to reduce the impact of the brittleness of high-grade silicon steel on the starting process, reduces the bilateral stress of the strip to decrease the risk of strip breakage, and achieves the starting process of thin-gauge ultra-high grade non-oriented silicon steel in continuous rolling processes. This solves the problem of strip breakage during the starting process of thin-gauge high-grade non-oriented silicon steel in existing technologies.

[0012] To achieve the above objectives, the present invention adopts the following technical solution: Step 1: Adjust the preset rolling pressure of stands S1 to S4.

[0013] Preset formula for starting rolling force: F x = F Sx *(1+a x ).

[0014] In the formula: S x :S x Rack, x=1, 2, 3, 4;

[0015] F x :S x Actual rolling pressure of the stand, in tons;

[0016] F Sx Sx stand setting rolling pressure, t;

[0017] a x : Rolling pressure correction factor, a x =0.05~0.15, x=1, 2, 3, 4.

[0018] Step 2: Adjust the preset rolling pressure of the S5 stand.

[0019] The rolling pressure of the S5 stand is fixed at 900~1000t.

[0020] Step 3: Adjust the bending force of the working rolls and the bending force of the intermediate rolls on each frame.

[0021] Preset formula for bending force of starting work roll: W x = W Sx *(1- b x ).

[0022] In the formula: S x :S x Rack, x=1, 2, 3, 4, 5;

[0023] W x :S x Actual bending force of the working roll on the frame, t;

[0024] W Sx :Sx frame setting work roll bending force, t;

[0025] b x : Correction coefficient for bending force of work roll, b x =0.1~0.3, x=1, 2, 3, 4, 5.

[0026] Preset formula for bending force of intermediate roller during startup: I x = I Sx *(1-c x ).

[0027] In the formula: S x :S x Rack, x=1, 2, 3, 4, 5;

[0028] I x :S x Actual bending force of the working roll on the frame, t;

[0029] I Sx :Sx frame setting work roll bending force, t;

[0030] c x : Correction coefficient for bending force of intermediate roll, c x =0.05~0.25, x=1, 2, 3, 4, 5.

[0031] Step 4: Adjusting tension deviation during the start-up process.

[0032] At the moment of starting the rolling mill, the strip is tensioned, and a tension deviation is generated between each stand. As rolling progresses, the tension deviation value will decrease, maintaining the tension deviation value within the range of -0.3t to 0.3t during the starting process.

[0033] Step 5: Recovery of bending roller force during the start-up process.

[0034] As the original plate is started, the strip thickness of each frame will gradually be pressed to the corresponding set thickness value. When the actual strip thickness value deviates from the set thickness value within the range of 0~150μm, the bending roller of the corresponding frame is increased to gradually restore the set bending roller force. The S5 frame adjusts the bending roller according to the actual exit plate shape value.

[0035] Step 6: Split and cut.

[0036] Once the thickness of each stand reaches the corresponding set thickness value, and the strip shape value at the S5 stand exit is within 15I, shearing and coiling can be performed, and the original plate is ready for shipment. (Strip shape is a unique quality indicator for strip steel, and the unit of measurement for strip shape is I. I represents the relative increase in the length of the wavy section of the strip relative to the standard length of the straight section. It is generally expressed as the relative length difference between the longest and shortest longitudinal strips on the strip width. Because this value is very small, internationally, the relative length difference is usually multiplied by 105 before being used to represent the straightness of the strip. This indicator is I unit. One I unit represents a relative length difference of 10⁻⁵. The description in step six, "the strip shape value at the S5 stand exit is within 15I", can be modified to "the S5 stand exit has a slightly wavy strip shape, and the strip shape value is controlled within the range of 0~15I", which means that within a 1m periodic wave length, the wave height must not exceed 15mm).

[0037] In this invention: 1. Step one, increasing the rolling pressure of stands S1 to S4 can quickly roll silicon steel from the base material thickness to the set thickness of each stand, shorten the start-up time of the original plate, reduce the amount of rolling scrap during the start-up process, and reduce the loss of yield.

[0038] 2. In step two, the constant rolling pressure mode of the S5 stand eliminates the impact of the main motor overcurrent protection tripping due to the large rolling load of the S5 stand, or the strip breakage caused by insufficient deformation and the inability to form tension continuous rolling between the S4 and S5 stands.

[0039] 3. Combining the conditions in step one and step three forms a high-pressure, low-bending roll pattern, which can ensure that the strip rolling plate shape of each stand is double-sided wave during the start-up process, reduce the brittleness of high-grade non-oriented silicon steel, reduce the double-sided tension of the strip, and thus achieve the effect of avoiding strip breakage during the start-up of the original plate.

[0040] 4. Step four: Control the tension deviation of each frame within a certain range, and ensure that the dynamic tension of the strip on both sides of each frame is consistent to avoid strip deviation and reduce the risk of strip breakage during startup.

[0041] 5. Timely restoration of the bending roll force to the set value can ensure that the finished rolled strip shape meets the requirements and reduce the risk of strip breakage caused by excessive edge waviness on both sides of the strip on each stand.

[0042] The actual application is as follows.

[0043] The changes in various parameters and thickness of each stand during the startup process of the high-grade silicon steel slab: The thickness deviation of the two stands is 69μm (within the range of <200μm), and the parameter status when the mill speed is increased to 50m / min; the tension deviation of each stand is within the range of -0.3t to 0.3t, and the startup process is stable and normal.

[0044] During startup, the strip between the frames exhibits a double-sided wavy shape, effectively reducing the tension on both sides of the strip, lowering the stress on both sides during startup, and reducing the risk of strip breakage.

[0045] Condition of strip steel between frames after starting the machine: The strip shape between frames is good after starting the machine. Example

[0046] This example is applied to the rolling of a high-grade non-oriented silicon steel plate with a silicon content of 2.8%, with the thickness rolled from 2.2mm to 0.35mm. The operation method is as follows: 1. The rolling pressure correction coefficient 'a' for stands S1 to S4 is 0.05, 0.07, 0.1, and 0.13 respectively, and the rolling pressure for stand S5 is 1000t.

[0047] 2. The working roll bending force correction coefficient b takes values ​​of 0.18, 0.18, 0.2, 0.2, and 0.28 respectively.

[0048] 3. The intermediate roll bending force correction coefficient c takes the values ​​of 0.05, 0.05, 0.05, 0.05, and 0.2 respectively.

[0049] 4. During the start-up process, control the tension deviation of each frame within the range of -0.3t to 0.3t. Gradually restore the bending roll force of each frame according to the thickness of each frame. Finally, the strip steel is successfully started from the original plate without any strip breakage.

[0050] This example is applied to the rolling of high-grade non-oriented silicon steel slabs with a silicon content of 2.8%, with the thickness rolled from 2.2mm to 0.345mm. The operation method is as follows: 1. The rolling pressure correction coefficient 'a' for stands S1 to S4 is 0.08, 0.1, 0.12, and 0.12 respectively, and the rolling pressure for stand S5 is 950t.

[0051] 2. The working roll bending force correction coefficient b takes the values ​​of 0.2, 0.2, 0.21, 0.21, and 0.25 respectively.

[0052] 3. The intermediate roll bending force correction coefficient c takes the values ​​of 0.05, 0.05, 0.05, 0.05, and 0.15 respectively.

[0053] 4. During the start-up process, control the tension deviation of each frame within the range of -0.3t to 0.3t. Gradually restore the bending roll force of each frame according to the thickness of each frame. Finally, the strip steel is successfully started from the original plate without any strip breakage.

[0054] After this operating method was promoted and used, the production efficiency of high-grade silicon steel in the pickling and rolling mill was greatly improved, the proportion of broken strip and empty winding of high-grade silicon steel was greatly reduced, the proportion of empty winding recovery was greatly reduced, and the production cost of high-grade silicon steel was greatly reduced.

[0055] The pickling and rolling mill uses a single-channel uncoiling process to produce high-grade silicon steel, with a mill exit rolling speed of 400 m / min. After adopting dual-channel production, the rolling speed is increased to 500 m / min, and the production efficiency is increased by 25%. In 2019, the pickling and rolling mill produced 125,000 tons of high-grade silicon steel. By adopting this original plate starting method to achieve dual-channel uncoiling production, the annual output can be increased by 31,200 tons. Calculated at a profit of 300 yuan per ton for high-grade silicon steel, the annual profit can be increased by 9.36 million yuan.

[0056] The pickling and rolling mill produces 5 coils of high-grade silicon steel each month due to strip breakage and empty winding. These empty coils require two additional processes: heavy pickling and single-stand rolling, before they can be produced. The original plate starting method of this high-grade non-oriented silicon steel continuous rolling process can basically eliminate empty winding, greatly reducing the production process cost of high-grade non-oriented silicon steel.

[0057] In 2019, the energy consumption per ton of high-grade non-oriented silicon steel in the pickling and rolling mill was 140 kWh / t. After adopting this original plate starting method, the energy consumption per ton of high-grade non-oriented silicon steel was reduced to 120 kWh / t, resulting in an energy saving of 20 kWh per ton of steel.

[0058] The S5 stand of this invention adopts a constant rolling pressure mode, with the rolling pressure during the initial rolling of the raw plate specified as 900t~1000t. This invention eliminates the main motor protection tripping caused by excessive rolling load on the S5 stand during the initial rolling of the original raw plate, while also ensuring that the S5 stand has a certain amount of deformation, better realizing the tension construction between stands during the initial rolling stage and maintaining continuous rolling. This invention is the first application and should be within the protection scope of this invention.

[0059] This invention standardizes and formulates the selection ranges for rolling pressure correction coefficients, work roll bending force correction coefficients, and intermediate roll bending force correction coefficients during the roll start-up process, which should fall within the protection scope of this invention. The selection of each correction coefficient is primarily aimed at establishing a double-sided wave rolling pattern for strip steel with high pressure and low bending rolls between stands during the roll start-up process. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in this invention, based on the concept of this invention, should be included within the protection scope of this invention.

[0060] In this invention, ensuring that the S5 frame strip shape value is controlled within the range of 0~15I can greatly reduce the risk of brittle fracture of the strip edge during the initial processing of high-grade silicon steel, and should be covered within the scope of protection of this invention.

[0061] This invention greatly reduces the impact of the brittleness of high-grade non-oriented silicon steel raw materials on the starting process of the rolling mill, significantly reduces the risk of strip breakage in the original starting process, perfectly solves the drawbacks of the original production process, realizes dual-channel production at the entrance, greatly improves production efficiency, reduces energy consumption and process costs, and also lays a solid foundation for the development of continuous rolling processes for other high-grade and ultra-high-grade non-oriented silicon steel.

[0062] The above description is only a specific embodiment of the present invention, but the structural features protected by the present invention are not limited thereto. Any changes or modifications made by those skilled in the art within the scope of the present invention are covered by the patent scope of the present invention.

Claims

1. A method for starting the rolling mill of thin-gauge, ultra-high grade non-oriented silicon steel in continuous rolling processes, characterized in that: Includes the following steps: Step 1: Adjust the preset rolling pressure for stands S1~S4: The preset formula for the starting rolling pressure is: F x = F Sx *(1+a x In the formula: S x :S x Rack, x=1, 2, 3, 4, F x :S x Actual rolling pressure of the stand, t, F Sx Sx stand setting rolling pressure, t, a x : Rolling pressure correction factor, a x =0.05~0.15, x=1, 2, 3, 4; Step 2: Adjust the preset rolling pressure of the S5 stand: Fix the rolling pressure of the S5 stand at 900~1000t; Step 3: Adjust the bending force of the work rolls and intermediate rolls on each frame: Preset formula for the bending force of the work rolls during startup: W x =W Sx *(1- b x In the formula: S x :S x Rack, x=1, 2, 3, 4, 5, W x :S x Actual bending force of the working roll on the frame, t, W Sx :Sx frame setting work roll bending force, t, b x : Correction coefficient for bending force of work roll, b x =0.1~0.3, x=1, 2, 3, 4, 5; Preset formula for the bending force of the intermediate roller during startup: I x = I Sx *(1-c x In the formula: S x :S x Rack, x=1, 2, 3, 4, 5, I x :S x Actual bending force of the working roll on the frame, t, I Sx :Sx frame setting work roll bending force, t, c x : Correction coefficient for bending force of intermediate roll, c x =0.05~0.25, x=1, 2, 3, 4, 5; Step 4: Adjustment of tension deviation during start-up: Maintain the tension deviation value within the range of -0.3t to 0.3t during start-up; Step 5, Recovery of bending roll force during start-up: As the original plate is started up, the strip thickness of each frame will gradually be pressed to the corresponding set thickness value. When the actual strip thickness value deviates from the set thickness value within the range of 0~150μm, the bending roll of the corresponding frame is increased to gradually restore it to the set bending roll force. The S5 frame adjusts the bending roll according to the actual exit plate shape value. Step 6, Slitting and Cutting: Once the thickness of each frame reaches the corresponding thickness setting value, and the plate shape value at the S5 frame exit is within 15I, cutting and slitting can be performed, and the original plate is started.

2. The method for starting the rolling mill of thin-gauge ultra-high grade non-oriented silicon steel in continuous rolling process according to claim 1, characterized in that: In step five, the S5 frame adjusts the bending rollers according to the actual exit plate shape value as follows: if the plate shape is a medium wave, reduce the bending of the work roller or intermediate roller; if the plate shape is an edge wave, increase the bending of the work roller or intermediate roller to ensure that the plate shape value is within 15I.

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