A method for preventing surface adhesion defects of a cold-rolled low carbon steel sheet

Abstract

The application discloses a method for preventing surface sticking defects of cold-rolled low-carbon steel plates, and the molten iron conditions are as follows: Si is less than or equal to 0.08%, P is less than or equal to 0.140%, S is less than or equal to 0.040%, and the temperature is greater than or equal to 1280 DEG C. The molten iron needs desulfurization pretreatment, and the molten iron entering the converter is less than or equal to 0.003%. The sticking defects are further eliminated by the following process controls: converter process control, cold-rolled pickling unit process control, cold-rolled rolling mill process control, cover-type annealing furnace process control, skin pass mill process control and recoiling unit process control.

Description

TECHNICAL FIELD

[0001] The present application relates to a method for preventing surface sticking defects of cold-rolled low-carbon steel plates. BACKGROUND

[0002] After the acid continuous rolling mill unit of Bayi Steel Co., Ltd. was upgraded and transformed in 2018, the rolling model has been using light roller rolling all the time. When producing DC series cold forming stamping series products, sticking mark defects are prone to occur. During this period, professional and technical personnel have spent a lot of effort to study and solve the problem, but the effect is not good. Sticking mark defects occur in each batch of products, which not only causes the degradation of product quality, but also causes cost loss. After the sticking defect occurs, the steel coil is directly treated as degraded and out of contract, which makes it difficult to sell the steel coil, and the customer needs to be supplemented with rolling contract in time, which causes the delay of contract delivery period. The sticking defect has become a bottleneck for Bayi Steel to produce DC series automobile plate products, which affects the customer's use effect, affects the company's quality reputation, causes market loss, and affects the manufacturing capacity of Bayi Steel's cold rolling mill unit. SUMMARY

[0003] The purpose of the present application is to provide a method for preventing surface sticking defects of cold-rolled low-carbon steel plates, which can further eliminate the occurrence of sticking defects.

[0004] A method for preventing surface sticking defects of cold-rolled low-carbon steel plates,

[0005] 1) The acceptance standard of cold-rolled raw materials is as follows:

[0006] ;

[0007] Note: Residual elements [Cr]≤0.1%, [Ni]≤0.1%, [Cu]≤0.15%;

[0008] 2) Hot metal conditions: Si≤0.08%, P≤0.140%, S≤0.040%, temperature≥1280 degrees Celsius; Hot metal needs desulfurization pretreatment, and [S] of hot metal entering the converter≤0.003%;

[0009] 3) Converter process control: end point composition: [C]≤0.04%, [P]≤0.010%, [S]≤0.008%; Definite oxygen in the furnace before tapping, add deoxidizer according to the definite oxygen condition, maintain the tapping hole well, the tapping time is≥3.5 minutes, slide plate slag stopping tapping, the thickness of the ladle slag layer is controlled, and the phosphorus return of the converter tapping is not more than 0.003%;

[0010] 4) Hot coil convexity requirement: convexity≤40µm, wedge shape should not be greater than convexity;

[0011] 5) Process control design of cold rolling pickling unit: The temperature of hydrochloric acid in pickling unit 1-4# tank is controlled to 65-75℃, and the running speed of process section is controlled to 60-130m / min; 4 hours before producing special steel, the pickling unit is replaced with new acid 60-80m³ to ensure that the HCL content in 1# acid tank is ≥80g / L, and the iron ion content is ≤100g / L, so as to avoid the occurrence of under-pickling phenomenon; the temperature of water outlet of filter in 1# rinsing tank of pickling unit is 60-80℃, the conductivity of rinsing water in 2# rinsing tank is ≤100us / cm, and the conductivity of rinsing water in 4# rinsing tank is ≤20us / cm, so as to reduce the surface chloride ion content; the surface and running state of all squeezing rollers of pickling unit must be perfect, the roller surface is not allowed to have serious defects such as wear, bonding, scratch, peeling and thermal damage, and the running must not have the phenomenon of locked-rotor to prevent the occurrence of watermark defects on the surface of steel coil; the roller surface of each rotating roller, pinch roller and tension roller must not be attached with oil stains and dust; the pipe joint and valve table of acid circulation system of pickling unit are strictly prohibited to have acid leakage, and the opening of squeezing roller is strictly prohibited to have acid steam overflow to avoid environmental pollution; the drying temperature after rinsing is ≥80℃; the entry loop of pickling unit is ≥60%; the production plan of pickling entry is as follows: SPCC transition material requirements: 5 coils of SPCC are arranged for rolling with the same specification and width, and the raw material thickness is reduced by 1 stop steel, and the total reduction rate is controlled to be below 80%;

[0012] 6) Process control design of cold rolling mill unit: In addition to the conventional parameter control, the following 5 points are mainly controlled: emulsion system control: 2 hours before production, the indicators of emulsion of rolling mill are implemented, emulsion A system: 1.5%-3.0%, saponification value 140-160 mg KOH / g, impurity oil content ≤20%, iron powder content ≤200ppm, emulsion temperature requirement: 50-60℃, PH value requirement: 6.0-6.5, conductivity <300us / cm, chloride ion content ≤30ppm; emulsion B system: emulsion concentration 0.8%-1.5%, saponification value 140-160 mg KOH / g, impurity oil content ≤15%, iron powder content ≤150ppm, chloride ion content ≤30ppm; 5 racks work with roughness 3.0±0.2μm, rough rolling mode is adopted for rolling model, the total reduction rate is controlled to be 70%-82%, and the reduction rate of 5 racks is controlled to be 2-8%; oil leakage is not allowed between racks, the blowing pressure at the outlet of rolling mill is >0.5MPA; the nozzle is not allowed to be missing or blocked, the blowing angle of plate surface is 45-60°, and the condensed water at the outlet of rolling mill must not drop on the plate surface; plate shape control requirements: the target plate shape is controlled according to micro double edge wave, and the coiling tension stress is ≤29.5Mpa; the reflectivity of steel coil surface must be ≥60%, and the value below the value must be disposed in the later process;

[0013] 7) Process control design of batch annealing furnace: The process of batch annealing furnace is full hydrogen complete annealing, the temperature of steel coil out of the furnace should not be higher than 105℃, according to this principle, a set of process control points of batch annealing furnace is developed: the ash and carbon black on the furnace table is cleaned before production; the hydrogen blowing quantity of the second section is controlled at 25-30m³ / h to ensure that the emulsion residual liquid is fully volatilized; when the steel coil is heated, the heating cover in good condition is selected to avoid or reduce the alarm frequency of the furnace table; the problem points of the heating cover are fully combed and solved to ensure that the gas electric regulating valve operates normally without jamming; the number of operating burners reaches more than 6; the pipe gallery of the final cooling table is cleaned once every quarter to prevent the ash and sundries in the pipe gallery from being sucked into the steel coil; the surface reflectivity of the incoming steel coil should be less than 60%, and the 430℃ holding platform should be increased for at least 6h; the cooling temperature out of the furnace is ≤45℃;

[0014] 8) Process control design of skin pass mill: The plate and roll of the skin pass mill are executed according to the clean production regulations, the skin pass liquid nozzles are checked before production, the emulsion nozzles in the middle of the strip should not be blocked, among which when the width of the steel coil is less than 1000mm, the upper roll edge 2 nozzles are blocked to prevent the skin pass liquid from leaking out of the roll gap at the edge of the strip and splashing onto the strip surface; the temperature of the skin pass liquid mixing tank, the original liquid tank and the desalted water tank is controlled at 25-40℃; the blowing jet pressure is >0.43MPA, and the blowing angle is controlled at 45°-60°; the skin pass liquid should be in a fan shape and sprayed to the upper and lower work roll gap without blocking; the constant rolling force mode is adopted, and other parameters such as bending roll force are adjusted according to the plate shape, the rolling force of IF steel should not be too large, only the plate shape and roughness should be controlled to prevent hardening; the skin pass rolling force is set as follows: the finished product thickness ≤0.85mm, the finished product width ≤1035mm, the rolling force is 1000kN; the finished product width >1035mm, the rolling force is 1100kN; the finished product thickness >0.85mm, the finished product width is all the widths, and the rolling force is 1200kN;

[0015] 9) Process control design of recoiling mill: The rotating roll system, leveler roll system and deburring roll are cleaned and wiped once, especially the leveler roll system and deburring roll surface should be clean and natural; the outer ring of the incoming material has skin pass liquid residue or oil stains, which should be cut off at the entrance to prevent defects from adhering to the rotating roll system and then being copied to the strip surface; the oiling quantity standard of the recoiling mill is 1.1-1.5g / m², and there should be no leakage or uneven coating; the edge cutting requirement is that after edge cutting, the edge should be free of burrs, edge cracks, ears and edge wires.

[0016] By this method, the bonding defects of DC series products are reduced from 90% in 2022 to 0% in 2023, and the bonding defects of DC series products are completely solved. The application is suitable for the production of all kinds of cold-rolled steel, and has important significance for batch production of deep drawing performance strip steel, wide application range and wide promotion value. DETAILED DESCRIPTION

[0017] A method for preventing surface bonding defects of cold-rolled low-carbon steel plate,

[0018] 1) The acceptance standard of cold-rolled raw materials is as follows: the chemical composition control of the raw materials is as follows:

[0019] ;

[0020] Note: residual elements [Cr]≤0.1%, [Ni]≤0.1%, [Cu]≤0.15%;

[0021] 2) Hot metal conditions: Si≤0.08%, P≤0.140%, S≤0.040%, temperature≥1280℃; the hot metal needs desulfurization pretreatment, and the [S] of the hot metal entering the converter is≤0.003%;

[0022] 3) Converter process control: end point composition: [C]≤0.04%, [P]≤0.010%, [S]≤0.008%; oxygen is determined in the furnace before tapping, deoxidizing agent is added according to the oxygen determination, the tapping hole is maintained well, the tapping time is≥3.5 minutes, the slide plate is used for slag blocking, the thickness of the ladle slag layer is controlled, and the phosphorus return of the converter tapping is not more than 0.003%;

[0023] 4) Hot coil convexity requirement: convexity≤40µm, and the wedge shape should not be greater than the convexity;

[0024] 5) Process control design for the cold rolling pickling line: The hydrochloric acid temperature in the pickling line's 1-4# tanks is controlled to 65-75°C, and the process section operating speed is controlled to 60-130m / min. Before producing special steel grades, the pickling line replaces 60-80m³ of new acid 4 hours in advance to ensure that the HCl content of the acid solution in the 1# acid tank is ≥80g / L and the iron ion content is ≤100g / L to prevent under-pickling. The water outlet temperature of the filter in the 1# rinsing tank of the pickling line is 60-80°C, the conductivity of the rinse water in the 2# rinsing tank is ≤100us / cm, and the conductivity of the rinse water in the 4# rinsing tank is ≤20us / cm to reduce the surface chloride ion content. All squeeze rollers in the pickling line are cleaned. The surface and running condition must be intact. The roller surface is not allowed to have serious wear, adhesion, scratches, peeling, thermal damage and other defects. There must be no stalling during operation to prevent watermark defects on the surface of the steel coil. The roller surfaces of the steering rollers, pinch rollers, tension rollers and other operating rollers must not be stained with oil or dust. The acid circulation system pipe joints and valve tables of the pickling unit are strictly prohibited from leaking acid, and the acid steam is strictly prohibited from overflowing at the opening of the squeeze roller to avoid polluting the environment. The drying temperature after rinsing is ≥80℃. The amount of loops at the inlet of the pickling unit is ≥60%. The production plan arrangement at the pickling inlet: SPCC transition material requirements: 5 rolls of SPCC with the same specifications and width are arranged for rolling, the raw material thickness should be reduced by 1 steel stop, and the total reduction rate is controlled below 80%;

[0025] 6) Process control design of cold rolling mill unit: In addition to conventional parameter control, the rolling mill unit mainly controls the following 5 points: Emulsion system control: 2 hours before production, the emulsion indicators of the rolling mill are implemented, emulsion A system: 1.5%~3.0%, saponification value 140-160 mg KOH / g, miscellaneous oil content ≤20%, iron powder content ≤200ppm, emulsion temperature requirement: 50~60℃, pH value requirement: 6.0~6.5, conductivity <300us / cm, chloride ion content ≤30ppm; emulsion B system: emulsion concentration 0.8%~1.5%, saponification value 140~160 mg KOH / g, miscellaneous oil content ≤15%, iron powder content ≤150ppm, chloride ion content ≤30ppm; the 5-stand working surface adopts a roughness of 3.0±0.2μm, the rolling model adopts a rough roller rolling method, the total reduction rate is controlled at 70%~82%, and the 5-stand reduction rate is controlled at 2-8%; oil leakage is not allowed between stands, and the purge pressure at the rolling mill outlet is greater than 0.5MPA; nozzles are not allowed to be missing or blocked, the plate surface purge angle is 45-60°, and condensate at the rolling mill outlet must not drip onto the strip surface; plate shape control requirements: the target plate shape is controlled as slight double-sided wave, and the curling tensile stress is ≤29.5Mpa; the surface reflectivity of the steel coil must be ≥60%. If it is lower than this value, emergency treatment must be carried out in the subsequent process.

[0026] 7) Process control design of batch annealing furnace: The process of batch annealing furnace is full hydrogen complete annealing, the temperature of steel coil out of the furnace should not be higher than 105℃, according to this principle, a set of process control points of batch annealing furnace are formulated: the accumulated dust and carbon black on the furnace table are cleaned before production; the hydrogen blowing amount of the second section is controlled at 25-30m³ / h to ensure that the emulsion residual liquid is fully volatilized; when the steel coil is heated, a good heating cover is selected to avoid or reduce the number of alarm of the furnace table; the problem points of the heating cover are fully combed and solved to ensure that the gas electric regulating valve operates normally without jamming; the number of operating burners reaches more than 6; the pipe gallery of the final cooling table is cleaned once every quarter to prevent the accumulated dust and sundries in the pipe gallery from being sucked into the steel coil; the surface reflectivity of the incoming steel coil should be less than 60%, and the 430℃ holding platform should be increased for at least 6h; the cooling temperature out of the furnace is ≤45℃;

[0027] 8) Process control design of skin pass mill: The plate way and roll way of the skin pass mill are executed according to the clean production regulations, the skin pass liquid nozzles are checked before production, the emulsion nozzles in the middle of the strip steel should not be blocked, among which when the width of the steel coil is less than 1000mm, the upper roll edge 2 nozzles are blocked to prevent the skin pass liquid from spilling out from the roll gap of the strip steel edge to the strip steel plate surface; the temperature of the skin pass liquid mixing liquid tank, the original liquid tank and the desalted water tank is controlled at 25-40℃; the blowing jet pressure is >0.43MPA, the blowing angle control value is 45°-60°; the skin pass liquid should be in a fan shape and sprayed to the upper and lower work roll gap without blocking; the constant rolling force mode is adopted, the bending roll force and other parameters are adjusted according to the plate shape, the IF steel does not adopt excessive rolling force, only the plate shape and roughness are controlled to prevent hardening; the skin pass rolling force is set as follows: the finished product thickness ≤0.85mm, the finished product width ≤1035mm, the rolling force is 1000kN; the finished product width >1035mm, the rolling force is 1100kN; the finished product thickness >0.85mm, the finished product width is all the widths, and the rolling force is 1200kN;

[0028] 9) Process control design of recoiling mill: The rotating roll system, leveler roll system is cleaned and wiped once, especially the leveler roll system and deburring roll surface must be clean and see the original color; the incoming outer ring plate surface has skin pass liquid residue or oil stains, which must be cut off cleanly at the entrance to prevent defects from adhering to the rotating roll system and then copied to the strip steel plate surface; the recoiling mill oiling amount standard: medium coating oil 1.1-1.5g / m², without leakage or uneven coating; edge cutting requirement: after edge cutting, the edge should be free of burrs, edge cracks, ears and edge wires and other defects attached to the edge.

[0029] Example:

[0030] 1, The composition is strictly executed according to the control requirements, the molten iron needs desulfurization pretreatment, the [S] of the molten iron into the converter is ≤0.003%, the convexity is ≤40µm, and the wedge shape should not be greater than the convexity.

[0031] 2. The temperature of the water outlet of the pickling unit 1# rinsing tank filter is 60-80℃, the rinsing water conductivity of 2# rinsing tank is ≤100us / cm, and the rinsing water conductivity of 4# rinsing tank is ≤20us / cm, reducing the surface chloride ion content.

[0032] 3. The surface and running state of all squeezing rollers of the pickling unit must be in good condition. The roller surface is not allowed to have serious defects such as wear, bonding, scratches, peeling, thermal damage, etc. No blocking phenomenon occurs during operation, and the steel coil surface is strictly prohibited from having water mark defects that cannot be dried.

[0033] 4. The rolling mill unit further controls the cleanliness of the steel coil surface, and the reflectivity of the steel coil surface must be ≥60%. If the value is lower, the information of the steel coil must be fed back to the bell-type furnace, flattening, and rewinding unit in time.

[0034] 5. Check the blowing effect of the rolling mill unit. The outlet plate surface cannot have obvious emulsion residue. Track and check the emulsion performance index every day, pay attention to control the iron powder content, A system <200ppm, B system <150ppm. The concentration of emulsion B system is 1.0% (0.8%-1.5%).

[0035] 6. The roughness of 5 stands is 3.0±0.2μm, the rolling model adopts rough roller rolling mode, and the total reduction rate is controlled at 70%-82%, and the reduction rate of 5 stands is controlled at 2-8%.

[0036] 7. The target plate shape is controlled according to the micro-double edge wave, and the curling tension stress is ≤29.5Mpa.

[0037] 8. The bell-type furnace unit cleans the accumulated ash on the furnace table before annealing to prevent ash residue from remaining on the furnace table. During annealing, the second stage hydrogen blowing amount is controlled at 25-30m³ / h. When the temperature of the furnace table material chamber is 350-450℃ and the alarm affects the heating and temperature rising of the steel coil, the second stage hydrogen blowing time must be extended, the evaporation of emulsion must be improved, the surface reflectivity of the incoming steel coil must be lower than 52%, and the 430℃ holding platform must be increased by at least 6h.

[0038] 9. The bell-type furnace unit must start the furnace fan within 15 minutes. The top layer of the convection plate of each furnace table of the final cooling table must be covered to prevent uneven cooling, and the cooling temperature after discharge is ≤45℃.

[0039] 10. The temperature of the leveling liquid mixing tank, the original liquid tank, and the desalination water tank is controlled at 25-40℃.

[0040] 11. The leveling liquid must be sprayed in a fan shape to the gap between the upper and lower work rolls, and the phenomenon of blockage must not occur.

[0041] 12. The angle of the blowing device of the flattening unit is controlled at 45°-60°, and the position is adjusted in time when it is found to be deviated.

[0042] 13. When the blowing pressure of the leveler unit is lower than 4.3 bar of the process requirement, the machine must be stopped in time, and the production can continue after the pressure returns to normal.

[0043] 14. The winding machine unit cleans and wipes each rotating roller system and the stretch leveler roller system once a week, especially the roller surface of the stretch leveler roller system and the deburring roller must be clean and white.

[0044] 15. The oiling amount standard of the winding machine unit: 1.1-1.5 g / m² for medium oiling, and there must be no missing or uneven oiling phenomenon.

Claims

1. A method for preventing surface adhesion defects of cold-rolled low-carbon steel sheets, characterized in that: 1) Acceptance criteria for cold-rolled raw materials, the chemical composition of raw materials is controlled as follows: ； Note: Residual elements [Cr]≤0.1%, [Ni]≤0.1%, [Cu]≤0.15%; 2) Hot metal conditions: Si≤0.08%, P≤0.140%, S≤0.040%, temperature≥1280 degrees Celsius; hot metal needs to be pre-treated with desulfurization, hot metal entering the converter [S]≤0.003%; 3) Converter process control: End point composition: [C] ≤ 0.04%, [P] ≤ 0.010%, [S] ≤ 0.008%; oxygen is determined in the furnace before tapping, deoxidizer is added according to the oxygen determination, the tapping port is well maintained, the tapping time is ≥ 3.5 minutes, the slide plate is used to block the slag during tapping, the ladle slag layer thickness is controlled, and the phosphorus recovery of the converter tapping is required to be no more than 0.003%; 4) Hot coil convexity requirements: convexity ≤ 40µm, wedge shape shall not be greater than convexity; 5) Process control design for the cold rolling pickling line: The hydrochloric acid temperature in the 1-4# tanks of the pickling line is controlled to 65-75°C, and the operating speed of the process section is controlled to 60-130m / min. Before producing special steel grades, the pickling line should replace 60-80m³ of new acid 4 hours in advance to ensure that the HCl content of the acid solution in the 1# acid tank is ≥80g / L and the iron ion content is ≤100g / L to prevent under-pickling. The water outlet temperature of the filter in the 1# rinsing tank of the pickling line is 60-80°C, the conductivity of the rinse water in the 2# rinsing tank is ≤100us / cm, and the conductivity of the rinse water in the 4# rinsing tank is ≤20us / cm to reduce the surface chloride ion content. The surface and operating condition of all squeeze rollers in the pickling line must be intact, and the roller surface must not have severe wear, adhesion, scratches, peeling, or thermal damage defects. There must be no stalling during operation to prevent watermark defects on the surface of the steel coil. The roller surface must be free of oil, dirt, and dust during operation. Acid leakage from the pipe joints and valve tables of the acid circulation system of the pickling unit is strictly prohibited, and acid vapor must not overflow from the opening of the squeeze rollers to avoid environmental pollution. The drying temperature after rinsing must be ≥80°C. The amount of loops at the inlet of the pickling unit must be ≥60%. Pickling entrance production plan arrangement: SPCC transition material requirements: 5 rolls of SPCC with the same specifications and width are arranged for rolling, the raw material thickness should be reduced by 1 steel, and the total reduction rate should be controlled below 80%; 6) Process control design of cold rolling mill unit: In addition to conventional parameter control, the rolling mill unit mainly controls the following 5 points: Emulsion system control: 2 hours before production, the emulsion indicators of the rolling mill are implemented, emulsion A system: 1.5%~3.0%, saponification value 140-160 mg KOH / g, miscellaneous oil content ≤20%, iron powder content ≤200ppm, emulsion temperature requirement: 50~60℃, pH value requirement: 6.0~6.5, conductivity <300us / cm, chloride ion content ≤30ppm; emulsion B system: emulsion concentration 0.8%~1.5%, saponification value 140~160 mg KOH / g, miscellaneous oil content ≤15%, iron powder content ≤150ppm, chloride ion content ≤30ppm; the 5-stand working surface adopts a roughness of 3.0±0.2μm, the rolling model adopts a rough roller rolling method, the total reduction rate is controlled at 70%~82%, and the 5-stand reduction rate is controlled at 2-8%; oil leakage is not allowed between stands, and the purge pressure at the rolling mill outlet is greater than 0.5MPA; nozzles are not allowed to be missing or blocked, the plate surface purge angle is 45-60°, and condensate at the rolling mill outlet must not drip onto the strip surface; plate shape control requirements: the target plate shape is controlled as slight double-sided wave, and the curling tensile stress is ≤29.5Mpa; the surface reflectivity of the steel coil must be ≥60%. If it is lower than this value, emergency treatment must be carried out in the subsequent process. 7) Process control design of bell-type annealing furnace: The bell-type annealing process uses full hydrogen annealing, and the temperature of the steel coil out of the furnace shall not exceed 105℃. According to this principle, a complete set of process control points for bell-type annealing furnaces are formulated: Before production, the ash and carbon black on the furnace table must be cleaned until there is no ash accumulation; the hydrogen blowing rate in the second stage is controlled at 25-30m³ / h to ensure that the residual emulsion is fully volatilized; when heating the steel coil, use a heating hood in good condition to avoid or reduce the number of furnace alarms; comprehensively sort out and solve the problem points of the heating hood to ensure that the gas electric regulating valve operates normally without obstruction; the number of burners in operation reaches more than 6; the final cooling station corridor is cleaned once a quarter to prevent the accumulation of ash and debris in the corridor from being sucked into the steel coil; the surface reflectivity of the incoming steel coil must be less than 60%, and a 430℃ insulation platform must be added for at least 6 hours; the cooling temperature out of the furnace is ≤45℃; 8) Process control design of the leveling mill: The plate and roller tables of the leveling mill shall be operated in accordance with the clean production regulations. The leveling liquid nozzles shall be inspected before production. The emulsion nozzles in the middle of the strip shall not be clogged. When producing steel coils with a width of less than 1000mm, the two nozzles on the edge of the upper roller shall be blocked to prevent the leveling liquid from escaping from the roller gap at the edge of the strip and splashing onto the strip surface. The temperature of the leveling liquid mixture tank, raw liquid tank, and desalted water tank shall be controlled at 25-40℃; the purge jet pressure shall be greater than 0.43MPA, and the purge angle shall be controlled at 45°-60°. The leveling fluid is sprayed in a fan-shaped manner to the gap between the upper and lower working rolls, and no clogging is allowed. A constant rolling force mode is used, and the bending roll force parameters are adjusted according to the plate shape. Excessive rolling force is not used for IF steel, and only the plate shape and roughness are controlled to prevent hardening. The leveling rolling force is set as follows: for finished product thickness ≤ 0.85mm, finished product width ≤ 1035mm, the rolling force is 1000kN; for finished product width > 1035mm, the rolling force is 1100kN; for finished product thickness > 0.85mm, and finished product width is all widths, the rolling force is 1200kN. 9) Process control design of the rewinding unit: Clean and wipe each rotating roller system and the straightening machine roller system once. If there is leveling liquid residue or oil on the outer ring of the incoming material, the outer ring shall be cut off at the entrance to prevent defects from adhering to the rotating roller system and then being replicated on the strip surface; the oiling amount standard of the rewinding unit: 1.1-1.5g / m² of medium oiling, and no omissions or uneven oiling shall occur; edge trimming requirements: After edge trimming, there shall be no burrs, cracks, ears or wire defects attached to the edge.

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