A high-efficiency rolling production method for hot-rolled carbon steel thin gauge strips

Abstract

The present application relates to the technical field of metallurgy, more particularly to a kind of high-efficiency rolling production method of plain carbon thin gauge hot-rolled strip.The present application comprises heating device, descaling device, rolling device, cooling device and packing device, through the optimization of the chemical composition and size of plain carbon steel continuous casting billet and hot charging continuous casting billet, through the heating device, the rough rolling, finish rolling and rough descaling and finish descaling of the strip steel are carried out by the rolling device in combination with the descaling device, after cooling by the cooling device, the strip steel is coiled, and finally the packing of the strip steel is completed by the packing device.The present application has the beneficial effects of improving production efficiency, being stable and reliable in production, small in oxidation loss, high in material yield, small in size fluctuation, good in plate shape, and low in thickness of iron oxide scale.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of metallurgy, more particularly, to a production method for high-efficiency rolling of plain carbon thin-gauge hot-rolled strips. BACKGROUND

[0002] Hot-rolled strips are one of the important basic metallurgical products for the development of the national economy in China, and have excellent properties such as high strength, good toughness and easy processing. Hot-rolled strips are not only used as finished steel products, but also as raw materials, which can be punched, bent and welded into steel pipes, section steels, channel steels, I-beams and other structural members with complex cross sections and various metal products according to needs. Hot-rolled strips are important steel products with large output, wide application and various types. They are mainly used for the production of welded steel pipes, cold-bending section steels, cold-rolled strips, photovoltaic supports, high-speed guardrails, home appliance and furniture accessories, automobile accessories and the like. With the development of the national economy, hot-rolled strips are developing towards high strength, weight reduction and environmentally friendly materials such as hot-to-cold, i.e. the use of plain carbon thin-gauge strips is gradually increasing, and the market demand is huge.

[0003] The plain carbon thin-gauge strips have the following technical problems: first, the production efficiency of thin-gauge products is low, and the daily output of a single line is from 1800 tons to 6000 tons, which cannot be produced efficiently, resulting in high production cost. Second, the combustion control mode of the heating furnace is manually adjusted, and the fireman adjusts the flow and ratio of coal gas and air according to his own experience, which causes uneven furnace temperature control, low temperature control accuracy, improper air-fuel ratio control, large fuel gas consumption, serious oxidation loss, long heating time of continuous casting billets for thin-gauge strips and high heating temperature, and the continuous casting billets are easy to bend at both ends during the heating process. Third, since no cooling device is applied after rolling of the production line, the oxide scale of the cold-rolled base material is too thick, which causes long pickling time, high acid consumption and low production efficiency of downstream users. Fourth, the plate shape of thin-gauge strips is not good, which is an important reason for production accidents and quality accidents. Rolling accidents are easy to occur during the production of thin-gauge strips, which are mostly caused by poor plate shape, and steel temperature change and large reduction have a great influence on the plate shape of thin-gauge strips. SUMMARY

[0004] To solve the above technical problems, the present application relates to the technical field of metallurgy, more particularly, to a production method for high-efficiency rolling of plain carbon thin-gauge hot-rolled strips.

[0005] The technical scheme adopted by the present application is as follows: a production device for high-efficiency rolling of plain carbon thin-gauge hot-rolled strips, comprising a heating device, a descaling device, a rolling device, a cooling device, a coiling device and a packaging device, characterized in that:

[0006] The heating device can be used for heating the strip by setting the heating time, heating temperature and furnace pressure in the heating device;

[0007] A descaling device is arranged on one side of the heating device to remove the scale layer on the surface of the strip steel after being heated by the heating device.

[0008] A rolling device is connected with the descaling device and can roll the strip steel.

[0009] A cooling device is connected with the rolling device and can cool the rolled strip steel.

[0010] A packing device can pack the strip steel.

[0011] Further, the heating device is provided with a heating furnace and a temperature control system, the strip steel can be heated and preformed by the heating furnace, and the temperature control system can control the heating time, heating temperature and furnace pressure of the heating furnace.

[0012] Further, the rolling device includes a rough rolling mill and a finish rolling mill, the rough rolling mill can roll the strip steel by a rough rolling process, and the finish rolling mill can roll the strip steel by a finish rolling process.

[0013] Further, the rough rolling mill and the finish rolling mill are provided with the descaling device on one side, and the descaling device can remove the scale by high-pressure water.

[0014] Further, the cooling device includes A / B line vertical cooling device and A / B line chain plate transport cooling device.

[0015] Further, a high-efficiency rolling production method for common carbon thin-gauge hot-rolled strip steel is characterized in that the steps of the method are as follows:

[0016] S1, the chemical composition and size of the preferred common carbon steel continuous casting billet are selected;

[0017] S2, the continuous casting billet is hot sent at 600-800℃;

[0018] S3, the continuous casting billet in S2 is sent into the heating furnace for heating, the heating section temperature is 1100-1250℃, the soaking section temperature is 1200-1260℃, and the furnace heating time is 65-80min;

[0019] S4, the descaling device is used to remove the scale after the furnace by high-pressure water, and the descaling pressure is 16-22MPa;

[0020] S5. Rough rolling and rough descaling: Rough rolling is performed using a continuous rolling process on the rough rolling mill, including 8 passes: 1 vertical-1 horizontal-2 horizontal-2 vertical-3 horizontal-4 horizontal-3 vertical-5 horizontal. The initial rolling temperature is set to 1120-1160℃. After the first vertical pass, high-pressure water descaling is performed using the descaling device, with a descaling pressure of 10-16MPa. The time interval between the first vertical pass being thrown out and the next pass being bitten in is controlled to be 14-16s. The speed of the fifth horizontal pass is set to 2.2-2.5m / s. The cumulative reduction rate of the rough rolling is set to 83.03-84.24%. The first and second vertical passes are rolled using vertical roll pass profiles, with a reduction per pass of ≤40mm.

[0021] S6. The intermediate billet is insulated with a heat insulation cover. The thickness of the intermediate billet is 26-28mm, and the temperature drop is controlled within 20℃.

[0022] S7. Finishing and Descaling: Finishing is performed using a continuous rolling process on the finishing mill, including 11 passes, each pass consisting of 1 vertical-1 horizontal-2 horizontal-2 vertical-3 horizontal-4 horizontal-5 horizontal-6 horizontal-7 horizontal-8 horizontal-9 horizontal. The starting temperature for finishing is set to 1010–1050°C. After the first vertical pass, the descaling device is used to descale the steel using high-pressure water. The descaling pressure is set to 10–16 MPa. The time interval between the first vertical pass being discarded and the next steel pass being bitten in can be controlled to be 3.5–4 seconds. 0s, the finishing rolling adopts one-time speed-up rolling, and the speed remains unchanged after acceleration. The speed does not decrease when the steel is thrown. The finishing rolling 9-level strip threading speed is 16.3-15.8m / s, the 9-level acceleration speed is 17.5-18.2m / s, the 9-level steel throwing speed is set to 17.5-18.2m / s, and the speed difference between the acceleration speed and the threading speed is set to 2.2-2.4m / s. At the same time, looper control is adopted, and rolling is carried out under constant low tension. The looper height is set to 8-20° to avoid steel pulling and steel piling, and to ensure rolling stability.

[0023] S8. Twist: The strip steel passes through a twist guide groove, changing from flat to upright.

[0024] S9. Vertical cooling is performed using the A / B line. After the strip is twisted, it is alternately switched to the A / B line by the forked guide plate to perform vertical cooling of the strip.

[0025] S10. The strip steel is transported and cooled via the A / B line chain plate. The strip steel is fed into the flat chain conveyor for air cooling by a serpentine vibrator. Each flat chain conveyor can hold two strip steel pieces.

[0026] S11, winding;

[0027] S12. Circumferential packaging: Steel strapping can be used for circumferential welding packaging.

[0028] S13. Laser marking: A multi-dimensional laser robot system can be used for marking. The robot has 6 axes and 6 degrees of freedom. The maximum speed of the axis movement is set to 175-360° / s. It can mark information such as steel grade, furnace number, factory name, and date.

[0029] S14. Lateral marking: Steel strip can be used for lateral welding and packaging to complete the production of the hot-rolled strip steel.

[0030] Furthermore, the preferred chemical composition of the carbon steel continuous casting billet, by mass percentage, includes the following chemical components: C: ≤0.25%, Si: ≤0.35%, Mn: ≤1.50%, P: ≤0.035%, S: ≤0.045%, Cr ≤0.30%, Ni ≤0.30%, Cu ≤0.30%, and the remainder is Fe.

[0031] Furthermore, the dimensions of the continuously cast billet are set to 165mm*380mm*11.1m.

[0032] Furthermore, the reduction rate of the finishing flat rolling pass is set to 8-40%, the reduction rate of each pass gradually decreases, and the reduction rate of the last two passes is set to 8-20%. The finishing 1st and 2nd vertical rolling passes are rolled with vertical rolls, the reduction amount per pass is ≤20mm, and the finishing rolling temperature is set to 900-930℃.

[0033] Furthermore, the cooling rate of the vertical A / B line cooling system is 210-280℃ / s, and the outlet temperature is 730-780℃.

[0034] Furthermore, the winding adopts A / B line vertical winding, and a five-roll tension roller is set in front of the vertical winding machine to generate a certain tension between the winding machine and the tension roller. The maximum winding speed is 6.5m / s, and the winding temperature is 500-650℃.

[0035] The advantages and positive effects of this invention are as follows: Due to the use of intelligent combustion technology for heating, the target values ​​for the heating and soaking sections are controlled with an accuracy of ±10℃, improving the temperature uniformity of the billet's cross-section and length, ensuring minimal temperature fluctuations during initial rolling, uniform strip deformation, improved rolling stability, and enhanced uniformity of the finished product's mechanical properties. The air-fuel ratio is automatically optimized by dynamically adjusting the combustion air flow based on the gas flow rate. Under certain heating load conditions, the furnace temperature change rate is statistically analyzed to maintain the optimal air-fuel ratio, achieving optimal and fastest combustion. The furnace atmosphere, with a residual oxygen content of 0.5-2.5% and a furnace pressure controlled at 5-25 Pa, can be controlled as a slightly oxidizing atmosphere, reducing over-oxidation of the continuously cast billet and minimizing yield reduction.

[0036] To improve yield and rolling efficiency, this invention eliminates the use of flying shearing and tail-cutting processes on the intermediate billet before finishing rolling.

[0037] The present application adopts a one-time speed-up rolling process, and the speed is unchanged after one-time speed-up, and the steel is not speeded down during the steel throwing, so as to improve the rolling efficiency. The strip steel head runs at a speed of 15.3-15.8 m / s during the threading, and the threading speed cannot be too low to prevent the head temperature from being too low, the strip steel head from being cracked, and the roll from being damaged. The threading speed cannot be too high to reduce the risk of head folding and cracking. Then, the speed is accelerated to 17.5-18.2 m / s at one time until the steel throwing is completed, and the speed is not reduced during the steel throwing, so as to reduce the pure rolling time and improve the production efficiency. The speed difference between the acceleration speed and the threading speed is controlled, and the smaller the speed difference between the acceleration speed and the threading speed, the smaller the strip steel same strip difference and the size fluctuation. On the contrary, the larger the speed difference between the acceleration speed and the threading speed, the larger the strip steel same strip difference and the size fluctuation.

[0038] The finishing rolling flat rolling reduction rate of the present application gradually decreases, ensures the stable rolling of thin specifications, the reduction rate of the last two passes is not easy to be too large, prevents the buckling head from being generated due to the too large reduction rate, and the high speed and large reduction rate has an adverse effect on the plate shape.

[0039] The production efficiency is improved, the production is stable and reliable, the oxidation burning loss is small, the material yield is high, the size fluctuation is small, the plate shape is good, and the iron oxide skin thickness is low. BRIEF DESCRIPTION OF DRAWINGS

[0040] Figure 1 is a flowchart of an embodiment of the present application; DETAILED DESCRIPTION

[0041] In order to make the purpose, technical scheme and advantages of the present application more clear and explicit, the present application is further described in detail below in combination with specific embodiments and with reference to the drawings. It should be understood that these descriptions are only exemplary and are not intended to limit the scope of the present application. In addition, in the following description, the description of the technology of the known structure is omitted to avoid unnecessary confusion of the concept of the present application.

[0042] The embodiments of the present application are described below in combination with the drawings.

[0043] In the description of the embodiments of the present application, it should be understood that the orientation or positional relationship indicated by the terms "top", "bottom" and the like is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present application and simplifying the description, and therefore cannot be understood as indicating or implying that the indicated device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present application. In the description of the present application, it should be noted that unless otherwise explicitly specified and limited, the terms "set", "connected" should be understood broadly, for example, it can be fixedly connected, or it can be detachably connected, or integrally connected; it can be directly connected, or indirectly connected through an intermediate medium, or it can be connected inside two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood through specific circumstances.

[0044] The application discloses a high-efficiency rolling production device for hot-rolled thin-gauge carbon steel strips, which comprises a heating device, a descaling device, a rolling device, a cooling device and a packing device, wherein the heating device is heated by intelligent combustion technology, and the heating time, the heating temperature and the furnace pressure in the heating device are used for heating the strip; the descaling device can remove the scale on the surface of the strip heated by the heating device through high-pressure water; the rolling device comprises rough rolling mills and finishing rolling mills; the surface impurities of the strip are removed by the descaling device after the rough rolling and the finishing rolling; the strip after the rough rolling and the finishing rolling is vertically straightened by a twist guide groove and is cooled by the cooling device; finally, the strip is packed and marked by the packing device, the rolling production of the hot-rolled strip is completed, the production efficiency is improved, the production is stable and reliable, the oxidation loss is small, the material yield is high, the size fluctuation is small, the plate shape is good, and the thickness of the iron oxide scale is low.

[0045] Preferably, the heating device comprises a heating furnace and a temperature control system, the temperature control system is used for controlling the temperature of the heating furnace, the heating section temperature is 1100-1250 DEG C, the soaking section temperature is 1200-1260 DEG C, the target control precision is ± 10 DEG C, the air-fuel ratio is self-optimizing controlled, the air-fuel ratio is 0.60-0.95, the residual oxygen content is 0.50-2.5%, the furnace pressure is controlled to be 5-25 Pa, the coal gas heat value is 800-950 Kcal / Nm3, and the furnace heating time is 65-80 min.

[0046] Preferably, the rolling device comprises rough rolling mills and finishing rolling mills; in the embodiment, the strip is rough-rolled by the rough rolling mills and is finishing-rolled by the finishing rolling mills; the rough rolling adopts full continuous rolling process, including 8 passes of continuous rolling, and the rolling form is 1 vertical-1 horizontal-2 horizontal-2 vertical-3 horizontal-4 horizontal-3 vertical-5 horizontal; the rough rolling temperature is 1120-1160 DEG C, and the high-pressure water descaling is performed after the rough rolling 1 vertical in combination with the descaling device, and the descaling pressure is set to be 10-16 MPa; the time interval between the 1 vertical rough rolling and the next strip biting is controlled to be 14-16 s, the interval between the two strip billets is shortened, and the rear-end collision is ensured; the rough rolling 5 horizontal speed is set to be 2.2-2.5 m / s; the rough rolling speed is improved; in order to ensure the rolling temperature of the thin-gauge finishing rolling, the higher and more uniform the finishing rolling temperature is, the more stable the rolling is, the non-uniform deformation, the tailing, the unstable loop angle and the intermediate billet temperature drop are reduced; the rough rolling horizontal rolling cumulative reduction is 83.03-84.24%; the rough rolling 1 vertical and 2 vertical adopt vertical roll pass rolling, and the pass reduction is ≤40 mm; the intermediate billet thickness is 26-28 mm; the intermediate billet thickness ensures the stable rolling of the thin gauge; if the intermediate billet is too thin, the temperature drop speed is fast, the temperature is too low in the finishing rolling stage, and the vertical roll reduction is easy to produce bending, which is not conducive to the stable rolling; if the intermediate billet thickness is too thick, the finishing rolling speed is slow, and the high-speed rolling is not conducive.

[0047] Preferably, the intermediate blank is kept warm by a heat preservation cover in the embodiment, and the temperature drop is controlled within 20℃.

[0048] Preferably, the intermediate blank is kept warm by a heat preservation cover in the embodiment, and the temperature drop is controlled within 20℃.

[0049] Preferably, the cooling device comprises A / B line vertical cooling device and A / B line chain plate transport cooling device. The strip steel is changed from flat to vertical by the twist guide groove, and then is switched to A / B line alternately by the bifurcated guide plate after twisting, and is cooled vertically. Both sides are sprayed to cool, the cooling speed is 210-280℃ / s, and the outlet temperature is 730-780℃. The conversion of the two lines of A / B line can improve the rolling rhythm and the production efficiency. The strip steel is sent to the flat plate chain conveyor by the serpentine oscillator, and is air cooled. Each flat plate chain conveyor can store 2 steel.

[0050] Preferably, the strip steel is coiled vertically by A / B line vertical coiler before being packed. Five-roller tension rollers are arranged in front of the vertical coiler to generate certain tension between the coiler and the tension rollers. The maximum coiling speed is 6.5m / s, and the coiling temperature is 500-650℃.

[0051] Preferably, the packing device completes the process by the way of circumferential packing-laser coding-horizontal packing. The circumferential packing is the circumferential welding packing using strip steel. The laser coding is the coding of steel type, furnace number, factory name, date, etc. using multi-dimensional laser robot system. The robot axis number is 6-axis 6-freedom, and the maximum speed of axis action is 175-360° / s. The horizontal packing is the horizontal welding packing using steel belt.

[0052] A high-efficiency rolling production method of mild steel thin gauge hot-rolled strip steel, comprising the following steps: preferably selecting chemical composition and size of continuous casting billet of mild steel, hot charging the continuous casting billet, heating by intelligent combustion technology, high-pressure water descaling after the furnace, rough rolling and rough descaling, intermediate billet heat preservation cover heat preservation, finishing rolling and finishing descaling, twisting, A / B line vertical cooling, A / B line chain plate transport cooling, A / B line vertical coiling, circumferential packaging, laser coding, and horizontal packaging.

[0053] The specific technical measures include:

[0054] 1. The chemical composition of the continuous casting billet of the preferred mild steel includes the following chemical components in terms of mass percentage: as shown in Table 1.

[0055] Table 1 Chemical composition Unit: (%)

[0056]

[0057]

[0058] The optimized continuous casting billet size is 165mm*380mm*11.1m. The optimized continuous casting billet size can ensure high production efficiency. For example, using 165mm*330mm*11.1m or 165mm*380mm*9.0m will result in reduced production.

[0059] 2. Hot charging of the continuous casting billet: The continuous casting billet is hot charged at 600-800℃. The continuous casting billet uses a higher hot charging temperature to ensure heating efficiency.

[0060] 3. Heating by intelligent combustion technology: The intelligent combustion system is used for heating control. The heating section temperature is 1100-1250℃, the soaking section temperature is 1200-1260℃, the target control precision is ±10℃, the air-fuel ratio is self-optimizing controlled, the air-fuel ratio is 0.60-0.95, the residual oxygen content is 0.50-2.5%, the furnace pressure is controlled at 5-25Pa, the coal gas heat value is 800-950Kcal / Nm3, and the furnace heating time is 65-80min.

[0061] 4. High-pressure water descaling after the furnace: High-pressure water descaling is used after the furnace, and the descaling pressure is 16-22MPa.

[0062] 5. Rough rolling and rough descaling:

[0063] The rough rolling adopts full continuous rolling process, including 8 passes of continuous rolling, 1 vertical-1 horizontal-2 horizontal-2 vertical-3 horizontal-4 horizontal-3 vertical-5 horizontal; the rough rolling starting temperature is 1120-1160℃; high-pressure water descaling is adopted after the first vertical pass, and the descaling pressure is 10-16MPa; the time interval between the first vertical pass and the next pass is controlled to be 14-16s, the interval between two passes is shortened, and the tailing is ensured not to be caught; the speed of the fifth horizontal pass is 2.2-2.5m / s; the rolling speed of the full continuous rough rolling is improved; in order to ensure the rolling temperature of the thin gauge, the higher and more uniform the finishing rolling temperature is, the more stable the rolling is, the uneven deformation, tailing and unstable loop angle are reduced, and the intermediate blank temperature is reduced; the cumulative reduction of the rough rolling horizontal pass is 83.03-84.24%; the first vertical pass and the second vertical pass adopt vertical roll pass rolling, and the pass reduction is ≤40mm; the intermediate blank thickness is 26-28mm; the intermediate blank thickness ensures the stable rolling of the thin gauge; if the intermediate blank is too thin, the temperature reduction speed is fast, the temperature is too low in the finishing rolling stage, and the vertical roll reduction is easy to produce bending, which is not conducive to stable rolling. If the intermediate blank thickness is too thick, the finishing rolling speed is slow, which is not conducive to high-speed rolling.

[0064] 6, Intermediate blank heat preservation cover heat preservation: the intermediate blank adopts heat preservation cover heat preservation, and the temperature drop is controlled to be within 20℃.

[0065] In order to improve the yield and rolling efficiency, the intermediate blank does not adopt the flying shear cutting head and tail process before finishing rolling.

[0066] 7, Finishing rolling and finishing descaling:

[0067] The finishing rolling adopts full continuous rolling process, including 11 passes of continuous rolling, each pass is rolled once, 1 vertical-1 horizontal-2 horizontal-2 vertical-3 horizontal-4 horizontal-5 horizontal-6 horizontal-7 horizontal-8 horizontal-9 horizontal; the finishing rolling starting temperature is 1010-1050℃; high-pressure water descaling is adopted after the first vertical pass, and the descaling pressure is 10-16MPa; the time interval between the first vertical pass and the next pass is controlled to be 3.5-4.0s, the interval between two passes is shortened, and the tailing is ensured not to be caught; the finishing rolling adopts one-time speed-up rolling, the speed is unchanged after acceleration, and the steel is thrown without speed reduction; the strip speed of the ninth horizontal pass is 15.3-15.8m / s, and the acceleration speed of the ninth horizontal pass is 17.5-18.2m / s; the steel throwing speed of the ninth horizontal pass is 17.5-18.2m / s, the speed difference between the acceleration speed and the strip speed is 2.2-2.4m / s; at the same time, loop control is adopted, the steel is rolled in a constant small tension state, the loop height is 8-20°, the steel is avoided to be pulled and stacked, and the rolling stability is ensured; the pass reduction rate of the finishing rolling horizontal pass is 8-40%; the pass reduction rate is gradually reduced, and the last two pass reduction rates are 8-20%; the first vertical pass and the second vertical pass adopt vertical roll pass rolling, and the pass reduction is ≤20mm; the finishing rolling final rolling temperature is 900-930℃.

[0068] 8, Torsion: the strip steel passes through the torsion guide groove, and changes from horizontal to vertical.

[0069] 9. A / B line vertical cooling: after twisting, the strip is switched to A / B line alternately by diverging guide plates, vertical cooling of the strip is carried out, both sides are sprayed and cooled, the cooling speed is 210-280℃ / s, and the outlet temperature is 730-780℃. The conversion of the A / B line can improve the rolling rhythm and improve the production efficiency.

[0070] 10. A / B line chain plate transport cooling: the strip is sent to the flat plate chain conveyor by the serpentine oscillator and is air-cooled. Each flat plate chain conveyor can store two strips.

[0071] 11. A / B line vertical coiling: five-roller tension rollers are arranged in front of the vertical coiler, so that a certain tension is generated between the coiler and the tension rollers, the maximum coiling speed is 6.5m / s, and the coiling temperature is 500-650℃.

[0072] 12. Circumferential packaging: manual circumferential welding packaging using steel strips.

[0073] 13. Laser coding: using a multi-dimensional laser robot system for coding, the robot has 6 axes and 6 degrees of freedom, the maximum speed of axis action is 175-360° / s, and the coded information includes steel type, furnace number, factory name, date, etc.

[0074] 14. Transverse packaging: manual transverse welding packaging using steel strips.

[0075] In the embodiment of the present application, the thickness of the strip is 2.0mm-3.0mm.

[0076] Compared with the prior art, the following key indicators are broken through: thickness deviation 0-0.04mm, oxidation loss≤0.7%, daily output 8000-8800 tons, yield 98.94-99.16%, thickness deviation 0-0.04mm, plate shape qualified rate 100%, edge crack rate: 0, iron oxide skin thickness≤12μm, completely meeting the quality requirements of downstream cold rolling and pipe making.

[0077] Embodiment 2:

[0078] 1. The chemical composition of the preferred plain carbon steel continuous casting billet, in terms of mass percentage content, includes the following chemical components: as shown in Table 1;

[0079] Table 1 Chemical composition unit: (%)

[0080]

[0081] The optimized continuous casting billet size is 165mm*380mm*11.1m.

[0082] 2. Hot delivery continuous casting billet: the continuous casting billet adopts hot delivery 600-800℃ billet, and the continuous casting billet adopts higher hot delivery temperature to ensure heating efficiency.

[0083] 3. Intelligent combustion technology heating: intelligent combustion system is used for heating control, heating section temperature: 1100-1250°C; soaking section temperature 1200-1260°C, target control precision ±10°C; air-fuel ratio self-optimizing control, air-fuel ratio 0.60-0.95, residual oxygen content 0.50-2.5%, furnace pressure controlled at 5-25Pa, coal gas heat value 800-950Kcal / Nm3, furnace heating time 65-80min.

[0084] 4. High-pressure water descaling after furnace: high-pressure water descaling is used after furnace, descaling pressure 18MPa.

[0085] 5. Rough rolling and rough descaling:

[0086] Full continuous rolling process is used for rough rolling, including 8 passes of continuous rolling, 1 vertical-1 horizontal-2 horizontal-2 vertical-3 horizontal-4 horizontal-3 vertical-5 horizontal; rough rolling opening temperature 1120-1160°C; high-pressure water descaling is used after 1 vertical, descaling pressure 12MPa; time interval of 1 vertical steel throwing to next steel biting is controlled at 14-16s, rough rolling 5 horizontal speed 2.2m / s; improve full continuous rough rolling speed, to ensure thin gauge finishing rolling temperature, higher and more uniform finishing rolling temperature, more stable rolling, reduce non-uniform deformation, tail throwing and unstable loop angle, reduce intermediate blank temperature drop; rough rolling horizontal cumulative reduction 84.24%; 1 vertical and 2 vertical rough rolling use vertical roll pass rolling, pass reduction: ≤40mm; intermediate blank thickness 26mm.

[0087] 6. Intermediate blank heat preservation cover heat preservation: intermediate blank uses heat preservation cover heat preservation, temperature drop controlled within 20°C.

[0088] To improve yield and rolling efficiency, intermediate blank does not use flying shear head and tail cutting process before finishing rolling.

[0089] 7. Finishing rolling and finishing descaling:

[0090] The finishing mill adopts a continuous rolling process, including 11 passes of continuous rolling, with each pass being rolled once: 1 vertical-1 horizontal-2 horizontal-2 vertical-3 horizontal-4 horizontal-5 horizontal-6 horizontal-7 horizontal-8 horizontal-9 horizontal. The starting temperature of the finishing mill is 1010-1050℃. After the first vertical pass, the finishing mill uses high-pressure water descaling at a pressure of 12MPa. The time interval between the first vertical pass being discarded and the next steel being bitten in is controlled at 3.5-4.0s. The threading speed of the finishing mill at the 9th horizontal pass is 15.3m / s, and the acceleration speed at the 9th horizontal pass is 17.5m / s. The rolling speed for the 9th horizontal rolling mill is 17.5 m / s, with a speed difference of 2.2 m / s between the acceleration speed and the threading speed. Simultaneously, a looper control is employed, and rolling is carried out under constant low tension. The looper height is 8-20° to avoid steel pulling and piling, ensuring rolling stability. The reduction rate per pass in the finishing flat rolling mill is 8-40%, gradually decreasing to 8-20% for the last two passes. The finishing vertical mills 1 and 2 use vertical roll pass profiles, with a reduction of ≤20 mm per pass. The final finishing temperature is 900-930℃.

[0091] 8. Twist: The strip steel changes from flat to vertical after passing through the twist guide groove.

[0092] 9. Vertical Cooling on A / B Lines: After twisting, the strip is alternately switched to A / B lines by bifurcated guide plates for vertical cooling of the strip. Water is sprayed from both sides for cooling, with a cooling rate of 210-280℃ / s and an outlet temperature of 730-780℃. Switching between the A / B lines can improve the rolling rhythm and increase production efficiency.

[0093] 10. Cooling of A / B line chain conveyor: The steel is air-cooled by being fed into the flat chain conveyor by a serpentine vibrator. Each flat chain conveyor can hold two steel pieces.

[0094] 11. Vertical winding of A / B line: A five-roll tension roller is installed in front of the vertical winding machine to generate a certain tension between the winding machine and the tension roller. The maximum winding speed is 6.5m / s and the winding temperature is 500-650℃.

[0095] 12. Circumferential Packaging: Circumferential welding and packaging is carried out manually using steel straps.

[0096] 13. Laser marking: A multi-dimensional laser robot system is used for marking. The robot has 6 axes and 6 degrees of freedom, with a maximum axis movement speed of 175-360° / s. Information such as steel grade, furnace number, factory name, and date is marked.

[0097] 14. Horizontal Packaging: Manually use steel straps for horizontal welding and packaging.

[0098] In this embodiment of the invention, the strip thickness is 2.0 mm.

[0099] As the further optimized technical scheme of the embodiment of the present application, a high-efficiency rolling method for common carbon thin-gauge hot-rolled strip steel is adopted, which has the following key indexes: thickness deviation 0-0.04 mm, oxidation loss ≤0.7%, daily output 8000-8800 tons, material yield 98.94-99.16%, thickness deviation 0-0.04 mm, plate shape qualified rate 100%, edge crack rate 0, iron oxide skin thickness ≤8.9 μm, completely meeting the quality requirements of downstream cold rolling and pipe making.

[0100] Embodiment 3:

[0101] 1. The chemical composition of the common carbon steel continuous casting billet, in terms of mass percentage content, comprises the following chemical components: as shown in Table 1.

[0102] Table 1 Chemical composition Unit: (%)

[0103]

[0104] The optimized continuous casting billet size is 165 mm*380 mm*11.1 m.

[0105] 2. Hot delivery continuous casting billet: the continuous casting billet adopts hot delivery 600-800℃ billet, and the continuous casting billet adopts higher hot delivery temperature to ensure heating efficiency.

[0106] 3. Intelligent combustion technology heating: intelligent combustion system is adopted for heating control, heating section temperature: 1100-1250℃; soaking section temperature 1200-1260℃, target control precision ±10℃; air-fuel ratio self-optimization control, air-fuel ratio 0.60-0.95, residual oxygen content 0.50-2.5%, furnace pressure control in 5-25 Pa, coal gas heat value 800-950 Kcal / Nm3, and furnace heating time 65-80 min.

[0107] 4. High-pressure water descaling after the furnace: high-pressure water descaling is adopted after the furnace, and the descaling pressure is 20 MPa.

[0108] 5. Rough rolling and rough descaling:

[0109] The rough rolling adopts full continuous rolling process, including 8 passes of continuous rolling, 1 vertical-1 horizontal-2 horizontal-2 vertical-3 horizontal-4 horizontal-3 vertical-5 horizontal; the rough rolling starting temperature is 1120-1160 °C; high-pressure water descaling is adopted after the first vertical pass, and the descaling pressure is 13 MPa; the time interval of the first vertical pass to the next steel biting is controlled to be 14-16 s, and the rough rolling speed of the fifth horizontal pass is 2.5 m / s; the rough rolling speed is improved; in order to ensure the rolling temperature of the thin gauge finishing rolling, the higher and more uniform the finishing rolling temperature is, the more stable the rolling is, the lower the non-uniform deformation, tail throwing and unstable loop angle are, and the intermediate blank temperature drop is reduced; the cumulative reduction of the rough rolling horizontal pass is 83.03%; the first vertical pass and the second vertical pass adopt vertical roll pass rolling, and the pass reduction is ≤40 mm; the intermediate blank thickness is 28 mm.

[0110] 6, Intermediate blank heat preservation cover heat preservation: the intermediate blank adopts heat preservation cover heat preservation, and the temperature drop is controlled to be within 20 °C.

[0111] In order to improve the yield and rolling efficiency, the intermediate blank does not adopt flying shear cutting head and tail cutting process before finishing rolling.

[0112] 7, Finishing rolling and finishing descaling:

[0113] The finishing rolling adopts full continuous rolling process, including 11 passes of continuous rolling, each pass is rolled once, 1 vertical-1 horizontal-2 horizontal-2 vertical-3 horizontal-4 horizontal-5 horizontal-6 horizontal-7 horizontal-8 horizontal-9 horizontal; the finishing rolling starting temperature is 1010-1050 °C; high-pressure water descaling is adopted after the first vertical pass, and the descaling pressure is 13 MPa; the time interval of the first vertical pass to the next steel biting is controlled to be 3.5-4.0 s, the finishing rolling 9 horizontal pass threading speed is 15.8 m / s, and the 9 horizontal pass acceleration speed is 18.2 m / s; the 9 horizontal pass steel throwing speed is 18.2 m / s, and the speed difference between the acceleration speed and the threading speed is 2.4 m / s; loop control is adopted at the same time, and the rolling is carried out in a constant small tension state, the loop height is 8-20 °, the steel is prevented from being pulled and stacked, and the rolling stability is ensured; the finishing rolling horizontal pass reduction is 8-40%; the pass reduction gradually decreases, and the last two pass reductions are 8-20%; the first vertical pass and the second vertical pass of the finishing rolling adopt vertical roll pass rolling, and the pass reduction is ≤20 mm; the finishing rolling final rolling temperature is 900-930 °C.

[0114] 8, Twisting: the strip steel is twisted through a twisting guide groove, and is changed from horizontal to vertical.

[0115] 9, A / B line vertical cooling: after twisting, the strip steel is alternately switched to A / B line by bifurcated guide plate, and vertical cooling of the strip steel is carried out, both sides are sprayed and cooled, the cooling speed is 210-280 °C / s, and the outlet temperature is 730-780 °C. The conversion of the two A / B lines can improve the rolling rhythm and production efficiency.

[0116] 10, A / B line chain plate transportation cooling: the strip steel is sent into the flat chain conveyor air cooling by the serpentine oscillator. Each flat chain conveyor can store two steels.

[0117] 11. A / B line vertical coiling: five-roller tension roller is arranged in front of the vertical coiling machine, so that certain tension is generated between the coiling machine and the tension roller, the maximum coiling speed is 6.5 m / s, and the coiling temperature is 500-650 DEG C.

[0118] 12. Circumferential packing: artificial circumferential welding packing is performed by using a steel band.

[0119] 13. Laser coding: coding is performed by using a multi-dimensional laser robot system, the robot has 6 axes and 6 degrees of freedom, the maximum speed of axis action is 175-360 DEG / s, and the information such as steel grade, furnace number, factory name and date is coded.

[0120] 14. Transverse packing: artificial transverse welding packing is performed by using a steel band.

[0121] The strip steel thickness of the embodiment of the present application is 2.5 mm.

[0122] As a further optimized technical scheme of the embodiment of the present application, a kind of high-efficiency rolling method for plain carbon thin gauge hot-rolled strip steel is adopted, with the following key indicators: thickness deviation 0-0.04 mm, oxidation loss ≤0.7%, daily output 8000-8800 tons, yield 98.94-99.16%, thickness deviation 0-0.04 mm, plate shape qualified rate 100%, edge crack rate: 0, iron oxide skin thickness 9.2 μm, fully meeting the quality requirements of downstream cold rolling and pipe making.

[0123] The present application has the advantages and positive effects that: due to the adoption of intelligent combustion technology for heating, the target value control precision of heating section and soaking section is ±10 DEG C, the uniformity of temperature in the cross section and length direction of the billet is improved, the opening rolling temperature fluctuation is ensured to be small, the strip steel is uniformly deformed, the rolling stability is improved, and the uniformity of the mechanical properties of finished products is improved. The air-fuel ratio is self-optimizing controlled, the combustion-supporting air flow is dynamically adjusted according to the gas flow, the furnace temperature change rate is counted under certain heating load conditions, the optimal air-fuel ratio is maintained accordingly, and the best and fastest combustion is achieved. The furnace atmosphere is controlled to be a micro-oxidizing atmosphere with residual oxygen content of 0.5-2.5% and furnace pressure controlled to be 5-25 Pa, the over-oxidation of continuous casting billets is reduced, and the yield is decreased.

[0124] The present application is to improve the yield and rolling efficiency, and the intermediate billet is not cut by flying shears before finish rolling.

[0125] The present application adopts a one-time speed-up rolling process, and the speed is unchanged after one-time speed-up, and the steel is not thrown down to improve the rolling efficiency. The strip head runs at a speed of 15.3-15.8 m / s during threading, and the threading speed cannot be too low to prevent the head temperature from being too low, which will cause the strip head to crack and prevent the roll from being damaged. The threading speed cannot be too high to reduce the risk of head folding and cracking. Then, the speed is accelerated to 17.5-18.2 m / s at one time until the end of the steel throwing, and the speed is not reduced during the steel throwing to reduce the pure rolling time and improve the production efficiency. The speed difference between the acceleration speed and the threading speed is controlled, and the smaller the speed difference between the acceleration speed and the threading speed, the smaller the strip same difference and the smaller the size fluctuation. On the contrary, the larger the speed difference between the acceleration speed and the threading speed, the larger the strip same difference and the larger the size fluctuation.

[0126] The finishing rolling flat rolling reduction rate of the present application gradually decreases to ensure stable thin gauge rolling, and the reduction rate of the last two passes is not easy to be too large to prevent the generation of buckling head caused by too large reduction rate, and high speed and large reduction rate have adverse effects on the shape. The production efficiency is improved, the production is stable and reliable, the oxidation loss is small, the yield is high, the size fluctuation is small, the shape is good, and the thickness of the iron oxide skin is low.

[0127] The above embodiments of the present application are described in detail, but the content described is only the preferred embodiment of the present application, and cannot be considered to limit the scope of the present application. Any equivalent changes and improvements made according to the scope of the present application should still belong to the scope of the present application.

Claims

1. A high-efficiency rolling production method for mild steel thin gauge hot-rolled strip steel, characterized in that: the method uses a high-efficiency rolling production device for mild steel thin gauge hot-rolled strip steel, which comprises a heating device, a descaling device, a rolling device, a cooling device, a coiling device, and a packing device, the heating device can heat the strip steel by setting the heating time, heating temperature, and furnace pressure in the heating device; the heating device is provided with a heating furnace and a temperature control system, the strip steel can be heated by the heating furnace; the temperature control system can control the heating time, heating temperature, and furnace pressure of the heating furnace; the descaling device is arranged on one side of the heating device and can remove the scale layer on the surface of the strip steel after heating by the heating device; the descaling device is arranged on one side of the rough rolling mill and the finishing rolling mill; the rolling device is connected with the descaling device and can roll the strip steel; the rolling device comprises a rough rolling mill and a finishing rolling mill, the rough rolling mill can roll the strip steel by a rough rolling process, and the finishing rolling mill can roll the strip steel by a finishing rolling process; the cooling device is connected with the rolling device and can cool the rolled strip steel; the cooling device comprises A / B line vertical cooling devices and A / B line chain plate transport cooling devices; the packing device can pack the strip steel; the steps of the method are as follows: S1, selecting the chemical composition and size of the continuous casting billet for mild steel; S2, using the hot charging 600-800℃ continuous casting billet; S3, feeding the continuous casting billet in S2 into the heating furnace for heating; the heating section temperature is 1100-1250℃, the soaking section temperature is 1200-1260℃, the furnace heating time is 65-80min, the air-fuel ratio is 0.60-0.95, the residual oxygen content is 0.50-2.5%, and the furnace pressure is controlled at 5-25Pa; S4, using high-pressure water descaling after the furnace through the descaling device, and the descaling pressure is 16-22MPa; S5, rough rolling and rough descaling, using full continuous rolling process for rough rolling through the rough rolling mill, including 8 passes of continuous rolling, 1 vertical-1 horizontal-2 horizontal-2 vertical-3 horizontal-4 horizontal-3 vertical-5 horizontal, the rough rolling opening rolling temperature is set to 1120-1160℃, high-pressure water descaling is performed after 1 vertical through the descaling device, the descaling pressure is set to 10-16MPa, the time interval for throwing the steel after 1 vertical to the next steel biting is controlled to 14-16s, the rough rolling horizontal rolling speed is set to 2.2-2.5m / s, the rough rolling horizontal rolling cumulative reduction is set to 83.03-84.24%, the vertical roll pass is used for 1 vertical, 2 vertical, and 3 vertical rough rolling, and the pass reduction amount is set to ≤40mm; S6, using the heat preservation cover to preserve the temperature of the intermediate billet, the thickness of the intermediate billet is 26-28mm, and the temperature drop is controlled to be within 20℃. ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ S7, finishing and finishing descaling, the finishing is carried out by adopting full continuous rolling process through the finishing mill, including 11 passes of continuous rolling, 1 pass of rolling each time, 1 vertical-1 horizontal-2 horizontal-2 vertical-3 horizontal-4 horizontal-5 horizontal-6 horizontal-7 horizontal-8 horizontal-9 horizontal, the finishing roughing temperature is set to 1010-1050℃, the descaling device is used to descale through high-pressure water after 1 vertical of the finishing, the descaling pressure is set to 10-16MPa, the time interval of 1 vertical of the finishing to the next steel biting is controlled to be 3.5-4.0s, the finishing adopts one-time speed-up rolling, the speed is unchanged after acceleration, the steel is not slowed down, the 9 horizontal of the finishing has a speed of 16.3-15.8m / s, the acceleration speed is 17.5-18.2m / s, the steel throwing speed of the 9 horizontal is set to be 17.5-18.2m / s, the speed difference between the acceleration speed and the speed of the strip is set to be 2.2-2.4m / s, and the looper control is used at the same time, the rolling is carried out in a constant small tension state, the looper height is set to be 8-20°, the steel pulling and the steel piling can be avoided, and the rolling stability is ensured; S8, twisting, the strip steel passes through a twisting guide groove and changes from horizontal to vertical; S9, the A / B line vertical cooling is used, the strip steel is alternately switched to the A / B line by the bifurcated guide plate after being twisted and is subjected to vertical cooling; S10, the A / B line chain plate transportation cooling is used, the strip steel is sent into the flat plate chain conveyor by the snake-shaped oscillator and is subjected to air cooling, each flat plate chain conveyor can store two strip steels; S11, coiling; S12, circumferential packaging, the steel belt can be used for circumferential welding and packaging; S13, laser coding, a multi-dimensional laser robot system can be used for coding, the robot has 6 axes and 6 degrees of freedom, the maximum speed of the axis action is set to be 175-360° / s, and the information such as steel grade, furnace number, factory name and date can be coded; S14, transverse coding, the steel belt can be used for transverse welding and packaging, and the production of the hot-rolled strip steel is completed.

2. The high efficiency rolling production method of mild thin gauge hot rolled strip steel according to claim 1, characterized in that: The chemical composition of the preferred plain carbon steel continuous casting billet includes the following chemical components in terms of mass percentage: C: ≤0.25%, Si: ≤0.35%, Mn: ≤1.50%, P: ≤0.035%, S: ≤0.045%, Cr ≤0.30%, Ni ≤0.30%, Cu ≤0.30%, and the rest is Fe.

3. The high efficiency rolling production method of mild thin gauge hot rolled strip steel according to claim 1, characterized in that: The finishing horizontal rolling pass reduction rate is set to be 8-40%, the pass reduction rate gradually decreases, and the last two pass reduction rates are set to be 8-20%, the finishing 1 vertical and 2 vertical adopt vertical roll pass rolling, the pass reduction amount is ≤20mm, and the finishing final rolling temperature is set to be 900-930℃.

4. The high efficiency rolling production method of mild thin gauge hot rolled strip steel according to claim 1, characterized in that: The cooling speed of the A / B line vertical cooling is 210-280℃ / s, and the outlet temperature is 730-780℃.

5. The high efficiency rolling production method of mild thin gauge hot rolled strip steel of claim 1, wherein: The coiling adopts A / B line vertical coiling, five-roller tension rollers are arranged in front of the vertical coiler, a certain tension is generated between the coiler and the tension rollers, the maximum coiling speed is 6.5m / s, and the coiling temperature is 500-650℃.

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