Rolling method of long fixed-length continuous casting steel billet

Abstract

The invention relates to the technical field of steel casting, and particularly discloses a long fixed-length continuous casting steel billet rolling method which comprises the following steps: continuously casting a hot billet; a conveying roller way with the length of 70 m is installed between a continuous casting machine and a rolling mill, the width meets the requirement that six steel billets are placed side by side, and the conveying roller way is sealed and covered with a heat preservation cover. When a steel billet is rolled, the head and the tail of a first flying shear, a second flying shear, a third flying shear and a wire rod need to be sheared once respectively; after a steel billet is rolled, the rolled steel billet is subjected to water cooling, spinning and air cooling in sequence; the steel billet subjected to air cooling is divided into coils; and after the steel billets are subjected to coil separation, the steel billets are subjected to coil collection, inspection, weighing and listing, and then warehousing is completed. The continuous casting steel billet with the long fixed length is adopted for rolling, the loss of the rolled shear head and tail is reduced, the proportion of the rolling mill idling time is greatly reduced, the production efficiency of the rolling mill is improved, and the production rhythm is accelerated.

Description

Technical Field

[0001] The invention relates to the technical field of steel casting, and in particular to a method for rolling a long fixed-length continuous casting steel billet. Background Art

[0002] At present, the continuous casting process is a process in which molten steel releases heat and gradually solidifies into a certain shape of ingot under continuous production. After the upstream processing, the molten steel is transported to the turntable in a bucket, divided into several strands by a molten steel distributor, injected into the mold, cooled and solidified into shape, and then the ingot is drawn into the arc casting channel, and continues to solidify until it is completely solidified after secondary cooling. It is then cut after straightening. When the ingot head reaches the cutting point, the ingot head is cut.

[0003] However, in the prior art, the cut length is limited by the size of the heating furnace, the transport vehicle and the cooling bed. The cut length is short, the idling time of the rolling mill is long, which reduces the production capacity of the rolling mill, and the secondary heating will increase the manufacturing cost. Summary of the invention

[0004] The object of the present invention is to provide a method for rolling long fixed-length continuous casting steel billets, aiming to solve the technical problems in the prior art that the fixed-length is limited by the size of a heating furnace, a transport vehicle, and a cooling bed, the fixed-length is short, the idling time of the rolling mill is long, the production capacity of the rolling mill is reduced, and secondary heating will increase the manufacturing cost.

[0005] To achieve the above object, the present invention adopts a long fixed-length continuous casting steel billet rolling method, comprising the following steps:

[0006] Continuous casting of hot billets;

[0007] A conveyor roller with a length of 70m is installed between the continuous casting machine and the rolling mill. The width is enough to place 6 billets side by side. The conveyor roller is covered with a heat preservation cover.

[0008] When the billet is rolled, it needs to be sheared once at the No. 1 flying shear, No. 2 flying shear, No. 3 flying shear and the head and tail of the coil;

[0009] After the steel billet is rolled, the rolled steel billet is sequentially subjected to water cooling, wire drawing and air cooling;

[0010] The air-cooled billet is divided into coils;

[0011] After the steel billets are divided into coils, they are rolled, inspected, weighed and labeled before being put into storage.

[0012] Among them, a blocking device is installed in front of the No. 1 rolling mill to ensure that only one billet enters the rolling mill to avoid blockage caused by simultaneous entry of billets.

[0013] Among them, a shearing machine is installed on the air-cooled roller 5m in front of the coiling to cut the coil into two parts, and then increase the speed of the roller 5m in front of the coiling to make the front and rear parts of the coil staggered, which is convenient for subsequent coiling.

[0014] Among them, when the steel billet is water-cooled, the cooling water flows into the grouting device from the cooling pipe, and then sprays onto the surface of the billet at a specific angle and direction through the nozzle to form water mist or water splashes. The secondary cooling zone adopts gas mist cooling or water spray cooling.

[0015] Among them, mist cooling sprays a water vapor mixture through a nozzle to achieve slow and uniform cooling of the steel billet.

[0016] Among them, water spray cooling directly sprays water mist onto the surface of the steel billet to accelerate heat transfer, thereby achieving cooling of the steel billet.

[0017] Among them, the secondary cooling zone is divided into multiple spray areas, each of which is independently controlled, which can adapt to the different needs of the steel billet during the cooling process and control the spray water volume, water pressure and water temperature parameters accordingly.

[0018] The beneficial effects of the long fixed-length continuous casting steel billet rolling method of the present invention are: using long fixed-length continuous casting steel billets for rolling, reducing the shear head and tail losses of rolling, greatly reducing the proportion of rolling mill idling time, improving the production efficiency of the rolling mill, and accelerating the production rhythm. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0020] Figure 1 The invention discloses a flow chart of the steps of a method for rolling a long fixed-length continuous casting steel billet. DETAILED DESCRIPTION

[0021] See also Figure 1 The present invention provides a method for rolling a long fixed-length continuous casting steel billet, comprising the following steps:

[0022] S1: continuous casting of hot billet;

[0023] S2: A conveyor roller with a length of 70m is installed between the continuous casting machine and the rolling mill. The width is sufficient to place 6 billets side by side. The conveyor roller is covered with a heat preservation cover;

[0024] S3: When the billet is rolled, it needs to be sheared once at No. 1 flying shear, No. 2 flying shear, No. 3 flying shear and the head and tail of the coil;

[0025] S4: After the steel billet is rolled, the rolled steel billet is sequentially subjected to water cooling, wire drawing and air cooling;

[0026] S5: Coil the air-cooled billet;

[0027] S6: After the steel billets are divided into coils, they are rolled, inspected, weighed and labeled before being put into storage.

[0028] In this embodiment, the steel billet does not need to be cooled on the cooling bed, transferred and heated in the heating furnace after coming out of the continuous casting machine. The fixed length is no longer limited by the size of the cooling bed, the transfer vehicle and the heating furnace. The fixed length of the steel billet can be increased from 6m to 20m. The long fixed-length continuous casting steel billet is used for rolling, which reduces the shearing loss of rolling, greatly reduces the proportion of idling time of the rolling mill, improves the production efficiency of the rolling mill, and speeds up the production rhythm.

[0029] Furthermore, a blocking device is provided in front of the No. 1 rolling mill to ensure that only one billet enters the rolling mill, thereby avoiding blockage caused by simultaneous entry of billets.

[0030] In this embodiment, the blocking device is used to prevent multiple billets from entering at the same time and causing blockage, thereby ensuring the stability of the billets during the length-sizing process. Improving the stability can effectively improve the efficiency of billet processing.

[0031] Furthermore, a shearing machine is provided on the air-cooled roller 5 m in front of the coiling to cut the coil into two parts, and then the rotation speed of the roller 5 m in front of the coiling is increased to offset the front and rear parts of the coil, so as to facilitate the subsequent coiling.

[0032] In this embodiment, the sheared coil is offset-adjusted to facilitate subsequent coiling, thereby improving the production efficiency of the steel billet.

[0033] Furthermore, when the steel billet is water-cooled, the cooling water flows from the cooling pipe into the slurry injector, and then is sprayed onto the surface of the billet at a specific angle and direction through the nozzle to form water mist or water splashes. The secondary cooling zone adopts gas mist cooling or water spray cooling.

[0034] In this embodiment, billet water cooling is intermediate water cooling in the steel rolling process, and its main purpose is to quickly cool the heated billet through a high-pressure water jet. Intermediate water cooling can quickly reduce the billet temperature to reach the designed forming temperature, thereby improving the rolling efficiency. The plastic deformation stress of the billet can be reduced by cooling, and the generation of tensile and shear stresses can be reduced, making the billet easier to deform, thereby improving the rolling efficiency. Intermediate water cooling helps to improve the structure and properties of the billet surface, making the rolling process more stable, thereby improving the quality of the product. The rollers at high temperatures are prone to deformation or even cracking. Intermediate water cooling can effectively reduce the roller temperature, reduce wear and deformation, protect equipment and extend service life. The secondary cooling zone is an area where the billet is subjected to secondary cooling. The billet water cooling and the secondary cooling zone work together to improve product quality, protect production equipment and improve production efficiency during the processing and preparation process. The billet cooling has the beneficial effects of improving cooling efficiency, improving cooling uniformity, saving water, improving working environment, improving product quality, and flexibility and adaptability.

[0035] Furthermore, the mist cooling sprays a water vapor mixture through a nozzle to achieve slow and uniform cooling of the steel billet.

[0036] In this embodiment, aerosol cooling is to atomize water droplets through compressed air, so that the diameter of the water droplets is greatly reduced, and most of them are less than 100 μm, which is conducive to more uniform distribution of water droplets on the surface of the steel billet and improve cooling efficiency. The atomized water droplets can cover a wider surface of the steel billet, thereby effectively increasing the cooling area and making the cooling more uniform. Due to uniform cooling, the thermal stress generated by the steel billet during the cooling process will also be relatively reduced, which helps to reduce cracks. The amount of water required for aerosol cooling is greatly reduced compared to complete water cooling, which saves water resources to a certain extent. The atomized water droplets evaporate quickly on the hot billet and can use water resources more effectively for cooling. Due to uniform cooling, the residual stress generated by the steel billet during the cooling process will also be reduced accordingly, thereby improving product quality. The improvement of cooling uniformity and cooling efficiency helps to reduce crack defects generated by the steel billet during the cooling process. Aerosol cooling can quickly reduce the surface temperature of the steel billet, thereby shortening the cooling time and improving production efficiency. The shortened cooling time means that the equipment can be put into the next round of production more quickly, thereby improving the utilization rate of the equipment.

[0037] Furthermore, water spray cooling directly sprays water mist onto the surface of the steel billet to accelerate heat transfer, thereby achieving cooling of the steel billet.

[0038] In this embodiment, water spray cooling atomizes water into fine water droplets through a nozzle. These water droplets can quickly contact the surface of the steel billet and take away a large amount of heat, thereby achieving rapid cooling. The atomized water droplets can cover a wider surface of the steel billet, thereby effectively increasing the cooling area and improving the cooling efficiency. The water spray cooling system can ensure that the water droplets are evenly distributed on the surface of the steel billet, avoiding local overheating or overcooling, and improving the uniformity of cooling. Due to the uniform cooling, the thermal stress generated by the steel billet during the cooling process will also be reduced accordingly, which helps to reduce the occurrence of crack defects. The water spray cooling system can adjust parameters such as spray volume and water pressure as needed to meet the needs of different steel grades and cooling requirements. The nozzle and other components of the water spray cooling system are relatively simple and easy to maintain and replace.

[0039] Furthermore, the secondary cooling zone is divided into multiple spray areas, each of which is independently controlled, so as to control the spray water volume, water pressure and water temperature parameters accordingly to meet the different needs of the steel billet during the cooling process.

[0040] In this embodiment, through zoning control, it can be ensured that the ingot reaches the required cooling effect in a shorter time, thereby shortening the cooling time and improving production efficiency. The shortening of cooling time means that the equipment can be put into the next round of production more quickly, thereby improving the utilization rate of the equipment. For continuous casting ingots of different specifications, the parameters of each spray area can be adjusted to meet their cooling needs, thereby improving the flexibility and adaptability of the production line. When process conditions change, such as drawing speed adjustment, steel type change, etc., these changes can be responded to by adjusting the parameters of each spray area to ensure the stability of the ingot quality. The division of the secondary cooling zone into multiple spray areas has significant beneficial effects on improving cooling efficiency and uniformity, improving ingot quality, improving production efficiency, and enhancing flexibility and adaptability.

[0041] Furthermore, when the steel billets are air-cooled, they are placed on a turning cooling bed or a stacking area. At the same time, when placing the steel billets, each group of steel billets needs to be spaced apart to ensure air circulation and improve heat dissipation efficiency.

[0042] In this embodiment, air cooling is a relatively simple cooling method, which does not require additional cooling equipment, such as cooling towers, water pumps, etc., thereby saving equipment investment and operating costs. Compared with water cooling, air cooling does not require the use of a large amount of water resources, especially in areas where water resources are scarce, air cooling is particularly economical and feasible. During the air cooling process, the steel billet directly uses natural convection and radiation in the air to dissipate heat without consuming additional energy. During the air cooling process, the cooling speed of the steel billet is relatively slow and uniform, which helps to reduce the thermal stress caused by rapid cooling, thereby reducing the generation of crack defects. Air cooling is suitable for a variety of steel types, especially those steel types that do not form martensite or semi-martensite structures after cooling in air, such as low carbon steel, ordinary low alloy high-strength steel, etc. Air cooling is generally carried out on a special cooling bed, and the cooling bed has various forms, such as step-type, disc roller type, etc. The design of the cooling bed should ensure that the steel billet can dissipate heat evenly and reduce scratches caused by bending and friction.

[0043] Furthermore, during air cooling, in order to control the cooling rate and quality of the steel billet, the temperature of the steel billet in the air cooling section is monitored, and real-time adjustment and control are performed based on the monitoring data so that the monitoring data reaches a reasonable range.

[0044] In this embodiment, by monitoring the data of the steel billet, the cooling of the steel billet can be adjusted in real time so that the cooling temperature and rate are consistent with the temperature range.

[0045] In the present invention, long fixed-length continuous casting billets are used for rolling, which reduces the shear head and tail loss of rolling, greatly reduces the proportion of the idling time of the rolling mill, improves the production efficiency of the rolling mill, and speeds up the production rhythm;

[0046] Billet water cooling is the intermediate water cooling in the steel rolling process. Its main purpose is to quickly cool the heated billet through high-pressure water jets. Intermediate water cooling can quickly reduce the billet temperature to the designed forming temperature, thereby improving rolling efficiency. By cooling, the plastic deformation stress of the billet can be reduced, the generation of tensile and shear stress can be reduced, and the billet can be deformed more easily, thereby improving rolling efficiency. Intermediate water cooling helps to improve the organization and performance of the billet surface, making the rolling process more stable, thereby improving product quality. Rollers at high temperatures are prone to deformation or even cracking. Intermediate water cooling can effectively reduce the roller temperature, reduce wear and deformation, protect equipment and extend service life. The secondary cooling zone is the area where the billet is cooled for the second time. Billet water cooling and the secondary cooling zone work together to improve product quality, protect production equipment and improve production efficiency during the processing and preparation process. Billet cooling has many beneficial effects, including improving cooling efficiency, improving cooling uniformity, saving water, improving working environment, improving product quality, and flexibility and adaptability.

[0047] Among them, aerosol cooling is to atomize water droplets through compressed air, so that the diameter of water droplets is greatly reduced, most of which are less than 100μm, which is conducive to more even distribution of water droplets on the surface of steel billets and improve cooling efficiency. Atomized water droplets can cover a wider range of steel billet surfaces, thereby effectively increasing the cooling area and making cooling more uniform. Due to uniform cooling, the thermal stress generated by the steel billet during the cooling process will also be relatively reduced, which helps to reduce cracks. Compared with complete water cooling, aerosol cooling greatly reduces the amount of water required, which saves water resources to a certain extent. Atomized water droplets evaporate quickly on the hot billet, and water resources can be used more effectively for cooling. Due to uniform cooling, the residual stress generated by the steel billet during the cooling process will also be reduced accordingly, thereby improving product quality. The improvement of cooling uniformity and cooling efficiency helps to reduce crack defects generated by the steel billet during the cooling process. Aerosol cooling can quickly reduce the surface temperature of the steel billet, thereby shortening the cooling time and improving production efficiency. The shortening of cooling time means that the equipment can be put into the next round of production faster, improving the utilization rate of the equipment.

[0048] Among them, water spray cooling atomizes water into fine water droplets through the nozzle. These water droplets can quickly contact the surface of the steel billet and take away a large amount of heat, thereby achieving rapid cooling. The atomized water droplets can cover a wider range of the steel billet surface, thereby effectively increasing the cooling area and improving the cooling efficiency. The water spray cooling system can ensure that the water droplets are evenly distributed on the surface of the steel billet, avoiding the phenomenon of local overheating or overcooling, and improving the uniformity of cooling. Due to the uniform cooling, the thermal stress generated by the steel billet during the cooling process will also be reduced accordingly, which helps to reduce the generation of crack defects. The water spray cooling system can adjust the spray volume, water pressure and other parameters as needed to meet the needs of different steel grades and cooling requirements. The nozzles and other components of the water spray cooling system are relatively simple and easy to maintain and replace;

[0049] In billet rolling, it is necessary to shear once at No. 1 flying shear, No. 2 flying shear, No. 3 flying shear and the round head and tail of the coil, and the fixed loss after shearing is recorded as t. When the billet length is 12m, the shearing loss per meter of billet is t / 12. When the length is adjusted to 50m, the shearing loss per meter of billet is t / 50, and the shearing loss of the billet is reduced by 76%. The rolling speed of No. 1 rolling mill is 0.3m / s. The shortest time interval between one billet and another billet entering No. 1 rolling mill is 10s. When rolling a billet with a length of 12m, the billet load rolling time is 40s, and the idling time is the interval time of 10s. The load rate of No. 1 rolling mill = load rolling time / (load rolling time+idling time) = 80%;

[0050] When rolling a 50m billet, the load rolling time is 166.7s, the idle time is the interval time of 10s, and the load rate of the No. 1 rolling mill = load rolling time / (load rolling time + idle time) = 94.3%;

[0051] The load rate of No. 1 rolling mill has increased by 17.9%, the electricity consumption per ton of steel has decreased, and the corresponding rolling line production capacity has increased by 17.9%. Previously, due to the limited production capacity of the rolling line, the continuous casting machine could only start 5-strand casting, which slowed down the pace of steelmaking production. After the production capacity of the rolling line was improved, the continuous casting machine can be opened to 6 strands, which improves the production rhythm.

[0052] What is disclosed above is only a preferred embodiment of the present invention, and it certainly cannot be used to limit the scope of rights of the present invention. Ordinary technicians in this field can understand that all or part of the processes of the above embodiment and equivalent changes made according to the claims of the present invention still fall within the scope of the invention.

Claims

1. A method for rolling a long fixed-length continuous casting steel billet, characterized in that: The steps include: Continuous casting of hot billets; A conveyor roller with a length of 70m is installed between the continuous casting machine and the rolling mill. The width is enough to place 6 billets side by side. The conveyor roller is covered with a heat preservation cover. When the billet is rolled, it needs to be sheared once at the No. 1 flying shear, No. 2 flying shear, No. 3 flying shear and the head and tail of the coil; After the steel billet is rolled, the rolled steel billet is sequentially subjected to water cooling, wire drawing and air cooling; The air-cooled billet is divided into coils; After the steel billets are divided into coils, they are rolled, inspected, weighed and labeled before being put into storage.

2. A method for rolling a long fixed-length continuous casting steel billet as claimed in claim 1, characterized in that: A blocking device is installed in front of the No. 1 rolling mill to ensure that only one billet enters the rolling mill and avoid blockage caused by simultaneous entry of billets.

3. A method for rolling a long fixed-length continuous casting steel billet according to claim 1, characterized in that: A shearing machine is installed on the air-cooled roller 5m in front of the coiling to cut the coil into two parts. Then the speed of the roller 5m in front of the coiling is increased to make the front and rear parts of the coil staggered, which is convenient for subsequent coiling.

4. A method for rolling a long fixed-length continuous casting steel billet as claimed in claim 1, characterized in that: When the steel billet is water-cooled, the cooling water flows from the cooling pipe into the slurry injector, and then is sprayed onto the surface of the billet at a specific angle and direction through the nozzle to form water mist or water splashes. The secondary cooling zone adopts gas mist cooling or water spray cooling.

5. A method for rolling a long fixed-length continuous casting steel billet as claimed in claim 4, characterized in that: Mist cooling sprays a water vapor mixture through a nozzle to achieve slow and uniform cooling of the steel billet.

6. A method for rolling a long fixed-length continuous casting steel billet as claimed in claim 4, characterized in that: Water spray cooling directly sprays water mist onto the surface of the billet to accelerate heat transfer and thus cool the billet.

7. A method for rolling a long fixed-length continuous casting steel billet as claimed in claim 4, characterized in that: The secondary cooling zone is divided into multiple spray areas, each of which is independently controlled to meet the different needs of the billet during the cooling process and to control the spray water volume, water pressure and water temperature parameters accordingly.

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