Method for producing 18mm-specification straight deformed steel bar on high-speed bar production line

Abstract

The invention relates to the technical field of ferrous metallurgy, and particularly discloses a method for producing 18mm-specification straight deformed steel bar on a high-speed bar production line, which comprises the following steps of: heating: uniformly heating a continuous casting square billet through a heating furnace; the rough rolling area, the intermediate rolling area and the pre-finish rolling area of the rolling line totally use 16 horizontal and vertical alternating type rolling mills; the pressure and the cooling temperature of a cooling water tank are controlled, the rolled piece enters a finishing mill group after passing through a 3 # flying shear head, and a produced rolled piece finished product reaches the required product size; water cooling after the finish rolling procedure: after the rolled piece is cooled by one water tank, controlling the temperature of the rolled piece to pass through two rack units, and finally performing segmented uniform cooling by three water tanks to produce the deformed steel bar; online real-time monitoring of the deformed steel bar: controlling the size of the deformed steel bar According to the method, high-in-furnace-temperature steel billet production is achieved, so that gas consumption is reduced, product performance is improved, precious metal alloy use is reduced, and alloy cost is reduced.

Description

Technical Field

[0001] This invention relates to the field of iron and steel metallurgy technology, specifically to a method for producing 18mm straight rebar on a high-speed bar production line. Background Technology

[0002] 18mm diameter straight rebar has become one of the mainstream specifications for rolled steel due to its large usage and wide range of applications. Currently, the production of Φ18mm rebar on high-speed bar production lines generally uses steel billets with dimensions of (150*150*12000)mm, which are heated at a constant temperature in a heating furnace, rolled into finished products, and then cooled after rolling.

[0003] The addition of large amounts of trace elements increases production costs and precious metal resource consumption. Furthermore, the use of high-temperature initial rolling and high-temperature cooling beds limits rolling speed, making the product surface prone to quality defects such as peeling, bulging, and bubbles, resulting in large fluctuations in product performance. Using 12000mm short square billets for rolling leads to low production efficiency, low yield, and increased energy consumption during the rolling process. Therefore, it is necessary to explore a high-speed bar production line method for producing 18mm straight rebar to solve the problems of poor surface quality and low yield in existing Φ18mm rebar production. Summary of the Invention

[0004] In view of the problems existing in the prior art, the purpose of this invention is to provide a method for producing 18mm straight threaded steel bars on a high-speed bar production line.

[0005] The technical solution adopted by this invention to solve its technical problem is: a method for producing 18mm straight rebar on a high-speed bar production line, comprising the following steps:

[0006] S1. Heating process: Continuously cast square billets are used and uniformly heated in a heating furnace. The chemical composition of the steel billets used in the continuous casting process is as follows (mass percentage): C: 0.23~0.25%, Si: 0.22~0.42%, Mn: 1.18~1.38%, S+P≤0.02%, V: 0.023~0.033%, and nitrogen content≤70ppm.

[0007] S2, Roughing, Intermediate and Pre-finishing Rolling Processes: The roughing, intermediate and pre-finishing rolling areas of the rolling line use a total of 16 alternating horizontal and vertical rolling mills;

[0008] S3. Water cooling before finishing rolling: Control the pressure and temperature of the cooling water tank. After passing through the No. 3 flying shear head, the product enters the finishing mill to produce finished rolled products that meet the required dimensions.

[0009] S4. Water cooling after finishing rolling: After the rolled piece is cooled by a water tank, the temperature of the rolled piece is controlled to pass through two stand units, and finally it is cooled evenly in three sections by three water tanks to produce rebar.

[0010] S5. Real-time online monitoring of rebar: Controlling the dimensions of rebar products.

[0011] Specifically, the dimensions of the continuously cast square billet in step S1 are 165*165*16000mm.

[0012] Specifically, the heating furnace in step S1 is a four-segment walking beam furnace, employing a gradient heating method:

[0013] The furnace feed temperature is above 800℃. When producing with cool billets, the temperature of the third heating section is controlled at 870±30℃, the second heating section at 910±20℃, the first heating section at 1060±20℃, and the soaking section at 1070±20℃. When producing with hot billets, the temperature of the third heating section is controlled at 900±30℃, the second heating section at 900±20℃, the first heating section at 1060±20℃, and the soaking section at 1070±20℃. The initial rolling temperature for both cool and hot billets is controlled at 960±10℃.

[0014] Specifically, in step S2, the alternating horizontal and vertical rolling mill controls the material shape to a 23.5mm round billet with a cross-sectional area of ​​423~425mm². 2 .

[0015] Specifically, in step S3, the water cooling process involves two water tanks, with the water supply pressure controlled at over 14 Bar and the temperature controlled at 860±10℃.

[0016] Specifically, the finishing mill in step S3 uses two SMS finishing mills, and the steel billet passes through two 45° top-crossing finishing mills.

[0017] Specifically, in step S4, the temperature of the rolled piece is controlled to 840±10℃ before entering the two-stand mill for empty run. After being cooled by three water tanks, the temperature of the upper cooling bed is finally controlled to 800±10℃.

[0018] Specifically, in step S5, the online real-time monitoring of rebar uses high-definition cameras and image processing algorithms to display the dimensions of the inner diameter, longitudinal ribs, and transverse ribs of the rebar product in real time, automatically calculate the actual tolerance of the rebar product, and, in conjunction with the tolerance early warning system, automatically provide adjustment suggestions to assist the operator in controlling the dimensions of the rebar product.

[0019] The present invention has the following beneficial effects:

[0020] This invention presents a high-speed bar production line for producing 18mm straight rebar. It employs novel controlled rolling and cooling technology to achieve high furnace-entry temperature billet production and high-speed rolling at 20m / s, thereby reducing gas consumption, achieving "water-based" production, improving product performance, reducing the use of precious metal alloys, and lowering alloy costs. The use of online product dimension detection equipment and a tolerance early warning system allows for timely adjustments to the rolling process, ensuring precise dimensions. Finished product dimension fluctuations are controlled within 0.15mm, and overall bar tolerance fluctuations are controlled within 0.2%, resulting in a 1.02% increase in yield. Detailed Implementation

[0021] The technical solutions in the embodiments of the present invention will be described clearly, completely, and in further detail below. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0022] A high-speed steel rolling bar production line for producing 18mm straight thread bars has been developed. By optimizing temperature control and process matching throughout the heating, rolling, and cooling processes, it is possible to achieve higher rolling speed and yield, lower alloy costs and energy consumption, and reduce production costs while ensuring the mechanical properties of the product.

[0023] Example 1:

[0024] 1. Using 165*165*16000mm continuously cast square billets, the billets are uniformly heated in a four-stage walking beam furnace. After exiting the furnace, the billets undergo 18 passes of rough rolling, intermediate rolling, pre-finish rolling, and finish rolling to produce the finished product. Water cooling is installed before and after finish rolling to adjust the cooling rate of the steel, control the grain deformation and phase transformation temperature, and adjust the internal structure of the finished steel to ferrite + pearlite to improve the strength and plasticity of the steel.

[0025] 2. The four-stage walking beam furnace adopts a gradient heating process. Different temperature range standards are set according to different steel grades. Combined with a regenerative combustion system, the heating temperature of each stage is automatically collected to realize the automatic start and stop of the burners. Intelligent combustion control technology is used to automatically heat the steel billet.

[0026] 3. The maximum acceptable furnace temperature is above 800℃. When producing with cooled billets, the temperature of the third heating section is controlled at 840℃, the temperature of the second heating section is controlled at 890℃, the temperature of the first heating section is controlled at 1040℃, and the temperature of the soaking section is controlled at 1050℃; the initial rolling temperature is controlled at 960℃.

[0027] 4. The roughing, intermediate rolling, and pre-finishing rolling areas of the rolling line use a total of 16 alternating horizontal and vertical rolling mills. A large reduction is used to control the material shape to a circle of 23.5mm and a cross-sectional area of ​​423mm². The material is then cooled by two water tanks with a water supply pressure controlled above 14 Bar to control the cooling rate and temperature of the rolled piece at 860℃. After passing through the No. 3 flying shear head, the material enters the SMS finishing mill unit and passes through two 45° top-crossing finishing mills to produce the finished product that meets the required dimensions.

[0028] 5. After cooling in one water tank, the temperature of the rolled piece is controlled at 840℃ before entering the two-stand mill (dry run). Finally, it is cooled evenly in three sections by three water tanks, and the temperature of the upper cooling bed is finally controlled at 800℃ to ensure that the product surface is dense, uniform and smooth.

[0029] 6. By applying high-definition cameras and image processing algorithms, online real-time monitoring of Φ18mm threaded steel bars is achieved. This allows for real-time display of key dimensions such as the product's inner diameter, longitudinal ribs, and transverse ribs. It automatically calculates actual product tolerances and, combined with a tolerance early warning system, automatically provides adjustment suggestions to assist in precise control of product dimensions and improve yield rates.

[0030] 7. The chemical composition of the steel billet used in continuous casting is as follows (by weight): C: 0.23%, Si: 0.22%, Mn: 1.18%, impurity elements such as S and P ≤ 0.02%, V: 0.023%, and nitrogen content ≤ 70 ppm.

[0031] This invention utilizes online product dimension inspection equipment and a tolerance early warning system to stabilize product dimensions, improve yield, and reduce energy consumption, resulting in a cost reduction of 20 yuan per ton of steel. Using controlled rolling and cooling processes, product quality surpasses national standards, with a stable yield strength above 425 MPa and a uniform ferrite + pearlite microstructure with a grain size of grade 9 or higher. It also reduces the use of precious metal alloys, further reducing costs by approximately 20 yuan per ton of steel. The rolling speed reaches 20 m / s, and the hourly output can reach 260 tons / hour.

[0032] Example 2:

[0033] 1. Using 165*165*16000mm continuously cast square billets, the billets are uniformly heated in a four-stage walking beam furnace. After exiting the furnace, the billets undergo 18 passes of rough rolling, intermediate rolling, pre-finish rolling, and finish rolling to produce the finished product. Water cooling is installed before and after finish rolling to adjust the cooling rate of the steel, control the grain deformation and phase transformation temperature, and adjust the internal structure of the finished steel to ferrite + pearlite to improve the strength and plasticity of the steel.

[0034] 2. The four-stage walking beam furnace adopts a gradient heating process. Different temperature range standards are set according to different steel grades. Combined with a regenerative combustion system, the heating temperature of each stage is automatically collected to realize the automatic start and stop of the burners. Intelligent combustion control technology is used to automatically heat the steel billet.

[0035] 3. The maximum acceptable furnace temperature is above 800℃. When producing hot billets, the temperature of the third heating section is controlled at 930℃, the temperature of the second heating section is controlled at 920℃, the temperature of the first heating section is controlled at 1080℃, and the temperature of the soaking section is controlled at 1090℃; the initial rolling temperature is controlled at 960℃.

[0036] 4. The roughing, intermediate rolling, and pre-finishing rolling areas of the rolling line use a total of 16 alternating horizontal and vertical rolling mills. A large reduction is used to control the material shape to a circle of 23.5mm and a cross-sectional area of ​​425mm². The material is then cooled by two water tanks with a water supply pressure controlled above 14 Bar to control the cooling rate and temperature of the rolled piece at 860℃. After passing through the No. 3 flying shear head, the material enters the SMS finishing mill unit and passes through two 45° top-crossing finishing mills to produce the finished product that meets the required dimensions.

[0037] 5. After cooling in one water tank, the temperature of the rolled piece is controlled at 840℃ before entering the two-stand mill (dry run). Finally, it is cooled evenly in three sections by three water tanks, and the temperature of the upper cooling bed is finally controlled at 800℃ to ensure that the product surface is dense, uniform and smooth.

[0038] 6. By applying high-definition cameras and image processing algorithms, online real-time monitoring of Φ18mm threaded steel bars is achieved. This allows for real-time display of key dimensions such as the product's inner diameter, longitudinal ribs, and transverse ribs. It automatically calculates actual product tolerances and, combined with a tolerance early warning system, automatically provides adjustment suggestions to assist in precise control of product dimensions and improve yield rates.

[0039] 7. The chemical composition of the steel billet used in continuous casting is as follows (by weight): C: 0.25%, Si: 0.42%, Mn: 1.38%, impurity elements such as S and P ≤ 0.02%, V: 0.033%, and nitrogen content ≤ 70 ppm.

[0040] This invention utilizes online product dimension detection equipment and a tolerance early warning system to stabilize product dimensions, improve yield, and reduce energy consumption, resulting in a cost reduction of 18 yuan per ton of steel. Using controlled rolling and cooling processes, product quality surpasses national standards, with a stable yield strength above 425 MPa and a uniform ferrite + pearlite microstructure with a grain size of grade 9 or higher. It also reduces the use of precious metal alloys, further reducing costs by approximately 18 yuan per ton of steel. The rolling speed reaches 20 m / s, and the hourly output can reach 258 tons / hour.

[0041] This invention is not limited to the above-described embodiments. Anyone should know that any structural changes made under the guidance of this invention, and any technical solutions that are the same as or similar to this invention, fall within the protection scope of this invention.

[0042] The technologies, shapes, and structures not described in detail in this invention are all known technologies.

Claims

1. A method for producing 18mm straight rebar on a high-speed bar production line, characterized in that, Includes the following steps: S1. Heating process: Continuously cast square billets are used and uniformly heated in a heating furnace. The chemical composition of the steel billets used in the continuous casting process is as follows (mass percentage): C: 0.23~0.25%, Si: 0.22~0.42%, Mn: 1.18~1.38%, S+P≤0.02%, V: 0.023~0.033%, and nitrogen content≤70ppm. S2, Roughing, Intermediate and Pre-finishing Rolling Processes: The roughing, intermediate and pre-finishing rolling areas of the rolling line use a total of 16 alternating horizontal and vertical rolling mills; S3. Water cooling before finishing rolling: Control the pressure and temperature of the cooling water tank. After passing through the No. 3 flying shear head, the product enters the finishing mill to produce finished rolled products that meet the required dimensions. S4. Water cooling after finishing rolling: After the rolled piece is cooled by a water tank, the temperature of the rolled piece is controlled to pass through two stand units, and finally it is cooled evenly in three sections by three water tanks to produce rebar. S5. Real-time online monitoring of rebar: Controlling the dimensions of rebar products.

2. The method for producing 18mm straight rebar on a high-speed bar production line according to claim 1, characterized in that, The dimensions of the continuously cast square billet in step S1 are 165*165*16000mm.

3. The method for producing 18mm straight rebar on a high-speed bar production line according to claim 1, characterized in that, The heating furnace in step S1 is a four-segment walking beam furnace, employing a gradient heating method. The furnace feed temperature is above 800℃. When producing with cool billets, the temperature of the third heating section is controlled at 870±30℃, the second heating section at 910±20℃, the first heating section at 1060±20℃, and the soaking section at 1070±20℃. When producing with hot billets, the temperature of the third heating section is controlled at 900±30℃, the second heating section at 900±20℃, the first heating section at 1060±20℃, and the soaking section at 1070±20℃. The initial rolling temperature for both cool and hot billets is controlled at 960±10℃.

4. The method for producing 18mm straight rebar on a high-speed bar production line according to claim 1, characterized in that, In step S2, the alternating horizontal and vertical rolling mill controls the material shape to a 23.5mm round billet with a cross-sectional area of ​​423~425mm². 2 .

5. The method for producing 18mm straight rebar on a high-speed bar production line according to claim 1, characterized in that, In step S3, the water cooling process involves two water tanks. The water supply pressure to the tanks is controlled to be above 14 Bar, and the temperature is controlled at 860±10℃.

6. The method for producing 18mm straight rebar on a high-speed bar production line according to claim 1, characterized in that, The finishing mill in step S3 uses two SMS finishing mills, and the billet passes through two 45° top-crossing finishing mills.

7. The method for producing 18mm straight rebar on a high-speed bar production line according to claim 1, characterized in that, In step S4, the temperature of the rolled piece is controlled to 840±10℃ before entering the two-stand mill for empty run. After being cooled by three water tanks, the temperature of the upper cooling bed is finally controlled to 800±10℃.

8. The method for producing 18mm straight rebar on a high-speed bar production line according to claim 1, characterized in that, In step S5, the online real-time monitoring of rebar uses high-definition cameras and image processing algorithms to display the dimensions of the inner diameter, longitudinal ribs, and transverse ribs of the rebar product in real time. It automatically calculates the actual tolerance of the rebar product and, in conjunction with the tolerance early warning system, automatically provides adjustment suggestions to assist the operator in controlling the dimensions of the rebar product.