Double-high-speed bar flexible production line and bar production process

Abstract

The invention provides a double-high-speed bar flexible production line and a bar production process. The double-high-speed bar flexible production line comprises a plurality of finish rolling lines, a roughing rolling unit, a first flying shear, an intermediate rolling unit, a second flying shear, a pre-finishing rolling unit and a first pre-water-cooling device, wherein the roughing rolling unit, the first flying shear, the intermediate rolling unit, the second flying shear, the pre-finishing rolling unit and the first pre-water-cooling device are sequentially arranged; wherein each finish rolling line comprises a diameter measuring instrument, a third flying shear, a first finish rolling unit, a second pre-water-cooling device, a fourth flying shear, a second finish rolling unit, a third pre-water-cooling device, a fifth flying shear, a third finish rolling unit and a water cooling device which are arranged in sequence; and a fourth pre-water-cooling device is arranged between the first pre-water-cooling device and the diameter measuring instrument of each finish rolling line. The double-high-speed bar flexible production line is high in structural reliability, high-speed controlled rolling and controlled cooling can be achieved, then the product quality can be guaranteed, and reduced green production of hot-rolled steel bar alloy is achieved.

Description

Technical Field

[0001] This application relates to the field of bar rolling technology, and in particular to a dual high-speed bar flexible production line and bar production process. Background Technology

[0002] With the increase in demand and production capacity for small-diameter ribbed steel bars, the single high-speed bar production process has evolved into a dual high-speed bar production process. This means that small-diameter rolled products are double-cut and then enter two independent finishing rolling lines and a dual high-speed steel loading system.

[0003] The typical rolling zone layout scheme of a dual high-speed bar production line is as follows: Figure 1 As shown. The main equipment includes: roughing mill 1-1, first flying shear 1-2, intermediate mill 1-3, second flying shear 1-4, pre-finishing mill 1-5, first pre-water cooling device 1-6, third flying shear 1-7, first finishing mill 1-8, second pre-water cooling device 1-9, fourth flying shear 1-10, second finishing mill 1-11, and water cooling device 1-12. After being slit and rolled in the intermediate mill, the workpiece is fed into the dual-line (A / B) pre-finishing mill for rolling. It then passes through pre-water cooling one before entering the first finishing mill, and then through pre-water cooling two before entering the second finishing mill. The finished product enters the water cooling device after being rolled out of the finishing mill. The dual-line equipment has the same configuration and is arranged side-by-side. The six finishing stands adopt a "2+4" arrangement, with each line having one 1-to-2 modular mill forming the first finishing mill; and two 1-to-2 modular mills forming the second finishing mill. The two finishing mills are arranged separately, with a pre-water cooling device in between. Each line has three 1-to-2 modular mills with centralized drive and fixed speed ratios. This arrangement has the following drawbacks:

[0004] From an investment perspective, centralized transmission machinery has a complex structure and requires high motor power, resulting in high investment in equipment and transmission. From a production perspective, process adjustments are complex, flexibility is limited, and temperature control is not precise enough. From a product perspective, the rapid temperature rise of the rolled piece during high-speed rolling is detrimental to fine grain structure and alloy weight reduction. Summary of the Invention

[0005] To address at least one problem in the prior art, this application proposes a dual high-speed bar flexible production line and bar production process. The dual high-speed bar flexible production line has high structural reliability and can achieve high-speed controlled rolling and cooling, thereby ensuring product quality and realizing green production of hot-rolled steel alloy with reduced volume.

[0006] To address the aforementioned technical problems, this application provides the following technical solution:

[0007] In a first aspect, this application provides a dual high-speed bar flexible production line, comprising: multiple finishing rolling lines, a roughing mill, a first flying shear, an intermediate rolling mill, a second flying shear, a pre-finishing mill, and a first pre-water cooling device arranged sequentially; wherein...

[0008] Each finishing mill line includes, in sequence: a diameter gauge, a third flying shear, a first finishing mill unit, a second pre-water cooling device, a fourth flying shear, a second finishing mill unit, a third pre-water cooling device, a fifth flying shear, a third finishing mill unit, and a water cooling device; a fourth pre-water cooling device is provided between the first pre-water cooling device and the diameter gauge of each finishing mill line.

[0009] In one embodiment, the roughing mill unit includes: multiple roughing mills; each roughing mill and the first flying shear are arranged sequentially.

[0010] In one embodiment, the intermediate rolling mill group includes: multiple intermediate rolling mills; the first flying shear, each intermediate rolling mill, and the second flying shear are arranged sequentially.

[0011] In one embodiment, the pre-finishing mill unit includes: multiple pre-finishing mills; the second flying shear, each pre-finishing mill, and the first pre-water cooling device are arranged sequentially.

[0012] In one embodiment, the roughing mill, intermediate mill, and pre-finishing mill are all short stress line mills.

[0013] In one embodiment, the roughing mills in the roughing mill group are arranged in an alternating horizontal and vertical configuration, the intermediate mills in the intermediate mill group are arranged in an alternating horizontal and vertical configuration, and the pre-finishing mills in the pre-finishing mill group are arranged in a horizontal-vertical-horizontal-horizontal-horizontal-horizontal-horizontal-horizontal-horizontal-horizontal-horizontal configuration.

[0014] In one embodiment, the first finishing mill group in each finishing mill line includes two finishing mills, the second finishing mill group includes two finishing mills, and the third finishing mill group includes two finishing mills.

[0015] In one embodiment, the finishing mills in the first finishing mill group, the second finishing mill group, and the third finishing mill group are all driven by independent drives.

[0016] In one embodiment, the roughing mill in the roughing mill group has six stands, the intermediate mill in the intermediate mill group has four stands, and the pre-finishing mill in the pre-finishing mill group has six stands.

[0017] Secondly, this application provides a bar manufacturing process, implemented using the aforementioned dual high-speed bar flexible production line, the bar manufacturing process comprising:

[0018] The heated steel billet is fed into the roughing mill for rolling, and after passing through the first flying shear head, it enters the intermediate mill for rolling.

[0019] The steel billet rolled by the intermediate rolling mill is then passed through the second flying shear head and entered the pre-finishing rolling mill for slitting and rolling to form multiple rolled pieces;

[0020] Each rolled piece is fed into a different finishing mill line via the first pre-cooling device. Each rolled piece is then sequentially passed through the corresponding fourth pre-cooling device, diameter gauge, third flying shear, first finishing mill, second pre-cooling device, fourth flying shear, second finishing mill, third pre-cooling device, fifth flying shear, third finishing mill, and water cooling device to form a bar.

[0021] As can be seen from the above technical solution, this application provides a dual high-speed bar flexible production line and bar production process. The dual high-speed bar flexible production line includes: multiple finishing mill lines, a roughing mill group, a first flying shear, an intermediate mill group, a second flying shear, a pre-finishing mill group and a first pre-water cooling device arranged in sequence; wherein, each finishing mill line includes: a diameter measuring instrument, a third flying shear, a first finishing mill group, a second pre-water cooling device, a fourth flying shear, a second finishing mill group, a third pre-water cooling device, a fifth flying shear, a third finishing mill group and a water cooling device arranged in sequence; a fourth pre-water cooling device is provided between the first pre-water cooling device and the diameter measuring instrument of each finishing mill line, which has high structural reliability and can realize high-speed controlled rolling and controlled cooling, thereby improving the quality of the finished product; specifically, (1) the finishing mill group adopts a "2+2+2" arrangement, and each finishing mill group is equipped with a pre-water cooling device. By setting up pre-water cooling devices between each group of finishing mills, the rolling temperature rise can be offset, effectively shortening the length of the process section, i.e., the finishing mill line; the near-constant temperature rolling of the rolled pieces can ensure the grain refinement effect, effectively meeting the requirements of microstructure and performance, thereby reducing the consumption of alloys such as V and Mn, and realizing the green production of hot-rolled steel rebar alloys with reduced quantity. (2) The finishing mill group is split into a single-drive module mill, and the stands can be flexibly adjusted and extended, which can meet the pressing requirements of each specification and each stand, and can meet the needs of a wide range of product specifications and final rolling speeds, maximizing the process flexibility. (3) The finishing mill 6 stands are driven separately, reducing the equipment idling rate, reducing production costs such as electricity and water consumption, and is conducive to energy conservation and emission reduction. (4) The mill adopts the arrangement of "6+4+6+(2+2+2)×2", which reduces the total number of mills, but the number of rolling passes through which the rolled pieces pass does not change. Under the condition of meeting the process pass type, the number of maintenance points and spare parts investment of the rolling line are reduced, empowering production enterprises to reduce costs and increase efficiency. Attached Figure Description

[0022] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0023] Figure 1 This is a schematic diagram of the structure of a dual high-speed bar flexible production line in the existing technology;

[0024] Figure 2 This is a schematic diagram of the structure of the dual high-speed bar flexible production line in the embodiments of this application.

[0025] Symbol Explanation

[0026] 1-1 Roughing mill; 1-2 First flying shear; 1-3 Intermediate mill; 1-4 Second flying shear; 1-5 Pre-finishing mill; 1-6 First pre-water cooling unit; 1-7 Third flying shear; 1-8 First finishing mill; 1-9 Second pre-water cooling unit; 1-10 Fourth flying shear; 1-11 Second finishing mill; 1-12 Water cooling unit; 2-1 Roughing mill; 2-2 First flying shear; 2-3 Intermediate mill; 2 -4. Second flying shear; 2-5. Pre-finishing mill; 2-6. First pre-water cooling device; 2-7. Diameter gauge; 2-8. Third flying shear; 2-9. First finishing mill; 2-10. Second pre-water cooling device; 2-11. Fourth flying shear; 2-12. Second finishing mill; 2-13. Third pre-water cooling device; 2-14. Fifth flying shear; 2-15. Third finishing mill; 2-16. Water cooling device; 2-17. Fourth pre-water cooling device. Detailed Implementation

[0027] To enable those skilled in the art to better understand the technical solutions in this specification, the technical solutions in the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments in this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this application.

[0028] Specific embodiments of this application are disclosed in detail with reference to the following description and accompanying drawings, indicating how the principles of this application can be adopted. It should be understood that the embodiments of this application are not limited in scope. Within the spirit and scope of the appended claims, embodiments of this application include many changes, modifications, and equivalents.

[0029] Features described and / or illustrated for one embodiment may be used in the same or similar manner in one or more other embodiments, combined with features in other embodiments, or substituted for features in other embodiments.

[0030] It should be emphasized that the term "including / comprises" as used herein refers to the presence of a feature, whole, step, or component, but does not exclude the presence or addition of one or more other features, wholes, steps, or components.

[0031] Hot-rolled ribbed steel bars, as a major type of construction steel, are widely used in civil engineering projects such as houses, bridges, and roads. Currently, there are two main production processes for straight steel bars: one is slitting and rolling, with a typical mill arrangement of "6+4+6+2," capable of a designed annual output of 1-1.3 million tons (all specifications), with a yield of approximately 96%; the other is high-speed bar production, with a typical mill arrangement of "6+6+6+6," capable of a designed annual output of 700,000-800,000 tons when small specifications account for a high proportion, and 800,000-1,050,000 tons when large specifications account for a high proportion, with a yield of approximately 98%.

[0032] The high-speed bar production line employs continuous, high-speed, and twist-free rolling, offering advantages such as high-speed straight bars, excellent appearance quality, stable negative tolerances, and low alloy content. Dual-line high-speed rolling of small-diameter ribbed steel bars increases the output of small-diameter products, meeting the large market demand for small-diameter straight bars. This avoids the problems and waste caused by using high-strength wire rod coiling and reduces the defects of low product quality, frequent defects, and low yield associated with traditional slitting and rolling of small-diameter ribbed steel bars. Equipped with corresponding high-quality and advanced facilities, it achieves stable and efficient production, maximizing the market competitiveness and economic benefits of products from the building materials-focused production line.

[0033] exist Figure 1 In the typical rolling mill layout of a dual high-speed bar production line, this rolling mill is a fully continuous bar mill with a maximum final rolling speed of 45 m / s. The entire line has 32 stands, divided into 5 groups: roughing mill group 1-1 (6 stands), intermediate mill group 1-3 (6 stands), two pre-finishing mill groups 1-5 (4×2 stands), two first finishing mill groups 1-8 (2×2 stands), and two second finishing mill groups 1-11 (4×2 stands). The roughing and intermediate mills use short stress line mills, which have high rigidity, long roll bearing life, symmetrical roll adjustment, convenient operation, and can be replaced as a whole stand with short roll change time. The roughing mill uses an alternating horizontal and vertical arrangement, while the intermediate mill uses a "horizontal-vertical-horizontal-horizontal-horizontal-horizontal" arrangement. The pre-finishing mill adopts a cantilevered tungsten carbide roll ring mill with alternating horizontal and vertical arrangements and independent drives. The mill layout is compact and can provide high-precision rolled products for the finishing mill. The finishing mill is a heavy-duty high-speed, twist-free mill with a top angle of 45°. The six stands are divided into three groups of drives and use cantilevered tungsten carbide roll rings. The mill has good stability and low vibration. The rolled products are rolled in a single line without torsion and with low tension between the finishing mills, resulting in high dimensional accuracy and good surface quality of the finished products.

[0034] The first finishing mill is equipped with pre-water cooling devices before and after it, and the second finishing mill is equipped with a water cooling device after it. This enables controlled rolling and controlled cooling technology. The minimum temperature entering the finishing mill is controlled at 800-830℃. The bars exiting the finishing mill immediately enter the water cooling device for staged cooling, which rapidly cools the temperature of the rolled piece to about 750-800℃ to control the growth of austenite and ferrite grains, ultimately obtaining higher tensile strength and improving the microstructure of the steel reinforcement.

[0035] To address the problems existing in the prior art, this application provides a dual high-speed bar flexible production line and bar production process. It can split the three sets of one-to-two modular rolling mills into three sets of single-drive modular rolling mills, and arrange pre-water cooling devices between each set of modular rolling mills, thereby achieving true high-speed controlled rolling and cooling. The one-to-two modular rolling mill can represent a configuration where one motor drives two rolling mills simultaneously through a transmission system. The entire rolling line can adopt a "6+4+6+(2+2+2)×2" arrangement, reducing the total number of rolling mills while maintaining the same number of rolling passes for the rolled product. While meeting the process pass requirements, it reduces the number of rolling line maintenance points and spare parts investment, empowering production enterprises to reduce costs and increase efficiency. In this application embodiment, the spacing of the main equipment and the arrangement of transition equipment can be adjusted according to different project product specifications, external environment, and other factors.

[0036] The following examples illustrate this in detail.

[0037] To improve the reliability of the dual high-speed bar flexible production line structure, achieve high-speed controlled rolling and cooling, and thus improve the quality of the finished product, this embodiment provides a dual high-speed bar flexible production line, such as... Figure 2 As shown, the dual high-speed bar flexible production line specifically includes: multiple finishing mill lines, a roughing mill 2-1, a first flying shear 2-2, an intermediate mill 2-3, a second flying shear 2-4, a pre-finishing mill 2-5, and a first pre-water cooling device 2-6 arranged sequentially; wherein, each finishing mill line includes: a diameter gauge 2-7, a third flying shear 2-8, a first finishing mill 2-9, a second pre-water cooling device 2-10, a fourth flying shear 2-11, a second finishing mill 2-12, a third pre-water cooling device 2-13, a fifth flying shear 2-14, a third finishing mill 2-15, and a water cooling device arranged sequentially; a fourth pre-water cooling device 2-17 is provided between the first pre-water cooling device 2-6 and the diameter gauge 2-7 of each finishing mill line.

[0038] Specifically, the roughing mill 2-1, the first flying shear 2-2, the intermediate mill 2-3, the second flying shear 2-4, the pre-finishing mill 2-5, and the first pre-water cooling device 2-6 can be arranged sequentially along the rolling direction; the multiple finishing mill lines can be two parallel finishing mill lines. The rolled piece is subjected to torsion-free, low-tension rolling in the roughing mill 2-1 and the intermediate mill 2-3. The first pre-water cooling device 2-6 may include a dual-channel water tank; the fourth pre-water cooling device 2-17 may include multiple single-channel water tanks; the first pre-water cooling device 2-6 and the fourth pre-water cooling device 2-17 can be integrated into a single pre-water cooling device. The steel billet can be cut into two pieces by the pre-finishing mill 2-5, and after passing through the first dual-channel water tank, it enters the upper and lower separate finishing mill lines. Figure 2 The arrow in the image indicates the rolling direction.

[0039] The roughing mill 2-1 may include multiple roughing mills; each roughing mill and the first flying shear 2-2 are arranged sequentially. The intermediate mill 2-3 may include multiple intermediate mills; the first flying shear 2-2, each intermediate mill, and the second flying shear 2-4 are arranged sequentially. The pre-finishing mill 2-5 may include multiple pre-finishing mills; the second flying shear 2-4 is installed, each pre-finishing mill, and the first pre-water cooling device 2-6 are arranged sequentially. The roughing mill 2-1, intermediate mill 2-3, and pre-finishing mill 2-5 may all be short-stress-line mills. The roughing mills in the roughing mill 2-1 may be arranged in an alternating horizontal and vertical configuration; the intermediate mills in the intermediate mill 2-3 may be arranged in an alternating horizontal and vertical configuration; and the pre-finishing mills in the pre-finishing mill 2-5 may be arranged in a horizontal-vertical-horizontal ... In order to achieve tension-free rolling and ensure the dimensional accuracy of the rolled pieces, each pre-finishing mill in the pre-finishing mill group 2-5 can be equipped with a looper.

[0040] Preferably, the roughing mill in the roughing mill group 2-1 has six stands, the intermediate mill in the intermediate mill group 2-3 has four stands, and the pre-finishing mill in the pre-finishing mill group 2-5 has six stands.

[0041] Specifically, each finishing mill (i.e., the first to third finishing mills) is equipped with a pre-water cooling device to achieve temperature-controlled and constant-temperature rolling. All finished product specifications are rolled out from the finishing mills, which are all designed for low-temperature rolling at 800–830℃. A water cooling device, also known as a quenching water cooling device, is installed after the third finishing mill. This device controls the cooling rate of the rolled workpiece after rolling, rapidly cooling it to the phase transformation region to prevent rapid austenite grain growth. It ensures that the surface does not enter the martensite and bainite transformation regions, and that the base circle does not exhibit tempered martensite or closed-loop structures different from the matrix. Simultaneously, the core-to-surface hardness difference is ≤40HV, meeting the new national standard requirements for hot-rolled steel bars. It can also produce export building materials such as British standard steel bars through post-rolling residual heat quenching technology. The entire water cooling system (i.e., the first to fourth pre-water cooling devices and the water cooling device in the dual high-speed bar flexible production line) adopts a closed structure to prevent water or steam leakage. The aforementioned temperature control measures can significantly improve the final performance of the product and upgrade the product grade at a low cost, thereby enhancing the product's market competitiveness.

[0042] In one embodiment of this application, each finishing mill line includes a first finishing mill group comprising two finishing mill stands, a second finishing mill group comprising two finishing mill stands, and a third finishing mill group comprising two finishing mill stands. The finishing mills in the first, second, and third finishing mill groups can all be driven independently.

[0043] Specifically, the finishing mills in the first to third finishing mill groups can all be heavy-duty, twist-free mills with a top angle of 45°; the six finishing mills can be divided into six groups of drives; cantilevered tungsten carbide roll rings can be used, and the rolled parts can be rolled in a single-line, twist-free, micro-tension process between the finishing mill groups to produce products with high dimensional accuracy and high surface quality. The minimum temperature entering each finishing mill group is controlled at 800–830℃, and the bars exiting the finishing mill group can immediately enter a water cooling device for cooling, reducing the temperature of the rolled parts to about 750–800℃ to control the growth of austenite and ferrite grains, achieving the purpose of fine grain strengthening, and ultimately obtaining higher tensile strength and improving the microstructure of the reinforcing steel.

[0044] In this embodiment, the first finishing mill unit's two-module rolling mill can be split into single-drive module rolling mills. The stands can be flexibly adjusted and extended to meet the pressing requirements of each specification and each stand, satisfying a wide range of product specifications and final rolling speeds, and maximizing process flexibility. The individual drive method of the six-stand finishing mill can reduce equipment idling rate, reduce production costs such as electricity and water consumption, and is conducive to energy conservation and emission reduction.

[0045] To further illustrate this solution, this application provides an application example of a dual high-speed bar production line. In this application example, the dual high-speed bar production line mainly includes:

[0046] Roughing mill 2-1, First flying shear 2-2, Intermediate mill 2-3, Second flying shear 2-4, Pre-finishing mill 2-5, First pre-water cooling device 2-6, Fourth pre-water cooling device 2-17, Diameter gauge 2-7, Third flying shear 2-8, First finishing mill 2-9, Second pre-water cooling device 2-10, Fourth flying shear 2-11, Second finishing mill 2-12, Third pre-water cooling device 2-13, Fifth flying shear 2-14, Third finishing mill 2-15, Water cooling device 2-16.

[0047] The rolling mills in the dual high-speed bar production line are fully continuous bar mills with a maximum finishing speed of 45 m / s. The main rolling mill consists of 28 stands, divided into 5 groups: a roughing mill group with 6 stands, an intermediate mill group with 4 stands, a pre-finishing mill group with 6 stands, two first-finishing mill groups with a total of 2×2 stands, two second-finishing mill groups with a total of 2×2 stands, and two third-finishing mill groups with a total of 2×2 stands. The roughing, intermediate, and pre-finishing mills all employ short stress line mills. The roughing and intermediate mills are arranged alternately in a horizontal-vertical configuration, while the pre-finishing mills are arranged in a "horizontal-vertical-horizontal-horizontal-horizontal" configuration. The finishing mill is a heavy-duty high-speed, twist-free mill with a top angle of 45°. It adopts a "2+2+2" layout, with all six stands using single-stand drive and tungsten carbide roller rings. Each mill is compactly arranged, with good stability and low vibration. The rolled pieces are rolled in a single-line, twist-free, and low-tension manner between the finishing mills, resulting in high dimensional accuracy and good surface quality of the finished products.

[0048] Each finishing mill is equipped with a pre-water cooling device to achieve temperature-controlled and constant-temperature rolling. All finished product specifications are rolled out from the finishing mill, which is designed for low-temperature rolling at 800–830℃. A water-cooling device is installed after the finishing mill to control the cooling rate of the rolled workpiece, ensuring rapid cooling to the phase transformation region, preventing rapid austenite grain growth, ensuring the surface does not enter the martensite and bainite transformation regions, and preventing the formation of tempered martensite and closed-loop structures different from the matrix in the base circle. Simultaneously, the core-to-surface hardness difference is ≤40HV, meeting the new national standard requirements for hot-rolled steel bars. It can also produce export building materials such as those meeting British standards through post-rolling residual heat quenching technology. The entire water cooling system adopts a closed structure to prevent water or steam leakage. These temperature control measures significantly improve the final performance of the product and enable low-cost improvement in product grade, thereby enhancing the product's market competitiveness.

[0049] To achieve high-speed controlled rolling and cooling and improve the quality of finished products, this application provides a bar production process, implemented using the aforementioned dual high-speed bar flexible production line. This bar production process includes: feeding a heated steel billet into a roughing mill for rolling; passing it through a first flying shear head and then into an intermediate mill for rolling; passing the steel billet rolled by the intermediate mill through a second flying shear head and then into a pre-finishing mill for slitting and rolling to form multiple rolled sections; feeding each rolled section through a first pre-water cooling device into different finishing mill lines; and sequentially passing through a corresponding fourth pre-water cooling device, a diameter gauge, a third flying shear, a first finishing mill, a second pre-water cooling device, a fourth flying shear, a second finishing mill, a third pre-water cooling device, a fifth flying shear, a third finishing mill, and a water cooling device to form a bar.

[0050] Specifically, the heated and qualified steel billets directly enter the rolling mill area for rolling. First, they are rolled for 6 passes in the roughing mill (650×6). After the first flying shear head (tail), they enter the intermediate mill (450×4) for 2-4 passes. After the second flying shear head (tail), they enter the pre-finishing mill (350×6) for 6 passes. After being split and rolled in the pre-finishing mill, they are sent to the twin-line (A / B) rolling mill. The twin-line rolled pieces are then rolled for 2-6 passes in the first finishing mill (310×2), second finishing mill (310×2), and third finishing mill (310×2), respectively, after the third flying shear head (tail). A fourth and fifth flying shear are installed between the mills. The workpieces undergo twist-free, low-tension rolling in the roughing and intermediate mills. Loops are installed before each stand in the pre-finishing mill to allow for tension-free rolling, ensuring dimensional accuracy. The finishing mill is a heavy-duty, twist-free mill with a top angle of 45°. It has six stands with six sets of drives and uses cantilevered tungsten carbide roll rings. The workpieces undergo single-line, twist-free, low-tension rolling between the finishing mills, producing products with high dimensional accuracy and high surface quality.

[0051] The first and second finishing mills are equipped with pre-cooling devices before and after them, while the third finishing mill is equipped with a water-cooling device after it. The number of sections and water volume of the water-cooling devices are set according to the product requirements of different steel grades and specifications to achieve the required workpiece temperature and meet the needs of controlled rolling and cooling. The minimum temperature entering each finishing mill is controlled at 800–830℃. The bars exiting the finishing mills can immediately enter the quenching cooling device for cooling, reducing the workpiece temperature to approximately 750–800℃. This controls the growth of austenite and ferrite grains, achieving fine-grain strengthening and ultimately obtaining higher tensile strength and improving the microstructure of the reinforcing steel.

[0052] This application uses specific embodiments to illustrate the principles and implementation methods of this application. The description of the above embodiments is only for the purpose of helping to understand the method and core ideas of this application. At the same time, for those skilled in the art, there will be changes in the specific implementation methods and application scope based on the ideas of this application. Therefore, the content of this specification should not be construed as a limitation of this application.

Claims

1. A flexible production line for dual high-speed bars, characterized in that, include: Multiple finishing rolling lines, a roughing mill, a first flying shear, an intermediate rolling mill, a second flying shear, a pre-finishing mill, and a first pre-water cooling unit arranged sequentially; among them, Each finishing mill line includes, in sequence: a diameter gauge, a third flying shear, a first finishing mill unit, a second pre-water cooling device, a fourth flying shear, a second finishing mill unit, a third pre-water cooling device, a fifth flying shear, a third finishing mill unit, and a water cooling device; a fourth pre-water cooling device is provided between the first pre-water cooling device and the diameter gauge of each finishing mill line.

2. The dual high-speed bar flexible production line according to claim 1, characterized in that, The roughing mill unit includes: multiple roughing mills; each roughing mill and the first flying shear are arranged sequentially.

3. The dual high-speed bar flexible production line according to claim 1, characterized in that, The intermediate rolling mill group includes: multiple intermediate rolling mills; the first flying shear, each intermediate rolling mill, and the second flying shear are arranged in sequence.

4. The dual high-speed bar flexible production line according to claim 1, characterized in that, The pre-finishing mill unit includes: multiple pre-finishing mills; the second flying shear, each pre-finishing mill, and the first pre-water cooling device are arranged in sequence.

5. The dual high-speed bar flexible production line according to claim 1, characterized in that, The roughing mill, intermediate mill, and pre-finishing mill all employ short stress line mills.

6. The dual high-speed bar flexible production line according to claim 1, characterized in that, The roughing mills in the roughing mill group are arranged in an alternating horizontal and vertical configuration, the intermediate mills in the intermediate mill group are arranged in an alternating horizontal and vertical configuration, and the pre-finishing mills in the pre-finishing mill group are arranged in a horizontal-vertical-horizontal-horizontal-horizontal-horizontal-horizontal-horizontal-horizontal-horizontal configuration.

7. The dual high-speed bar flexible production line according to claim 1, characterized in that, The first finishing mill group in each finishing mill line consists of two finishing mills, the second finishing mill group consists of two finishing mills, and the third finishing mill group consists of two finishing mills.

8. The dual high-speed bar flexible production line according to claim 1, characterized in that, The finishing mills in the first, second, and third finishing mills all have independent drive systems.

9. The dual high-speed bar flexible production line according to claim 1, characterized in that, The roughing mill unit has six roughing mill stands, the intermediate mill unit has four intermediate mill stands, and the pre-finishing mill unit has six pre-finishing mill stands.

10. A bar manufacturing process, characterized in that, The dual high-speed bar flexible production line according to any one of claims 1 to 9 is used to achieve this, wherein the bar production process includes: The heated steel billet is fed into the roughing mill for rolling, and after passing through the first flying shear head, it enters the intermediate mill for rolling. The steel billet rolled by the intermediate rolling mill is then passed through the second flying shear head and entered the pre-finishing rolling mill for slitting and rolling to form multiple rolled pieces; Each rolled piece is fed into a different finishing mill line via the first pre-cooling device. Each rolled piece is then sequentially passed through the corresponding fourth pre-cooling device, diameter gauge, third flying shear, first finishing mill, second pre-cooling device, fourth flying shear, second finishing mill, third pre-cooling device, fifth flying shear, third finishing mill, and water cooling device to form a bar.

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