A headless continuous casting and rolling production process for rod and wire products

Abstract

The present invention discloses a headless continuous casting and rolling production process for bar and wire products, comprising the following steps: ① continuous casting: firstly injecting refined molten steel into a tundish and a crystallizer, and using a straightening machine to pull out a continuous casting billet from the outlet of the crystallizer; ② initial rolling: sending the continuous casting billet obtained in step ① to an initial rolling unit for initial rolling to obtain an intermediate billet; ③ butt-joining of the intermediate billet: butt-joining and welding the preceding intermediate billet after the rough rolling in step ② and the subsequent intermediate billet immediately following the preceding intermediate billet; ④ heating of the intermediate billet: temperature detection of the intermediate billet after the butt-joining in step ③, if the temperature reaches the inlet temperature requirement of the continuous rolling unit, heating is not performed, if the temperature is insufficient, heating is performed; ⑤ continuous rolling; ⑥ finishing rolling and reducing diameter; ⑦ cooling. This method not only saves the construction cost, reduces the energy consumption of the device, simplifies the construction operation process, but also effectively improves the continuous casting and rolling quality of bar products and improves production efficiency.

Description

Technical Field

[0001] The invention belongs to the technical field of steelmaking production, and specifically relates to a headless continuous casting and rolling production process for rod and wire products. Background Art

[0002] my country is the world's largest steel producer. According to incomplete statistics from relevant industry organizations, by the end of 2020, China's crude steel output had exceeded 1 billion tons and steel output had exceeded 1.2 billion tons. The steel industry is the industrial foundation of my country and the pillar of national defense construction. However, with the overcapacity of domestic steel production and the intensification of environmental protection pressure, the steel industry needs to seek change and development. Headless continuous casting and rolling technology is the core technology in the steel field. This technology has developed relatively fast in the plate and strip field. For example, ESP continuous casting and rolling has made great progress and is in a leading position worldwide. Bar and wire products occupy half of the steel market and occupy an important position in the national economy and basic industries. Therefore, the continuous casting and rolling technology of bars and wires is the key to our overcoming difficulties. In the fiercely competitive steel market, if we do not actively transform and innovate new models, we will face the fate of being eliminated. Rods and wires mainly refer to rods and wires. The headless continuous casting and rolling technology of rods and wires mainly eliminates the cutting and heating processes in the continuous casting area, reduces fuel consumption, and also reduces metal loss. Only by eliminating the cutting and heating processes of the ingots in the continuous casting area, the metal recovery rate is increased by 2.5 percentage points. The headless continuous casting and rolling technology is a major leap forward in the steel processing flow. It integrates steelmaking, continuous casting, and steel rolling, and has a smooth production process, compact equipment layout, and small plant area, which improves metal recovery rate and saves energy. Coupled with highly centralized automation and unified management, the steel process is continuous and short, raising the steel process to an unprecedented level. However, the existing headless continuous casting and continuous casting process for rods and wires still has some shortcomings during use. First, the continuous casting billet produced by the continuous casting billet straightening machine has a lot of slag inclusions, unstable quality, and uneven surface temperature of the continuous casting billet, which leads to the quality and size of the intermediate billet after initial rolling not being able to meet the subsequent docking requirements; second, the existing docking process of the intermediate billet is cumbersome, the supporting structure is complex, the investment cost is high, the connection strength of the intermediate billet joint after docking is low, and there will be fractures during the continuous rolling process; third, the temperature control and heating device after the intermediate billet is docked cannot realize automatic temperature control, which will cause the temperature of the intermediate billet after the temperature is supplemented to be too high, thereby affecting the efficiency and quality of the continuous rolling. Therefore, the purpose of the present invention is to provide a headless continuous casting and continuous rolling production process for rod and wire products with a short process flow, easy operation, low energy consumption, which can reduce processing costs and effectively improve product quality and production efficiency. Summary of the invention

[0003] In order to solve the problems existing in the background technology, the purpose of the present invention is to provide a headless continuous casting and rolling production process for rod and wire products with a short process flow, easy operation, low energy consumption, which can not only reduce processing costs but also effectively improve product quality and production efficiency.

[0004] The headless continuous casting and rolling production process for rod and wire products of the present invention comprises the following steps:

[0005] ①Continuous casting: First, the refined molten steel is injected into the tundish, so that the superheat of the molten steel in the tundish is 30-40℃, and then the molten steel in the tundish is injected into the crystallizer for cooling. The surface of the molten steel in the crystallizer is covered with protective slag for protecting the molten steel. The thickness of the protective slag is 5-10mm. The molten steel is cooled and crystallized along the inner wall of the crystallizer to form a solidified billet with molten steel as the liquid core. Finally, the solidified billet is pulled out from the outlet of the crystallizer by a straightening machine to obtain a continuously cast billet. The cooling water flow rate in the crystallizer is 130-140m 3 / h, the pulling speed of the straightening machine is 6.8~8.5m / min, and the temperature of the continuous casting billet in the straightening machine is controlled to be 1150~1250℃;

[0006] ② Preliminary rolling: The continuous casting billet obtained in step ① is sent to the preliminary rolling unit for preliminary rolling to obtain an intermediate billet. The width of the intermediate billet is controlled at 80-120 cm, the thickness is 10-20 cm, the inlet temperature of the preliminary rolling is controlled at 1050-1100°C, the speed is controlled at 2.0-3.0 m / s, and the intermediate billet is sprayed with water for cooling after leaving the rough rolling unit, and the surface temperature is controlled at 950-980°C;

[0007] ③ Butt connection of the intermediate billet: the preceding intermediate billet after the rough rolling in step ② and the subsequent intermediate billet following the preceding intermediate billet are outputted by the conveying roller 1. During the conveying process of the preceding intermediate billet and the subsequent intermediate billet, the tail of the preceding intermediate billet and the head of the subsequent intermediate billet are first positioned and centered by the positioning mechanism, and then the tail of the preceding intermediate billet is sheared by the front shearing machine 2 to form a first notch, and the head of the subsequent intermediate billet is sheared by the rear shearing machine 3 to form a second notch, and then the butt gap between the first notch and the second notch is controlled to be no more than 2mm, so that a welding groove 6 is formed between the first notch and the second notch, and then the welding wire conveyor 4 is used to convey the metal welding wire to the laser beam emitted by the laser beam welding device 5 to perform laser beam oscillation welding on the welding groove 6, the oscillation direction of the laser beam is perpendicular to the welding direction, the oscillation frequency of the laser beam is at least 400-500HZ, and the oscillation amplitude of the laser beam is 1-1.5mm;

[0008] ④ Heating of the intermediate billet: The temperature of the intermediate billet after docking in step ③ is detected. If the temperature reaches the inlet temperature requirement of the continuous rolling mill, no heating is performed. If the temperature is insufficient, the continuous casting billet needs to be heated by an automatic heating device. The intermediate billet needs to be cut before entering the continuous rolling mill.

[0009] ⑤ Continuous rolling: the intermediate billet after the temperature supplementation in step ④ is introduced into the rolling mill of the continuous rolling unit for continuous rolling to obtain a primary rolled piece. The continuous rolling unit includes rough rolling, intermediate rolling and pre-finishing rolling processes. The inlet temperature of the rough rolling is controlled at 1020-1050° C., the speed is controlled at 1.5-2.5 m / s, the number of passes of the rough rolling is 5-7 times, the inlet temperature of the intermediate rolling is controlled at 980-1000° C., the speed is controlled at 1.5-2.5 / s, the number of passes of the intermediate rolling is 5-7 times, the inlet temperature of the pre-finishing rolling is controlled at 940-960° C., the speed is controlled at 2.5-3.5 m / s, and the number of passes of the pre-finishing rolling is 3-5 times;

[0010] ⑥ Finishing rolling and reducing diameter: the first rolled piece after step ⑤ continuous rolling is cut off the head by flying shear, and then enters the sizing unit for finishing rolling and reducing diameter to obtain the target specification bar and wire products. The inlet temperature of finishing rolling and reducing diameter is controlled at 800-850℃, the speed is controlled at 5-10m / s, and the number of passes of the sizing unit is 2-3 times;

[0011] ⑦ Cooling: The target specification rod and wire products obtained through the steps are cooled by water mist and then put on a cooling bed. The surface temperature of the target specification rod and wire products is reduced to below 360°C, and then they are collected, cut to length, collected, and bundled.

[0012] Compared with the prior art, the present invention has the following beneficial effects:

[0013] First, the present invention can realize that the continuous casting billet can be directly rolled into the primary rolling unit after being pulled out from the crystallizer, eliminating the heating, supplementary heat and post-treatment processes, and realizing the direct delivery and direct rolling technology of the continuous casting billet. At the same time, the present invention can reasonably control the temperature of the tundish, the flow rate of cooling water in the crystallizer and the pulling speed of the straightening machine in the continuous casting process. In addition to enabling the continuous casting billet to be directly sent to the rolling mill via the high-speed roller after being cut, the surface temperature of the continuous casting billet basically reaches the start-rolling temperature during conventional rolling, and the center temperature of the continuous casting billet is much higher than the surface temperature, which is easy to deform deeply in the primary rolling unit, and is conducive to the pressing and elimination of internal defects of the continuous casting billet, thereby promoting the improvement of the internal quality of the casting billet. In addition, protective slag is added to the surface of the molten steel. The protective slag can reduce the longitudinal cracks and bonding leakage on the surface of the solidified billet, avoid the phenomenon of slag inclusion in the continuous casting billet, and can effectively improve the quality and qualified rate of the continuous casting billet.

[0014] Second, the butt joint method adopted by the present invention is relatively advanced. A shearing machine is first used to perform groove shearing on the corresponding intermediate billet ends. The groove after shearing uses laser rays to melt the metal welding wire to achieve the head and tail connection of the intermediate billet. The improved welding method not only has a fast welding speed, effectively reduces the production cost and the complexity of the process, but also adopts the welding method of melting the metal welding wire, which can effectively increase the connection strength between the welded joints, completely solves the problem of the intermediate billet joint breaking during the continuous rolling process, can effectively ensure the continuous rolling quality of the intermediate billet, and further improve the production efficiency of continuous rolling;

[0015] Third, the heating device provided in the present invention can make the temperature of the entire intermediate billet meet the rolling temperature requirements when entering the continuous rolling mill, effectively ensuring the quality of the product after rolling. This device introduces an automatic controller in the heating device, and uses automatic control to realize automatic heating and temperature compensation of the intermediate billet. It not only has a high degree of automation, can effectively reduce manual operation errors, and improve the on-site working environment, but also reduces the investment and construction costs of the heating furnace and reduces fuel consumption. While improving the heating effect, the energy consumption of the heating device is low, which is more in line with the current energy-saving and environmental protection needs.

[0016] In summary, the present invention simplifies the process of continuous casting and rolling, and the entire production process is advanced and easy to operate. The research and development of the present invention not only saves construction costs, reduces energy consumption of the device, simplifies the construction operation process, but also effectively improves the continuous casting and rolling quality of bar products, further improves production efficiency, can bring better production benefits to enterprises, and is easy to promote and use. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 Schematic diagram of the process structure of the docking and temperature compensation process of the conveyor rollers between the blooming mill and the continuous rolling mill;

[0018] Figure 2 is a schematic top view of the lower electromagnetic induction heating plate 15;

[0019] In the figure: 1-conveying roller, 2-front shearing machine, 3-rear shearing machine, 4-welding wire conveyor, 5-laser beam welding device, 6-welding groove, 7-first portal frame, 8-second portal frame, 9-infrared thermometer, 10-upper lifting mechanism, 11-upper supporting frame, 12-upper electromagnetic induction heating plate, 13-lower lifting mechanism, 14-lower supporting frame, 15-lower electromagnetic induction heating plate, 16-controller, 17-heating plate body, 18-first joint part, 19-second joint part, 20-heating part. DETAILED DESCRIPTION

[0020] The present invention is further described below in conjunction with the embodiments and accompanying drawings, but the present invention is not limited in any way. Any changes or substitutions made based on the teachings of the present invention belong to the protection scope of the present invention.

[0021] Example 1

[0022] The headless continuous casting and rolling production process for rod and wire products described in Example 1 comprises the following steps:

[0023] ①Continuous casting: First, the refined molten steel is injected into the tundish, so that the superheat of the molten steel in the tundish is 30℃, and the temperature of the molten steel in the tundish is optimized to reduce the molten steel temperature in the tundish that is too low and affects the fluidity of the molten steel, and also reduce the molten steel temperature in the tundish that is too high and increases the casting cost, avoiding the situation where the molten steel temperature in the tundish is too low and affects the fluidity of the molten steel and causes the pouring to stop. Then, the molten steel in the tundish is injected into the crystallizer for cooling. The surface of the molten steel in the crystallizer is covered with protective slag for protecting the molten steel. The thickness of the protective slag is 5mm. The molten steel is cooled and crystallized along the inner wall of the crystallizer to form a solidified billet with molten steel as the liquid core. Finally, the solidified billet is pulled out from the outlet of the crystallizer by a straightening machine to obtain a continuous casting billet. The cooling water flow rate in the crystallizer is 130m 3 / h, the pulling speed of the straightening machine is 6.8m / min, the temperature of the continuous casting billet in the straightening machine is controlled to be 1150℃, and the cooling water flow and pulling speed of the crystallizer are optimized, which is conducive to the pressing and elimination of internal defects of the continuous casting billet, promotes the improvement of the internal quality of the billet, and improves the stability of the continuous casting production of the continuous casting billet;

[0024] Further, in step ①, the molten steel protective slag includes the following composition by mass percentage: 30% calcium oxide, 36% silicon dioxide, 6% aluminum oxide, 5% magnesium oxide, 10% sodium oxide, 5% calcium fluoride, 2% carbon, 5% monolayer graphene, and 1% R2O alkali metal oxide. The protective slag is added to the crystallizer, and the protective slag covers the steel liquid surface of the molten steel in the crystallizer. At the same time, when the molten steel is cooled and crystallized in the crystallizer to form a primary finished product, part of the protective slag also flows into the gap formed between the primary finished product and the crystallizer, which has a good lubrication and heat transfer effect, and promotes the uniform growth of the shell of the initially solidified billet, thereby improving the stability of the continuous casting production of the continuous casting billet, as well as the quality and qualified rate of the continuous casting billet;

[0025] Furthermore, in step ①, a three-stage water distribution is set between the crystallizer and the straightening machine to control the temperature of the continuous casting billet in the straightening machine. The three-stage water distribution improves the cooling strength of the continuous casting billet at a specific drawing speed, and also ensures that the surface of the continuous casting billet can be cooled uniformly in the horizontal and vertical directions at the same time. The three-stage water distribution includes full roller water, first zone water and second zone water in sequence. The full roller water flow rate is 7m 3 / h, the water flow in zone 1 is 11.5 m 3 / h, the water flow rate in zone 2 is 9.0 m 3 / h, the above three-stage water distribution and specific flow control can further improve the uniform cooling of the surface of the continuous casting billet in the horizontal and vertical directions at the same time, improve the quality of the continuous casting billet, and further promote the improvement of the internal quality of the billet after entering the initial rolling process;

[0026] ② Initial rolling: The continuous casting billet obtained in step ① is sent to the initial rolling unit for initial rolling to obtain the intermediate billet. The initial rolling unit adopts the steel rolling system used in the prior art. For the rolling of the intermediate billet, 5 passes of rolling are preferably adopted. The width of the intermediate billet is controlled at 80 cm, the thickness is 10 cm, the inlet temperature of the initial rolling is controlled at 1050°C, and the speed is controlled at 2.0 m / s. After the intermediate billet leaves the roughing unit, it is sprayed with water for cooling, and the surface temperature is controlled at 950°C. The initial rolling unit is located after the straightening machine. The distance from the inlet of the straightening machine after the continuous casting machine to the inlet of the roughing machine is preferably 10 m, which reduces the temperature drop of the continuous casting billet, can increase the inlet temperature of the continuous casting billet entering the initial rolling unit, reduce the motor load of the initial rolling unit, reduce the failure rate in the production process, increase the yield rate, reduce energy consumption, and increase the profit;

[0027] ③ Butt connection of intermediate billets: The preceding intermediate billet after the rough rolling in step ② and the subsequent intermediate billet following the preceding intermediate billet are outputted by the conveying roller 1. During the conveying process of the preceding intermediate billet and the subsequent intermediate billet, the tail of the preceding intermediate billet and the head of the subsequent intermediate billet are first positioned and centered by the positioning mechanism, and then the tail of the preceding intermediate billet is sheared by the front shearing machine 2 to form a first notch, and the head of the subsequent intermediate billet is sheared by the rear shearing machine 3 to form a second notch, and then the butt gap between the first notch and the second notch is controlled to be no more than 2mm, so that a welding groove 6 is formed between the first notch and the second notch. The welding groove 6 is preferably a U-shaped structure, and then the welding wire conveyor 4 is used to convey the metal welding wire to the laser beam emitted by the laser beam welding device 5 to perform laser beam vibration on the welding groove 6. Oscillating welding, by feeding a metal welding wire with stable austenite properties into a molten pool generated by means of a laser beam, the welding of the preceding intermediate billet and the subsequent intermediate billet is realized, the oscillation direction of the laser beam is perpendicular to the welding direction, the oscillation frequency of the laser beam is at least 400 Hz, and the oscillation amplitude of the laser beam is 1 mm; by oscillating the laser beam transversely to the welding direction, the weld seam is further uniformed, which is conducive to improving the welding quality, and the connection strength of the preceding intermediate billet and the subsequent intermediate billet can be improved by the oscillation of the laser beam; the amplitude of the laser beam oscillation in this order of magnitude allows a high welding speed and thus a high productivity of the welding method, and the relatively small amplitude of the laser beam oscillation can be realized by means of a compactly constructed laser beam guiding device, preferably by means of a rotating or oscillating deflection mirror;

[0028] Furthermore, in step ③, the metal welding wire is composed of the following components in percentage by mass: 70% iron, 10% aluminum, 1% carbon, 4% silicon, 2% manganese, 2% chromium, 5% molybdenum, 5% nickel and 1% cerium. By using this metal welding wire in the case of using the method according to the present invention, it is possible to ensure that the weld is completely transformed into a martensitic structure and improve the connection strength.

[0029] Furthermore, in step ③, the metal welding wire needs to be preheated to 70°C before being delivered to the molten pool, which can achieve a higher process speed or higher productivity;

[0030] ④ Heating of the intermediate billet: The temperature of the intermediate billet after docking in step ③ is detected. If the temperature reaches the inlet temperature requirement of the continuous rolling mill, no heating is performed. If the temperature is insufficient, the continuous casting billet needs to be heated by an automatic heating device. The intermediate billet needs to be cut before entering the continuous rolling mill.

[0031] Further, in step ④, the automatic heating device includes a first portal frame 7 and a second portal frame 8 erected between the conveying rollers 1, an infrared thermometer 9 is installed on the first portal frame 7, and the infrared thermometer 9 is a prior art. An upper lifting mechanism 10 is installed between the first portal frame 7 and the second portal frame 8 above the conveying roller 1, an upper supporting frame 11 is installed below the upper lifting mechanism 10, and a plurality of upper electromagnetic induction heating plates 12 are evenly spaced on the upper supporting frame 11, a lower lifting mechanism 13 is installed between the first portal frame 7 and the second portal frame 8 below the conveying roller 1, a lower supporting frame 14 is installed below the lower lifting mechanism 13, and a plurality of lower electromagnetic induction heating plates 15 are evenly spaced on the lower supporting frame 14, and a controller 16 is installed on the outer side of the conveying roller 1, and the infrared thermometer 9, the upper lifting mechanism 10, the upper electromagnetic induction heating plate 12, the lower lifting mechanism 13. The lower electromagnetic induction heating plate 15 is electrically connected to the controller 16. The upper electromagnetic induction heating plate 12 and the lower electromagnetic induction heating plate 15 have the same structure, and both include a heating plate body 17 and an electromagnetic induction coil. The electromagnetic induction coil includes a first joint portion 18, a second joint portion 19, and a heating portion 20 installed between the first joint portion 18 and the second joint portion 19. The heating portion 20 is arranged in a serpentine structure. The heating plate body 17 is provided with a mounting groove on which the electromagnetic induction coil is installed. During installation, the electromagnetic induction coil 12 of the upper electromagnetic induction heating plate is installed on the lower surface of the heating plate body 17, and the electromagnetic induction coil of the lower electromagnetic induction heating plate 15 is installed on the upper surface of the heating plate body 17. The electromagnetic induction coil is placed in the mounting groove of the heating plate body 17, which avoids the problem of adjacent coils being easily short-circuited, and improves the utilization rate of the alternating magnetic field, thereby improving the heating efficiency;

[0032] The method for the automatic heating device to supplement the temperature of the intermediate billet is as follows: the entrance rolling temperature of the intermediate billet continuous rolling, the cross-sectional size of the intermediate billet and the conveying speed of the intermediate billet are respectively input on the operation interface of the controller 16, and then the intermediate billet is conveyed toward the continuous rolling mill by the conveying roller 1. When the intermediate billet passes under the infrared thermometer 9, the infrared thermometer 9 collects the real-time temperature data of the intermediate billet and transmits the temperature data to the control system of the controller 16. The controller compares the real-time temperature data of the intermediate billet with the target rolling temperature data. When the real-time temperature of the intermediate billet is lower than the target rolling temperature, the controller 16 sends a control instruction to the upper electromagnetic induction heating plate 12 and the lower electromagnetic induction heating plate 15. At the same time, the controller automatically calculates the amount of supplementary heat required for the intermediate billet. The upper electromagnetic induction heating plate 12 and the lower electromagnetic induction heating plate After receiving the control command, the controller 16 controls the upper lifting mechanism 10 to drive the upper electromagnetic induction heating plate 12 to move downward, controls the lower lifting mechanism 13 to drive the lower electromagnetic induction heating plate 15 to move upward, and controls the upper electromagnetic induction heating plate 12 and the lower electromagnetic induction heating plate 15 to be powered on to compensate the temperature of the intermediate billet. After the compensation operation is completed, the upper electromagnetic induction heating plate 12 and the lower electromagnetic induction heating plate 15 are controlled to stop being powered on, and the intermediate billet after compensation directly enters the continuous rolling unit to complete rolling. This method can realize accurate compensation of the intermediate billet on the basis of the original continuous casting and direct rolling equipment, and can make the temperature of the entire intermediate billet meet the rolling temperature requirements when entering the finishing rolling unit, effectively ensuring the quality of the rolled product, and the device has a simple structure and a high degree of automation, which can effectively reduce manual operation errors and improve the on-site working environment.

[0033] ⑤ Continuous rolling: the intermediate billet after the temperature supplementation in step ④ is introduced into the rolling mill of the continuous rolling unit for continuous rolling to obtain a rolled piece. The continuous rolling unit includes rough rolling, intermediate rolling and pre-finishing rolling processes. The inlet temperature of the rough rolling is controlled at 1020°C and the speed is controlled at 1.5m / s. The number of passes of the rough rolling is 5 times. The inlet temperature of the intermediate rolling is controlled at 980°C and the speed is controlled at 1.5 / s. The number of passes of the intermediate rolling is 5 times. The inlet temperature of the pre-finishing rolling is controlled at 940°C and the speed is controlled at 2.5m / s. The number of passes of the pre-finishing rolling is 3 times. The intermediate billet is deformed and penetrated into the core of the casting billet by applying a large pass deformation, thereby reducing defects such as segregation and looseness in the core. The continuous casting steel output speed and the continuous rolling steel feeding speed are matched by the compression deformation of the continuous rolling unit, so that the intermediate billet meets the rolling conditions of the continuous rolling unit and realizes continuous casting and continuous rolling production;

[0034] ⑥ Finishing rolling and reducing diameter: the first rolled piece after step ⑤ continuous rolling is sheared to remove the head, and then enters the sizing unit for finishing rolling and reducing diameter to obtain the target specification bar and wire products. The inlet temperature of the finishing rolling and reducing diameter is controlled at 800℃, the speed is controlled at 5m / s, and the number of passes of the sizing unit is 2;

[0035] ⑦ Cooling: The target specification rod and wire products obtained through the steps are cooled by water mist and then put on a cooling bed. The surface temperature of the target specification rod and wire products is reduced to below 360°C, and then they are collected, cut to length, collected, and bundled.

[0036] Example 2

[0037] The headless continuous casting and rolling production process for rod and wire products described in Example 2 comprises the following steps:

[0038] ① Continuous casting: First, the refined molten steel is injected into the tundish, so that the superheat of the molten steel in the tundish is 35℃, and the temperature of the molten steel in the tundish is optimized to reduce the molten steel temperature in the tundish that is too low and affects the fluidity of the molten steel, and also reduce the molten steel temperature in the tundish that is too high and increases the casting cost, avoiding the situation where the molten steel temperature in the tundish is too low and affects the fluidity of the molten steel and causes the pouring to stop. Then, the molten steel in the tundish is injected into the crystallizer for cooling. The surface of the molten steel in the crystallizer is covered with protective slag for protecting the molten steel. The thickness of the protective slag is 8mm. The molten steel is cooled and crystallized along the inner wall of the crystallizer to form a solidified billet with molten steel as the liquid core. Finally, the solidified billet is pulled out from the outlet of the crystallizer by a straightening machine to obtain a continuous casting billet. The cooling water flow rate in the crystallizer is 135m 3 / h, the pulling speed of the straightening machine is 7.2m / min, the temperature of the continuous casting billet in the straightening machine is controlled to be 1200℃, and the cooling water flow and pulling speed of the crystallizer are optimized, which is conducive to the pressing and elimination of internal defects of the continuous casting billet, promotes the improvement of the internal quality of the billet, and improves the stability of the continuous casting production of the continuous casting billet;

[0039] Further, in step ①, the molten steel protective slag includes the following composition by mass percentage: 40% calcium oxide, 34% silicon dioxide, 5% aluminum oxide, 4% magnesium oxide, 7% sodium oxide, 4% calcium fluoride, 1.5% carbon, 3.5% monolayer graphene, and 1% R2O alkali metal oxide. The protective slag is added to the crystallizer, and the protective slag covers the steel liquid surface of the molten steel in the crystallizer. At the same time, when the molten steel is cooled and crystallized in the crystallizer to form a primary finished product, part of the protective slag also flows into the gap formed between the primary finished product and the crystallizer, which has a good lubrication and heat transfer effect, and promotes the uniform growth of the shell of the initially solidified billet, thereby improving the stability of the continuous casting production of the continuous casting billet, as well as the quality and qualified rate of the continuous casting billet;

[0040] Furthermore, in step ①, a three-stage water distribution is set between the crystallizer and the straightening machine to control the temperature of the continuous casting billet in the straightening machine. The three-stage water distribution improves the cooling strength of the continuous casting billet at a specific drawing speed, and also ensures that the surface of the continuous casting billet can be uniformly cooled in the horizontal and vertical directions at the same time. The three-stage water distribution includes full roller water, first zone water and second zone water in sequence. The flow rate of the full roller water is 8 3 / h, the water flow rate of zone 1 is 11.8h, and the water flow rate of zone 2 is 9.5 / h. The above three-stage water distribution and specific flow control can further improve the uniform cooling of the surface of the continuous casting billet in the horizontal and vertical directions at the same time, improve the quality of the continuous casting billet, and further promote the improvement of the internal quality of the billet after entering the initial rolling process;

[0041] ② Initial rolling: The continuous casting billet obtained in step ① is sent to the initial rolling unit for initial rolling to obtain the intermediate billet. The initial rolling unit adopts the steel rolling system used in the prior art. For the rolling of the intermediate billet, 5 or 7 rolling passes are preferably adopted. The width of the intermediate billet is controlled at 100 cm, the thickness is 15 cm, the inlet temperature of the initial rolling is controlled at 1080°C, and the speed is controlled at 2.5 m / s. After the intermediate billet leaves the roughing unit, it is sprayed with water for cooling, and the surface temperature is controlled at 975°C. The initial rolling unit is located after the straightening machine. The distance from the inlet of the straightening machine after the continuous casting machine to the inlet of the roughing machine is preferably 20 m, which reduces the temperature drop of the continuous casting billet, can increase the inlet temperature of the continuous casting billet entering the initial rolling unit, reduce the motor load of the initial rolling unit, reduce the failure rate in the production process, increase the yield rate, reduce energy consumption, and increase the profit;

[0042] ③ Butt connection of intermediate billets: The preceding intermediate billet after rough rolling in step ② and the subsequent intermediate billet following the preceding intermediate billet are output by the conveying roller 1. During the conveying of the preceding intermediate billet and the subsequent intermediate billet by the conveying roller 1, the tail of the preceding intermediate billet and the head of the subsequent intermediate billet are first positioned and centered by the positioning mechanism, and then the tail of the preceding intermediate billet is sheared by the front shearing machine 2 to form a first notch, and the head of the subsequent intermediate billet is sheared by the rear shearing machine 3 to form a second notch, and then the butt gap between the first notch and the second notch is controlled to be no more than 2mm, so that a welding groove 6 is formed between the first notch and the second notch, and then the metal welding wire is conveyed by the welding wire conveyor 4 to the laser beam emitted by the laser beam welding device 5 to perform laser beam oscillation welding on the welding groove 6, and then the welding wire conveyor 4 is used to convey the metal welding wire to the laser beam emitted by the laser beam welding device 5 to perform laser beam oscillation welding on the welding groove 6. A metal welding wire with stable austenite properties is fed into a molten pool generated by means of a laser beam to achieve welding of a preceding intermediate billet and a subsequent intermediate billet, wherein the oscillation direction of the laser beam is perpendicular to the welding direction, the oscillation frequency of the laser beam is at least 450 Hz, and the oscillation amplitude of the laser beam is 1.2 mm; by oscillating the laser beam transversely to the welding direction, further uniformity of the weld seam is achieved, which is beneficial to improving the welding quality, and the connection strength of the preceding intermediate billet and the subsequent intermediate billet can be improved by the oscillation of the laser beam; the amplitude of the laser beam oscillation in this order of magnitude allows a high welding speed and thus a high productivity of the welding method, and the relatively small amplitude of the laser beam oscillation can be achieved by means of a compactly constructed laser beam guiding device, preferably by means of a rotating or oscillating deflection mirror;

[0043] Furthermore, in step ③, the metal welding wire is composed of the following components in percentage by mass: 80% iron, 6% aluminum, 0.5% carbon, 1.5% silicon, 0.5% manganese, 1.5% chromium, 2% molybdenum, 2% nickel and 1% cerium. By using this metal welding wire in the case of using the method according to the present invention, it is possible to ensure that the weld is completely transformed into a martensitic structure and improve the connection strength.

[0044] Furthermore, in step ③, the metal welding wire needs to be preheated to 75°C before being delivered to the molten pool, which can achieve a higher process speed or higher productivity;

[0045] ④ Heating of the intermediate billet: The temperature of the intermediate billet after docking in step ③ is detected. If the temperature reaches the inlet temperature requirement of the continuous rolling mill, no heating is performed. If the temperature is insufficient, the continuous casting billet needs to be heated by an automatic heating device. The intermediate billet needs to be cut before entering the continuous rolling mill.

[0046] Further, in step ④, the automatic heating device includes a first portal frame 7 and a second portal frame 8 erected between the conveying rollers 1, an infrared thermometer 9 is installed on the first portal frame 7, and the infrared thermometer 9 is a prior art. An upper lifting mechanism 10 is installed between the first portal frame 7 and the second portal frame 8 above the conveying roller 1, an upper supporting frame 11 is installed below the upper lifting mechanism 10, and a plurality of upper electromagnetic induction heating plates 12 are evenly spaced on the upper supporting frame 11, a lower lifting mechanism 13 is installed between the first portal frame 7 and the second portal frame 8 below the conveying roller 1, a lower supporting frame 14 is installed below the lower lifting mechanism 13, and a plurality of lower electromagnetic induction heating plates 15 are evenly spaced on the lower supporting frame 14, and a controller 16 is installed on the outer side of the conveying roller 1, and the infrared thermometer 9, the upper lifting mechanism 10, the upper electromagnetic induction heating plate 12, the lower lifting mechanism 13. The lower electromagnetic induction heating plate 15 is electrically connected to the controller 16. The upper electromagnetic induction heating plate 12 and the lower electromagnetic induction heating plate 15 have the same structure, and both include a heating plate body 17 and an electromagnetic induction coil. The electromagnetic induction coil includes a first joint portion 18, a second joint portion 19, and a heating portion 20 installed between the first joint portion 18 and the second joint portion 19. The heating portion 20 is arranged in a serpentine structure. The heating plate body 17 is provided with a mounting groove on which the electromagnetic induction coil is installed. During installation, the electromagnetic induction coil 12 of the upper electromagnetic induction heating plate is installed on the lower surface of the heating plate body 17, and the electromagnetic induction coil of the lower electromagnetic induction heating plate 15 is installed on the upper surface of the heating plate body 17. The electromagnetic induction coil is placed in the mounting groove of the heating plate body 17, which avoids the problem of adjacent coils being easily short-circuited, and improves the utilization rate of the alternating magnetic field, thereby improving the heating efficiency;

[0047] The method for the automatic heating device to supplement the temperature of the intermediate billet is as follows: the entrance rolling temperature of the intermediate billet continuous rolling, the cross-sectional size of the intermediate billet and the conveying speed of the intermediate billet are respectively input on the operation interface of the controller 16, and then the intermediate billet is conveyed toward the continuous rolling mill by the conveying roller 1. When the intermediate billet passes under the infrared thermometer 9, the infrared thermometer 9 collects the real-time temperature data of the intermediate billet and transmits the temperature data to the control system of the controller 16. The controller compares the real-time temperature data of the intermediate billet with the target rolling temperature data. When the real-time temperature of the intermediate billet is lower than the target rolling temperature, the controller 16 sends a control instruction to the upper electromagnetic induction heating plate 12 and the lower electromagnetic induction heating plate 15. At the same time, the controller automatically calculates the amount of supplementary heat required for the intermediate billet. The upper electromagnetic induction heating plate 12 and the lower electromagnetic induction heating plate After receiving the control command, the controller 16 controls the upper lifting mechanism 10 to drive the upper electromagnetic induction heating plate 12 to move downward, controls the lower lifting mechanism 13 to drive the lower electromagnetic induction heating plate 15 to move upward, and controls the upper electromagnetic induction heating plate 12 and the lower electromagnetic induction heating plate 15 to be powered on to compensate the temperature of the intermediate billet. After the compensation operation is completed, the upper electromagnetic induction heating plate 12 and the lower electromagnetic induction heating plate 15 are controlled to stop being powered on, and the intermediate billet after compensation directly enters the continuous rolling unit to complete rolling. This method can realize accurate compensation of the intermediate billet on the basis of the original continuous casting and direct rolling equipment, and can make the temperature of the entire intermediate billet meet the rolling temperature requirements when entering the finishing rolling unit, effectively ensuring the quality of the rolled product, and the device has a simple structure and a high degree of automation, which can effectively reduce manual operation errors and improve the on-site working environment.

[0048] ⑤ Continuous rolling: the intermediate billet after the temperature supplementation in step ④ is introduced into the rolling mill of the continuous rolling unit for continuous rolling to obtain a rolled piece. The continuous rolling unit includes rough rolling, intermediate rolling and pre-finishing rolling processes. The inlet temperature of the rough rolling is controlled at 1040°C, the speed is controlled at 2m / s, the number of passes of the rough rolling is 6 times, the inlet temperature of the intermediate rolling is controlled at 990°C, the speed is controlled at 2.0 / s, the number of passes of the intermediate rolling is 6 times, the inlet temperature of the pre-finishing rolling is controlled at 950°C, the speed is controlled at 3m / s, and the number of passes of the pre-finishing rolling is 4 times; the intermediate billet is subjected to a large pass deformation, and the deformation penetrates into the core of the casting billet to reduce defects such as segregation and looseness in the core, and the compression deformation of the continuous rolling unit is used to match the continuous casting steel output speed and the continuous rolling steel feeding speed, so that the intermediate billet meets the rolling conditions of the continuous rolling unit and realizes continuous casting and continuous rolling production;

[0049] ⑥ Finishing rolling and reducing diameter: the first rolled piece after step ⑤ continuous rolling is cut off the head by flying shear, and then enters the sizing unit for finishing rolling and reducing diameter to obtain the target specification bar and wire products. The inlet temperature of finishing rolling and reducing diameter is controlled at 830℃, the speed is controlled at 8m / s, and the number of passes of the sizing unit is 2;

[0050] ⑦ Cooling: The target specification rod and wire products obtained through the steps are cooled by water mist and then put on a cooling bed. The surface temperature of the target specification rod and wire products is reduced to below 360°C, and then they are collected, cut to length, collected, and bundled.

[0051] Example 3

[0052] The headless continuous casting and rolling production process for rod and wire products described in Example 3 comprises the following steps:

[0053] ① Continuous casting: First, the refined molten steel is injected into the tundish, so that the superheat of the molten steel in the tundish is 40℃, and the temperature of the molten steel in the tundish is optimized to reduce the molten steel temperature in the tundish that is too low and affects the fluidity of the molten steel, and also reduce the molten steel temperature in the tundish that is too high and increases the casting cost, avoiding the situation where the molten steel temperature in the tundish is too low and affects the fluidity of the molten steel and causes the pouring to stop. Then, the molten steel in the tundish is injected into the crystallizer for cooling. The surface of the molten steel in the crystallizer is covered with protective slag for protecting the molten steel. The thickness of the protective slag is 10mm. The molten steel is cooled and crystallized along the inner wall of the crystallizer to form a solidified billet with molten steel as the liquid core. Finally, the solidified billet is pulled out from the outlet of the crystallizer by a straightening machine to obtain a continuous casting billet. The cooling water flow rate in the crystallizer is 140m 3 / h, the pulling speed of the straightening machine is 8.5m / min, the temperature of the continuous casting billet in the straightening machine is controlled to be 1250℃, and the cooling water flow and pulling speed of the crystallizer are optimized, which is conducive to the pressing and elimination of internal defects of the continuous casting billet, promotes the improvement of the internal quality of the billet, and improves the stability of the continuous casting production of the continuous casting billet;

[0054] Further, in step ①, the molten steel protective slag includes the following composition by mass percentage: 50% calcium oxide, 30% silicon dioxide, 2% aluminum oxide, 1% magnesium oxide, 8% sodium oxide, 4% calcium fluoride, 1% carbon, 3.5% monolayer graphene, and 0.5% R2O alkali metal oxide. The protective slag is added to the crystallizer, and the protective slag covers the steel liquid surface of the molten steel in the crystallizer. At the same time, when the molten steel is cooled and crystallized in the crystallizer to form a primary finished product, part of the protective slag also flows into the gap formed between the primary finished product and the crystallizer, which has a good lubrication and heat transfer effect, and promotes the uniform growth of the shell of the initially solidified billet, thereby improving the stability of the continuous casting production of the continuous casting billet, as well as the quality and qualified rate of the continuous casting billet;

[0055] Furthermore, in step ①, a three-stage water distribution is set between the crystallizer and the straightening machine to control the temperature of the continuous casting billet in the straightening machine. The three-stage water distribution improves the cooling strength of the continuous casting billet at a specific drawing speed, and also ensures that the surface of the continuous casting billet can be cooled uniformly in the horizontal and vertical directions at the same time. The three-stage water distribution includes full roller water, first zone water and second zone water in sequence. The full roller water flow rate is 8.5m 3 / h, the water flow in zone 1 is 12 m 3 / h, the water flow in zone 2 is 10.0 m3 / h, the above three-stage water distribution and specific flow control can further improve the uniform cooling of the surface of the continuous casting billet in the horizontal and vertical directions at the same time, improve the quality of the continuous casting billet, and further promote the improvement of the internal quality of the billet after entering the initial rolling process;

[0056] ② Initial rolling: The continuous casting billet obtained in step ① is sent to the initial rolling unit for initial rolling to obtain the intermediate billet. The initial rolling unit adopts the steel rolling system used in the prior art. For the rolling of the intermediate billet, 5 or 7 rolling passes are preferably adopted. The width of the intermediate billet is controlled at 120 cm, the thickness is 20 cm, the inlet temperature of the initial rolling is controlled at 1100°C, and the speed is controlled at 3.0 m / s. After the intermediate billet leaves the roughing unit, it is sprayed with water for cooling, and the surface temperature is controlled at 980°C. The initial rolling unit is located after the straightening machine. The distance from the inlet of the straightening machine after the continuous casting machine to the inlet of the roughing machine is preferably 30 m, which reduces the temperature drop of the continuous casting billet, can increase the inlet temperature of the continuous casting billet entering the initial rolling unit, reduce the motor load of the initial rolling unit, reduce the failure rate in the production process, increase the yield rate, reduce energy consumption, and increase the profit;

[0057] ③ Butt connection of intermediate billets: The preceding intermediate billet after rough rolling in step ② and the subsequent intermediate billet following the preceding intermediate billet are output by the conveying roller 1. During the conveying of the preceding intermediate billet and the subsequent intermediate billet by the conveying roller 1, the tail of the preceding intermediate billet and the head of the subsequent intermediate billet are first positioned and centered by the positioning mechanism, and then the tail of the preceding intermediate billet is sheared by the front shearing machine 2 to form a first notch, and the head of the subsequent intermediate billet is sheared by the rear shearing machine 3 to form a second notch, and then the butt gap between the first notch and the second notch is controlled to be no more than 2mm, so that a welding groove 6 is formed between the first notch and the second notch, and then the metal welding wire is conveyed by the welding wire conveyor 4 to the laser beam emitted by the laser beam welding device 5 to perform laser beam oscillation welding on the welding groove 6, and then the welding wire conveyor 4 is used to convey the metal welding wire to the laser beam emitted by the laser beam welding device 5 to perform laser beam oscillation welding on the welding groove 6. A metal welding wire with stable austenite properties is fed into a molten pool generated by means of a laser beam to achieve welding of a preceding intermediate billet and a subsequent intermediate billet, wherein the oscillation direction of the laser beam is perpendicular to the welding direction, the oscillation frequency of the laser beam is at least 500 Hz, and the oscillation amplitude of the laser beam is 1.5 mm; by oscillating the laser beam transversely to the welding direction, further uniformity of the weld seam is achieved, which is beneficial to improving the welding quality, and the connection strength of the preceding intermediate billet and the subsequent intermediate billet can be improved by the oscillation of the laser beam; the amplitude of the laser beam oscillation in this order of magnitude allows a high welding speed and thus a high productivity of the welding method, and the relatively small amplitude of the laser beam oscillation can be achieved by means of a compactly constructed laser beam guiding device, preferably by means of a rotating or oscillating deflection mirror;

[0058] Further, in step ③, the metal welding wire is composed of the following components in mass percentage: the metal welding wire is composed of the following components in mass percentage: 90% iron, 2% aluminum, 0.2% carbon, 1% silicon, 0.5% manganese, 2% chromium, 2.1% molybdenum, 2% nickel and 0.2% cerium. By using this metal welding wire in the case of using the method according to the present invention in a very reliable manner in the butted intermediate blanks, it can be ensured that the weld is completely transformed into a martensitic structure, thereby improving the connection strength;

[0059] Furthermore, in step ③, the metal welding wire needs to be preheated to 80°C before being delivered to the molten pool, which can achieve a higher process speed or higher productivity;

[0060] ④ Heating of the intermediate billet: The temperature of the intermediate billet after docking in step ③ is detected. If the temperature reaches the inlet temperature requirement of the continuous rolling mill, no heating is performed. If the temperature is insufficient, the continuous casting billet needs to be heated by an automatic heating device. The intermediate billet needs to be cut before entering the continuous rolling mill.

[0061] Further, in step ④, the automatic heating device includes a first portal frame 7 and a second portal frame 8 erected between the conveying rollers 1, an infrared thermometer 9 is installed on the first portal frame 7, and the infrared thermometer 9 is a prior art. An upper lifting mechanism 10 is installed between the first portal frame 7 and the second portal frame 8 above the conveying roller 1, an upper supporting frame 11 is installed below the upper lifting mechanism 10, and a plurality of upper electromagnetic induction heating plates 12 are evenly spaced on the upper supporting frame 11, a lower lifting mechanism 13 is installed between the first portal frame 7 and the second portal frame 8 below the conveying roller 1, a lower supporting frame 14 is installed below the lower lifting mechanism 13, and a plurality of lower electromagnetic induction heating plates 15 are evenly spaced on the lower supporting frame 14, and a controller 16 is installed on the outer side of the conveying roller 1, and the infrared thermometer 9, the upper lifting mechanism 10, the upper electromagnetic induction heating plate 12, the lower lifting mechanism 13. The lower electromagnetic induction heating plate 15 is electrically connected to the controller 16. The upper electromagnetic induction heating plate 12 and the lower electromagnetic induction heating plate 15 have the same structure, and both include a heating plate body 17 and an electromagnetic induction coil. The electromagnetic induction coil includes a first joint portion 18, a second joint portion 19, and a heating portion 20 installed between the first joint portion 18 and the second joint portion 19. The heating portion 20 is arranged in a serpentine structure. The heating plate body 17 is provided with a mounting groove on which the electromagnetic induction coil is installed. During installation, the electromagnetic induction coil 12 of the upper electromagnetic induction heating plate is installed on the lower surface of the heating plate body 17, and the electromagnetic induction coil of the lower electromagnetic induction heating plate 15 is installed on the upper surface of the heating plate body 17. The electromagnetic induction coil is placed in the mounting groove of the heating plate body 17, which avoids the problem of adjacent coils being easily short-circuited, and improves the utilization rate of the alternating magnetic field, thereby improving the heating efficiency;

[0062] The method for the automatic heating device to supplement the temperature of the intermediate billet is as follows: the entrance rolling temperature of the intermediate billet continuous rolling, the cross-sectional size of the intermediate billet and the conveying speed of the intermediate billet are respectively input on the operation interface of the controller 16, and then the intermediate billet is conveyed toward the continuous rolling mill by the conveying roller 1. When the intermediate billet passes under the infrared thermometer 9, the infrared thermometer 9 collects the real-time temperature data of the intermediate billet and transmits the temperature data to the control system of the controller 16. The controller compares the real-time temperature data of the intermediate billet with the target rolling temperature data. When the real-time temperature of the intermediate billet is lower than the target rolling temperature, the controller 16 sends a control instruction to the upper electromagnetic induction heating plate 12 and the lower electromagnetic induction heating plate 15. At the same time, the controller automatically calculates the amount of supplementary heat required for the intermediate billet. The upper electromagnetic induction heating plate 12 and the lower electromagnetic induction heating plate After receiving the control command, the controller 16 controls the upper lifting mechanism 10 to drive the upper electromagnetic induction heating plate 12 to move downward, controls the lower lifting mechanism 13 to drive the lower electromagnetic induction heating plate 15 to move upward, and controls the upper electromagnetic induction heating plate 12 and the lower electromagnetic induction heating plate 15 to be powered on to compensate the temperature of the intermediate billet. After the compensation operation is completed, the upper electromagnetic induction heating plate 12 and the lower electromagnetic induction heating plate 15 are controlled to stop being powered on, and the intermediate billet after compensation directly enters the continuous rolling unit to complete rolling. This method can realize accurate compensation of the intermediate billet on the basis of the original continuous casting and direct rolling equipment, and can make the temperature of the entire intermediate billet meet the rolling temperature requirements when entering the finishing rolling unit, effectively ensuring the quality of the rolled product, and the device has a simple structure and a high degree of automation, which can effectively reduce manual operation errors and improve the on-site working environment.

[0063] ⑤ Continuous rolling: the intermediate billet after the temperature supplementation in step ④ is introduced into the rolling mill of the continuous rolling unit for continuous rolling to obtain a rolled piece. The continuous rolling unit includes rough rolling, intermediate rolling and pre-finishing rolling processes. The inlet temperature of the rough rolling is controlled at 1050°C, the speed is controlled at 2.5m / s, the number of passes of the rough rolling is 7 times, the inlet temperature of the intermediate rolling is controlled at 1000°C, the speed is controlled at 2.5 / s, the number of passes of the intermediate rolling is 7 times, the inlet temperature of the pre-finishing rolling is controlled at 960°C, the speed is controlled at 3.5m / s, and the number of passes of the pre-finishing rolling is 5 times; the intermediate billet is subjected to a large pass deformation, and the deformation penetrates into the core of the casting billet to reduce defects such as segregation and looseness in the core, and the compression deformation of the continuous rolling unit is used to match the continuous casting steel output speed and the continuous rolling steel feeding speed, so that the intermediate billet meets the rolling conditions of the continuous rolling unit and realizes continuous casting and continuous rolling production;

[0064] ⑥ Finishing rolling and reducing diameter: the first rolled piece after step ⑤ continuous rolling is cut off the head by flying shear, and then enters the sizing unit for finishing rolling and reducing diameter to obtain the target specification bar and wire products. The inlet temperature of finishing rolling and reducing diameter is controlled at 850℃, the speed is controlled at 10m / s, and the number of passes of the sizing unit is 3;

[0065] ⑦ Cooling: The target specification rod and wire products obtained through the steps are cooled by water mist and then put on a cooling bed. The surface temperature of the target specification rod and wire products is reduced to below 360°C, and then they are collected, cut to length, collected, and bundled.

[0066] The bar products obtained by using the above-mentioned embodiments 1 to 3 not only have a high product qualification rate, but also have high production efficiency. Compared with the traditional headless continuous casting process, the product qualification rate is more than 99.5%, and the production efficiency is increased by 10 to 15%. The results of the embodiment show that the rolling method can not only realize that the continuous casting billet is directly rolled into the rolling mill after being pulled out of the crystallizer, but also eliminates the heating, supplementary heat and post-treatment processes, and realizes the direct delivery and direct rolling technology of the continuous casting billet. At the same time, the present invention adopts advanced laser butt welding technology, which not only improves the speed of butt welding, but also improves the connection strength of butt welding, and adopts advanced electromagnetic induction heating device to control the temperature and supplement the heat of the intermediate billet. It has low energy consumption, saves the cost of investment and construction of heating furnace, and has a high degree of automation of temperature control and heating. This method can provide a new way to reduce emissions, improve efficiency, optimize costs, and improve product quality and efficiency.

Claims

1. A process for producing rod and wire products by continuous casting and rolling, characterized in that , including the following steps: ①Continuous casting: First, the refined molten steel is injected into the tundish, so that the superheat of the molten steel in the tundish is 30-40℃, and then the molten steel in the tundish is injected into the crystallizer for cooling. The surface of the molten steel in the crystallizer is covered with protective slag for protecting the molten steel. The thickness of the protective slag is 5-10mm. The molten steel is cooled and crystallized along the inner wall of the crystallizer to form a solidified billet with molten steel as the liquid core. Finally, the solidified billet is pulled out from the outlet of the crystallizer by a straightening machine to obtain a continuously cast billet. The cooling water flow rate in the crystallizer is 130-140m 3 / h, the pulling speed of the straightening machine is 6.8~8.5m / min, and the temperature of the continuous casting billet in the straightening machine is controlled to be 1150~1250℃; ② Preliminary rolling: The continuous casting billet obtained in step ① is sent to the preliminary rolling unit for preliminary rolling to obtain an intermediate billet. The width of the intermediate billet is controlled at 80-120 cm, the thickness is 10-20 cm, the inlet temperature of the preliminary rolling is controlled at 1050-1100°C, the speed is controlled at 2.0-3.0 m / s, and the intermediate billet is sprayed with water for cooling after leaving the rough rolling unit, and the surface temperature is controlled at 950-980°C; ③ Butt connection of the intermediate billet: the preceding intermediate billet after the rough rolling in step ② and the subsequent intermediate billet following the preceding intermediate billet are outputted by the conveying roller (1). During the conveying process, the tail of the preceding intermediate billet and the head of the subsequent intermediate billet are first positioned and centered by using a positioning mechanism, and then the tail of the preceding intermediate billet is sheared by using a front shearing machine (2) to form a first notch, and the head of the subsequent intermediate billet is sheared by using a rear shearing machine (3) to form a second notch. Then, the butt gap between the first notch and the second notch is controlled to be no greater than 2 mm, so that a welding groove (6) is formed between the first notch and the second notch. Then, the welding wire conveyor (4) is used to convey the metal welding wire to the laser beam welding device (5). The laser beam emitted by the laser beam welding device (5) performs laser beam oscillation welding on the welding groove (6). The oscillation direction of the laser beam is perpendicular to the welding direction. The oscillation frequency of the laser beam is 400 to 500 Hz, and the oscillation amplitude of the laser beam is 1 to 1.5 mm. ④ Heating of the intermediate billet: The temperature of the intermediate billet after docking in step ③ is detected. If the temperature reaches the inlet temperature requirement of the continuous rolling mill, no heating is performed. If the temperature is insufficient, the continuous casting billet needs to be heated by an automatic heating device. The intermediate billet needs to be cut before entering the continuous rolling mill. ⑤ Continuous rolling: the intermediate billet after the temperature supplementation in step ④ is introduced into the rolling mill of the continuous rolling unit for continuous rolling to obtain a rolled piece. The continuous rolling unit includes rough rolling, intermediate rolling and pre-finishing rolling processes. The inlet temperature of the rough rolling is controlled at 1020-1050°C, the speed is controlled at 1.5-2.5 m / s, and the number of passes of the rough rolling is 5-7 times; the inlet temperature of the intermediate rolling is controlled at 980-1000°C, the speed is controlled at 1.5-2.5 / s, and the number of passes of the intermediate rolling is 5-7 times; the inlet temperature of the pre-finishing rolling is controlled at 940-960°C, the speed is controlled at 2.5-3.5 m / s, and the number of passes of the pre-finishing rolling is 3-5 times; ⑥ Finishing rolling and reducing diameter: the first rolled piece after step ⑤ continuous rolling is cut off the head by flying shear, and then enters the sizing unit for finishing rolling and reducing diameter to obtain the target specification bar and wire products. The inlet temperature of finishing rolling and reducing diameter is controlled at 800-850℃, the speed is controlled at 5-10m / s, and the number of passes of the sizing unit is 2-3 times; ⑦ Cooling: The target specification rod and wire product obtained in step ⑥ is cooled by water mist and then put on a cooling bed. The surface temperature of the target specification rod and wire product is reduced to below 360°C, and then the target specification rod and wire product is collected, cut to length, collected, and bundled.

2. The endless continuous casting and rolling production process for rod and wire products according to claim 1, characterized in that: In step ①, the molten steel protection slag includes the following components by mass percentage: 30-50% calcium oxide, 20-40% silicon dioxide, 2-6% aluminum oxide, 1-5% magnesium oxide, 5-10% sodium oxide, 2-5% calcium fluoride, 0.5-2% carbon, 1-5% single-layer graphene, and 0.5-1% R2O alkali metal oxide.

3. The endless continuous casting and rolling production process for rod and wire products according to claim 1, characterized in that: In step ①, three-stage water distribution is set between the crystallizer and the straightening machine to control the temperature of the continuous casting billet in the straightening machine. The three-stage water distribution includes full roller water, first zone water and second zone water in sequence. The flow rate of the full roller water is 7-8.5m 3 / h, the water flow rate in zone 1 is 11.5~12 m 3 / h, the water flow rate in zone 2 is 9.0~10.0 m 3 / h.

4. The endless continuous casting and rolling production process for rod and wire products according to claim 1 is characterized in that: In step ③, the metal welding wire is composed of the following components in percentage by mass: 70-90% iron, 2-10% aluminum, 0.2-1% carbon, 1-4% silicon, 0.5-2% manganese, 1-2% chromium, 2-5% molybdenum, 2-5% nickel and 0.2-1% cerium.

5. The endless continuous casting and rolling production process for rod and wire products according to claim 1 is characterized in that: In step ③, the metal welding wire needs to be preheated to 70-80°C before being transported to the molten pool.

6. The endless continuous casting and rolling production process for rod and wire products according to claim 1 is characterized in that: In step ④, the automatic heating device comprises a first portal frame (7) and a second portal frame (8) mounted between the conveying rollers (1), an infrared thermometer (9) being mounted on the first portal frame (7), an upper lifting mechanism (10) being mounted between the first portal frame (7) and the second portal frame (8) above the conveying rollers (1), an upper support frame (11) being mounted below the upper lifting mechanism (10), a plurality of upper electromagnetic induction heating plates (12) being mounted on the upper support frame (11) at equal intervals, and a first portal frame (7) being mounted below the conveying rollers (1). A lower lifting mechanism (13) is installed between the portal frame (7) and the second portal frame (8); a lower support frame (14) is installed below the lower lifting mechanism (13); a plurality of lower electromagnetic induction heating plates (15) are installed at equal intervals on the lower support frame (14); a controller (16) is installed on the outer side of the conveying roller (1); and the infrared thermometer (9), the upper lifting mechanism (10), the upper electromagnetic induction heating plate (12), the lower lifting mechanism (13), and the lower electromagnetic induction heating plate (15) are all electrically connected to the controller (16).

7. The endless continuous casting and rolling production process for rod and wire products according to claim 6 is characterized in that: The upper electromagnetic induction heating plate (12) and the lower electromagnetic induction heating plate (15) have the same structure, both comprising a heating plate body (17) and an electromagnetic induction coil, the electromagnetic induction coil comprising a first joint portion (18), a second joint portion (19), and a heating portion (20) installed between the first joint portion (18) and the second joint portion (19), the heating portion (20) being arranged in a serpentine structure, and a mounting groove for mounting the electromagnetic induction coil is provided on the heating plate body (17).

8. The endless continuous casting and rolling production process for rod and wire products according to claim 6 is characterized in that: The method for automatically heating the intermediate billet to compensate for the temperature is as follows: the inlet rolling temperature of the intermediate billet continuous rolling, the cross-sectional dimensions of the intermediate billet and the conveying speed data of the intermediate billet are respectively inputted on the operation interface of the controller (16); then the intermediate billet is conveyed by the conveying roller (1) toward the continuous rolling mill; when the intermediate billet passes under the infrared thermometer (9), the infrared thermometer (9) collects the real-time temperature data of the intermediate billet and transmits the temperature data to the control system of the controller (16); the controller compares the real-time temperature data of the intermediate billet with the target rolling temperature data; when the real-time temperature of the intermediate billet is lower than the target rolling temperature, the controller (16) controls the upper electromagnetic induction heating plate (12) and the lower electromagnetic induction heating plate (15) to heat the intermediate billet. A control command is issued, and the controller automatically calculates the amount of heat required for the intermediate billet. After the upper electromagnetic induction heating plate (12) and the lower electromagnetic induction heating plate (15) receive the control command, the controller (16) controls the upper lifting mechanism (10) to drive the upper electromagnetic induction heating plate (12) to move downward, controls the lower lifting mechanism (13) to drive the lower electromagnetic induction heating plate (15) to move upward, and controls the upper electromagnetic induction heating plate (12) and the lower electromagnetic induction heating plate (15) to be powered on to supplement the temperature of the intermediate billet. After the supplementary temperature operation is completed, the upper electromagnetic induction heating plate (12) and the lower electromagnetic induction heating plate (15) are controlled to stop being powered on, and the intermediate billet after the supplementary temperature directly enters the continuous rolling unit to complete rolling.

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