Slab continuous casting method for realizing high-temperature ejection

Abstract

The invention discloses a slab continuous casting method for realizing high-temperature ejection. A plurality of water tanks are arranged on the back surface of a copper plate of a crystallizer of a continuous casting machine and the positions of fixing bolts; a casting blank high-temperature area at the upper part of the continuous casting machine adopts different cooling strengths; heat insulation materials are arranged between the fan-shaped sections of the continuous casting machine and between the rollers in the fan-shaped sections; cooling water pipelines are arranged in the rollers of the arc-shaped section, the straightening section and the horizontal section of the continuous casting machine. According to the method, the surface temperature of the casting blank out of a casting machine is increased under the condition that the casting blank has a solidified blank shell which is thick enough at the high pulling speed, continuous casting production of the plate blank at the high pulling speed can be achieved, and the high surface temperature of the plate blank can also be achieved.

Description

Technical Field

[0001] The invention relates to continuous casting production technology, and more specifically to a slab continuous casting method for realizing high-temperature billet discharge. Background Art

[0002] The development of hot delivery and hot charging technology for continuous casting billets is a reflection of the comprehensive and coordinated progress of high-tech in all processes of the metallurgical process. The progress of steelmaking and refining, high-quality and efficient continuous casting, near-net-shape continuous casting and a series of rolling technologies, combined with in-depth research in physical chemistry and metallurgy, has ensured the sustainable development of hot delivery and hot charging. The application degree of hot delivery and hot charging of continuous casting billets has become a new technical indicator for measuring the technical level of steel production. It has promoted the integration of steelmaking, continuous casting and steel rolling production, and accelerated the development of steel production towards continuous, low-cost and high-quality. The energy-saving and emission-reduction effect of hot delivery and hot charging of continuous casting billets mainly depends on the hot delivery rate and hot delivery temperature of the billets. Therefore, the surface temperature of the slab casting machine is an important factor in measuring whether the hot delivery is successful, and high-temperature hot delivery of slabs has become a necessary condition for hot delivery and hot charging.

[0003] At present, the continuous casting speed of the casting machine is generally low, resulting in a low temperature of the slab out of the casting machine, and a low temperature when it is transported into the heating furnace through the roller. The main technical measures to increase the temperature of the slab at present are high-speed continuous casting and fast transportation.

[0004] Among the existing patent applications, Chinese patent CN112605360A discloses a high-speed production method for hypoperitectic steel slabs, which provides a crystallizer cooling water volume for peritectic steel. The wide surface water volume of the crystallizer cooling is 4050-4500L / min, the narrow surface water volume is 430-540L / min, and the secondary cooling specific water volume is 0.61±0.05L / Kg. Chinese patent CN1824429A discloses a high-speed slab low-carbon steel crystallizer protective slag, which improves the quality problems such as bonding leakage and slag inclusion on the surface of the casting caused by the thin slag layer and poor lubrication of the high-speed continuous casting liquid. Chinese patent CN201773433A discloses a high-speed continuous casting machine crystallizer copper plate, which is characterized by a surface coating divided into two parts, the upper part is a high-temperature resistant coating, and the lower part is a wear-resistant coating, which overcomes the current single coating peeling and wear. Chinese patent CN204413139U discloses an immersed nozzle suitable for high-speed slab continuous casting. The nozzle is characterized by a concave spherical surface at the bottom. When molten steel flows into the bottom of the immersed nozzle, it impacts and rebounds, thereby offsetting the downward molten steel to consume kinetic energy and reduce the occurrence of slag rolling.

[0005] High drawing speed is used to increase production on one hand, and to increase the temperature of the billet and reduce heat loss on the other hand. From the above analysis of patent technologies, it can be seen that the current patent technologies for high drawing speed of slabs are mostly considered from the perspective of casting equipment, and the purpose is mostly to improve the quality of the billet. However, the high temperature billet created for hot delivery of slabs is less considered, so it is necessary to develop high-speed high-temperature continuous casting process technology. Summary of the invention

[0006] In view of the defects existing in the prior art, the purpose of the present invention is to provide a slab continuous casting method that can achieve high-temperature slab discharge, and to increase the surface temperature of the slab casting machine while ensuring that the slab has a sufficiently thick solidified slab shell at a high drawing speed, thereby achieving both continuous casting production of the slab at a high drawing speed and a high slab surface temperature.

[0007] To achieve the above object, the present invention adopts the following technical solution:

[0008] A slab continuous casting method for achieving high temperature billet discharge:

[0009] A plurality of water grooves are arranged on the back of the copper plate of the crystallizer of the continuous casting machine and on the position of the fixing bolts;

[0010] Different cooling intensities are used in the high temperature area of ​​the slab at the top of the continuous casting machine;

[0011] Disposing heat insulating materials between rollers in the sector of the continuous casting machine;

[0012] The fan-shaped segments include a curved segment, an arc segment, a straightening segment and a horizontal segment;

[0013] Cooling water pipes are arranged inside the rollers of the arc section, straightening section and horizontal section of the continuous casting machine. The cooling water flows in from the central pipe of the roller, and then cools the roller surface through the pipes arranged on the surface of the roller, and then flows out from the outer layer of the central pipe.

[0014] Preferably, a plurality of water grooves are arranged on the back of the copper plate of the crystallizer, specifically including:

[0015] The depth of the water tank is 5-10 mm, the width is 15-22 mm, and the spacing between the water tanks is 10-20 mm;

[0016] The flow rate of the cooling water in the water tank is 6-13 m / S.

[0017] Preferably, the water tanks are arranged at equal intervals.

[0018] Preferably, the high temperature area of ​​the casting billet at the upper part of the continuous casting machine adopts different cooling intensities, specifically including:

[0019] The cooling intensity between the foot roll area and the fan-shaped segment is 200-900 L / m 2 / min;

[0020] The cooling intensity of the arc segment is 50-400L / m 2 / min.

[0021] Preferably, the diameters of the foot roll area at the top of the continuous casting machine and the rolls in the bending section are 90 to 200 mm, and the spacing between the rolls is 100 to 230 mm.

[0022] Preferably, the water flow density of the straightening section and the horizontal section of the continuous casting machine is 0 to 150 L / m 2 / min.

[0023] Preferably, the cooling water pipeline includes an inlet pipe arranged at the center of the roller, and an outlet pipe arranged at a position close to the surface of the roller.

[0024] The present invention provides a slab continuous casting method for achieving high-temperature billet discharge. Through the cooling process development of the slab continuous casting, the surface temperature of the billet discharge machine is increased while ensuring the safety of the initial solidified billet shell of the billet. For this purpose, an efficient cooling structure is adopted in the copper plate of the crystallizer, and in order to prevent the billet hot spots caused by uneven cooling of the crystallizer due to high drawing speed, a cooling water trough is added to the copper plate bolt position for cooling. In the secondary cooling part, a cooling method of strong top and weak bottom is adopted, and a heat insulation plate is used in the horizontal section of the casting machine to reduce the heat dissipation of the billet. At the same time, internal water-cooled rollers are used. This method can reduce the damage of the high-temperature billet to the casting machine equipment. Through the above-mentioned technology, stable high-drawing speed continuous casting is achieved, and the temperature of the billet discharge machine is increased, providing high-temperature slabs for hot delivery and hot loading of the slabs, reducing the heating time of the billets in the heating furnace, reducing gas consumption, reducing carbon emissions, and realizing low-carbon green manufacturing. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is a schematic diagram of the arrangement of the continuous casting machine;

[0026] Figure 2 Schematic diagram of setting a water tank on the back of a copper plate in a slab continuous casting method of the present invention, (a) is a schematic diagram of copper plate installation, (b) is a schematic diagram of setting a water tank;

[0027] Figure 3 It is a schematic diagram of setting cooling water pipelines inside the rollers of the horizontal section in the slab continuous casting method of the present invention. DETAILED DESCRIPTION

[0028] In order to better understand the above technical solution of the present invention, the technical solution of the present invention is further described below in conjunction with the accompanying drawings and embodiments.

[0029] In the slab continuous casting process, the cooling of molten steel from liquid phase to solid phase and the cooling of solid phase are all related to heat transfer, mainly including mold cooling, secondary cooling, contact heat transfer of fan-shaped rollers, environmental radiation heat exchange, etc. In order to improve the safety and quality of high-speed casting and increase the surface temperature of the cast billet, the present invention provides a slab continuous casting method for achieving high-temperature billet discharge, including the following aspects:

[0030] Combination Figure 1 and Figure 2 As shown, the copper plate 2 on the crystallizer 1 of the continuous casting machine is the first device to contact the molten steel. Its function is to form a sufficiently thick initial solidified shell and ensure uniform cooling to avoid leakage and cracks. In the slab continuous casting method of the present invention, a plurality of dense water grooves 3 are arranged on the back of the copper plate 2 of the crystallizer 1 of the continuous casting machine to increase the heat exchange between cooling water and molten steel. The depth of the water grooves 3 is 5 to 10 mm, the width is 15 to 22 mm, the water grooves 3 are arranged at equal intervals, the spacing between the water grooves 3 is 10 to 20 mm, and the flow rate of the cooling water in the water grooves 3 is 6 to 13 m / S. In order to increase the uniformity of the initial solidified shell, the copper plate 2 of the crystallizer 1 is required to uniformly cool the initial solidified shell. The water grooves 3 need to be added at the position of the fixing bolts 4 on the copper plate 2 to form a uniform cooling area to avoid the formation of regional hot spots at the position of the fixing bolts 4.

[0031] Refer to Figure 1 As shown, secondary cooling is a continuation of the cooling of the crystallizer 1. It is necessary to continue cooling the ingot out of the crystallizer 1 to take away the heat of the molten steel inside the ingot and reduce the ferrostatic pressure of the internal molten steel on the shell of the ingot to cause bulging, which will cause cracks in the middle of the ingot. In the slab continuous casting method of the present invention, different cooling intensities are used in the high-temperature area of ​​the ingot at the top of the continuous casting machine, that is, the cooling intensity from the foot roll area 5 to the bending section 6 is 200 to 900 L / m 2 / min, the cooling intensity in the arc section 7 is 50~400L / m 2 / min to ensure that a stronger cooling method is adopted in the high temperature area of ​​the billet at the top of the continuous casting machine.

[0032] At the end of the continuous casting process, the ingot has formed a thick solidified shell. In order to increase the surface temperature of the ingot after leaving the casting machine, the straightening section 8 and the horizontal section 9 adopt a smaller cooling intensity, and the water flow density is set to 0-150L / m 2 / min.

[0033] In order to prevent the billet from bulging, the rollers in the sector segment need to provide sufficient support for the billet. In the slab continuous casting method of the present invention, the diameters of the rollers in the foot roller area 5 and the curved section 6 at the top of the continuous casting machine are 90 to 200 mm, and the spacing between the rollers is 100 to 230 mm. The rollers are densely arranged in the sector segment to provide sufficient support for the billet and reduce the squeezing of the billet shell by the static pressure of the molten steel.

[0034] In order to reduce the radiation heat exchange between the casting and the surrounding environment in the horizontal section 9, in the slab continuous casting method of the present invention, heat insulation materials are arranged between the sectors of the continuous casting machine and between the rollers in the sectors to keep the casting warm. At the same time, the solidification latent heat released by the liquid core during the solidification process is used to slow down the temperature drop of the casting surface, and even to make the casting surface temperature rise again.

[0035] Since the rollers in the curved section are in contact with the high-temperature slab for a long time, the surface of the rollers will be damaged. In order to reduce the damage of the high-temperature slab to the rollers in the arc section 7, the straightening section 8 and the horizontal section 9 of the casting machine and increase the fatigue life of the rollers, in the slab continuous casting method of the present invention, cooling water pipes 10 are arranged inside the rollers of the arc section 7, the straightening section 8 and the horizontal section 9 of the continuous casting machine. Water is passed through the cooling water pipes 10 to cool the rollers. The cooling water flows in from the central pipe of the roller, and then cools the roller surface through the pipes arranged on the surface layer of the roller, and then the cooling water flows out from the outer layer of the central pipe.

[0036] Example 1

[0037] In this embodiment 1, a high-speed drawing of low-carbon steel is used as an example, and the drawing speed is 1.8 m / min. The continuous casting machine is composed of a crystallizer 1, a foot roll area 5, a bending section 7, an arc section 7, a straightening section 8 and a horizontal section 9. Figure 1 As shown. The copper plate 2 of the crystallizer 1 adopts a dense water trough form, the water trough 3 is 6mm wide, 18mm deep, and the spacing between the water troughs 3 is 17mm. The flow rate of cooling water in the water trough 3 at the back of the copper plate 2 of the crystallizer 1 is 9.8m / S. In order to avoid the uniformity of the initial solidified shell, it is also necessary to add a water trough 3 at the position of the fixing bolt 4 on the copper plate 2, such as Figure 2 As shown, heat exchange is increased at the position of fixing bolt 4.

[0038] Secondary cooling requires a strong cooling method at the top and weak cooling method at the bottom, i.e. the cooling intensity in the foot roll area 5 and the bending section 6 is 620L / m 2 / min and 380L / m 2 / min, the cooling intensity in the arc section 7 area is 52~286L / m 2 / min, the cooling intensity of the straightening section 8 and the horizontal section 9 is 6~27L / m 2 / min.

[0039] In order to reduce the radiation heat exchange between the ingot and the surrounding environment in the horizontal section 9 area, ceramic fibers are used between the rollers in the sector and between the sector to insulate the ingot on all four sides.

[0040] In order to reduce the damage of high temperature slab to the rollers in the fan-shaped segment, the rollers in the arc segment 7, straightening segment 8 and horizontal segment 9 use internally cooled long-life support rollers, such as Figure 3 As shown, a cooling water pipe 10 is arranged inside the roller for water cooling to cool the roller surface, and the heat transferred from the casting to the roller is taken away by the cooling water.

[0041] Example 2

[0042] In this embodiment 2, the high-speed drawing of peritectic steel is taken as an example, and the drawing speed is 1.6 m / min. The continuous casting machine is composed of a crystallizer 1, a foot roll area 5, a vertical section bending section 6, a fan section 7, a straightening section 8 and a horizontal section 9. Figure 1 As shown. The copper plate 2 of the crystallizer 1 adopts a dense water trough form, the width of the water trough 3 is 5mm, the depth is 15mm, and the spacing of the water trough 3 is 16mm. The flow rate of cooling water in the water trough 3 at the back of the copper plate 2 of the crystallizer 1 is 8m / S. In order to avoid the uniformity of the initial solidified shell, it is also necessary to add a water trough 3 at the position of the fixing bolt 4 on the copper plate 2, such as Figure 2 As shown, heat exchange is increased at the position of fixing bolt 4.

[0043] Secondary cooling requires a strong cooling method at the top and weak cooling method at the bottom, i.e. the cooling intensity in the foot roll area 5 and the bending section 6 is 350L / m 2 / min and 250L / m 2 / min, the cooling intensity in the arc section 7 area is 60~150L / m 2 / min, the cooling intensity of the straightening section 8 and the horizontal section 9 is 3-20L / m 2 / min.

[0044] In order to reduce the radiation heat exchange between the ingot and the surrounding environment in the horizontal section 9 area, ceramic fibers are used between the rollers in the sector and between the sector to insulate the ingot on all four sides.

[0045] In order to reduce the damage of high temperature slab to the rollers in the fan-shaped segment, the rollers in the arc segment 7, straightening segment 8 and horizontal segment 9 use internally cooled long-life support rollers, such as Figure 3 As shown, a cooling water pipe 10 is arranged inside the roller for water cooling to cool the roller surface, and the heat transferred from the casting to the roller is taken away by the cooling water.

[0046] Example 3

[0047] In this embodiment 3, high carbon steel high speed drawing is used as an example, and the drawing speed is 1.4m / min. The continuous casting machine is composed of a crystallizer 1, a foot roll area 5, a vertical section 9, a fan section 6, a straightening section 7 and a horizontal section 8. Figure 1As shown. The copper plate 2 of the crystallizer 1 adopts a dense water trough form, the width of the water trough 3 is 6mm, the depth is 18mm, and the spacing of the water trough 3 is 16mm. The flow rate of cooling water in the water trough 3 at the back of the copper plate 2 of the crystallizer 1 is 9m / S. In order to avoid the uniformity of the initial solidified shell, it is also necessary to add a water trough 3 at the position of the fixing bolt 4 on the copper plate 2, such as Figure 2 As shown, heat exchange is increased at the position of fixing bolt 4.

[0048] Secondary cooling requires a strong cooling method at the top and weak cooling method at the bottom, i.e. the cooling intensity in the foot roll area 5 and the bending section 6 is 330L / m 2 / min and 280L / m 2 / min, the cooling intensity in the arc section 7 area is 70~200L / m 2 / min, the cooling intensity of the straightening section 8 and the horizontal section 9 is 8~30L / m 2 / min.

[0049] In order to reduce the radiation heat exchange between the ingot and the surrounding environment in the horizontal section 9 area, ceramic fibers are used between the rollers in the sector and between the sector to insulate the ingot on all four sides.

[0050] In order to reduce the damage of high temperature slab to the rollers in the fan-shaped segment, the rollers in the arc segment 7, straightening segment 8 and horizontal segment 9 use internally cooled long-life support rollers, such as Figure 3 As shown, a cooling water pipe 10 is arranged inside the roller for water cooling to cool the roller surface, and the heat transferred from the casting to the roller is taken away by the cooling water.

[0051] Those skilled in the art should recognize that the above embodiments are only used to illustrate the present invention, and are not intended to limit the present invention. As long as they are within the spirit of the present invention, any changes or modifications to the above embodiments will fall within the scope of the claims of the present invention.

Claims

1. A slab continuous casting method for achieving high temperature billet discharge, characterized in that: A plurality of water grooves are arranged on the back of the copper plate of the crystallizer of the continuous casting machine and on the position of the fixing bolts; Different cooling intensities are used in the high temperature area of ​​the slab at the top of the continuous casting machine; Disposing heat insulating materials between rollers in the sector of the continuous casting machine; The fan-shaped segments include a curved segment, an arc segment, a straightening segment and a horizontal segment; Cooling water pipelines are arranged inside the rollers of the arc section, the straightening section and the horizontal section.

2. The slab continuous casting method for achieving high temperature billet discharge according to claim 1, characterized in that: The plurality of water grooves provided on the back of the copper plate of the crystallizer specifically include: The depth of the water tank is 5-10 mm, the width is 15-22 mm, and the spacing between the water tanks is 10-20 mm; The flow rate of the cooling water in the water tank is 6-13 m / S.

3. The slab continuous casting method for achieving high temperature billet discharge according to claim 2, characterized in that: The water tanks are arranged at equal intervals.

4. The slab continuous casting method for achieving high temperature billet discharge according to claim 1, characterized in that: The high temperature area of ​​the cast billet at the top of the continuous casting machine adopts different cooling intensities, specifically including: The cooling intensity between the foot roll area and the fan-shaped segment of the continuous casting machine is 200-900 L / m 2 / min; The cooling intensity in the arc section is 50-400 L / m 2 / min.

5. The slab continuous casting method for realizing high temperature billet discharge according to claim 4, characterized in that: The diameters of the foot roll area at the top of the continuous casting machine and the rolls in the bending section are 90-200 mm, and the distance between the rolls is 100-230 mm.

6. The slab continuous casting method for realizing high temperature billet discharge according to claim 1, characterized in that: The water flow density of the straightening section and the horizontal section is 0-150 L / m 2 / min.

7. The slab continuous casting method for realizing high temperature billet discharge according to claim 1, characterized in that: The cooling water pipeline comprises an inlet pipe arranged at the center of the roller, and an outlet pipe arranged at a position close to the surface of the roller.

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