A method for dynamic roll gap control of a continuous caster

Abstract

The application relates to a static roll gap dynamic pressing method of a continuous casting machine, and the corresponding relationship among the steel grade C content, the pulling speed V and the specific water quantity of the continuous casting machine is as follows: 0.2%<=C<0.4%, the pulling speed 1.7<=V<=1.9 m / min, and the specific water quantity 1.5 L / kg; 0.4%<=C<0.6%, the pulling speed 1.5<=V<1.7 m / min, and the specific water quantity 1.4 L / kg; 0.6%<=C<0.8%, the pulling speed 1.4<=V<1.5 m / min, and the specific water quantity 1.3 L / kg; and then the solidification end position of the continuous casting billet is located between the 6# and 7# pull-straightening machines, the opening degree of the vertical roller on the 7# pull-straightening machine side is 185 mm, and the corresponding relationship between the pressing amount of the upper and lower rollers and the steel grade C content is as follows: 0.2%<=C<0.4%, the pressing amount is 10 mm; 0.4%<=C<0.6%, the pressing amount is 7 mm; and 0.6%<=C<0.8%, the pressing amount is 3 mm. According to the steel grade C content, different continuous casting pulling speeds, specific water quantities and pressing amounts are set, the center quality of the continuous casting billet is ensured, and the length, width and thickness of the continuous casting fixed-length billet are controlled to be consistent.

Description

Technical Field

[0001] This invention relates to a method for dynamic reduction of static roll gap in a continuous casting machine, belonging to the technical field of steel continuous casting. Background Technology

[0002] The Longteng No. 3 continuous casting machine is a six-strand, six-cup, full-arc continuous casting machine with a copper tube crystallizer. The lower opening of the copper tube remains constant, with dimensions of 187*183 mm. This continuous casting machine has seven leveling machines, with distances from the leveling machines to the meniscus of 11.61 m, 12.73 m, 13.84 m, 14.96 m, 16.07 m, 17.17 m, and 18.47 m respectively. The production process casting speed ranges from 1.4 to 1.9 m / min. Due to its light reduction function, to better utilize the light reduction effect and improve the internal quality of the cast billet, the reduction amount varies when producing different steel grades of the same specification, resulting in different billet specifications at different casting speeds.

[0003] During the rolling of cast billets, steel rolling usually takes into account the requirement of fixed length to improve the yield of rolled products. However, the yield of rolled products is unstable due to the different cross-sectional specifications of the cast billets, which range from a maximum of 184*180 to a minimum of 181*180. Summary of the Invention

[0004] To address the aforementioned problems, this invention discloses a method for dynamic reduction of static roll gap in a continuous casting machine, the specific technical solution of which is as follows: A method for dynamic reduction of static roll gap in a continuous casting machine. The continuous casting machine has 7 straightening machines, numbered 1#, 2#, 3#, 4#, 5#, 6#, and 7#. Straightening machines 1# and 2# are located in the straightening section, with upper and lower rolls, and only straighten the continuous casting billet. Straightening machines 3#, 4#, 5#, and 6# are located in the horizontal section, with upper and lower rolls, and only reduce the continuous casting billet. Straightening machine 7# is located in the horizontal section, with upper and lower rolls and side vertical rolls. The relationship between the carbon content, casting speed (V), and specific water content of the steel grade produced by the casting machine is as follows: When the mass content of C is 0.2%≤C<0.4%, the pulling speed is 1.7≤V≤1.9m / min, and the specific water content is 1.4-1.5L / kg; When the mass content of C is 0.4%≤C<0.6%, the pulling speed is 1.5≤V<1.7m / min, and the specific water content is 1.3-1.4L / kg; When the mass content of C is 0.6%≤C<0.8%, the pulling speed is 1.4≤V<1.5m / min, and the specific water content is 1.2-1.3L / kg; This allows the solidification endpoint of the continuously cast billet to be controlled between the No. 6 and No. 7 straightening machines. The opening degree of the side vertical rollers of the No. 7 tension leveler is 184-185mm, and the corresponding relationship between the upper and lower roller reduction and the C content of the steel grade is as follows: When the mass content of C is 0.2% ≤ C < 0.4%, the reduction is 9-10 mm; When the mass content of C is 0.4% ≤ C < 0.6%, the reduction is 6-7 mm; When the mass content of C is 0.6%≤C<0.8%, the reduction is 3-4mm.

[0005] Furthermore, the relationship between the C content of the steel grade and the reduction amount is as follows: when the mass content of C is 0.2%≤C<0.4%, the reduction amount is 5mm, and the reduction amounts of #3, #4, #5, and #6 are 0~1mm, 0~1mm, 1~2mm, and 1~2mm, respectively; When the mass content of C is 0.4%≤C<0.6%, the reduction is 8mm, and the reduction of #3, #4, #5, and #6 is 1~2mm, 1~2mm, 2~3mm, and 2~3mm respectively; When the mass content of C is 0.6%≤C<0.8%, the reduction is 12mm, and the reduction of #3, #4, #5, and #6 is 2~3mm, 2~3mm, 3~4mm, and 3~4mm, respectively.

[0006] Furthermore, the continuous casting machine crystallizer is a copper tube type, with a lower opening size of 187mm in width and 183mm in thickness.

[0007] Furthermore, the continuous casting billet has a fixed length of 9m, a width of 185mm, and a thickness of 178mm.

[0008] Furthermore, the continuously cast billet is heated in a heating furnace and then subjected to rough rolling with a flying shear, with a shearing amount of 0.3m at both the head and tail.

[0009] Furthermore, the weight of the finished bar is 2.40 ± 0.05 t.

[0010] The working principle of this invention is: First, with the increase of carbon content in the steel grade, the length of the mushy zone in the continuously cast billet increases. At the same casting speed, the solidification endpoint of high-carbon steel is later than that of low-carbon steel. By setting the casting speed and specific water volume of the continuous casting machine, the solidification endpoint of the continuously cast billet is controlled to be between the No. 6 and No. 7 straightening machines. Second, with the increase of carbon content in the steel grade, V-shaped segregation is prone to form in the core of the continuously cast billet. Appropriately increasing the total reduction is beneficial to improving the center quality of the continuously cast billet. Third, after the continuously cast billet is completely solidified, a certain amount of reduction is applied to the billet to control the consistency of the length, width, and thickness of the continuously cast billet without affecting the center quality. Combined with the control of shearing amount in the rolling process, the weight of the finished bar is stably controlled at 2.40±0.05t.

[0011] The beneficial effects of this invention are: This invention, based on the C content of the steel grade, sets different continuous casting speeds, specific water content, and reduction amounts to ensure the center quality of the continuously cast billet while controlling the consistency of the length, width, and thickness of the continuously cast billet. Combined with the control of shearing amount in the rolling process, the weight of the finished bar is stably controlled at 2.40±0.05t, improving the yield of rolled products. Detailed Implementation

[0012] The present invention will be further illustrated below with reference to specific embodiments. It should be understood that the following specific embodiments are for illustrative purposes only and are not intended to limit the scope of the invention.

[0013] The final product obtained by this invention is a bar stock, which is prepared by: processing molten iron through a molten iron pretreatment process, a primary refining furnace process, a refining process, a continuous casting process, and a rolling process to obtain the finished bar stock.

[0014] The continuous casting machine has seven straightening machines, numbered 1#, 2#, 3#, 4#, 5#, 6#, and 7#. Machines 1# and 2# are located in the straightening section, equipped with upper and lower rollers, and are used only to straighten the continuously cast billets. Machines 3#, 4#, 5#, and 6# are located in the horizontal section, equipped with upper and lower rollers, and are used only to press down the continuously cast billets. Machine 7# is located in the horizontal section and has upper and lower rollers and a side vertical roller. The continuous casting machine's crystallizer is a copper tube type, with a lower opening dimension of 187mm width × 183mm thickness.

[0015] When the mass content of C is 0.2%≤C<0.4%, the pulling speed is 1.7≤V≤1.9m / min, and the specific water content is 1.4-1.5L / kg; When the mass content of C is 0.4%≤C<0.6%, the pulling speed is 1.5≤V<1.7m / min, and the specific water content is 1.3-1.4L / kg; When the mass content of C is 0.6%≤C<0.8%, the pulling speed is 1.4≤V<1.5m / min, and the specific water content is 1.2-1.3L / kg; This allows the solidification endpoint of the continuously cast billet to be controlled between the No. 6 and No. 7 straightening machines. The opening degree of the side vertical rollers of the No. 7 tension leveler is 184-185mm, and the corresponding relationship between the upper and lower roller reduction and the C content of the steel grade is as follows: When the mass content of C is 0.2% ≤ C < 0.4%, the reduction is 9-10 mm; When the mass content of C is 0.4% ≤ C < 0.6%, the reduction is 6-7 mm; When the mass content of C is 0.6%≤C<0.8%, the reduction is 3-4mm.

[0016] The opening of the side vertical rollers of the No. 7 tension leveling machine is 185mm. The corresponding relationship between the pressing amount of the upper and lower rollers and the C content of the steel grade is as follows: when the mass content of C is 0.2%≤C<0.4%, the pressing amount is 9mm; when the mass content of C is 0.4%≤C<0.6%, the pressing amount is 7mm; when the mass content of C is 0.6%≤C<0.8%, the pressing amount is 3mm.

[0017] The following examples illustrate the implementation effect of the present invention. The data on the reduction amount of the examples are shown in Table 1, and the data on the cross-sectional specifications of the product billets of the examples are shown in Table 2.

[0018] Table 1

[0019] The continuous casting billet has a fixed length of 9m, a width of 185mm, and a thickness of 178mm.

[0020] The continuously cast billet is heated in a heating furnace, and the shearing amount of the rough rolling flying shear is 0.3m at both the head and tail.

[0021] The weight of the finished bar stock is 2.40±0.05t.

[0022] Table 2

[0023] This invention relates to a continuous casting process that controls the solidification endpoint of the continuously cast billet based on factors such as the carbon content of the steel grade, casting speed, and specific water content. It also sets the reduction amount for each straightening machine to ensure consistent billet thickness, width, and length, guaranteeing the internal quality of the continuously cast billet while stably controlling the weight of the billet at the specified length. This solves the problem of low rolled product yield due to substandard bar length.

[0024] This invention designs a novel dynamic reduction mode: at 18.47 meters on the 7th straightening stand, the interior of the billet has completely solidified, and the reduction amount will not affect the quality of the billet. Therefore, a solid roll gap parameter is set on the 7th straightening stand of the continuous casting machine, and an automatic program is implemented by the electrical program. A new interface is added, and the roll gap value is input. Regardless of the thickness of the billet, more pressure is applied to thicker billets and less pressure is applied to thinner billets, resulting in billet specifications that are the same. This improves the yield of rolled products during billet rolling.

[0025] Based on the above-described preferred embodiments of the present invention, and through the above description, those skilled in the art can make various changes and modifications without departing from the technical concept of the present invention.

Claims

1. A method for dynamically reducing the static roll gap in a continuous casting machine, wherein the continuous casting machine has 7 straightening machines, numbered 1#, 2#, 3#, 4#, 5#, 6#, and 7#, wherein straightening machines 1# and 2# are located in the straightening section, have upper and lower rolls, and only straighten the continuous casting billet; straightening machines 3#, 4#, 5#, and 6# are located in the horizontal section, have upper and lower rolls, and only reduce the continuous casting billet; straightening machine 7# is located in the horizontal section and has upper and lower rolls and a side vertical roll, characterized in that... The relationship between carbon content, casting speed (V), and specific water content in steel produced by a continuous casting machine is as follows: When the mass content of C is 0.2%≤C<0.4%, the pulling speed is 1.7≤V≤1.9m / min, and the specific water content is 1.4-1.5L / kg; When the mass content of C is 0.4%≤C<0.6%, the pulling speed is 1.5≤V<1.7m / min, and the specific water content is 1.3-1.4L / kg; When the mass content of C is 0.6%≤C<0.8%, the pulling speed is 1.4≤V<1.5m / min, and the specific water content is 1.2-1.3L / kg; This allows the solidification endpoint of the continuously cast billet to be controlled between the No. 6 and No. 7 straightening machines. The opening degree of the side vertical rollers of the No. 7 tension leveler is 184-185mm, and the corresponding relationship between the upper and lower roller reduction and the C content of the steel grade is as follows: When the mass content of C is 0.2% ≤ C < 0.4%, the reduction is 9-10 mm; When the mass content of C is 0.4% ≤ C < 0.6%, the reduction is 6-7 mm; When the mass content of C is 0.6% ≤ C < 0.8%, the reduction is 3-4 mm.

2. The method for dynamic reduction of static roll gap in a continuous casting machine according to claim 1, characterized in that, The relationship between the C content and the reduction amount of the steel grade is as follows: when the mass content of C is 0.2%≤C<0.4%, the reduction amount is 5mm, and the reduction amounts of 3#, 4#, 5#, and 6# are 0~1mm, 0~1mm, 1~2mm, and 1~2mm, respectively. When the mass content of C is 0.4%≤C<0.6%, the reduction is 8mm, and the reduction of #3, #4, #5, and #6 is 1~2mm, 1~2mm, 2~3mm, and 2~3mm respectively; When the mass content of C is 0.6%≤C<0.8%, the reduction is 12mm, and the reduction of #3, #4, #5, and #6 is 2~3mm, 2~3mm, 3~4mm, and 3~4mm, respectively.

3. The method for dynamic reduction of static roll gap in a continuous casting machine according to claim 1, characterized in that, The continuous casting machine crystallizer is a copper tube type, with a bottom opening size of 187mm in width and 183mm in thickness.

4. The method for dynamic reduction of static roll gap in a continuous casting machine according to claim 1, characterized in that, The continuous casting billet has a fixed length of 9m, a width of 185mm, and a thickness of 178mm.

5. The method for dynamic reduction of static roll gap in a continuous casting machine according to claim 1, characterized in that, The continuously cast billet is heated in a heating furnace and then rough rolled by a flying shear, with a shearing amount of 0.3m at both the head and tail, to obtain the finished bar stock.

6. The method for dynamic reduction of static roll gap in a continuous casting machine according to claim 5, characterized in that, The weight of the finished bar is 2.40 ± 0.05 t.

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