A method for controlling the temperature of a head portion of a finish-rolled billet to be low and the temperature of a tail portion to be high

Abstract

The present application relates to a method for controlling the temperature of the head of the finished steel billet to be low and the temperature of the tail to be high, by adjusting the opening of the air and gas valve above the flame burner of the soaking section of the heating furnace and the length of the flame of the flame adjusting burner below the soaking section, so that the tail of the steel billet is heated to be higher than the head in the soaking section, combined with the different distribution of the steel billets of different lengths in the furnace, to offset the temperature drop of the tail in the rolling process, to improve the temperature curve of the steel billet before entering the finishing mill, to gradually increase the temperature of the steel billet from the head to the tail, to make the temperature of each part of the slab in the finishing mill similar, and to ensure the stability of the rolling.

Description

Technical Field

[0001] This invention relates to the manufacture of hot-rolled strip, and particularly to a method for controlling the temperature of the head of the finished steel billet to be low and the temperature of the tail to be high. Background Technology

[0002] The temperature difference between the beginning and end of the steel billet exiting the heating furnace is always present after the initial rolling and before entering the finishing mill, influenced by factors such as the quality of the heated steel and the cooling time. The beginning is hotter, while the end temperature decreases continuously as rolling progresses, resulting in a significant temperature difference with the beginning. When the temperature difference is large, it increases the adjustment resistance, rolling pressure, and mill bounce during the rolling process. This is especially true when rolling high-strength steel grades and thin specifications, easily leading to a decrease in the final rolled thickness and width, and in severe cases, even causing steel jamming accidents. The required temperature curve of the through plate in the heating zone is an upward sloping shape, meaning that the temperature of the steel billet gradually increases as it enters the mill, with the rear of the plate gradually becoming hotter than the front. During the rolling process, the cooling time and contact with the cooling water at the rear are always longer than at the front. Therefore, to achieve a higher rear temperature than front temperature, it is only possible to adjust the heating process. Summary of the Invention

[0003] The technical problem to be solved by the present invention is to provide a method for controlling the temperature of the head of the finishing steel billet to be low and the temperature of the tail to be high, thereby improving the temperature curve of the steel billet before entering the finishing mill and achieving a higher tail temperature than head temperature.

[0004] To achieve the above objectives, the present invention employs the following technical solution:

[0005] A method for controlling the temperature of a finished steel billet to be low at the head and high at the tail includes:

[0006] 1. Adjustment of the burner in the heating furnace

[0007] 1) The proportion of outer ring air of the flame-adjusting burner on the mill side below the soaking zone of the heating furnace is controlled at 60%-70% to ensure that the flame center area is in the middle of the heating furnace in the transverse direction. The proportion of outer ring air of the flame-adjusting burner on the non-mill side below the soaking zone of the heating furnace is controlled at 40%-50% to shorten the flame length so that the flame center area is biased towards the non-mill side of the heating furnace and is located at 1 / 4-1 / 3 of the transverse direction of the heating furnace. The proportion of outer ring air of the flame-adjusting burner on both the mill side and the non-mill side is initially controlled at the lower limit.

[0008] 2) Control the opening degree of the air gas valve of the flat flame burner on the non-rolling mill side above the soaking section of the heating furnace to 100%, and decrease the opening degree of the air gas valve of the flat flame burner on the non-rolling mill side to the rolling mill side by 10%-15% respectively.

[0009] 3) When the feedback result of the billet exiting the initial rolling temperature does not meet the billet finishing rolling temperature conditions, the outer ring air ratio of the flame-adjusting burner on the mill side and the non-mill side is adjusted alternately from the lower limit to the upper limit until the heating furnace feedback temperature meets the finishing rolling temperature conditions.

[0010] 2. Slab charging position adjustment

[0011] 1) The billet length is greater than or equal to 90% of the designed maximum billet length, or the billet length is less than or equal to 75% of the designed maximum billet length, so that the billet is charged in the center position, that is, the center line of the billet is consistent with the center line of the heating furnace;

[0012] 2) 90% of the designed maximum billet length is less than the billet length, and the billet length is less than 75% of the designed maximum billet length, the billet is charged on the side of the rolling mill, and the head of the billet is kept at a safety distance of 350mm-380mm from the flame side in the furnace.

[0013] In step 1, the billet finishing rolling temperature condition is that the temperature of the billet gradually increases from the head to the tail, and the temperature of the head of the billet is 10-20℃ lower than the temperature of the tail.

[0014] In step 1, when the billet exit rough rolling temperature feedback result does not meet the billet finishing rolling temperature condition, the adjustment method is: first adjust the flame adjusting burner outer circle air proportion on the side of the rolling mill, and then adjust the flame adjusting burner outer circle air proportion on the non-rolling mill side in the order of alternation, and each adjustment is increased by 5% proportion, and after each adjustment, the adjusted heating furnace feedback temperature curve is obtained to judge whether the billet finishing rolling temperature condition is met, if yes, the existing rolling mill side and non-rolling mill side flame adjusting burner outer circle air proportion is kept, and if not, the adjustment is continued.

[0015] Compared with the prior art, the beneficial effects of the present application are:

[0016] The present application adjusts the opening degree of the air gas valve of the flat flame burner above the soaking section of the heating furnace and the flame length of the flame adjusting burner below the soaking section, so that the tail temperature is higher than the head temperature when the billet is heated in the soaking section, and the different distribution of the billet in the furnace is combined to offset part of the tail temperature drop in the rolling process, improve the billet temperature curve before entering the finishing rolling, realize the gradual increase of the billet temperature from the head to the tail, make the temperature of each part of the billet in the finishing rolling mill similar, and ensure the stability of the rolling. DETAILED DESCRIPTION

[0017] It is to be understood that unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used in the description herein is for describing particular embodiments only and is not intended to be limiting of the application. All publications, patent applications, patents, patent publications, and / or other references cited herein are incorporated by reference in their entireties for the teachings relevant to the sentence and / or paragraph in which the reference is presented. Reference herein to "an embodiment" means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the application. The appearances of the phrase "in an embodiment" in various places in the specification are not necessarily all referring to the same embodiment, nor are they necessarily all directed to the same embodiment, nor are they necessarily all mutually exclusive embodiments. Any feature or combination of features described in relation to an embodiment can be combined with any other feature or combination of features described in relation to any other embodiment. All combinations of features described herein can be combined with any other feature or combination of features described herein unless otherwise expressly stated or limited.

[0018] A method for controlling the head temperature of a finishing rolling billet heating head to be low and the tail temperature to be high, comprising:

[0019] 1. Heating furnace burner adjustment

[0020] 1) The flame adjusting burner outer ring air ratio of the rolling mill side below the soaking section of the heating furnace is controlled at 60%-70%, so that the flame center area is in the middle position of the transverse direction of the heating furnace. The flame adjusting burner outer ring air ratio of the non-rolling mill side below the soaking section of the heating furnace is controlled at 40%-50%, so that the flame length is shortened to the flame center area deviating to the non-rolling mill side of the heating furnace, and is in the 1 / 4-1 / 3 position of the transverse direction of the heating furnace. The flame adjusting burner outer ring air ratio of the rolling mill side and the non-rolling mill side is initially controlled at the lower limit.

[0021] 2) The air-gas valve opening degree of the flat flame burner on the non-rolling mill side above the soaking section of the heating furnace is controlled at 100%, and the air-gas valve opening degree of the flat flame burner on the non-rolling mill side to the rolling mill side is sequentially decreased by 10%-15%.

[0022] 3) The billet finishing rolling temperature condition is that the billet temperature gradually increases from the head to the tail, and the head temperature of the billet is 10-20℃ lower than the tail temperature.

[0023] When the billet initial rolling temperature feedback result does not meet the billet finishing rolling temperature condition, the flame adjusting burner outer ring air ratio of the rolling mill side and the non-rolling mill side is alternately adjusted from the lower limit to the upper limit, the flame adjusting burner outer ring air ratio of the rolling mill side is adjusted first, and then the flame adjusting burner outer ring air ratio of the non-rolling mill side is adjusted. Each adjustment is increased by 5% proportionally. After each adjustment, the adjusted heating furnace feedback temperature curve is obtained to determine whether the billet finishing rolling temperature condition is met. If yes, the existing flame adjusting burner outer ring air ratio of the rolling mill side and the non-rolling mill side is maintained. If not, the adjustment is continued until the heating furnace feedback temperature meets the finishing rolling temperature condition.

[0024] 2. Billet charging position adjustment

[0025] 1) Steel billet length ≥ 90% of the design maximum steel billet length, or steel billet length ≤ 75% of the design maximum steel billet length, to ensure that the steel billet is centrally positioned in the furnace, i.e. the center line of the steel billet is aligned with the center line of the heating furnace;

[0026] 2) 90% of the design maximum steel billet length < steel billet length < 75% of the design maximum steel billet length, the steel billet is positioned against the rolling mill side, and the head of the steel billet is kept 350-380 mm away from the flame side in the furnace.

[0027] The technical solutions in the embodiments of the present application will be clearly and completely described below in combination with the embodiments of the present application. Obviously, the described embodiments are only some of the embodiments of the present application, rather than all the embodiments.

[0028] Embodiment 1

[0029] The heating furnace in a certain plant has an inner width of 11.7 m, and the design maximum steel billet length is 11 m. There are 5 pairs of 10 flame adjusting burners below the soaking section, and 36 flat flame burners above the soaking section, arranged in six rows with six burners in each row. The steel billet length is 7.5 m.

[0030] A method for controlling the head temperature of a finished rolling steel billet to be low and the tail temperature to be high, comprising:

[0031] 1. The steel billet is centrally positioned in the furnace;

[0032] 2. First, the flame adjusting burner outer ring wind ratio on the rolling mill side below the soaking section of the heating furnace is controlled at 60%, and the flame adjusting burner outer ring wind ratio on the non-rolling mill side below the soaking section of the heating furnace is controlled at 40%. The air valve opening degree of the twelve burners in the two rows of flat flame burners above the soaking section from the rolling mill side is 70%, the air valve opening degree of the two middle rows is 85%, and the air valve opening degree of the two rows on the non-rolling mill side is 100%.

[0033] 3. If the feedback result of the initial rolling temperature of the steel billet is that the head temperature of the steel billet is 5-10℃ higher than the tail temperature, the flame adjusting burner outer ring wind ratio on the rolling mill side is adjusted to 65%. If the feedback result of the initial rolling temperature of the steel billet is that the head temperature of the steel billet is 10-15℃ lower than the tail temperature, the rolling condition is met, and the existing state is maintained.

[0034] Embodiment 2

[0035] The heating furnace in a certain plant has an inner width of 12.5 m, and the design maximum steel billet length is 11.8 m. There are 5 pairs of 10 flame adjusting burners below the soaking section, and 48 flat flame burners above the soaking section, arranged in six rows with eight burners in each row. The steel billet length is 11 m.

[0036] A method for controlling the head temperature of a finished rolling steel billet to be low and the tail temperature to be high, comprising:

[0037] 1. The steel billet is positioned against the rolling mill side in the limit position.

[0038] 2. First, the flame adjusting burner outer circle air ratio of the mill side below the heating furnace soaking section is controlled at 60%, the flame adjusting burner outer circle air ratio of the non-mill side below the heating furnace soaking section is controlled at 40%; the two rows of twelve burners of the flat flame burner above the soaking section from the mill side are opened at 70%, the middle two rows are opened at 85%, and the two rows of the non-mill side are opened at 100%;

[0039] 3. When the billet exit rough rolling temperature feedback result is that the head temperature and the tail temperature are 10-15℃ lower than the middle temperature, the flame adjusting burner outer circle air ratio of the mill side is adjusted to 65%; when the billet exit rough rolling temperature feedback result is that the head temperature is 0-5℃ higher than the tail temperature, the flame adjusting burner outer circle air ratio of the non-mill side is adjusted to 45%; when the billet exit rough rolling temperature feedback result is that the head temperature is 15-20℃ lower than the tail temperature, it is in line with the rolling condition, and the existing state is maintained.

[0040] Although the embodiments of the present application have been shown and described, it is to be understood that various changes, modifications, substitutions and alterations can be made to the embodiments without departing from the principles and spirit of the present application, and the scope of the present application is defined by the appended claims and their equivalents.

Claims

1. A method for controlling the temperature of a finished steel billet to be low at the head and high at the tail, characterized in that, include: I. Adjustment of the burner in the heating furnace 1) The proportion of outer ring air of the flame-adjusting burner on the mill side below the soaking zone of the heating furnace is controlled at 60%-70%, so that the flame center area is in the middle of the heating furnace in the transverse direction. The proportion of outer ring air of the flame-adjusting burner on the non-mill side below the soaking zone of the heating furnace is controlled at 40%-50%, so that the flame length is shortened to the point where the flame center area is biased towards the non-mill side of the heating furnace, at 1 / 4-1 / 3 of the transverse direction of the heating furnace. The proportion of outer ring air of the flame-adjusting burner on both the mill side and the non-mill side is initially controlled at the lower limit. 2) Control the opening degree of the air gas valve of the flat flame burner on the non-rolling mill side above the soaking section of the heating furnace to 100%, and decrease the opening degree of the air gas valve of the flat flame burner on the non-rolling mill side to the rolling mill side by 10%-15% respectively; 3) The billet finishing rolling temperature conditions are as follows: the billet temperature gradually increases from the head to the tail, and the billet head temperature is 10-20℃ lower than the tail temperature; when the billet exiting the initial rolling temperature feedback result does not meet the billet finishing rolling temperature conditions, the outer ring air ratio of the flame-adjusting burner on the mill side and the non-mill side is adjusted alternately from the lower limit to the upper limit until the heating furnace feedback temperature meets the finishing rolling temperature conditions. II. Adjustment of slab loading position 1) The billet length is greater than or equal to 90% of the maximum designed billet length, or the billet length is less than or equal to 75% of the maximum designed billet length, to ensure that the billet is loaded into the furnace in the center, that is, the center line of the billet is consistent with the center line of the heating furnace; 2) The billet length is less than 75% of the maximum designed billet length. The billet is loaded into the furnace from the side of the rolling mill, and the head of the billet is kept at a safe distance of 350mm-380mm from the flame side of the furnace.

2. The method for controlling the temperature of the heating head of a precision rolled steel billet to be low and the temperature of the heating tail to be high, as described in claim 1, is characterized in that... In step 1, 3), the adjustment method when the feedback result of the billet exiting the initial rolling temperature does not meet the billet finishing rolling temperature conditions is as follows: adjust the outer ring air ratio of the flame-adjusting burner on the rolling mill side first, and then adjust the outer ring air ratio of the flame-adjusting burner on the non-rolling mill side alternately. Each adjustment increases by 5%. After each adjustment, obtain the adjusted furnace feedback temperature curve to determine whether the billet finishing rolling temperature conditions are met. If they are met, maintain the existing outer ring air ratio of the flame-adjusting burner on the rolling mill side and the non-rolling mill side. If they are not met, continue to adjust.