Method for controlling the press-in of foreign matter on the surface of a thin strip

Abstract

The present application belongs to the technical field of steel production, and discloses a control method for foreign matter pressing into the surface of thin strip steel. 3 The control method comprises the following steps: (1) molten steel smelting control: controlling the oxygen blowing amount of the refining furnace to be 15-18 m 3 / h; controlling the total flow of the compressed air of the No. 3 hot box on the upper surface and the lower surface of the thin strip steel to be: when rolling the thin strip steel with a specification of 1.2 mm or above, the total flow of the compressed air is controlled to be lower than 100 m 3 / h; or when rolling the thin strip steel with a specification of 1.2 mm or below, the total flow of the compressed air is controlled to be not more than 350 m 3 / h. In addition, the control method further comprises (3) flow control of rolling oil: controlling the flow of the rolling oil in rolling to be not more than 150 cc / min on the upper surface and the lower surface of the thin strip steel, respectively.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of steel production, and particularly relates to a control method for foreign matter pressing into the surface of thin strip steel. BACKGROUND

[0002] The applicant found, during the hot commissioning of thin strip casting, that the surface of thin strip steel often has a serious problem of foreign matter pressing in. Some coils can only be sold at a lower grade due to too many foreign matters pressing in and too deep pressing in depth, resulting in a large loss of economic benefits.

[0003] In particular, the judgment rate of foreign matter pressing in can reach about 15% during peak periods.

[0004] Therefore, how to solve the problem of foreign matter pressing into the surface of thin strip steel in thin strip casting production is very important for improving the quality and economic benefits of thin strip steel. SUMMARY

[0005] To solve the above technical problems, according to a first aspect of the present application, a control method for foreign matter pressing into the surface of thin strip steel is disclosed, which comprises the following steps:

[0006] (1) Molten steel smelting control

[0007] The oxygen blowing amount of the refining furnace is controlled to be 15-18 m 3 ;

[0008] The molten steel amount in the tundish is controlled to be more than 15 t;

[0009] (2) Hot box atmosphere control

[0010] The nitrogen flow of the hot box is controlled to be not less than 2500 m 3 / h;

[0011] The total flow of the compressed air of the No. 3 hot box on the upper surface and the lower surface of the thin strip steel is controlled as follows:

[0012] (2.1) When rolling the thin strip steel with a specification of 1.2 mm or more, the total flow of the compressed air is controlled to be less than 100 m 3 / h; or

[0013] (2.2) When rolling the thin strip steel with a specification of 1.2 mm or less, the total flow of the compressed air is controlled to be not more than 350 m 3 / h.

[0014] According to the control method for foreign matter pressing into the surface of thin strip steel, preferably, the control method further comprises the following steps:

[0015] (3) Flow control of rolling oil

[0016] The flow of rolling oil in rolling is controlled to be no more than 150cc / min on the upper surface and lower surface of the thin strip respectively.

[0017] Beneficial technical effects

[0018] The control method of foreign matter pressing of the present application, through the analysis of foreign matter pressing morphology and causes, formulates the above technical means, solves the foreign matter pressing defects on the surface of the thin strip after debugging and solidification. More specifically, the foreign matter pressing judgment rate is reduced from 15% to less than 1%. BRIEF DESCRIPTION OF DRAWINGS

[0019] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings of the embodiments will be briefly introduced below. Obviously, the drawings in the following description only relate to some of the embodiments of the present application, but not limit the present application.

[0020] Figure 1 It is a schematic diagram of calcium oxide inclusions (source of refractory spalling);

[0021] Figure 2 It is a schematic diagram of iron oxide pressing;

[0022] Figure 3 It is a schematic diagram of slag in the ladle, covering agent in the tundish, and oxide precipitation in the molten steel in the molten pool. DETAILED DESCRIPTION

[0023] In order to make the purpose, technical solutions and advantages of the embodiments of the present application more clear, the technical solutions of the embodiments of the present application will be clearly and completely described below. Obviously, the described embodiments are part of the embodiments of the present application, but not all the embodiments. Based on the described embodiments of the present application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the present application.

[0024] Unless otherwise defined, the technical terms or scientific terms used in the present application should be understood as the usual meaning understood by those skilled in the art in the field to which the present application belongs.

[0025] The following are embodiments of the present application, and the described embodiments are only part of the embodiments of the present application. Based on the embodiments of the present application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the present application.

[0026] Through the research and practice of the inventor, in the thin strip continuous casting process, the sources of foreign matter pressing on the surface of the thin strip mainly have the following four factors:

[0027] (1) Influence from oxides in molten steel;

[0028] (2) from the core water pipe material impact;

[0029] (3) from the heat box and other equipment on the impact of the scale;

[0030] (4) from the roll box area of the oxide effect.

[0031] Based on the above research, the present application in order to control the foreign matter of thin strip steel surface into, using the following technical means:

[0032] I, the molten steel smelting aspect:

[0033] First, the refining furnace oxygen blowing amount is preferably controlled in 15-18m 3 , so as to avoid the problem of excessive oxygen blowing in molten steel.

[0034] Second, the tundish molten steel quantity is controlled to be more than 15t, so as to avoid the problem of slagging caused by low liquid level.

[0035] Finally, this aspect also includes: control the slag of ladle, when the ladle is casting the remaining 15t, the ladle worker checks the site and closes the ladle slide in time when the slag is found.

[0036] II, the atmosphere control aspect of hot box:

[0037] The nitrogen flow and air usage of hot box are strictly controlled during production:

[0038] The nitrogen flow of hot box cannot be less than 2500m 3 / h;

[0039] The total flow of compressed air of No. 3 hot box:

[0040] When rolling 1.2mm or more specifications, the flow is less than 100m 3 / h;

[0041] When rolling 1.2mm or less specifications, the total flow is not more than 350m 3 / h.

[0042] III, the rolling oil flow aspect:

[0043] The rolling oil flow is strictly controlled during production:

[0044] The rolling oil flow is not more than 150cc / min.

[0045] This means can effectively avoid the problem of too much oil mud at the inlet and outlet of the rolling mill caused by too much rolling oil, and improve the quality of thin strip steel.

[0046] Alternatively, the control of foreign matter intrusion on the surface of thin strip steel can be optimized from the aspects of equipment body cleaning and management.

[0047] IV. Equipment body cleaning:

[0048] First, after each shutdown, the mill inlet sealing frame, anti-wrinkle rolls, and rolling mill rolls need to be inspected and cleaned.

[0049] Secondly, after each watering stop, it is necessary to check for leaks in heating boxes No. 2 and No. 3. If leaks are found, they should be handled by a fitter or the regular shift liquid handling line.

[0050] Secondly, each time the roller box is changed or maintenance is performed, the iron oxide under the No. 3 hot box roller conveyor needs to be cleaned.

[0051] V. Management aspects:

[0052] Firstly, during the production process, it is necessary to inspect the surface of the strip steel on the post-rolling roller conveyor platform, and to randomly check for foreign objects pressed into the surface and pits.

[0053] Secondly, it is necessary to conduct spot checks on the surface quality on site. If three consecutive rolls are found to have obvious foreign objects pressed in or pits, the casting process should be stopped immediately after the furnace is completed for inspection and treatment.

[0054] The above description is merely a specific embodiment of the present invention. It should be noted that those skilled in the art can make several improvements and modifications without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method of controlling the press-in of foreign matter on the surface of a thin strip, characterized by, The control method comprises the following steps: (1) Molten steel smelting control The oxygen blowing rate of the refining furnace is controlled at 15-18 m 3 ; The tundish molten steel quantity is controlled to be above 15 t; (2) Hot box atmosphere control The hot box nitrogen flow rate is controlled to be no less than 2500 m 3 / h; The total flow of the compressed air of the No. 3 hot box on the upper surface and the lower surface of the thin strip steel is controlled to be: (2.1) When rolling thin strip steel of 1.2 mm or more gauge, the total flow of compressed air is controlled to be less than 100 m 3 / h; or (2.2) When rolling thin strip of 1.2 mm and below, the total flow of compressed air is controlled to be no more than 350 m 3 / h; (3) Flow control of rolling oil The flow of the rolling oil in rolling is controlled to be: on the upper surface and the lower surface of the thin strip steel, respectively, not more than 150 cc / min.

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