SU1330193A1 - Method of annealing coils in cupola furnace - Google Patents

Abstract

The invention relates to a metallurgical heat engineering and can be used in the process of annealing coils in bell-type furnaces equipped with a heating cap with burners. The purpose of the invention is to reduce the annealing time of the coils. The goal is achieved by the fact that in the method of annealing coils in a bell-type furnace with burner catfish on a removable cap in the area of the lower roll of the foot, including the formation of a roll foot, setting the muffle and heating cap, heating to the annealing temperature, holding, turning off the burners the cap, the cooling of the foot under the muffle, the burners are turned off no less than 2-4 hours before the end of exposure, and the heating cap is removed during the cooling period when the set temperature reaches 580- 550 C. 2 sludge. S (L oo oo with

Description

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The invention relates to metallurgical heat engineering and can be used in the process of annealing coils in bell-type furnaces equipped with heating caps with burners.

The purpose of the invention is to reduce the annealing time of the coils. Shortening the annealing time is ensured by shutting down the gas-burning devices 2-4 hours before the end of the exposure. In this case, the heating cap is removed during the cooling period at an upper roll temperature of 580-550 ° C. The burner of the lower roll to 690–710 ° C occurs due to the emission of burning burner. A reduction in the total processing time of the kiln in the furnace will provide an increase in the yield of the metal of the highest group of stretching and surface finishing of the strips.

Figure 1 presents the modes of the outgoing rolls of rolls weighing 75-76. t using a known method. figure 2 - the same, using the proposed method.

The proposed method of annealing coils in a bell-type furnace is carried out as follows.

At the stand, a stack of 3 to 4 rolls is formed, covered with a muffle, a circulation fan is turned on and a heating cap is installed. The rolls are heated to an annealing temperature and appropriate exposure is carried out. Moreover, the heating cap is extinguished not less than 2-4 hours before the end of the hold-up and the coil stack is cooled under the muffle and charging cap up to 580-550 C. After reaching the temperature of 580-550 С in the muffle space, the cap is removed and the coil stack is cooled under the muffle to the unpacking temperature, for example, 120-.

The productivity of the annealing process and, consequently, the reduction of energy costs increase as a result of reducing the holding time at annealing temperatures by no less than 2-4 hours. In turn, reducing the holding time and subsequent cooling of the rolls under the heating cap will reduce the residence time of the upper coil at annealing temperatures, but the residence time is lower

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His roll at this temperature does not change. The duration of the holding of the lower roll practically corresponds in this case to the duration of holding the upper roll. Moreover, the duration of exposure of the lower roll of the foot corresponds to the duration of its exposure when using a known method. This is due to the fact that when the burners are turned off, the laying of the heating cap continues to radiate heat to the muffle for a certain time, since in the area of the burner chamber, i.e. at the level of the lower roll of the foot, it is 100-120 ° C higher than the temperature of the muffle. In addition, the presence of a heating cap prevents the transfer of heat from the muffle to the surrounding space. As shown by the data presented in Figures 1 and 2, the use of the proposed method makes it possible to shorten the exposure time (heating period) by 6 hours, while after switching off the burners of the hood, the bottom roll temperature is in the optimal range of 700 and 4 hours. only then does it begin to decline. Compliance with the same residence time of the coils of the foot at recrystallization temperatures leads to an increase in the yield of the metal of the higher stretch groups. A reduction in the holding time of the upper coil metal at the annealing and Bbmie temperatures, as well as a decrease in the cooling rate at the initial moment, for example, in the first 5–20 min, contributes to sticking and welding the coils of the coils. Accordingly, this leads to a decrease in the kinks on the surface of the annealed strips, i.e. leads to an increase in the yield of bands of higher surface finishing groups. In addition, cooling the foot of coils to 580–550 ° C makes it possible to completely separate carbon and nitrogen from ferrite, i.e., to improve the properties of the annealed metal. The temperature of 580-550 ° C, to which the stack of coils under the heating hood is cooled, was written experimentally, based on the conditions for excluding the possibility of reducing the number of operating hours of the heating cap. When the heating cap is removed at these temperatures, the cooling rate of the foot of the coils does not exceed 40 deg / h. As shown by experimental data dItel. 3 1

The cooling of the rolls under the heating cap up to 580-550 ° C is 3-4 hours, i.e. the heating cap is again ready to work 1-2 hours earlier than when the rolls are annealed by a known method.

The use of the proposed method allows an increase in the yield of the sheet of the category of a very particularly complex drawing (WOSW).

Claims (1)

Invention Formula The method of annealing coils in a bell-type furnace with burner-type catfish for removal is #. .In 0 934 a cap in the area of the lower roll of the foot, including the formation of rolls, installation of the muffle and heating cap, heating to the annealing temperature, removal of the burners and removal of the cap, cooling of the foot under the muffle, characterized in that reduce the time of annealing the coils, turn off the burners at least 2-4 hours before the end of the exposure, and remove the heating cap during the cooling period when the setting temperature reaches 580, TSIZ fO 8 90 9S t T, H Compiled by V. Smirnov Editor I. Segl nik Tehred. Khodanych Proofreader H. Mycjca Order 3543/29 Circulation 549Subscribe VNIIPI USSR State Committee for inventions and discoveries 113035, Moscow, Zh-35, Raushsk nab., 4/5 Production and printing company, Uzhgorod, st. Project, 4