SU1227927A1 - Method of cooling steel rolls upon annealing - Google Patents

Description

one

The invention relates to ferrous metallurgy, in particular to the production of cold-rolled steel., And improves the process of cooling the coils after they are annealed in bell-type furnaces.

The aim of the invention is to increase the productivity of the cooling process and the stability of the mechanical properties of the annealed steel.

Fig. 1 shows a device for implementing the proposed method, a general view; in fig. 2 and 3 - cooling curves of the coils with the use of the known and proposed

ways.

A device for implementing the method includes a stand 1 with a central opening 2, a cap 3 with a fan 4, convector rings 5 and conical rings 6 with a central opening 8 placed between the rolls 7.

The method of cooling steel coils is carried out as follows.

On the.-Stand 1, a foot annealed in a bell-type furnace is formed, for example, from 3 rolls 7. Moreover, after installing the lower roll on ei o, the upper end of the convector ring 5 with the central hole m 8. Then install the middle roll, and on it the upper end of the convector ring 6 is placed, the central hole of which is blocked with the help of the plug 9, then the upper roll 7 is installed, the cap 3 with fan A. Simultaneously turn on the vacuum pumps (not shown) and fan 4. When the fan is working .4 main flow air under excess pressure enters the inner cavity of the upper roll 7 and moves along the lower end through the channels of the convector ring 6 from the inner turns to the outer ones into the annular gap between the cap 3 and the foot of the rolls. 3 further, the air from the annular gap, as well as the air entering through the NCD of the cap 3 under the action of the vacuum generated by the exhauster from the channels of the convector rings 5 and 6, removing heat from the rolls, enters 30 the internal cavity of the foot and further through the central opening 2 into the forest. After cooling the rolls of the foot, for example, up to 40-50 C, the fan 4 and the exhauster are disconnected, the cap 3 is removed and the rolls 7 are fed for dressing.

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The performance of the cooling process using the proposed method is achieved due to the fact that the volume of circulating

5, the air along the ends of the lagging along the cooling of the upper coil (as a result of the central hole’s hemming) increases 4-4.5 times, respectively, the speed increases.

10 movement and heat transfer coefficient. Closing the central hole reduces the resistance at the air outlet of the channels of the convector rings into the internal cavity, in

As a result, the air flow rate, which circulates through cone-rings, under the action of vacuum is increased. In addition, by changing the pattern of air movement along

20 ends of the upper roll, i.e. because the central hole in the convector ring under the upper roll (air moves from the inner turns to the outer one) is silenced, the cooling rate of the upper roll increases. The amount of heat taken by the air from the rolls is equal to

q)

30 where about - the heat transfer coefficient,

kcal / m "hail; t, tj, - respectively, temperature

metal and air, C. When cooling the foot coils under

With a muffle, protective gas circulates through the channels of the convector rings from the outer turns to the inner ones. As the gas moves from the periphery to the center, its temperature rises, i.e. the temperature difference between the metal and the gas decreases, the amount of heat drawn from the coils decreases, as a result of which, when cooled, the maximum temperature of the metal shifts to the inner turns. Therefore, the circulation of air with a minimum temperature from internal to external coils allows to intensify the process of cooling the upper roll of the foot, since in this area the temperature difference between the metal and the gas is greater.

These two factors lead to the fact that the cooling rate of the upper coil is at the same level with

55 cooling rate of the lower roll of the foot, i.e. The productivity of the coil foot cooling process as a whole increases.

40

45

3 .1

In turn, the increase in the uniformity of cooling leads to identical rates of carbon and nitrogen in the metal along the entire length (height) of the charge, i.e. leads to a increase in the stability of the properties of the annealed metal.

Similarly, the proposed method is carried out with cooling in the foot, for example, 4 rolls. In this case, convector rings with a closed central opening are installed under the top and above the bottom rolls.

In order to test the proposed method for cooling steel coils in industrial environments, a metal cork of 08KP with a total weight of 75 tons with strip parameters of 0.5-1210 mm was formed on a stand from unpacked after annealing of a vkolpak furnace of metal with thermocouples in coils. Between the lower and middle rolls of the foot is installed.

From the obtained data it follows that the use of the proposed method allows to increase the volume of air circulating along the ends of the upper coil, as compared with the known one, almost 4.5 times. The increase in air consumption, as well as the change in the circulation pattern along the ends of the upper coil according to the cooling curves shown in FIGS. 2 and 3, led to an increase in the cooling rate from 1.0 to 1.4 degrees / h, the cooling duration was reduced by an average of 24 h, i.e. the productivity of the process of cooling the foot of the rolls increased by an average of 25%,

At the same time, the cooling rate of the upper and lower coils of the foot is almost at the same level and amounts to 1.4 and 1.5 degrees / hour.

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Twisted double-sided convector ring with radial circulation channels and a central bore. Between the middle and upper coils, a two-way convector ring was installed with a closed central hole in the disk body, to which the supporting ribs, forming the circulation channels, were welded. Then, an accelerated cooling hood was installed on the foot with an axial fan in its upper part, with a capacity of 4 kW and a design capacity of 16-18 thousand m / h. Smoke exhausters turned on, axial fan

15 and the foot of thermocouples laid in rolls cooled to 50 C.

Table 1 shows the results of .aerodynamic studies on the flow of air circulating

along each roll of the foot, using known and proposed cooling methods.

Table 1

28.0

6.5 23.0 13.5 49.0

Table 2 presents the results of mechanical testing of annealed and cooled strips using known and proposed methods.

table 2

Mechanical properties of metal, S kg / mm

50

55

Notes e.The numerator is the mechanical properties of the metal tested after training; the denominator is the same, 14 days after the training.

The data obtained indicate that the equalization of the cooling rates of the lower and upper coils

Editor T.Porpenova

Compiled by G.Nazarova Tehred M, Ho Danich

Order 2795 Circulation 561 o

VNIIPI USSR State Committee

for inventions and discoveries 113035, Moscow, Zh-35, Raushsk nab., 4/5

Production and printing company, Uzhgorod, st. Project, 4

foot in the area of forced cooling contributes to the stability of mechanical properties

5 ozhozhenny bands in time

The technical advantage of the proposed method in comparison with the known method is an increase in the intensity of the heat transfer process by convection from the metal to the air.

Proofreader M.Sharoshi

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Claims (1)

METHOD FOR COOLING BALES OF STEEL AFTER ANNEALING, including placing rolls in the stack on the stand, installing convector rings with a central hole between them, covering the stack with a hood with a fan and organizing air circulation under the hood, characterized in that, in order to increase the performance of the cooling process and stability mechanical properties of annealed steel, air circulation under the hood is organized by overlapping the central holes of the upper and alternating through one convector ring. 1227927 A1