SU997888A1 - Method of cooling hot rolled stock - Google Patents

Description

(54) COOLING METHOD FOR HOT ROLLED ROLL

The invention relates to rolling production, improves the process of cooling the strips during rolling on broadband mills and can be used both for interstand cooling of the strips in the finishing group of stands, and for cooling them on the diverter rolls before winding into coils.

The rolling speed on modern broadband mills reaches 3035 m / s. Therefore, the necessary temperature range for the end of the rolling and winding of the strips must be ensured.

The temperature of the end of the rolling and coiling polrs thicker. 4.0 mm at operating mills are usually higher than optimal. You can achieve the required coiling temperature by increasing the roller table or by perfecting forced cooling.

A water-air cooling method is known, according to which a metal is cooled by water that is crushed to a fine state by compressed air flows.

However, this method has a relatively low cooling efficiency, especially when cooling

sheet metal rolled at high speeds.

The closest to the invention according to the technical essence is a method of cooling hot rolled products, which involves injecting a liquid jet into the low-pressure air jet on the cooled surface.

The injection is carried out in such a way that the particles of the liquid are distributed, throughout the entire volume of the gas jet, to form a mist in it, which is ejected onto the cooled metal Cll.

The disadvantage of this method is the relatively low cooling efficiency.

The aim of the invention is to increase the cooling efficiency.

This goal is achieved by

20 that, according to the method of cooling hot rolled steel, which includes injecting a cooled liquid into the low-pressure air surface into a low-pressure air jet, it is additionally measured

25, the rolling speed and the air supply are carried out in pulses whose frequency changes in direct proportion to the change in the rolling speed.

Claims (1)

The method is carried out as follows. In the process of supplying the cooling mixture to the hot strip, a vapor layer is formed which impedes heat exchange. The supply of air by impulses more intensively destroys the vapor layer, as the coolant strikes the vapor-water boundary layer, and the greater the amount of metal cooled per unit of time passes before the device that implements the method, the more intense the impulses of air are needed. . Figure 1 shows a device for implementing the method, a general view; figure 2 - the same. Cross section The device contains a speed meter 1, an analog-frequency converter 2, a frequency-pulse mechanism 3, a collector 4 for supplying water 4, with two rows of Siphon tubes 5, collectors 6 for supplying air with tapering nozzles 7. The device operates as follows. The speed meter 1 determines the rolling speed of the strip 8. The voltage obtained in analogue form at the output of the speed meter 1 is converted by the analog frequency converter 2 into a frequency proportional to the speed of the strip. The purpose of the frequency-pulse converter 9 is to receive the signal in a pulse form with the number of pulses proportional to the frequency applied to the input. Thus, at the output of converter 9 there are pulsed signals, the frequency of which is proportional to the speed of movement of the strip 8. Signals amplified by amplifier 10 are fed to the input of actuator 3, which controls the flow of air into the collector 6. Water is fed to the collector 4. After filling collector 4, it flows out of siphon tubes 5. Water jets flowing out of siphon tubes 5 fall under compressed air jets delivered in pulses. A water-air mixture is hit by a vapor interlayer formed as a result of water cooling. The more speed. The rolling speed, the more frequent the shock, the more intense the heat exchange. An example. End temperature rolling a strip of 6.0 x 1800 of steel Vzsp.nach 2500 MMK when rolling with a speed of 7.5 m / s is 980 °. This satisfies the conditions of providing properties and the category of GOST 380-71, but does not satisfy the conditions of providing properties of a higher quality llj category of GOST 380-71. To ensure a high level of mechanical properties of low carbon steel, the end of rolling temperature in the finishing group should be 850920 ° C. When testing the method, the rolling speed of the 6.0x1800 strip from WZsp steel is changed from 6.0 to 8.0 m / s. The frequency of the air supply pulses is then changed from 24 to 32 Hz. The temperature of the rolling end is 89 ° -910 ° C. The advantage of the proposed method is to increase the intensity of the cooling of the strips, which makes it possible to increase the rolling speed of the mechanical properties of the rolled stock or lower the temperature of the end of the rolling to a level that provides an increase in physical and mechanical properties. Improving the temperature conditions of rolling strips with a thickness greater than b, 0 mm with the production of such steel at the mill 2500 MMK 200,000 tons per year will provide an economic effect in the amount of 200000x2.16 432000 rubles. Claims The method of cooling rolled hot rolled products, which injects a jet onto a cooled surface. A liquid into a low-pressure air jet, characterized in that, in order to increase cooling efficiency, the rolling speed is additionally measured, and air is supplied in pulses whose frequency changes directly proportional to the change in rolling speed. Sources of information taken into account in the examination 1. French Patent 2444514,. cl. And 21 In 45/02, published. 1980