RU2044782C1 - Method of making cold rolled strips in combination equipment - Google Patents

Abstract

FIELD: rolled stock production. SUBSTANCE: method comprises steps of heating strips by feeding on them streams of gaseous heat transfer agent such as nitrogen; performing heating of the gaseous nitrogen in carried outside Cowper stoves; increasing flowrate of nitrogen along a motion direction of the strip in dependance upon its thickness and temperature according to an expression, given in a description of the invention. EFFECT: enhanced efficiency of the process, increased metal yielding. 3 cl

Description

 The invention relates to ferrous metallurgy, in particular to the production of sheet metal, and improves the process of heat treatment of cold rolled strips in continuous annealing units (ANO).

A known method for the production of cold-rolled strips in modern units, selected as a prototype, including a continuous process of etching hot-rolled strips, their cold rolling, heating in a continuous annealing unit, aging, accelerated cooling, reheating to the temperature of the tuning exposure, aging, cooling, training and winding per roll [1]
The aim of the invention is to increase the productivity of the process, increase the yield of metal and reduce energy costs.

The heating of the strips in the ANO is carried out by the jet supply of a gaseous coolant, for example, nitrogen. Heating of gaseous nitrogen is carried out in remote coolers. The nitrogen flow rate in the direction of the strip increases depending on its thickness and temperature, based on the expression
VV _o + 1.358 V _o (1-e ^st)
The gaseous coolant discharged from the heating chamber is supplied to the reheating chamber and then returned to the cooler.

where V _{o the} nominal flow rate of the coolant, m ³ / h;
1.358 coefficient of proportionality;
s strip thickness, m;
t is the temperature of the strip, ^about C.

The hot-rolled strip is continuously wound from the uncoilers of the pickling unit, etched to clean the surface, cold-rolled to the required size and fed to the ANO. In the heating chamber ANO strip is heated to 750-850 ^{° C} and for 1-3 minutes exposure is carried out at this temperature. Heating the cold rolled strips is effected by jet flow at their surface a gaseous coolant such as nitrogen, with a temperature of the order of 1000-1150 ° ^C. The feed gas is carried out through a coolant nozzle mounted on the adjustment of the heating chamber, on both sides of a vertically traveling strip. The nozzles are equipped with manifolds with throttle valves, to which a gaseous heat carrier from coolers, separately standing outside the ANO, is supplied under excessive pressure. The nozzles are installed with a certain step both in the width of the strip and in the height of the heating chamber, grouped into sections, each of which is equipped with a system for regulating the supply of gaseous coolant to the surface of the strips. The control system provides sectional application of the coolant flow rate along the strip, depending on its temperature and thickness. ANO incorporates 3 coolers, two of which are usually on heating, one on blast. The heating temperature of the gaseous coolant in the coolers is 1000-1200 ^about C.

The nominal flow rate of the coolant is initially evenly distributed over the number of control sections. Moreover, in the first section of the strip, it is left unchanged. In all subsequent sections, the flow rate of the coolant is increased, depending on the temperature and thickness of the strip, by a value of VV _o + + 1.358V _o (1- ^st ).

After holding strip fed in accelerated cooling chamber, wherein a temperature of 600-650 ^{° C} is carried out controlled cooling of the gaseous coolant. Temperature from 600-650 ^C to 20-40 ^C strip is cooled in a water bath and then subjected to purification in the pickling bath and fed into a reheating chamber to 450-500 ° ^C. The heating of the strip in a reheating chamber is effected by inkjet supplying coolant gas at its surface with a temperature of the order of 850-950 ^{° C} supplied from the heating chamber. Subsequently the gaseous coolant is directed through pipelines to Cowpers for subsequent heating to 1000-1200 ° ^C. From reheating the strip is fed into the exposure chamber perestarivayuschey chamber for release of carbon and nitrogen in the ferrite at a temperature of 450-500 ^C for 3-5 min, and then carry out the final cooling to 40-60 ^about C. After that, the strip is subjected to training and wound into rolls.

 An increase in the productivity of the production process of cold-rolled strips in combined units when using this method is achieved both due to the jet supply of gaseous coolant to the surface of the strip, and due to the fact that they increase the flow rate of the coolant along the strip.

Claims (3)

1. METHOD FOR PRODUCING COLD-ROLLED BANDS IN COMBINED UNITS, including the continuous process of etching hot-rolled strips, their cold rolling, heating in a continuous annealing unit, holding, accelerated cooling, re-heating to the temperature of the tuning shutter speed, holding, cooling, tempering and tempering characterized in that the heating of the bands is carried out by jet blasting with a gaseous coolant, for example nitrogen, while the flow rate of the coolant in the direction of the strip increases depending on its thickness and temperature and is determined from the ratio
V = V _o + 1.358 V _o (1-e ^st ),
where 1.358 coefficient of proportionality;
V _{o the} nominal flow rate of the coolant, m ³ / s;
s strip thickness, m;
t is the temperature of the strip, ^o C. 2. The method according to claim 1, characterized in that the heating of the gaseous coolant is carried out in remote coolers to a temperature of 1000 to 1200 ^o C.  3. The method according to p. 1, characterized in that the gaseous coolant discharged from the continuous annealing unit is supplied for re-heating, after which it is returned to the cooler.