RU2297294C2 - Etched steel strip coiling method - Google Patents

Abstract

FIELD: rolled stock production, namely manufacture of hot rolled etched strip steel.

SUBSTANCE: method is used for coiling strip, mainly with width more than 1.0 m at increased diameter of coil while applying to strip preset tension value. At coiling steel with σ_B ≤ 400 N/mm² tension value is set proportional to surface area of cross section of strip according to formula T = 75(h/2)^0,34 + 10(B -1.05),kN where h - strip thickness, mm, B - strip width, m. At coiling strips strip with σ_B > 400 N/mm² tension value is set according to formula T¹ = (1.02 - 1.05)T.

EFFECT: improved efficiency of cold rolling mills, enhanced consumer' properties of cold rolled sheet steel due to improved quality of hot rolled blank.

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Description

The invention relates to rolling production and can be used in the production of hot-rolled pickled roll strip.

This strip is most often used as a blank for subsequent cold rolling and is obtained after etching in solutions of sulfuric or hydrochloric acids. Winding the pickled strip into a roll is the final operation of the production of hot rolled steel, regardless of its subsequent redistribution. The technology of pickling hot rolled strips is described in sufficient detail, for example, in the book of VB Bakhtinov “Rolling production”. - M.: Metallurgy, 1987, p.337-339.

To form an etched strip roll on continuous etching units (NTA), rolling machines or drum coilers are used. The latter ensure the constancy of the inner diameter of the coil (this is especially important when using coils in subsequent stages, for example, in cold rolling mills) and a sufficiently tight winding, which reduces the mutual slippage of individual turns in the coil, thereby preventing injury to the surface of strip steel.

There is a method of winding a metal strip into a roll, in which the radius of curvature of the reeling strip changes during winding using special forming rollers, which improves the quality of winding (see Japanese Pat. Pat. N 3524, class B65H, publ. 31.01.72) . The disadvantage of this method is the need for additional equipment with a complex electrical circuit for its control, as well as the uncertainty of the magnitude of the tension when winding strips of different sizes, which can lead to loose winding of the roll with negative consequences.

The closest analogue to the claimed object is a method of winding into a strip of strip steel, described in A.S. USSR N 332883 class. B21C, publ. 10/02/72 g.

This method of winding with an increase in the diameter of the roll and with the application of tension to the strip is characterized in that the winding of the first five turns on the drum of the winder is carried out with a tension exceeding the technological by 2 ... 2.5 times, followed by a gradual decrease in the tension to technological by 50 ... 100 revolutions of the reel drum.

The disadvantage of this winding technology is also the uncertainty of the tension depending on the size of the strip, which causes the above consequences.

The technical task of the invention is to increase the productivity of cold rolling mills and improve the consumer properties of cold rolled sheet steel by improving the quality of the hot rolled billet.

To solve this problem, in the method of winding an etched steel strip into a roll, mainly more than one meter wide, with an increase in the diameter of the coil and applying a predetermined value to the strip, when winding steel with a temporary resistance σ _of ≤400 N / mm ² , the tension value is assumed proportional the cross-sectional area of the strip and equal to:

where h is the thickness of the strip, mm, B is its width, m, and for strips σ _in > 400 N / mm ^{2 the} tension is taken equal to T ¹ = (1,02 ... 1,05) T.

The given mathematical dependence is obtained in the processing of experimental data and is empirical.

The essence of the claimed technical solution lies in differentiating the magnitude of the tension of the reeled strip depending on its thickness and width, as well as on the magnitude of the temporary resistance of strip steel, and this value increases with the growth of these strip parameters. The change in the magnitude of the tension is carried out by the winder drive and is controlled by the magnitude of the current load of the motor of this drive.

Experimental verification of the proposed method was carried out at the NTA sheet rolling shop No. 5 of OJSC "Magnitogorsk Iron and Steel Works", supplying a rolled roll for the cold rolling mill 2500 of the same workshop.

For this purpose, when winding hot-rolled etched strips with a thickness of h = 2 ... 6 mm and a width of B = 1.0 ... 2.05 m with σ _at ≤450 N / mm ² , the tension was varied from 50 to 150 kN. The results of the experiments were evaluated by the hourly productivity of the mill 2500 and the yield of cold-rolled sheet. The highest productivity with a yield of up to 99.8% was achieved using the proposed winding technology, when the tension values corresponded to the T values determined by the above dependence. Deviations from the optimal values of T in any direction worsened the performance of the mill 2500.

For example, a decrease in the magnitude of the tension to (0.75 ... 0.98) T led to the appearance on the tackle for cold rolling of scratches and scratches, which were also observed on cold-rolled sheets. In some cases, at low tensions during the winding process, the resulting rolls had telescopicity (i.e., the exit of the strip turns from the end face of the roll) in excess of the permissible values.

An increase in tension to (1.02 ... 1.25) T caused (especially for h> 4 mm) the appearance of transverse shear lines ("Luders lines") on the metal on the inner turns of the rolls, which is a consequence of the large longitudinal forces combined with bending of strips when forming a roll.

When winding strips with σ _in > 400 N / mm ² with a tension of T ¹ = T, the yield decreased to 97.6% due to a decrease in the density of the winding. The control winding using known technology, taken as the closest analogue, gave a yield of not more than 98.0%, and the productivity of the mill 2500 when rolling such a rolled billet decreased by an average of 7%.

Thus, an experimental verification confirmed the acceptability of the technical solution found to achieve the goal and its advantages over a known object.

According to the Central Control Laboratory of OJSC MMK, the use of the invention in the production of sheet metal will increase the productivity of cold rolling mills by at least 10% with an increase in yield of approximately 99.7%.

Case Studies

1. The hot rolled pickled strip with h = 3,0 mm and B = 1.45 m from the steel σ _in = 350 N / mm ² is wound into a roll on the NTA.

The required amount of tension when winding:

2. A strip of the same dimensions, but σ _in = 420 N / mm ^{2 is} wound with tension:

T ¹ = 1,035 × T = 1,035 × 90 = 93 kN.

Claims (1)

The method of winding into a coil an etched steel strip, mainly with a width of more than 1.0 m, with an increase in the diameter of the coil and with the application of a predetermined amount to the tension strip, characterized in that when winding steel with a temporary resistance σ _of ≤400 N / mm ² , the tension value is proportional to the cross-sectional area of the strip and equal to:

where h is the strip thickness, mm, B is its width, m, and for strips with σ _in > 400 N / mm ^{2 the} tension is taken equal to T ¹ = (1.02 ... 1.05) T.