SU1493340A1 - Method of rolling strip stock - Google Patents

Abstract

The invention relates to rolling production and can be used in multi-pass training, for example, on two-stand mills of cold-rolled strips and tin of low-carbon steels. The aim of the invention is to improve the quality of the strips by providing uniform roughness along the length of the rolled strips. For this, rolling on double-ply mills with rollers having a roughness in the first and second lath x 2.5-3.5 and 0.13-0.5 μm, respectively, is forced by a force in the second cage greater than 2.0-5.0 times than in the first. The specific force ratio is determined depending on the roughness of the rolls and the predetermined roughness of the strip. 1 ill., 1 tab.

Description

The invention relates to rolling production and can be used in multi-pass training, for example, on two-stand mills, cold-rolled strips and tin of low-carbon steels.

The purpose of the invention is to improve the quality of the strips by providing uniform roughness along the length of the rolled strips.

At the two-stand mills, they roll in rolls with a regulated roughness of their surfaces, in the first stand 2.5-3.5 microns and in the second stand 0.13-0.5 microns, with the rolling force in the second stand greater than in the first. In this case, rolling is carried out with a rolling force in the second stand 2.0-5.0 times greater than in the first, and the ratio of the forces in the cells is determined by the dependence

Rab

-T

 b

(one)

where P,

TO

- rolling force in the first stand;

- rolling force in the second stand;

-oefI1D1ent proportionality 0.0356, 64;

Rgjj - the roughness of the rolls lane -. howling cage;

Cd is the roughness of the rolls of the second stand;

00 00 4

op

- the specified value of the strip roughness.

When the ratio of rolling forces in the second and first cage x is less than 2.0, the roughness of the strip surface is not stable, the roughness UR varies between 0.35-0.50 microns and the roughness of the strip falls outside the required range of 16-0.63 microns . An increase in the ratio of more than 5.0 leads to excessive hardening of the trained bands. With this ratio of forces in the second cage can reach the permissible values of loads on the training cage. Such a distribution of rolling forces over the cages is necessary because when using grooved rolls with a roughness of 2.5-3.5 µm in the first stand, the strip leaves the first stand with a roughness of Rg 1.5-3.3 µm, and for smoothing the peaks microprotrusions it is necessary to ensure plastic deformation of the surface metal layers in the second stand, i.e. create effort training 1.5-7.5 MN / m strip width. The studies performed allowed us to obtain an empirical relationship between the rolling forces in the first and second cells from the conditions of obtaining the same roughness of the rolled strips during the rolling of individual coils.

The coefficient of proportionality K was obtained experimentally and its value depends on the value of the ratio of a given roughness of the finished strip Cd and the roughness of the rolls of the second stand Rgt. The range of possible changes in the K coefficient is established from the following. The ratio varies from 2.0 to 5.0. The specified surface roughness values of the finished bands are Rg 0.16-0.62 μm. The surface roughness of the rolls used in the second stand, based on the experience of the factories, pierce 1 x tin, Rjjj, 0.13-0.50 microns. The maximum ratio Pj / P 5.0 ensures the production of tin with a roughness of Rgn of 0.16 μm with a maximum roughness of the rolls in the first stand of Rpiij 3.5 μm and a minimum ratio of Ran / Robi, Kdb 0.13 μm. Substituting these values into formula (1) was given to them

Зх5

1 + V OiJ3 OJ6- 1

0.13

-g - 1

where K 0.035

To obtain tin with a roughness of Rg 0.63 µm, using rolls with a roughness of Rgj, 3.5 µm in the first stand, the minimum ratio, 2.0, can be achieved with a maximum ratio of 0.63 / 0.13 3.85. Substituting these values in formula (1) we get

2.0 1 -f

3.5

TO

oh tz

whence K 0.64.

Limits of proportionality change

0.035 K 0.64.

0

five

0

0

The drawing shows the nature of the change in the coefficient K, depending on the ratio of the roughness of the prepared-. ROY strips and rolls of the second cage.

Example. The proposed method was tested on a two-station training mill 1400. Trained stripes with a thickness of 0.20 mm, width 850 mm from steel grade 08КП. In the first stand of the mill, rolls with unbroken fractions of a fraction less than 0.3 mm with a roughness of 3.5 µm were used. Effort in the first stand P 3,5 MN. The use of large efforts leads to overheating of the work rolls of the mill. In the second stand, rolls with different roughness were installed (table), for example, with a roughness Rgj, 0.35 μm (table example 2). To determine the ratio of rolling forces in the second t and first cage, first calculate the value Ra ,, / Rabi 0.5 / 0.35 1.43 (table example 2). For a mill of 1400, the ratio of the proportionality coefficient K to the ratio has the form shown in the drawing in accordance with schedule K 0.070. In accordance with formula (1), the magnitude of the rolling force in the second stand is calculated:

, (UK

Rab, / Rab, - 1 Kai / Rabo

), 5 (1 + 0.07

 .

. 0.35

Calculated force Pj 8,6

PL is installed in the second stand and blown.

The results of the experimental rolling are presented in the table.

A comparison of the proposed method with a known roll according to each of them is 320 tons of metal in the same way as the assortment. In both cases, the initial roll roughness in the first stand was Rg |, 3.5 µm, in the second stand R 0.35 µm. After rolling every 20-30 tons of metal, the roughness of the R-surface of the rolls and the strip was measured. According to the method, after measuring the roughness of the rolls and the strip, formula (1) was calculated and the training force was set in the second stand with a constant force in the first stand (TV 3 , 5 MN). When implementing the proposed method, the surface roughness of the strips varied within Nd = 0.48-0.60 µm. When using a known method in the process of rolling 320 tons of metal, the roughness of the surface of the strips was R 0.53-0.75 µm. When implementing the proposed method, the absolute change in strip roughness was Lg c 0.12 μm, and in the known method uR, i, y 0.22 μm. Thus, when using the proposed method, the amount of surface roughness of the strip is stabilized.

Technical and economic advantages of the proposed method are

14933406

increased yield of strips by increasing the roughness uniformity. In addition, the duration of the dressing mill without transshipments is increased, the roll consumption is reduced.

ten

 .

15

20

Claims (2)

1. A method of rolling the strips predominantly on two stand mills, including rolling in rolls with a rough surface in the first stand and in the second stand, characterized in that, in order to improve the quality of the strips by ensuring uniform roughness along the length of the rolled strips, the rolling is carried out by force in the second cages, 2.05, 0 times more than the first. 2. A method according to claim 1, characterized in that the ratio of the rolling forces is determined by the dependence 25  ab Pr P 1 + to ab RO. 7b R cage effort rolling in first i rolling in the WTO- 0 five Rab R "n swarms of cage,%; coefficient depending on the OS t of the noBi-rlchos roughness; her strip and aalcon second stand; roughness of the surface of the first cage, microns; Isrohovatos; be surface eal. s second cage, microns; ead) (for the amount of roughness of the noHepxifocTH strip, µm. 3.5 3.5 3.5 2.0 3.5 3.5 3.5 3.3 3.5 3.5 2.5 2.5 3.5 3.5 0.50 0.13 0.35 0.32 0.35 0.5 3.13 3.5 2.5 0.35 7.0 17.5 8.6 4.2 7.0 6.0 18.0 0.05 0.03 0.04 0.04 0.04 0.07 0.03 7.0 0.07 Rolling instability, increase in cowliness and raenotol (stripes rolling in accordance with the known method