SU1551494A1 - Method of preparing semi-finished rolled products for producing cold-rolled strips - Google Patents

Abstract

The invention relates to rolling production, in particular to the rolling of a strip metal having welded seams. The purpose of the invention is to reduce the longitudinal thickness variation of the strips and increase the reliability of the welded joint by reducing the breaks during subsequent rolling. In order to increase the productivity of cold rolling mills, hot rolled coils are enlarged by welding the ends of individual strips butt. Before subsequent cold rolling, the burr is removed from the weld. By the described method the strip thickness at the site of the weld is established depending on the ratio of hardness of the weld and the welded strips as well as the thickness of the welded bands and is determined by the formula H _CHF = M {[(1,6HRB _CHF) / (HRB ₁ + HRB ₂ )] + 0.2} [(H ₁ + H ₂ ) / 2], where H ₁ , H ₂ - thickness of the welded strips, mm

_Swiss HRB, HRB _1, HRB ₂ - respectively, the hardness and hardness of the welded seam strips

M is an empirical coefficient of 0.09 - 1.1. By reducing the gusting strips, a simple mill is reduced. 2 tab.

Description

The invention relates to the field of rolling production, in particular to the rolling of strip metal having welded seams.

The aim of the invention is to reduce the longitudinal thickness variation of the strips and increase the reliability of the welded joint by reducing the breaks during the subsequent rolling.

The essence of the invention is that the preparation of a steel strip for the production of cold-rolled strips is accomplished by butt-welding of the ends of individual hot-rolled strips followed by the removal of bur from the welded joints, and the thickness of the strip in the spot of the weld during deburring is set in accordance with the equation

h -JoUilS y, + b

(one)

: M5ag + n mh «ibal

, + HRB2 J

where h, h2 is the thickness of the welded strips, mm;

HRBue,

HRB ,,

HRB is respectively the hardness of the seam and the hardness of the welded polo c;

m is an empirical coefficient, equal to 0.9-1.1.

According to the described method, the thickness of the strip at the weld site is set in accordance with the ratio of weld hardness and hardness of the welded strips, as well as in accordance with the thickness of the welded strips. The thickness of the strip at the weld seam after the deburring may be less, greater and equal to the thickness welded strips.

In order to determine the mathematical relationship (dependence (1), an experimental study was conducted on a laboratory mill-200. The samples with weld sections were rolled over. The thickness of the welded strips and the weld seam, as well as the hardness of the weld strips and the weld seam was varied | within practical limits: thickness of strips 1.0-3.0 mm, hardness of strips 40-60 HRB, thickness of a weld 0.7-4.2 mm, hardness of a weld 30 - 80 HRB Rolling speed was 2 m / The rolling was carried out without tension. the end of the sample (& УЫ6 / У) using a tachometer roller installed at the outlet of the deformation zone. The studies were carried out on samples of steel and copper, which allowed us to simulate all possible combinations of the ratio of hardness of the weld and the bands to be joined. The results of the studies were statistically processed and presented in Table 1 in the form of generalized characteristic h + h2

...

seam and strip hardness

2HRB HRB7 + HRBi

Such ratios of the specified parameters were selected as the optimum, which ensured rolling at a constant speed

strip thickness tick

and ratios

output (), i.e. without jerking tension.

For ease of use, the field of the obtained experimental results, which determine the dependence

, - 2HRBjjjjj

n & iVHRB7 + HRB

h (.,

and allowing to stabilize the kinematics of the cold rolling process

5 0 5

0

five

0

five

0

five

with seams, an analytical description of the field was obtained in the form of an equation - (1)

h Y (ibNK: Vsh§ + o 2Hh iM «-NI3 2 -I

Coefficient range

m (0.9i: m 1, 1) takes into account the set of values that can take hectares with the given other parameters.

If, 9, i.e. below the lower limit of the experimental field, a tension jerk will occur, leading to an increase in the thickness and probability of strip breakage.

If, 1, i.e. above the upper boundary of the experimental field, the rolling process is disturbed by the conditions of strip capture in the deformation zone.

Since the field constructed from the experimental points corresponds to the optimal values of BL, B, the coefficients of equation (1) describing this field are optimal.

The described method can be pea-; It is as follows.

Before rolling on the mill, the thickness of the bands to be welded (or statistics on the thickness of the bands to be welded) is determined by X-ray thickness gauge, the hardness of the joined bands and the weld is determined using a coercimeter (or the statistical data obtained under laboratory conditions) are then used. formula (1), the required thickness of the weld for this class of size is calculated and, using a welder, after welding, the thickness of the weld is determined to be equal to the calculated one. Thereafter, rolling begins on the tan.

For example, on the 1400 six-mill mill it is necessary to roll an enlarged hot-rolled coil of 2.0 mm thick steel from 08 lp. It is statistically established that, for a given size, the thickness of the front end of the hot rolled p / lon is 1.8 mm and that of the rear end is 2.2 mm, while their hardness is respectively 58 and 52 units. HRB.

The average hardness of the seams is 69 units. HRB. Before rolling on the mill (to carry out a continuous rolling process), the end of the previous and the beginning of the next hot rolled coils are welded. Therefore, when welding strips, the weld thickness will be according to equation (1)

h "e-1

to

S && 0.

J.4

. On an industrial mill 1400, experienced rolling of tin 0.22 mm thick from a 2.2 mm rolled strip was carried out, at which the weld thickness was set using the described method (with

and

average values of PA (L, beyond

mi method and in a known way. Hot-rolled strips having ht-2.0 mm were used for research; 4 mm; HRB (56 units; W -50 units; HRBlue 70 units. In each variant rolled 20 welds. The results of these studies are shown in Table 2,

Data analysis table. 2 shows that the use of the described method provides a reduction in the longitudinal thickness variation of the strips and an increase in the reliability of the welded joint by reducing the breaks during rolling.

To implement this method does not require additional capital expenditures.

The use of the invention will increase the productivity of cold rolling mills by reducing downtime by reducing pores.

oh x

15514946

BOB strips and improve quality by reducing their longitudinal thickness.

mm

Claims (1)

Invention Formula The method of preparation of the steel strip for the production of cold-rolled strips, including butt-welding of the ends of hot-rolled strips and deburring, is characterized in that, in order to reduce the longitudinal thickness variation of the strips and increase the reliability of the welded joint by reducing the breaks during subsequent rolling, place of the weld after removal of the bur is set in accordance with the expression ive where h  h, - thickness of the welded STRIP, MMJ UI6 HRB HRB,, HRBa , 9-1.1, respectively, the hardness of the seam and the welded strips; empirical coefficient. Table 1 2.77 3.04 3.10 1.67 Table 2 clone described way Average values by the described method Maximum deviation by the described method Slipping when the seam rolls seize By a known method