SU1435332A1 - Method of rolling strips - Google Patents

Abstract

The invention relates to rolling production and can be used in the production of strips on continuous strip mills. The purpose of the invention is to increase the service life of the rolls by reducing the wear of the active formation in each successive stand as a result of compensating for the wear in the previous stand. By turning the rolls, as they wear out at a regulated current angle, the original rectangular shape of the roll gap is restored, thereby increasing the service life of the rolls during one campaign. 2 tab., 8 Il.

Description

O9

ate

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The invention relates to rolling production and can be used in the production of strips on continuous strip mills,

The purpose of the invention is to increase the service life of the rolls by reducing the wear of the active generatrix in each subsequent stand as a result of compensation for wear in the previous stand.

Figure 1 shows the roll system, end view; Fig. 2 shows the same, the zid at the top and the initial angle of the rolls crossing; on fig.Z - profiled work roll; figure 4 is a barrel of the work roll, end view; on fig.Z - worn work roll, the location of the most worn sections; Fig. 6 is a diagram of a one-sided skew of the axes of the work rolls relative to the initial angle of their intersection; FIGS. 7 and 8 show possible concave profiling of the work rolls (possible laws of active forming the profile of the work roll).

The rolling method includes deformation in the rolls with the initial concave profile, the axes of which are crossed one relative to the other in the horizontal plane, determining the location of the greatest peripheral wear of the work rolls, as well as changing the angle of their crossing during the process.

The initial angle of crossing of the rolls is established, based on the provision of a rectangular shape of the roll gap, according to

with (., g, .2 arctg

2 () (

If

and the change of this angle in each stand along the process leads to the development of the value of the near-edge wear of the work rolls in the most worn sections, which are determined empirically according to the expression

.

Rtek (RICE Dten)

6

where Cj is the concavity of the original profile of the work rolls of the i-th stand, mm; the size of the inter-roll gap in the 1st stand to obtain the required mass band, mm; work roll diameter in the middle of the barrel length, mm |

h. DM d linear expansion coefficient

0 5

IN ARIS:

Rhenium material rolls, mm / C;

the mass-average temperature of the barrel of the work rolls of the i-th stand, C;

the distance between the most worn sections of the work rolls, mm;

D ,,, v. the initial diameter of the work rolls of the i-th stand in the places of their greatest near-edge wear, mm;

the current diameter of the work rolls of the i-th stand in the places of their greatest near-edge wear, mm;

Lr is the length of the roll barrel, mm. The calculation of the initial roll angle of the rolls, which provides a rectangular shape of the roll gap, is made as follows: W

5 d

tech;

 very little, then you can

but write

() (2.Kts + a) + (2d), ()

where b is the value of the roll gap

on the edge of the barrel, mm; a - the value of the roll gap in the center of the barrel, mm;

1 .tgci, cx / 2.

(2)

(Fig, 2).

Substituting (2) in (1), express the initial angle of the rolls crossing

. About and

out

v.cx

 C (2 - RP + bf - (2 Ra + aJ 2 arctg -1- -i-l-a-l,

s (3) By making a series of transformations of the radical expression, one obtains

2 (2-R6 + b) - () 2 (4 R + A-Rgbi-: (4Rц + 4Rц.a + a),

Since (Fig, 3), the final expression of the radical.

 Cts (8.C-4-b-4-a) + (2-C + b)

From the condition of the rectangular form, the roll gap is taken, then

R (8-C + 4 -b-4-a) + (2.C + b) -4-b -a aa. (- -. Tz 4 (C - -C-a-a / 4 + 2x

(2- C + a) +8 C-Ru X with RL,).

3 Formula (3) now takes the form

 arctg

(four)

2y (C + f) + C-DU,

f

H

Taking into account the thermal expansion of the rolls, the formula for determining the initial angle of the rolls' recalculation takes the final form

 .2 arctg 2ici2lligi2.Ili.tl 5) where a-h

inter roll gap of rectangular profile.

15

o (is the linear ratio of rolls of oh where from

1435332

current diameter of work rolls in most isopgen-sections, mm; the amount of wear of the work rolls in the most worn sections, mm,

or

10 & d arctg

„In tech (D ucx Edema) 2 G 51

(eight)

where Dyc is the initial diameter of the work roll over the most worn sections, mm. Therefore, the current roll angle of the rolls is about where from

width of roll material, mm / .С i

- the average mass temperature of the roll barrel during rolling,

° s-

The calculation of the current angle of intersection, taking into account the ring wear of the work rolls, providing compensation for the latter, and thus, the rectangular shape of the roll gap, is as follows.

The dependence of the skew angle of cylindrical rolls on the difference between the value of the roll gap at the edge and in the center of the barrel for small roll skew angles to

o (arctg 2 DJ / L (6) where D is the diameter of the roll barrel of cylindrical profiling, mm; length of the roll barrel, mm; the difference between the size of the roll gap at the edge and center of the barrel, mm; Calculation of the current angle of rolls crossover ring wear is produced to compensate for wear in the most worn sections of the roll II and II-II (FIG. 5, a cylinder of length B is marked by hatching

L /

and diameter.

Accept the assumption that the wear in the center of the roll barrel is negligible. Then, starting from (6), turning to the side, smaller angles to compensate for the wear of the work rolls are made on

p value

 & arctg 2f f- -: - - (7)

for 1 cylinder of length B and diameter Edema (figure 5), where B is the distance between the most worn sections,

mm;

"Tech" Czech - arctg 2

ID tech. (D nscx - DTEK), (9)

With the accepted assumption, formula (9) allows to calculate current yrjai roll intersections depending on the amount of wear.

It is possible to clarify the formula (9) by rejecting the assumption that in the center the roller wears very little in relation to the side edge wear,

In this case, the required initial angle should be recalculated using formula (5), taking into account the slight change due to wear of the roll gap h and the magnitude of the concavity of the initial profile of the rolls C, Then, replacing the new, worn out diameter of the center of the rolls D and recalculated angle of their intersection to the formula ( 9), it is possible to calculate the current angle л those of K. by the following, already refined, formula

40

 2 arctg

2 (C (l + o.t)

LS

five

where with

.arctg

From 4

T / DTEU (D fur - Drew) (

ten)

h h + / 1

four.

u,

L, wear of the barrel center, mm. The active forming roll profile can vary according to the following laws:

e 12-x1 ,,.

y (ii)

where e is the maximum cut-out value at the end of the barrel.

 X z

Rc

where b is a constant;

(12)

C - the magnitude of the concavity of the active

forming the work roll, for greater smoothness of the active work roll

at 2 - with, (13)

o1 is a constant (fig, 7, the numbers at the curves correspond to the numbers of the formulas in the text),

(1A)

1 L.

(Fig.8). When y

 WITH

L

2

Let us now express the exponent a, calculating both parts of the equation.

n In (b - C), then the formula (14) takes the form

L;

X

)

simplicity take the law

xg

y - (|)

L

 - C X - C.

To determine the cross sections that undergo maximum wear, it is assumed that

In this way

.AT

In C (1).

Knowing the law of the active forming profile of the roll and the amount of wear in the most worn sections, neglecting the wear in the center, the barrel, the formula (9) has the form

tech de y

 Czech

-arctg 2

JlI ii2 j l4i-J

1 V

- the ordinate of a point on the surface of the worn active agent in the section subjected to the greatest wear, mm,

or

,AT

() C (d-1) (- 4) 4 -arctg 2-J .----

.re

In practice, it is advisable to find the original recurring goal of the crossing of the rolls about the formula (5), and the current one according to the formula 9).

At the same time, the wide rolling without rolling shows the wear of the stand group of the finished rolls 300–35 of the finishing nose of working items for the rolling 500 stripes. In the distant cage, in dimension of which the number of intelligent but

Therefore d according to us

formula (9), rollers with allowance for and unequal

0

five

0

five

0

five

0

five

0

four

e

 relics

Table 1 gives the initial data for calculating the angles of intersection of the axes of the rolls before the start of the work roll campaign in the finishing group of the NShS-1700 hot rolling, and in table 2, the definition of o (the parameters of the strip rolling method.

Example. Before rolling, according to the formula (5), the initial angles are calculated on the CSB by crossing the axes of the rolls in each i-th stand. Calculations are made on the basis of the concavity value selected by the Pre-polishing from the work roll profile, set according to the Accepted roll size distribution h to obtain the required final strip thickness, the Hz work roll diameter in the middle of the barrel length, the work roll temperature t, which is thermal profile in the actual profile of the active generatrix (Table 1).

The resulting angles of intersection ensure the rectangular profile of the roll gap, and, consequently, rolled strips of various widths. In practice, during one campaign of work rolls, strips of various finite thicknesses are punched, therefore, the crossover angles should be calculated for the case of rolling each thickness (Table 2).

At the same time, the experience of running a continuous wide-strip hot rolling mill without crossing the roll axles shows that significant uneven wear of the work rolls of the finishing mill group (over 0.01 mm), which worsens the cross-sectional profile of the finished strips, appears after rolling 300 -3500 tonnes. However, in the first stand of the finishing group, the uneven wear of the work rolls, leading to the formation of local longitudinal thickenings during rolling, already occurs after rolling 500-700 tons (or two heats) of strips. Subsequently, in each subsequent stand, significant non-uniformity of wear arises, the absolute value of which decreases with an increase in the order number of the stand (Table 2).

Therefore, for the conditions of NSHS-1700, it is advisable to install the current angles of pecs (f g, calculated by the formula (9), to be performed during pro- skating rinks, taking into account the sequence number of the stand and uneven wear of workers

7

rolls in each stand, and these factors should be taken into account through the mass of rolled strips. Calculation for each i-th stand is carried out on the basis of the previously chosen angle of intersection of the current diameter of the work rolls at the places of their greatest wear and the distance between the most worn sections of the work rolls B. Quantitative knowledge of the last two parameters is determined empirically - processing and analysis of statistical data of measurements of the wear of the work rolls depending on the rolling conditions.

The presented data show the sequence of actions for rolling, using the proposed method. Roll roll as measure

tech

and

their wear at the current angle V by restoring due to this initial rectangular form of the roll gap, an increase in the service life of the rolls during one campaign is achieved. The current crossing angles are already set after rolling 610 tons of strips (two heats) of the same width, starting from the first stand of the finishing group, in which the work rolls are used at the end of the working bed of the barrel, i.e. with minimal hardness, and therefore with the greatest tendency to wear. Then, as wear develops and develops in the following cages, installation is made in each of them, taking into account the size and location of this wear. Application of the proposed method

rolling allows you to halve the consumption of rolls in the conditions of the NSVS-1700.

Claims (1)

Formula invented Method of rolling strips, including deformation in rolls with initial profiling, the axes of which are crossed one relative to another in the horizontal plane, determining the location of the greatest near-edge wear of the work rolls, and also changing the angle of their crossing during the process, defining 2 arctg so that, in order to increase the service life of the rolls by reducing the wear of the active generatrix in each subsequent stand. as a result of compensating the wear in the previous cell, the initial angle of roll crossover is determined based on the provision of a rectangular shape of the roll gap, - 2j (c,. | -) 4c, .D ,, ..:;:; ;;; .-. „,  2 arctg and the change of this angle in each stand along the process is carried out as a function of the development of the value of the side-by-side wear of the work rolls in the most worn sections according to the expression e tech ;:. , o Octoct (D WCX i-D tech O / dcx; - arctg 2-j- vg 5 Q h. ° C1 .. 0 five 0 where C- is the concavity of the initial pro-file of the work rolls of the stand, mm; - the value of the roll gap in the i-th stand for obtaining the required thickness strips, mm} diameter of the work roll in. the middle of the barrel length, mm; the coefficient of linear expansion of the material of the rolls, average mass temperature of the barrel of the work rolls of the i-th stand, ° С | the distance between the most worn sections of the work rolls, mm; the initial diameter of the work rolls of the i-th stand in the places of their greatest near-edge wear, mm; the current diameter of the work rolls of the 1st stand in the places of their greatest near-edge wear, mm; Lj - the length of the barrel rolls, mm. D, “CX. D. TSKi CN tS (N R 00 CN about G-  CO A vO about r about MF O r- about - CO about t tn about r m to a f  C - & , about SP about fo SP about SP CN  - about p with about with go about go about with go FIG. ; dt / cx 2 fieL Puz.5 Phage. 6 FIG. 7 FIG. eight