RU1787602C - Slab rolling method - Google Patents

Abstract

Usage: rolling precision tapes from mild steels used in the manufacture of shadow masks for picture tubes of color television receivers. SUMMARY OF THE INVENTION: the method includes cold rolling the tape in work rolls with controlled compression and intermediate annealing. Rolling is carried out in two stages with a total reduction of 47-52 and 37-45% with the ratios of the diameters of the work rolls to the average thickness of the tape in the deformation zone at each of the stages 100-160 and 300-500, respectively. Annealing is carried out at 640-730 ° C. 3 tab.

Description

The invention relates to metallurgy, and more particularly to rolling production, and can be used for the manufacture of precision tapes of low carbon steels used in the manufacture of shadow masks for picture tubes of color television receivers.

Cold-rolled mild steel tapes intended for the manufacture of shadow masks for picture tubes with a slit structure must have a combination of mechanical, magnetic and technological properties that ensure long and reliable operation of the picture tube, high color separation and color image, low rejection rate.

The set of mechanical and magnetic properties to which the film tube must meet is presented in Table. 1.

Index

oh along

characterizes the ratio of the values of temporary tensile strength measured on samples cut along and across the rolling direction. The residual magnetization of He and magnetic permeability characterize the magnetic properties of the tape, and the indicator of magnetic aging

A ns

-p-, increase in residual magnetization

news in time. A grain score, in addition to mechanical and magnetic properties, determines the accuracy of etching of the raster holes.

A known method of manufacturing a strip of mild steel, mainly for shadow masks of picture tubes of color television receivers, including cold rolling strips, decarburizing annealing, second cold rolling, recrystallization annealing, third hoXI

00

VI about

g

boat rolling, recrystallization annealing and fourth cold rolling, wherein recrystallization annealing is carried out at 640-680 ° C, and compression during the fourth cold rolling is maintained in the range of 28-35%.

The disadvantages of this method are that it does not provide a given set of physical and mechanical properties, and cold rolling in 4 stages with intermediate heat treatments reduces the productivity of the equipment. }

The closest in technical essence and the achieved results to the invention is a method of producing a kinescope tape from mild steel for shadow masks of color television sets, including cold rolling in three stages in work rolls with regulated compressions and two intermediate anneals, while crimping on the 3rd stage for the passage support within 20-40%, and the last annealing is carried out at a temperature of 580-640 ° C - the prototype.

The disadvantages of this method are that the kinescope tape is ready to have low mechanical and magnetic properties, as well as the poor trauma of the raster holes due to non-optimal microstructure. This degrades the quality of the tape. Cold rolling in 3 stages with two intermediate anneals reduces the productivity of the process.

The aim of the invention is to improve the quality of the tape while increasing productivity.

This is achieved by the fact that in the method for producing a kinescope tape, including cold rolling in work rolls with controlled compression and intermediate annealing, according to the proposal, the rolling is carried out in two stages with a total compression of 47-52% and 37-45% at ratios the diameters of the work rolls to the average thickness of the tape in the deformation zone at each of the stages 100-160 and 300-500, respectively, while annealing is carried out at 690-730 ° C.

Known and proposed technical solutions have the following general features. Both are kinetic tape manufacturing methods and include cold rolling in work rolls with controlled crimping and intermediate firing. Cold rolling in both cases is carried out in several stages.

The differences of the proposed method are that the rolling is carried out in two

stages with total reductions of 47-52% and 37-45%, and in the known - for three stages, with compression at the 3rd stage for a passage of 20-40%. In the proposed method, the rolling

when the ratio of the diameter of the work rolls to the average thickness of the tape in the deformation zone at the first and second stages is 100-160 and 300-500, respectively, and in the known these relations are not regulated. And finally in

the proposed method annealing is carried out at 690-730 ° C, and in the known - 580-640 ° C.

These distinctive features, as a whole, exhibit new properties that are not inherent in them in the known sets of features, and which consist in improving the quality of the tape and increasing productivity. In the method for producing cold-rolled pass bands per pass,%: 20-22; 5-27; 5-33, which provides a reduction in thickness variation. In the method of producing kinescope steel, rolling is carried out in two stages with reductions of 80-90% and 40-57%, which, however, does not provide the required properties (Table 1), because

Designed for the manufacture of masking tapes with a delta structure and reduces productivity due to an increase in the number of passes in the first step.

It should also be noted here that

cold rolling in 2 stages is subjected to a strip already subjected to the first cold rolling and heat treatment, i.e. essentially cold rolling is carried out in three stages with regulated compression

on the last two. In the technical solution, cold rolling is carried out with compression of 10-35% to a thickness of 0.2 mm, after which the tape is fired in a roll at 520-600 ° C for 2 hours and trained with compression of 0.3-0.8%. it

reduces coercive force.

The essence of the alleged invention is as follows. Cold rolled ribbon for shadow picture tube masks

with a slit structure before etching the raster holes should have a uniform ferritic microstructure in the mounted state, the formation of which is laid in the first stage

stage of cold rolling, intermediate annealing and ends in the second stage of cold rolling. The nature of the deformed structure and texture of the tape determines the mechanical and magnetic properties, the isotropy of the mechanical properties, and the tragedy of the raster holes. The last parameter is determined by the number of defects of the NFO (violation of the shape of the holes) - there should be no more than 5 on one shadow mask.

The implementation of the proposed modes allows both the formation of a given set of physicomechanical properties necessary to obtain masks with a slit structure and an increase in the productivity of the process by minimizing the number of stages of cold rolling and intermediate annealing.

It was experimentally established that, with a total reduction in the first stage of less than 47% and with a ratio of the diameter of the work rolls Dp to the average strip thickness in the deformation zone Hsp less than 100 (Dp / Hep 100), the required degree of deformation of the microstructure and the optimal orientation of the crystallographic texture are not achieved, which worsens the quality of the lelt (reduces the strength properties, worsens the etchability of the raster holes), and also requires an additional, third stage of cold rolling to bring the properties to an acceptable level. This reduces the performance of the process. When the total compression at the first stage is more than 52% or the ratio Dp / HCp 160, the anisatropic and mechanical properties increase, and the intensity of grain orientation in the favorable crystallographic direction {111} decreases. Obtaining a uniform microstructure of steel in this case is achieved by lengthening the annealing cycle, which reduces the productivity of the process. This increase in total reduction requires an increase in the number of passes during cold rolling, which also reduces productivity.

At an intermediate annealing temperature of more than 730 ° C, the strength of the finished tape decreases below an acceptable level, the grain of the microstructure coarsens excessively, the coercive force and magnetic aging of the finished masks increase, which is unacceptable. In order to obtain the optimum degree of hardening in this case, it is necessary to increase the number of passes at the last stage of cold rolling, leading to a decrease in the productivity of the process. At an annealing temperature below 690 ° C, the tape has high strength, insufficient ductility, maintains anisotropy of mechanical properties, has insufficient magnetic permeability and fine grain microstructure.

The total compression at the second stage of cold rolling of 37-45% with a Dp / Hep ratio of 300-500 allows us to finally form the optimal microstructure and physicomechanical properties of the finished tape. The Dp / HCp ratio determines the nature of the stress-strain co0

5

0

5

0

5

the metal in the deformation zone and, consequently, the uniform distribution of the accumulated deformation and texture. When the degree of total deformation is less than 37%, the strength of the tape decreases, the etchability of the raster holes decreases. An increase in the total strain of more than 45% leads to an increase in the anisotropy of the mechanical properties and to a deterioration in the magnetic characteristics of the tape. To obtain high degrees of total deformation, an increase in the number of passes during cold rolling is required, which reduces productivity.

At a Dp / Hep ratio of less than 300, the uniformity of the grains of the microstructure decreases, the crystallographic texture deteriorates, and the mechanical and magnetic properties of the steel decrease. An increase in the Dp / Hep ratio, in addition to an increase in the magnetic aging index, reduces the magnetic permeability of the tape. In this case, to increase the set of physicomechanical properties for the allowable limits, additional annealing and the third stage of cold rolling will be required, which leads to a decrease in productivity.

Examples. A strip of mild steel with a thickness of 0.5 mm is cold rolled on a 20-roll reversible Astana 720. Rolling is carried out in two passes with a total degree of deformation of 49% for an intermediate thickness of 0.255 mm according to the scheme:

0.5mm - 0.36, 255mm

At the first pass, work rolls with a diameter of 56 mm are used, which ensures 40

Dpi / HCpi ratio

 56 / (0 5t ° 36)

 130. In the second pass, work rolls with a diameter of 40 mm are used: Dpi / HCpi

40 / (0-36t ° -255) 130.

The rolled strip is subjected to recrystallization annealing in a protective atmosphere at 710 ° C and then to the second stage of cold rolling to a final thickness of 0.15 mm with a total degree of deformation according to the scheme

0.255, 195, 165 mm-M), 15 mm

The diameters of the work rolls along the aisles are I - 90 mm; II - 72 mm; III - 63 mm. This provides a Dp2 / HCp2 ratio in all three passes of 400.

Samples were taken from the finished tape to assess the mechanical and magnetic properties, and the relative hourly productivity of the manufacturing process was determined.

Method implementation options are given in table. 2, and indicators of the quality of the tape and the relative productivity of the process are in table. 3. The relative hourly production rate changes with a change in the number of passes, the number of cold rolling and annealing steps, which depends on the belt deformation pattern.

As follows from the table. 3, the implementation of the proposed method (options 2-4) provides an improvement in the quality of the tape while increasing productivity. In the case of prohibitive values of the claimed parameters (options 1.5-11), the complex of mechanical and magnetic properties deteriorates, and productivity decreases. When implementing the prototype method (option 12), there is also a deterioration in the quality of the tape while reducing production productivity.

The technical and economic advantages of the proposed method are that cold rolling in two stages with total reductions of 47-52% and 37-45% with Dp / HCp ratios of steps 100-160 and

300-500 with intermediate annealing at 690-730 ° C provide the formation of optimal microstructure and texture of the tape for masks with a slit structure with a minimum number of redistributions. This leads to improved tape quality while improving productivity.

FORMULA AND ZOBRETE N and

A method of manufacturing a precision strip of mild steel for shadow picture tubes masks, comprising cold rolling it in rolls with controlled compression and intermediate annealing, characterized in that, in order to improve the quality of the tape while increasing productivity, rolling is carried out in two stages with

total reductions of 47-52% and 37-45% with the ratio of the diameters of the work rolls to the average thickness of the tape in the deformation zone, at each of the stages 100-160 and 300-500, respectively, while annealing is carried out at

690-730 ° C.

Table 1 Properties of the kinescope tape in the delivery state (TU 14-1-1420-90)

Table 2 Production modes of the kinescope tape for shadow masks with a slit structure

Table 3 Indicators of quality kinescope tape and process performance

Editor

Compiled by E. Voronkova

Tehred M. Morgenthal Corrector 3. Salko

Order 29

VNIIIPI of the State Committee for Inventions and Discover at the USSR State Committee for Science and Technology 113035, Moscow, Zh-35, Rauska nab., 4/5

Production and Publishing Plant Patent, Uzhhorod, 101 Gagarin St.

STATE PATENT OFFICE OF THE USSR (GOSPATENT of the USSR)

# NOWLINE1

DESCRIPTION OF THE INVENTION

LIBRARY

TO AUTHOR'S CERTIFICATE

1

(21) 4788841/27

(22) 05.02.90

(46) 01/15/93. Bull. Number 2

(71) Mariupol Metallurgical Institute

(72) N.A. Karnaushenko, G.E. Zmievsky, G.I. Nalcha, E.N. Shebanits, G.F. Kuznetsov, V.M. Peftiev, V.S. Krivoklub, M.I. Kapustina , E.I. Reznichenko, A.F. Todurov, A.N. Vagin, M.V. Slizen, V.D. Veklichev, I.A. Pasko and V.A. Klimenko

(56) Copyright certificate of the USSR No. 1026852, cl. B 21 B 1/06, 1987.

USSR copyright certificate No. 716652, cl. B 21 B 1/02, 1978.

The invention relates to metallurgy, in particular to a technology for rolling slabs and subsequent rolling of sheets therefrom on broadband mills.

There is a known method of rolling slabs, as well as a method of rolling metals, in which, in order to reduce metal loss to the edge during further rolling, a certain profile is given to the end of the slab blank by a template or a wavy curve by thermal cutting.

The disadvantage of these methods is the additional loss of metal into the edge during profile cutting of the slab.

Known methods for crimping a slab in width are standardized in which crimping is normalized in vertical rolls.xx by rolling both ends of the slab in them as front ones, which reduces the loss with cutting.

The disadvantage of these methods is the lack of correlation of the rolling mode in vertical and horizontal rolls, which

COMMIT

LIBRARY

(54) METHOD FOR SLAB ROLLING (57) The invention relates to metallurgy, in particular to a technology for rolling slabs and subsequent rolling of sheets therefrom on broadband mills. The goal is to improve the quality of the sheets by reducing their width and cutting. The different thicknesses of the slabs are compensated by their thickening at the edges, for which rolling of the slabs on crimping mills is completed by crimping in width, which is determined by the dependence given in the text of the description. The method allows to reduce end and side trim. 5 ill., 2 tab.

ate

with

leads to an increase in metal loss with trim.

There is also a known method for adjusting lateral compression in a hot rolling mill, in which the front end of the slab is crimped from the sides only in the output vertical rolls after the horizontal ones, and the middle only in the input vertical rolls.

The disadvantage of this method is the lack of correlation with the profile of horizontal rolls, which also leads to the different width of the roll and an increased trim.

The closest technical solution to the achieved results and its essence is a method of rolling continuous slabs, in which, in order to reduce the end trim and improve the quality of the rolled surface, before pressing the slab in width, its central part is squeezed to a thickness equal to the thickness of the side edges as well as variable compression

by thickness. The disadvantage of this method is the lack of correlation of reduction in the rolls in width and the convexity of the wide face of the slab, which does not allow to reduce the end trim caused by these reasons.

The permissible boom of the production of horizontal rolls of crimping mills is very substantial and can be up to 15 mm or more on industrial sling. The slab obtained in such rolls, with its maximum width nWeef Width, has the same magnitude along the wide edge on both sides. During subsequent rolling in the descaler and the roughing group of the broadband mill stands, the front and rear ends are additionally distorted due to a larger stretch of the middle part of the roll, increasing the so-called tongue at the front and rear ends. In this case, a fan-shaped expansion of the front and rear ends occurs, which makes rolling in the subsequent stand with vertical rolls difficult. In addition, due to the presence of parts of the roll less pressed out in the first passes near the lateral edges, the roll receives an uneven length of the roll of the roll, which leads to the production of finished sheets in the middle part of the length of the rolls already face value, which is unacceptable by technical conditions and, moreover, results in finished sheets of different widths.

The purpose of the method is to reduce the trimming of sheets on a broadband mill caused by the lateral thickness difference of the slabs due to the generation of horizontal rolls of the crimping mill.

This is achieved by the fact that in the method of rolling a slab on a crimping mill, including compressing it in thickness and width, rolling is completed by compressing the roll in width, which is determined by the following relationship:

A hB Kef + Kn G, mm

I4v

Chush

(1)

where KEF - coefficient of efficiency;

KB is the coefficient of development of the upper roll of the crimping mill;

Kn - the coefficient of development of the lower roll of the crimping mill;

Kush is an indicator of broadening during compression of a slab in width;

G is the mass of metal rolled on a crimping mill from the beginning of the roll campaign, t.

The local broadening formed in the last pass when the slab was squeezed in width compensates for its transverse thickness difference resulting from the development of horizontal rolls of the crimp mill and, in the limit, gives the same or somewhat larger thickness along the edges compared to the thickness in the middle of the width

wow.

Upon further rolling of such a slab in the roughing group of a broadband mill, the roll receives a more evenly distributed reduction in width, while

greater compression of the metal near the edges reduces distortion of the ends, which reduces losses with the end image. The same compression of the edges causes additional broadening, eliminating the width of the iron, which

reduces the unevenness of the width of the roll lengthwise, eliminates the receipt of a sheet width less than the nominal.

The method is carried out as follows.

The slab is rolled on a crimping mill with worked out horizontal rolls so that before the last pass in the vertical rolls its width was greater than the required value by the value determined by dependence (1). In the last pass, the slab is crimped in width with a compression of AhB determined by dependence (1).

In FIG. 1 shows a view of the transverse

cross-section of the slab after rolling in worked out horizontal rolls and after compression in width; in FIG. 2 shows the unevenness of the width along the length of the roll when modeling rolling in the rough group

a broadband mill (strips 1350 mm wide from a slab compressed in width with varying degrees); in FIG. 3 and FIG. 4 - the same for a strip with a width of 1390 and 1500 mm, respectively; in FIG. 5-shape front

and the rear ends of the peals obtained in the draft group of a broadband mill from slabs compressed in width with varying degrees.

In FIG. 1 shows a cross section

slab after rolling in worked out horizontal rolls (dashed line) and after compression in width in the last pass (solid line), where hc is the thickness of the slab in the middle of the width, pK1 and hK are the thickness of the edges, respectively, after compression in thickness and after compression in width on the crimping mill; 5B - boom of the upper roll; bottom boom of the lower roll; AhB is the width reduction of the slab.

As an example of the application of this rolling method, modeling of rolling of slabs of various widths was carried out in relation to the conditions of slab 1150 and a continuous broadband mill

1700 Mariupol Metallurgical Plant. Ilyich. Three batches of lead models of slabs of various widths were made by rolling in a worked-out rolls of a laboratory rolling mill with a nominal roll diameter of 66.7 mm in a scale of 1: 12 to natural dimensions, taking the maximum arrow to produce horizontal rolls of an industrial mill based on measurements of their profile after transshipments 5V 15 mm, 5N 12 mm (5V 1.25mm, 5N 1.00mm on the model),

In each batch, one slab was rolled without compression in width, one with compression of 1.5 mm (18 mm in kind) and one with compression of 3.0 mm (36 mm in kind), and then according to the rolling mode in the rough group broadband mill.

In FIG. Figures 2-4 show that the unevenness of the width of the peals along the length is minimal for the case of rolling them from slabs with a compression in width of 36 mm (c), slightly more for compression in width - 18 mm (b). The data are given in terms of natural sizes. When rolling without reduction over the width of the convex, the shape of the wide edges of the slab leads to maximum unevenness of the width of the roll along the length (a), when the width in the middle part of the length of the roll becomes less than the nominal (line 1). Lines 2 - width with a plus tolerance of 20 mm.

Taking into account that in the finishing group of the broadband mill there are no vertical rolls and, therefore, the relative length of the distorted ends in it does not change, the relative mass of the distorted ends after the draft group can characterize the end cut after rolling the sheet on NSF. Therefore, from each roll after rolling according to the regime of the NSH roughing group, the front and rear end trim were selected, its weight was determined by weighing, and the loss with trim was calculated.

In FIG. Figure 5 shows a view of the front and rear end trims when rolling without reduction in width (a), with compression on models 1.5 mm (b) and 3.0 mm (c) for a width of 125 mm (1500 mm in kind). It can be seen that the reduction in width significantly reduces the end trim.

Based on the processing of the results of measuring the profile of the horizontal rolls of the sling 1150 of the metallurgical plant named after Ilyich established in a first approximation is directly proportional to the dependence of their arrows

production of the amount of metal rolled since the beginning of the rolls campaign.

dvc, bn-kns,

(2)

where 5B and bottom are the arrows of the development of the upper and lower rolls, respectively;

Kv and Kn - the coefficients of production of the upper and lower rolls;

G is the mass of metal rolled from the beginning of the roll campaign, thousand tons

The lateral thickness of the slab is the sum of the arrows for the production of two rolls

  (Q + kn) 0 (3)

The values of the coefficients Кв and Кн make it possible to determine the transverse thickness difference of the slab not only at the end of the roll campaign, but also at any stage depending on the mass of rolled metal, which makes it possible to control the shape of the cross section of the slab by adjusting the reduction

in width during the campaign. From (2):

 ICN (4)

By processing the results of measuring the arrow of the production of horizontal rolls of sling 1150 after transshipment at the end of the campaign, dependencies (4) determine the intervals of variation of the coefficients

Qu 0,039-0,054 mm / thousand tons and Kn 0,024-0,036 mm / thousand tons

Also, according to the results of the experimental rolling at the laboratory mill and in industrial conditions, the broadening index was determined when the slab was squeezed in width.

DKG ZGPG

0.6-0.7

where DK is edge-widening during compression of the slab in width, mm

A he - compression of the slab in width, mm. With the increase in compression over the width A he, the efficiency of the method increases, and

the positive effect consists of two processes: reducing the unevenness of the roll width and reducing the distortion of the ends. However, when exceeding a certain maximum, when in the simulation A hB was more than 3.8 and 4.0 mm (in nature - 45-48 mm), the width of the sheet obtained at the NShS went beyond the plus tolerance in width (see table 1), which is unacceptable. In this case, the thickness