Improving broad-strip hot-rolling mills

ISSN 0967�0912, Steel in Translation, 2014, Vol. 44, No. 3, pp. 221–227. © Allerton Press, Inc., 2014.Original Russian Text © V.A. Nikolaev, A.A. Vasil’ev, 2014, published in “Stal’,” 2014, No. 3, pp. 47–52.

221

The first semicontinuous broad�strip hot�rollingmill, introduced in 1926 in the United States, had asingle nonreversible cell and a single reversible cell inthe finishing group and four four�high cells in the fin�ishing group [1]. The development of such mills up to1979 involved increase in the number of four�highmills in the roughing and finishing groups and the useof universal cells (with a total of 11–13 working cells).After 1979, to reduce construction costs, the numberof cells in the roughing group was reduced to four incontinuous broad�strip hot�rolling mills and to two insemicontinuous broad�strip hot�rolling mills. In thisperiod, the process was constantly improved [1, 2]:continuous rolling in 2–3 roughing cells; increase inroller diameter; increase in drive power; increase inslab thickness (to 300 mm); decrease in final stripthickness (to 1.0–1.2 mm); introduction of hydraulicclamps in the finishing group; establishment of anintermediate coiling system (Coilbox); and increase inrolling speed in the finishing group (to 15–29 m/s). Onbroad�strip hot�rolling mills, strip is produced fromslabs obtained from ingots and also from slabs formed incontinuous�casting machines. The use of ingotsinvolves greater metal losses in cutting; for low�carbonsteel, the steel�consumption factor kco = 1.09–1.12.

In 1988 and 1989, an alternative system for the pro�duction of hot�rolled strip appeared: the casting androlling system, consisting of a continuous�castingmachine (producing thin billet) and a continuous hot�rolling mill [1, 3]. The first such systems containedonly four four�high cells in the finishing group; subse�quent designs included 1–2 roughing cells and 5–6 finishing cells. In rolling with acceleration, the stripleaves the last cell of the mill at 10–12 m/s, but therolling speed is 20 m/s or more after capture by thecoiling system.

The deficiencies of the broad�strip hot�rolling millwere discussed in detail in [1]. Here we consider justthree.

1. The use of the Coilbox permits increase in striptemperature by ~15–30°C ahead of the finishinggroup. However, in the absence of heat�conservingscreens, there are significant temperature losses up to(40–50°C) by inner turns of the coil produced in theintermediate coiling system, uncoiling of the strip, andits supply to the finishing group. The cooling time ofthe inner turns is about twice that for the outer turns.Consequently, the temperature and thickness are non�uniform over the length of the strip, and the thickeningat the rear end of the strip is ≥0.10 mm [4].

2. When the strip switches from the speed of 10–12 m/s to the maximum value of 20 m/s in the finish�ing group, additional power is consumed in accelerat�ing the rotation of the working and supporting rollersin all 6–7 cells. The gaps between the rollers must alsobe regulated, which involves additional power con�sumption and increases production costs.

3. To obtain ferrite structure in the metal ahead ofthe finishing group, an intermediate cooling unit isintroduced, so that the temperature at the end of thestrip is 750–800°C. All 6–7 cells of the mill areinvolved in rolling the cooled strip. That increases thepower consumption and the rollers’ surface wear.

These problems are largely eliminated by using anew mill design, which represents a new generationin terms of its configuration [5–11]. In the newdesign, much of the deformation is concentrated inthe roughing group, with higher strip temperatureahead of the intermediate conveyer and the interme�diate coiling system. In addition, an inductive fur�nace is introduced ahead of the three�cell finishinggroup, with the necessary ancillary equipment. Thenew mill structure is shown in Fig. 1. The roughing

Improving Broad�Strip Hot�Rolling MillsV. A. Nikolaeva and A. A. Vasil’evb

aZaporozhe National Technical University, Zaporozhe, UkrainebOAO Zaporozhstal’, Zaporozhe, Ukraine

e�mail: [email protected]

Abstract—New and traditional hot�rolling mills are compared. Calculations show that the position of theintermediate coiling system in traditional broad�strip mills does not permit sufficient efficiency. A new designis proposed to make better use of the strip temperature, produce strip with negative tolerances, and reducepower consumption.

Keywords: rolling, strip, broad�strip hot�rolling mills, roughing group, finishing group, temperature, longitu�dinal thickness variation

DOI: 10.3103/S0967091214030115

222

STEEL IN TRANSLATION Vol. 44 No. 3 2014

NIKOLAEV, VASIL’EV

group consists of 5–7 cells (4–6 cells in the continu�ous group), while the finishing group consists of three(Fig. 1). In the continuous roughing group, the firstcells are universal; the height and width of the stripare altered in those cells. In the roughing group, thedeformation conditions are determined by the thick�ness of the initial slab (165–300 mm) and the finalsheet (3–10 mm) and also by the diameter of theworking rollers (600–1000 mm). The rolling speed inthe roughing group is 0.45–0.5 m/s in cell 1 and 6–12 m/s in cell 6.

The number of cells in the roughing group, theroller diameters, and the slab thickness are determinedby the annual production schedule for the mill andmay be established in advance [4, 5, 11]. In the presentwork, we consider nine� and ten�cell mills of the newdesign, with provision for use of the three finishingcells freed up in reconstruction. Other options are alsopossible. For example, in setting up four�high cellswith a working�roller diameter of 1300–1400 mm, thenumber of cells in the roughing group may be reduced.

Beyond the roughing group, the strip is coiled inthe Coilbox or on drum rollers with heat�conservingscreens [6]. Between the Coilbox and the first cell ofthe finishing group, we introduce a traction device, apass�through induction furnace, cutters, sprayers, anda scale�removal unit. From the Coilbox, the stripenters the first cell of the finishing group at a speedequal to, less than, or more than its exit speed from theroughing group. The speed of the strip’s front end as itleaves the finishing group is 10–12 m/s. After captureby the coiling unit, the speed in the finishing groupincreases to the maximum possible value (≥20 m/s).Depending on the quality requirements on the stripahead of the finishing group, it is either cooled (so as toreduce the final rolling temperature) or heated furtherin the induction furnace. As a result, the strip enters thefirst cell of the finishing group at a controlled speed (t ≥900°C), without preliminary strengthening; that per�mits rolling with greater reduction.

Tables 1–4 present the parameters for strip rolling ona traditional 1700 mill with ten cells [1, 2] and mills of thenew design with nine and ten cells (Fig. 1) [5–11]. Thedeformation conditions are assumed to be the same in

the ten�cell mills; the conditions in the nine�cell millmatch those in the last cells of the traditional mill. Thevariation in rolling temperature, longitudinal thick�ness variation, forces, and rolling power over the cellsis investigated, at speeds of 10–20 m/s. The familiarcalculation method is employed [4, 5, 11]; however,no account is taken of the strip hardening on account ofincomplete recrystallization. All the rolling parametersare determined at the front of the strip (section 1); at adistance of 30 m from the front end (section 2); at adistance of ~30 m from the rear end (section 3); and atthe rear end (section 4). In section 2, which is thebaseline section, the longitudinal thickness variation isassumed to be zero, with a baseline strip thickness of2.5 mm. All the rolling parameters are calculated forall the sections; the comparison for all the mills restsmainly on baseline section 2. In the calculations, weconsider the production of 2.5 × 1250 mm strip fromslab whose thickness and length are 165 mm and 9 m,respectively. The mean strip temperature ahead ofcell 1 is assumed to be 1180°C in all cases. The work�ing�roller diameter is 940 mm in cell 1, 850 mm incell 2, and 600 mm in cell 3 (for ten� and nine�cellmills). The working rollers are made of 9X2 steel incells 1 and 2 and cast iron with a chilled surface(hardness >HSD 70) in cell 3.

It follows from Fig. 2a that, in the first four cells ofall the mills, the strip temperature (section 2) is prac�tically the same. Beyond cell 4 of the traditional mill(curve 1), the temperature of the strip’s front end inthe coil falls by ~104°C ahead of cell 5 (with allowancefor travel over the intermediate conveyer, coiling anduncoiling, and transportation to the finishing group)and then declines practically linearly to 832°C at theoutput from finishing cell 10 (Table 1). That corre�sponds to the actual strip�rolling conditions on a1680 mill [12]. (The total length of the intermediateconveyer is ~65 m.)

In the mills of the new design, the distance betweenthe last cell of the roughing group and the first cell ofthe finishing group is ~45 m; the temperature losses onthe intermediate conveyer are the same as in the tradi�tional mill. In addition, the strip may be heated to≥900°C in the induction furnace or may remain con�stant prior to entry in the finishing group. In the

1

2 3 4 5

6 7 8 9 10 11 12 13

1415 16

l = l + 10...15%

6 m 6 m 6 m 6 m L2 L3 6 m 6 m

Fig. 1. New design of broad�strip hot�rolling mill: (1) slab; (2) scale remover; (3) four�high roughing cell; (4) universal roughingcells with vertical rollers; (5) four�high roughing cells; (6) intermediate strip; (7) guide rollers; (8) drum�type coiling system withheat�conserving screens; (9) tractional rollers; (10) pass�through induction furnace; (11) cutters; (12) sprayers; (13) final scaleremover; (14) continuous finishing group; (15) spray system for final strip; (16) coiling system for final strip.


IMPROVING BROAD�STRIP HOT�ROLLING MILLS 223

present work, the influence of the induction furnaceon the temperature conditions of strip rolling is disre�garded in the calculations. Thus, in the mills of thenew design, the strip temperature on entering the fin�ishing group (section 2) is around 947°C for the ten�cell mill and around 933°C for the nine�cell mill

(Tables 2 and 3); those values somewhat exceed thevalues for cell 8 in the traditional mill: tin ≈ 924°C(Table 1).

By adjusting the rolling speed and the degree ofreduction in the roughing group and finishing group,we may increase the strip temperature in the finishing

0.35

0.31

0.27

0.23

0.19

76541 32

1

23

f(b)

1200

1100

1000

900

80076541 32

1

23

tf, °C (a)

8 9 10

250

200

150

100

504.03.53.02.51.0 2.01.5

1

2

3

pme, N/mm2(d)

4.5

160

120

100

80

60

1

23

σme, N/mm2(c)

140

Cell

CellCell

Fig. 2. Distribution of the initial strip temperature (a), frictional coefficient (b), mean deformational strength of the metal (c) andmean normal contact strength (d) over the cells of the mills for different configurations: (1) traditional broad�strip hot�rollingmill; (2) ten�cell mill of new design; (3) nine�cell mill of new design. Cells 1–7 (or 1–6), section 2.

Table 1. Rolling parameters for 2.5 × 1250 mm 08пс steel strip on a traditional 1700 broad�strip hot�rolling mill

Cell h, mm v, m/s ε lc/hme fσfr,

N/mm2

pme,

N/mm2 P, MN M, MN m N, kW

MN mmtin, °C tf, °C

1 83 0.90 0.408 1.47 0.315 69 91.5 18.76 3.02 5552 0.281 11802 50 1.01 0.398 1.78 0.330 76 107.0 15.84 1.81 4129 0.412 11583 32 1.58 0.360 1.79 0.330 86 120.1 11.01 0.78 3946 0.512 11304 23 2.20 0.281 1.89 0.330 96 132.9 8.62 0.43 3023 0.763 1096

Intermediate coiling5 14 1.79 0.393 2.81 0.331 137 217.1 14.44 0.60 3436 1.38 992 9816 8.8 2.84 0.371 3.46 0.303 155 248.1 12.65 0.48 4358 2.15 969 9577 5.7 4.39 0.352 4.21 0.265 177 298.2 11.94 0.32 4508 3.44 946 9348 3.8 6.58 0.333 5.03 0.225 203 347.1 11.13 0.22 4712 5.31 924 9119 2.9 8.62 0.237 4.90 0.205 209 330.0 7.50 0.10 2794 7.19 901 875

10 2.5 10.00 0.138 4.06 0.204 198 289.0 4.56 0.05 1738 9.23 866 832

The slab thickness is 165 mm (140 mm after scale removal). The rolling time is 182 s (δhstr = 0, baseline case, section 2).

rigidity modulus of the strip.

Mini

,

Mstri

,

224



group and at its input to 859–871°C (Tables 2 and 3);that is markedly higher than for the traditional mill(around 832°C; Table 1). The proposed new designincreases the rolling speed in cells 5–7 (Fig. 3a) andreduces the frictional coefficient by 20–25% (Fig. 2b)in the roughing group, when ld/hme = const.

In the mills of the new design, because of theincrease in rolling temperature and decrease in fric�tional coefficient, the resistance to deformation incells 4–6 (or 4–7) is markedly reduced (Fig. 2c), alongwith the mean normal contact stress (Fig. 2d), whenthe form factor ld/hme ≈ 2–4.3. The rolling force isreduced from 16–19 MN to 8–9 MN from cell 1 tocell 4 (traditional mill) or to cell 6 or 7 (mills of thenew design). After the temperature declines on inter�

mediate coiling, the rolling force increases in all themills, with subsequent decrease to 4–4.5 MN in thelast finishing cell (Fig. 2d). In cells 5–7 (4–6) of themills of the new design (especially the ten�cell mill),the rolling force is significantly less than in the tradi�tional mill (cells 5–7). Reducing the rolling force incells 5–7 permits marked decrease in longitudinalthickness variation of the final strip (Fig. 3b).

The rolling power is distributed nonuniformly overthe cells. It is greatest in cell 6 of the nine�cell mill ofnew design (Fig. 3c). In rolling strip of the same profile(v = 10 m/s in the last cell), the total rolling power inthe finishing cells of the mill of new design is practi�cally half that in the traditional mill, while the rollingpower for all the cells is less by 3–5.5%.

Table 2. Rolling parameters for 2.5 × 1250 mm 08пс steel strip on a ten�roller 1700 broad�strip hot�rolling mill of newdesign


N/mm2

pme,



1 87 0.46 0.380 1.39 0.288 65 82.5 16.29 2.54 5082 0.26 1180

2 54 0.73 0.379 1.68 0.310 79 106.6 15.78 1.81 2368 0.40 1135

3 34 1.17 0.370 1.76 0.303 86 112.0 10.83 0.85 3001 0.46 1125

4 21.5 1.84 0.368 2.20 0.288 97 132.6 10.14 0.61 3188 0.69 1114 1194

5 13.8 2.87 0.358 2.72 0.261 110 152.4 9.15 0.43 3596 1.02 1092 1075

6 8.9 4.46 0.355 3.38 0.233 130 182.2 8.73 0.33 3998 1.56 1064 1047

7 6.1 6.50 0.315 3.86 0.205 148 209.8 7.60 0.24 4704 2.35 1037 1018

Intermediate coiling

8 4 6.25 0.357 5.39 0.277 195 379.4 13.06 0.25 4993 5.40 937 942

9 2.95 8.47 0.263 5.61 0.231 200 341.7 8.33 0.12 3301 6.97 931 906

10 2.5 10.00 0.153 4.84 0.202 191 268.7 4.43 0.06 1798 8.06 896 859

The slab thickness is 165 mm (140 mm after scale removal). The rolling time is 176 s (section 2).

Mini

,

Table 3. Rolling parameters for 2.5 × 1250 mm 08пс steel strip on a nine�cell 1700 broad�strip hot�rolling mill of new design


N/mm2

pme,



1 80 0.50 0.430 1.53 0.286 67 87.4 18.39 3.03 3063 0.27 1180

2 46.5 0.85 0.419 1.89 0.306 82 114.4 17.06 1.95 3753 0.44 1135

3 37.2 1.46 0.415 2.06 0.294 90 123.1 11.69 0.89 4147 0.53 1125

4 16 2.48 0.412 2.68 0.269 102 148.6 10.75 0.60 4741 0.85 1114 1106

5 9.5 4.17 0.406 3.46 0.228 121 177.1 9.77 0.41 5518 1.36 1094 1081

6 6.1 6.50 0.358 4.09 0.195 140 205.7 8.05 0.28 5802 2.12 1070 1053


7 4 6.25 0.363 5.41 0.272 185 357.8 12.42 0.24 4822 5.02 965 957

8 2.95 8.47 0.263 5.59 0.229 193 327.6 7.96 0.12 3171 6.66 946 919

9 2.5 10.00 0.153 4.82 0.201 185 259.6 4.26 0.05 1755 7.76 909 871


Mini

,



In rolling 2.5 × 1250 mm strip, the correspondingfigures for the rolling power (finishing cells/all cells)are as follows:

The rolling power is reduced even more when v =15–20 m/s (that is, after acceleration of the mill).Thus, the total rolling power for all the cells is 15–16.5% for the mills of new design at v = 15 m/s and26–27% less at v = 20 m/s, mainly on account of thereduced rolling power in the first three cells at lowerrolling speed. In addition, the power consumed inacceleration of the three finishing cells of the new milldesign is less than half of that required in accelerationof the 6–7 finishing cells in the traditional mill, onaccount of the smaller mass of the rotating parts.

In Fig. 4, we illustrate the variation in strip thick�ness after rolling in the finishing cell in sections 1–4.In all cases, the specified strip thickness of 2.5 mmcorresponds to section 2. Section 1 is the front end ofthe strip, rolled in all the cells without front tension, and

v, m/s 10 15 20

N, kW

Traditional mill 21548/38196 31249/47897 42874/59522

New design, ten�cell mill

10091/36029 13915/39853 16453/42391

New design, nine�cell mill

9823/36772 13572/40521 16011/42960

section 4 is the rear end of the strip, rolled without reartension and at lower temperature than for section 2(Tables 2 and 4). In all cases, we assume a distance of30 m between sections 1 and 2 and also between sec�tions 3 and 4. The variation in strip thickness in sec�tions 2 and 3 is due to the temperature gradient overthe length of the strip and corresponds to the change in

the ratio P1/ in comparison with fixed section 2.For the assumed rolling parameters, the temperaturegradient over the length of the strip between sections 2

Mstri

0.25

0.15

0.05

0

–0.10109875 6

1

23

(b)

8

6

2

076541 32

1

2

3

v, m/s (a)

16

12

8

4

10971 65

1

2

3

P, MN (d)

3000

1000

1

23N, kW h (c)

5000

–0.05

0.10

0.20

0.30δhstr, mm

4

8432 CellCell

Cell

Fig. 3. Distribution of the rolling speed in section 2, cells 1–7 or 1–6 (a), thickening of the rear end in section 4 (b), power (c),and rolling force (d) over the cells of the mills for different configurations: (1) traditional broad�strip hot�rolling mill; (2) ten�cellmill of new design; (3) nine�cell mill of new design.

2.55

2.50

1

2

3

4

3

1

30 m 350 m 30 m

4

Str

ip t

hic

knes

s h,

mm

Sections over strip length

DR

TM

ND�9

ND�10

Fig. 4. Variation in strip thickness over sections 1–4. Therolling speed in the finishing cell is 10 m/s. Notation: DR,direction of rolling; TM, traditional mill; ND�9, newdesign, nine�cell mill; ND�10, new design, ten�cell mill.

226



and 4 is Δt1 = 20°C for the traditional mill and Δt1 =10°C (less than the temperature in section 4) for themills of the new design. The tensile stress between thelast six cells of all the mills is assumed to be σt =15 N/mm2. The thickness increment in sections 1, 3,and 4 in comparison with section 2 is determined fromthe formula [4, 10]

(1)

where Pi and P2 are the rolling forces in section i and

section 2 of the strip, respectively; and arethe strip’s rigidity moduli for sections i and 2; Mce isthe rigidity modulus of the cell.

As follows from Fig. 4, the maximum thickeningδhstr = 0.074 mm in the traditional mill corresponds tosection 4, where the strip thickness h4 = 2.574 mm. Inthe traditional 1680 mills at Zaporozhstal’ metallurgi�cal works, with an intermediate coiling system andwithout additional thermal stabilization of the strip inthe finishing cells, the thickening in section 4 may beeven greater, since the thermal conditions of the coiledstrip are not regulated [4].

In the finishing cells of the new mill design, forspecified strip thickness (section 2), thickening is onlyobserved in section 1 (the front end of the strip). Insections 3 and 4, the change in cell 10 (cell 9) is nega�tive (δhstr = –0.01…0.02 mm), since the strip is rolledwith higher temperature in cells 8 of the finishinggroup in the mills of new design (Tables 3 and 4) thanin the traditional mill, where t8 = 924°C (Table 2). Forexample, the temperature on entering cell 8 in the ten�cell mill of new design is 937°C (13°C higher). The dif�

δhstrPi P2–

Mce Mstri Mstr

2–( )+��,=

Mstri Mstr

2

ference of final rolling temperatures is even greater incell 10: 859°C as against 832°C (27°C; Tables 1 and 2).

The results for traditional broad�strip hot�rollingmills are entirely applicable to modern casting androlling systems with 5–7 four�high cells. Obviously, forcontinuous strip mills in such casting and rolling sys�tems, the installation of only three finishing cellsbeyond the intermediate coiling system (or the rough�ing group) may be expedient. The inclusion of coolingand inductive heating systems ahead of the finishinggroup permits regulation of the reduction and rollingtemperature and the production of strip with therequired mechanical properties and precision.

CONCLUSIONS

We have compared the rolling parameters of a tra�ditional broad�strip hot�rolling mill with an interme�diate coiling system ahead of the finishing group and anew design of broad�strip hot�rolling mill, in whichthe bulk of the deformation occurs in 6–7 roughingcells, with an intermediate coiling system and a pass�through induction furnace and with a finishing groupof three cells.

Even in the absence of the pass�through inductionfurnace, this configuration offers the following benefits.

(1) Increase in strip temperature by 25–39°Cbeyond the finishing cell and increase in the rollingprecision on account of the reduced thickness of thestrip’s rear end and reduced temperature gradient.

(2) The possibility of eliminating one cell in con�verting the traditional mill to a mill of the new design.

(3) Reduction in the total rolling power of the millby 15–25%, thanks to increase in the rolling tempera�ture and reduction from 6–7 to three in the number of

Table 4. Rolling parameters for 2.5 × 1250 mm 08пс steel strip on a ten�cell 1700 broad�strip hot�rolling mill of new design

Cell h, mm v, m/s εδhstr, mm

lc/hme fσfr,

N/mm2

pme,

N/mm2 P, MN M, MN m

N, kW

MN mm

tin, °C tf, °C

1 87.4 0.46 0.377 0.415 1.38 0.304 70 89.5 17.63 2.74 2591 0.28 1157

2 54.34 0.74 0.378 0.338 1.67 0.322 84 113.8 16.87 1.94 3255 0.43 1116

3 34.3 1.18 0.369 0.294 1.75 0.313 91 121.8 11.78 0.83 3123 0.49 1106

4 21.75 1.86 0.366 0.251 2.19 0.297 102 143.0 10.95 0.59 3539 0.74 1096 1087

5 14.07 2.87 0.353 0.273 2.68 0.267 114 163.3 10.05 0.39 3621 1.12 1076 1062

6 9.15 4.42 0.350 0.248 3.31 0.238 133 193.5 9.56 0.28 3980 1.69 1052 1038

7 6.22 6.50 0.320 0.118 3.86 0.207 151 215.3 7.98 0.21 4345 2.37 1029 1012


8 3.956 6.25 0.351 –0.044 5.39 0.278 196 381.0 12.91 0.21 4839 5.51 933 940

9 2.93 8.47 0.259 –0.018 5.58 0.232 200 348.0 8.27 0.10 2652 7.07 930 904

10 2.488 10.00 0.151 –0.013 4.83 0.202 191 268.3 4.39 0.06 1770 8.12 894 858


Mini

,



cells involved in the acceleration of the strip after thecapture of its front end by the coiling machine.

REFERENCES

1. Konovalov, Yu.V., Spravochnik prokatchika. Kn. 1.Proizvodstvo goryachekatanykh listov i polos (RollingHandbook, Vol. 1: Production of Hot�Rolled Sheet andStrip), Moscow: Teplotekhnik, 2008.

2. Saf’yan, M.M., Mazur, V.L., Saf’yan, A.M., and Mol�chanov, A.I., Tekhnologiya protsessov prokatki ivolocheniya. Listoprokatnoe proizvodstvo (Rolling andDrawing Technology: Rolled�Sheet Production), Kiev:Vishcha Shkola, 1988.

3. Fleming, R., Kappes, P., Rose, V., and Fogman, L.,Systems for the production of hot�rolled strip from thincontinuous�cast billet, Chern. Met., 1988, no. 3, pp. 3–13.

4. Nikolaev, V.A. and Putnoki, A.Yu., Formirovanie tolshchinypolosy pri prokatke na shirokopolosnykh stanakh (For�mation of Strip Thickness in Rolling on Broad�StripMills), Zaporozhe: Dikoe Pole, 2011.

5. Nikolaev, V.A. and Vasil’ev, A.A., Rolling on an inte�grated strip mill, Met. Lit. Ukr., 2011, no. 8, pp. 3–7.

6. Nikolaev, V.O., Mazur, V.L., and Vasil’ev, A.O., Ukrai�nian patent 70367, Byull. Izobret., 2012, no. 11.

7. Nikolaev, V.A. and Vasil’ev, A.A., Reconstruction ofcontinuous strip�rolling mills, Proizv. Prokata, 2012,no. 6, pp. 2–8.

8. Nikolaev, V.A., New production technology for broad�strip steel. Part 2, Met. Lit. Ukr., 2012, no. 7, pp. 23–26.

9. Nikolaev, V.O. and Vasil’ev, A.O., Ukrainian patent 77200,Byull. Izobret., 2013, no. 3.

10. Nikolaev, V.A. and Vasil’ev, A.A., Rational Coilboxposition in the production line of a broad�strip mill,Metallurg. Gornorud. Prom., 2012, no. 6, pp. 28–33.

11. Nikolaev, V.A., Issledovanie parametrov, sposoby iustroistva prokatki polos (Strip�Rolling Parameters,Methods, and Equipment), Zaporozhe: AktsentInvest�Trade, 2012.

12. Molchanov, A.I., Soltan, S.L., Yalanskii, V.P., et al.,Producing superthin hot�rolled steel strip at Zaporozh�stal’ metallurgical works, Metallurg. Gornorud. Prom.,2002, no. 8–9, pp. 11–14.

Translated by Bernard Gilbert

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Improving broad-strip hot-rolling mills