SU1563795A1 - Method of rolling billets with initial taper - Google Patents

Abstract

The invention relates to the processing of metals by pressure and can be used in rolling thick sheets of carbon steel grades. The purpose of the invention is to increase the yield by reducing the raznosichinnost sheets. The billet, when stretching and dividing the width, is set into rolls by the bottom part in odd passages and profitable even, while individual shrinkings are chosen in such a way that the ratio of the L _d / H _cp parameters of the even subsequent and odd previous passes is at step 0, 35 ... 0.45 and 0.50 ... 0.60 at the stage of dividing the width, where L _d - the length of the arc of capture in mm

H _cf is the average thickness of a sheet in a passage in mm, and the angle of the task of rolling into rolls in odd passes with a breakdown of width is determined from a mathematical expression. The method allows to reduce the sheet width of sheets by 2%. 3 tab.

Description

The invention relates to the processing of metals by pressure and can be used in the rolling of thick sheets of carbon steels.

The aim of the invention is to increase the yield by reducing the rasterity of the sheets.

In the method of rolling workpieces with an initial taper, which includes drawing a workpiece, splitting the width using angle rolling and subsequent longitudinal rolling, according to the invention, the workpiece is set into rolls by the bottom part in odd passages and the profitable part is even, at this single reduction is chosen so that the ratio of the parameters of the even subsequent to the odd previous passage is; at the step of stretching 0.35 ... O, 45 and at the stage of dividing the width 0.50 ... O, 60, where i a is the length of the gripping arc, mm; Hc - average thickness of the sheet in the aisle, mm; and the roll task angle into rolls in odd passes with the width breakdown is determined from the expression

 / ,, f а (JL9 / HcP) 1 ± 5 °

SP

O5

w 1

coke

where if and c. - the angle of the task of rolling into rolls, respectively, in i and i-1th odd

aisles;

a - coefficient, at C / N. e 0.3 ... O, 7 a 0.75;

with ig / HCf 0.7 and 0.45.

The method is carried out as follows.

Rolling is carried out on a plate mill 5000 with a roll diameter of 1200 mm. As a blank, a sheet ingot weighing 5.0 tons of carbon steel with an initial taper of 75 mm is used.

The ingot is heated in a furnace according to the existing technology and served on a roller table in front of the mill. When rolling, the ingot is oriented in the direction of rolling with the bottom part in the first pass. Since the mill is reversible, the condition of the task of rolling into rolls by the bottom part and odd passes and the profitable part in even ones is provided.

Compression in even passages is given by a constant equal to LF 10 mm. Exodus

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from this, the computations and the angles of the task of rolling into rolls in the corresponding odd passages are calculated using a computer. This process calculates the energy and power parameters of the process. The operator in the next odd pass sets such values L N and tf, at which the load on the equipment

10 (force, rolling moment) does not exceed 0.75 of permissible. In the course of the rolling process, the computer processes incoming information about the current thickness of the roll and calculates the reduction values and problem angles in successive odd passes.

In the absence of an automated process control system at the mill (automated process control system), the calculation of the reduction modes and the corners of the roll out task can be made manually and presented in the form of technological maps of the rolling process.

25 Approximate modes of reductions and the angles of the task of rolling into rolls are given in Table. 1 (for workpieces weighing 5.0 tons with an initial taper of 75 mm). Table 1

even)

even)

490

410 400 320

310 270 260 220 210 166 156 software

80

Stage I of Protzhka 219.1

0.487

90

0.39

0.40

0.55 0.56 0.56 0.58

51

This redistribution of reductions in even and odd passes is due to the following

In the first passes, the compression of the workpiece with the original taper causes an uneven broadening along the length of the roll. Since the head of the workpiece is thicker than the bottom, the roll has a smaller width to the bottom,

It is known that when rolling sheets, the broadening along the length of the roll is uneven. In this case, the broadening at the front (along the rolling) end is greater than at the rear. Taking into account this circumstance, they give increased reductions in

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passes when rolling the billet in the direction from the bottom to the profitable. When rolling in the opposite direction, reduced compression is set in order not to aggravate the existing raznosherinnost sheet. The angle of the task of roll into rolls in even passages, as a rule, is chosen the same as in odd passes.

In order to determine the rational modes of compression in even and odd passages, 25 billets of sheet ingots weighing 5.0 tons with an initial taper length of 75 mm were rolled,

The results of the experiment are given in table. 2,

table 2

This, in turn, increases the raznospirinnost roll. At the same time, rolling a roll with problem angles close to the transverse rolling pattern (for the purpose of dividing the width) entails the appearance of barrel-shaped roll ends, which also increases the width of the sheets.

Table 3 shows the angles of the task of rolling into rolls and the corresponding razrashirinnost roll.

Verification of the proposed technical40

45

11 0.95 304.1

and the breakdown of the width, the billet is set into rolls by the bottom part in odd passages and the profitable part in even, while rolling is carried out at the value of the parameter ratio .C / Hc-, the even subsequent and odd previous passes, equal in the stretching step - 0.35-0 , 45 and 0.50-0.60 at the stage of stripping the width, and the angle of the task of rolling into rolls in odd passages with the breakdown of the width is determined from the expression

if, - VMD a () 3 t 3 °,

1 where cd and if. ) - the angle of the task roll in

rolls respectively 55v i and i-1 odd

aisles; a - coefficient: at 0.3-0.7 and 0.75;

This decision shows the achievement of the goal - an increase in yield due to a decrease in sheet raznostirinnost compared with the prototype and other methods of rolling.

The application of the proposed method of rolling billets with the original taper provides, in comparison with the existing methods, a reduction in sheet rassiness by 2%, which leads to an increase in the yield of good. Ingenuity formula

The method of rolling billets with the initial taper, including stretching, breaking down the width using angle rolling and subsequent longitudinal rolling, characterized in that, in order to increase the yield of the sheet by reducing the width of the sheets,

One value of the angle of the problem in each

the passage is calculated according to the established dependence, the other values lie outside the limits of the calculation formula. The ratios index for rolling billets at angles other than those calculated by the proposed dependence has elevated values. Thus, it is advisable to carry out rolling at the angles of the problem, calculated according to the established dependence. Table 3

w1563795lu

at lg / HCp 7 0.7 and 0.45, HSP is the average leaf thickness in where 1 is the length of the gripping arc, mm; passage, mm.

Claims (1)

The application of the proposed method, rolling billets with initial taper provides a 2% reduction in sheet width compared to existing methods, which leads to an increase in yield ₍ Formula I-inventions A method for rolling billets with initial taper, including broaching, breakdown of the width of using an angle rolling minutes subsequent pro- _t Dolni rolling, characterized in that in order to increase the yield of usable by reducing raznoshirinnosti sheets, broaching 'and disaggregated preform width is set to a the alkaline bottom part in odd passages and the profitable part in even passages, while rolling is carried out at a ratio of the parameters Ι ^ / Η ^ of the even subsequent and odd previous passes, equal to 0.35-0.45 and 0.50-0 at the broaching stage , 60 at the stage of breaking the width, and the angle of the task of rolling into rolls in odd passages when breaking the width. Is determined from the expression 4> i = W ¹ - ^a ^ U ⁿ sr) ^r ] t s », 'where cf. and f. , is the angle of the rolling task in the 'rolls, respectively, in ί and i-Ι odd passes; a - coefficient: when ί ^ / Ης, ρ = 0.3-0.7 a = 0.75; ιϋ at 1 ₉ / N _Cp at 0.7 a = 0.45, where 1 is the length of the capture arc, mm; N _cf - the average thickness of the sheet in the passage, mm