SU1731303A1 - Method of rolling slabs from ingots - Google Patents

Abstract

The invention relates to rolling production, in particular, to rolling slab from ingots on reversible blooming-slabs. The method consists in the fact that by rolling a flat in each passage, the reduction is made variable in width, increased at the edges. Rolling on the central part of the smooth barrel, equal to 0.45-0.6 of the width of the roll, is carried out with a constant compression, and the edge parts - with variable compression, chosen from the relation. The method allows to improve the quality of slabs. 3 il.

Description

(L

WITH

The invention relates to rolling production, in particular, to rolling slab from ingots on reversing mills.

The aim of the invention is to save metal by reducing the bottom edge.

Figure 1 shows the rolls and roll when rolling the wide faces of the roll on a smooth barrel of the proposed method; Fig. 2 shows the cross-sectional shape of a roll after rolling on a smooth barrel according to the proposed method; on fig.Z - scheme of the proposed method.

The method is carried out as follows.

The ingot is supplied by the working roller table to the crimping stand and set into rolls by the bottom or profitable part. Several passes are made on the smooth part of the barrel with reversing rolls, roll and working roller table. In order to create a degree of deformation uneven across the width of the roll, for example, on the smooth part of the barrel, concave profiling having a cylindrical central part of a length of 45-0.60 from the maximum width of the rolls B and two lateral conical sections with diameters at a distance of 0.5 V are made. from the axis of rolling, it is 5 times larger than the diameter of the cylindrical part (figure 1). When compressing the wide edges in the first pass, the lateral conical sections create a compression A hK at the edges of the roll, which is more created by the cylindrical part of the compression barrel of the bottom center in the roll. Because of this, the degree of deformation of the edges to higher than in the central part of the piece EC (figure 2). As a consequence, the stretching of the side parts more than the central ones, this leads to filling the corners at the ends of the rolls, i.e. to eliminate the convexity of the ends, which is formed due to fan-like broadening in the unsteady rolling stages.

When compression of wide edges in subsequent passes, the difference Ј to and e occurs

vi

WITH

CO O CJ

due to the difference in the thickness of the roll at the edges and in the center (with the same absolute reduction of x), since the thickness at the edges is less than in the center, then ec Ј c.

The minimum difference in reductions, 036 (B-a) ensures the alignment of the ends when rolling slabs of maximum widths (i.e., 60), the maximum is 5½ 0.10 (B-a) - when rolling slabs of minimum widths (a / 0 45).

The necessary for alignment of the ends of the difference values of the reductions 5h, the width of the edges (B-a) / 2, on which the variable compression is performed, and the relationship between dh and a / b was found experimentally.

After making several passes on the smooth part of the barrel, the roll is turned 90 ° around its longitudinal axis and rolls onto the rib in several passes in the caliber. Then the roll is again turned by 90 ° and is rolled to a predetermined slab thickness on the smooth part of the barrel. At the same time, the fan-shaped broadening formed is compensated for by an increased degree of deformation of the edge of the roll. The smaller the thickness of the rolled out slab, the greater the total degree of deformation over the wide edges of the roll and the greater the convexity of the ends. However, the smaller the slab thickness, the same for the same difference in absolute reductions between the center and the edge, defined by the profile of the smooth part of the barrel and the width of the roll, for slabs of lesser thicknesses, the difference in the degrees of deformation

Apk

hi-i

Ahl

hi-i

where hi-i is the thickness of the roll before the i-th pass.

Therefore, the difference in stretch widths is greater, compensating for the increased end convexity. On the contrary, for slabs of large thickness, the total (for all passes through wide faces) the degree of deformation is less than that for slabs of lesser thickness. Therefore, the convexity of the ends is smaller, however, the difference in the degrees of deformation in this case decreases. Consequently, there is no excessive compensation leading to the formation of concavity of the ends, the elimination of which is also accompanied by an increase in the face cut.

After rolling in the pressing stand, the rolls are transferred to the shears, where the uneven ends are cut and cut to length. Bottom trim size

depends only on the roughness of the ends, so the rolls, rolled by the proposed method, it is less, resulting in reduced metal consumption in the production of 1 ton of slabs.

Variable width of roll on the specified dependence compression can be created not only by concave profiling of the smooth part of the roll barrel

0 on the blooming SL Bing. The same effect can be achieved if the smooth part of the upper roll barrel (Fig. 3 a) has, for example, a tapered section with a maximum diameter at a distance of 0.5 V from the axis of the roller, equal to 2-5. and a length of (B-a) / 2, and the rest of the part of the smooth barrel is cylindrical, and the smooth part of the barrel of the lower roll has the same conical section to the right. The efficiency of the method can be significantly increased if, in this case, the rolls can move axially one relative to the other (Fig. 3b). In this case, it is possible to smoothly change the value of the difference in reductions and the width

5 near-edge sections with variable crimping, to achieve complete alignment of the ends in the whole range of variation of thickness and width of slabs rolled in this mill.

0 PRI me R. On the blooming-binge 1250 rolls would be 220x1050x1800 mm out of 780x1210

ingot

h2580 mm.

660x1135 In accordance with the indicated formula 5, choose the elements of profiling of the smooth part of the barrel with a length of mean value 5n / (B-a) 0.068 and, 52 with the most user-wide slab width mm. From here, 52 1050 546 mm; 0, 068 (1054-546) 34 mm (the difference in diameters at a width of 0.5 and in the center).

Since, then the difference in diameters at the edge of the smooth part of the barrel and at the center D0 / 0b-a) h / (B-a). From here a d bk x

5 .54, hmm. (ti -a)

When rolling slab ba 200x1050 x 1800mm by a known method, i.e. at 5h 0 due, bottom end bulge arrow

0 is equal to an average of 224 mm. When rolling with variable crimping according to the proposed method with the maximum difference in compression (mm, the bulge of the end disappears (residual arrow foci has a slight concavity, 0 mm.

At the lower boundary of the controllable parameter (slab 150x1200 mm), there is some undershoot of the bulge (), and at the upper boundary - reclamation (focr 24.0 mm). This is due to the fact that the profiling of the smooth part of the barrel is chosen to be the most commonly used slab width mm. However, the underexposed and converted values of the convexity of the ends are small and are comparable to the tolerances for cutting the ends with scissors.

If the profiling is chosen so that the controllable parameters are below the lower and above the upper boundaries of the controllable parameters, then the f0cT4 170 mm residual boom and 64 mm focrs (convexity conversion) become significant.

The economic effect from the implementation of the proposed method can be estimated by reducing the metal consumption during rolling slabs on the blooming-slab. When rolling by a known method, the size of the bottom cut is 2-3% of the mass of ingots specified in rolling. The proposed method, the length of the cut off bottom end can be reduced to the size of the allowance for cutting with scissors, i.e. by 80-90 mm. The average for the range reduction in the length of the cut ends is 50-60 mm, which reduces the metal consumption by 0.7-0.8%. In the blooming slab 1250, for example, about 1,700 thousand tons of sheet ingots are rolled per year, of which about 800 tons have a significant bottom edge. Reducing bottom trim will give an annual economic effect.

g

(Ci-C2), where A 8000000 - the volume of production, t;

L, 7-0,8% (0,007-0,008t / t) - specific reduction of metal consumption;

Ci is the cost of 1 ton of slab, rub.

C2 - the cost of 1 ton of trimming, rub.

The proposed slab rolling method can also be used on slabs mainly in the production of blanks for plate and semi-continuous broadband mills.

Claims (1)

Invention Formula The method of rolling slab from ingots, including rolling wide edges of roll on a smooth barrel and narrow edges in caliber, characterized in that, in order to save metal by reducing the bottom cut, rolling on a smooth barrel of the central part equal to 0.45-0.60 the width of the roll, lead with a constant compression width, and the near-edge areas with variable compression are selected by the ratio ,18. where 5b is the value of variable reduction at the edges of the roll, mm; B - width of the central part of a smooth barrel of roll, mm; and - the width of the whole roll in the bottom passage, mm. at 9g1 2