SU1419764A1 - Finishing group of wide strip hot rolling mill - Google Patents

Abstract

The invention relates to procagation. The aim of the invention is the operative regulation of the transverse profile of the strip by changing in the process of deformation the mutual skew of the rolls and reduction of roll wear. Rolling is carried out in the finishing group of sequentially installed multi-roll stands. To ensure rapid adjustment of the transverse profile of the strip by skewing the rolls in the finishing group, one or two double roll stands are installed with the rolls in a horizontal plane, in which, due to the absence of backup rolls, the forces required to skew the rolls during the rolling process are significantly reduced. 3 Il.1 Table. BUT (/

Description

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The invention relates to rolling production and can be used in hot rolling broadband mills.

The aim of the invention is to quickly regulate the transverse profile of the strip by changing the mutual misalignment of the roll during the deformation process, reducing roll wear.

Figures 3 and 3 show a variant of the finishing scheme of a hot rolling mill stand.

The ChSP group of hot rolling stands contains a series of quarto 1 stands and, one (FIG. 1), the penultimate 2, or two, the penultimate 2, and the preceding 3 (FIG. 2), or two penultimate 2 and a third from the start 4 ( fig.Z), two-roll stand. Cages 2 - 4 are provided with a mechanism of mutual skew of the rolls in the horizontal plane. This mechanism is made, for example, in the form of wedges located between the pillows of the rolls and the bed and hydraulically driven, or in the form of hydraulic cylinders in the bed resting on the pillows of the rolls, or in another in the ideal (in figure 1 - 3 two-roll cages x 2-4 shown by dotted line), its presence is important. For this mechanism, it is also important to calculate it for an operative change in the amount of roll skew in the process of strip deformation depending on its transverse profile. The rolls are skewed simultaneously in cages 2 and 3 and 4 in opposite directions, and the rolls are skewed in stand 2 and 4 separately. Rolling strip 5 in the finishing mill group is carried out as shown in FIG. .1-3. The clean stand group is equipped with a well-known system for automatically adjusting the transverse thickness variation of the prokashshaemaya strip, complete with, for example, a tensorball. Skew control

rolls in a cage x 2-4. is an integral part of this system.

Chistovaya group of stands ShPS hot rolling on the example of ShPS 2000 works as follows.

The group contains seven finishing glues, the pas of which, during the course of rolling, are the first five and the last (output).

in FIG. 1, or the first four and the last (knock) in FIG. 2, or the first two, fourth and fifth, and the last (output) in FIG. 3 are four-roll with 1600 mm diameter rolls and 800 mm „Support rolls - steel, workers - cast iron. The six stand in FIG. 1, the fifth and the pole in FIG. 2, and the third and the pole in FIG. 3 are double-roll with a roll diameter of 1300 mm. Forged steel rolls.

When rolling in the cages of this group, the efforts of rolling from 29 MN in the penultimate (sixth) cage to 33 MN in the third in the course of rolling the cage are allowed.

When rolling in a two-roll stand, a transverse thickness difference of Ah 2 L occurs, and is caused by the deflection of the rolls. The value of d is determined by the equation A.I.Tselikova

88 ED 12,

rolling force; the distance between the axles of the pressure screws; The width of the line; roll diameter;

moduli of elasticity and stiffness of the material of the roll.

The value of the skew angle "f of each roll of the two-roll stand in the horizontal plane (the angle between the roll axes is 2 ° (), necessary to fully compensate for the negative effect of the roll deflection on the strip profile, defined by

about {arctg

: {2i5ilij) .dhj; 4h

at

where h is the thickness of the strip at the exit,

the value of which does not significantly affect oi. In the calculations, it is assumed: h 20 mm in the third and h 5 mm in the sixth cage, E 2.15-10 N / mm A 3270 mm. The following maximum values of roll skew angles in twin roll cages x 2 and 4 are obtained to completely eliminate the transverse thickness of the strip (Jh 0) under the action of the permissible rolling force and the resulting transverse thickness of the strip:

1800

0.55 /. 72.7 0.631 77.7

In the two-roll cages x 2 and A (Fig. 1, in the process of deformation of the strip 5, according to the signal from the automatic adjustment system by the skewing mechanism of the rolls in the horizontal plane, the rolls skewed angle within the specified values.

The use of two twin rollers (2 and 3 in FIG. 2, as well as 2 and 4 in FIG. 3) in the continuous continuous rolling stock PPS group reinforces the effect of regulation. The parameters for adjusting the skew angles of the rolls in these cages are given, and the peculiarity of the adjustment consists only in that the skew angles of the rolls in stand 3 and A are mutually opposite to stand 2.

The use of steel rolls in two-roll cages x 2 -A in FIGS. 1 -3 with a safety factor equal to 5 allows, in their necks (G of the neck 0.7 D, ПЖТ), a stress of 120-140 N / mm with a rolling force 29 - 33 MN. The transition from work rolls with a diameter of 800 mm in a four-roll stand in a known solution to a roll diameter of 1300 mm in a two-roll stand leads, with the same coatings, to an increase in rolling force by about 1.27 times. However, when the distortion of the roll, there is a decrease in the rolling force by about 10%, thus, in comparison with the known solution, the rolling force increases 1.17 times, which is quite acceptable. The rolling moment is almost unchanged, since there are no losses in the two-roll cells, which are necessary for the rotation of the support rolls and for overcoming considerable friction B between the contact of the work roll and the support roll.

The use of steel rolls in twin roll cages x 2-4 in Figures 1 -3 does not improve the quality of the strip surface, however, the presence of slip between the strip and the rolls in the transverse direction when the rolls are skewed, as well as rolling in rolling cells and especially in the last output stand cast iron work rolls eliminate the need to solve this problem. In the case of higher quality requirements for the surface of the strip in KjjeTHX 2-4 in FIGS. 1-3, bandaged rolls are used: the axis is steel, the bandage is cast iron. The use of steel rolls (as well as the axis) is caused by the need to perceive the stresses that occur in its neck without destroying the roll.

The number of two-roll stands in the final finishing group of no more than two is limited by the following reasons.

The profile coming out of the third finishing rolling stand is practically not adjusted in subsequent four-fold-up cages. This makes it advisable to use a double-roll stand in this case, especially in finishing groups designed for the production of strips with the most flat profile (for example, transformer steels). However, an increase in the number of two-roll stands in the first rolling mills of the finishing cages is undesirable due to the presence of metal flow across the rolling direction and an increase in energy to the drive of the rolls.

In the last finishing cages (except for the output one), the profile adjustment is necessary to adapt the configuration of the roll coil to the profile of the incoming roll, i.e. mainly to maintain the desired profile. For this, given the great potential for influencing L, one double-roll stand with adjustable rolls is necessary and sufficient. For the same reason, two twin cages; and, installed separately, provide a complete solution to the problem, but additionally improve the band stability. Increasing the number of twin-roll stands more than two is not appropriate.

Multi-roll stands, including quarto, to a better extent ensure the thinning of the thin strip in comparison with two-roll cages, therefore the application of the latter is determined only by the task to adjust the cross profile of the strip and should not go beyond its limits, preserved by the two previous positions .

In the case of the use of the sixth four-wheel stand (1600 mm. Dp - 800 mm, with the usually existing rolling force (20 MK), the following transverse thickness difference is polo (iJh): with a width of 1000 mm -

0.151 mm; with a strip width of 1400 mm 0.168 mm; with a strip width of 1800 mm O, 110 mm.

The skewing of the work rolls by an angle (Y 30 reduces the indicated values of 4h only by 0.02-0.03 mm, but increases the slipping of the work roll in contact with the support roll by 300-400 times or more, which proportionally increases the wear of the rolls due to their contact with bias.

The use of hot rolling mills in the finishing line of a broadband mill allows to enhance the effect of adjusting the cross section of the strip and reduce roll wear.

Formula of invention

The chistovaya group of stands of a wide-strip hot rolling mill, contains hops (and the individual quarto stands, which are able to skew the rolls in the horizontal plane, are due to the fact that, for the purpose of operative adjustment of the transverse profile of the strip by changing the mutual skew rolls and reduce roll wear, it is equipped with no more than two two-roll stands made with the possibility of skew rolls in the horizontal plane and installed in the mill line between quarto stands.

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Claims (1)

Claim Finishing group of stands of a broadband hot rolling mill, 20 living individual quarto stands made with the possibility of skewing the rolls in a horizontal plane, characterized in that, for the operational regulation of the transverse profile of the strip by changing the mutual skew of the rolls in the process of deformation and reducing the wear of the rolls, it is equipped with no more than transverse strip thickness (dh): with a strip width of 1000 mm - 30 0.151 mm; with a strip width of 1400 mm 0.168 mm; with a strip width of 1800 mm 0.110 mm. two double-roll stands made with the possibility of skewing the rolls in the horizontal plane and installed in the mill line between the quarters. <pue.f Fiz 2 FIE.Z