SU1411067A1 - Method of regulating the cross section of rolled stock - Google Patents

Abstract

The invention relates to ferrous and non-ferrous metallurgy and can be used in the hot and cold rolling of sheets of steel and non-ferrous metals and alloys. The purpose of the invention is to simplify the means of regulation while reducing the transverse sheet heterogeneity. It is shown that if, as a function of the width of the sheet, the location of the contact areas between the work rolls and the support rolls is transversely different, the innocence is minimized within the specified limits. The easiest way to achieve this is to roll the barrel-shaped cantilever support rolls along the generator of the work rolls. 7 il. €

Description

ABOUT)

The invention relates to ferrous and non-ferrous metallurgy and can be used in hot and cold rolling sheets of steel and non-ferrous metals and alloys.

The purpose of the invention is to simplify the means of adjustment while reducing the transverse thickness variation of the sheet.

FIG. 1 shows a stand for implementing the method; in fig. 2–4 are loading diagrams for the work roll; in fig. 5-7 - graphs of the values of the deflections given for proving the optimality of the parameters of the proposed method.

Sheet I deforms the two drive working rolls 2 and 3. In the pillows 4, cantilever support rolls 5 are installed, the position of which is determined by the pressure devices 6 in the bed 7. There are masses 8 for measuring forces. The cushions of the rolls can be turned by hydraulic cylinders 9.

In the process of continuous rolling, sheet dimensions and temperature distribution across its width are controlled. The tension distribution over the sheet width is controlled with the help of roller devices. From sheet to sheet, its width can be varied and it is advisable to change the contact points of the working and support rolls in order to optimize them. The deflection of the work rolls, determined by the one profile of sheet 1 and its transversal variation, is determined by the differential equation

tfcVC) J4 () ()

(one)

where ()) - deflection;

X is the coordinate, i.e. distance from 35

the first end of the beam {FIG. 2-4); M (k) is the bending moment;

E modulus of elasticity of the material of the roll

7 - ± --VinMPHT NNIPGGNI GGPI PNYALLRTPR N

four

moment of inertia with diameter d.

The boundary conditions W 0, at x a and x 1-a should be chosen from the conditions of optimization of the minimum transverse thickness variation, i.e. differences in deflections along the edges of the sheet and in its center (movements of points M and N, Fig. 1, due to deformation of the beds, cushions of support rolls 5, etc., change only the longitudinal thickness variation).

Consider three workload loading schemes. Under the action of a uniform constant load (Fig. 2) and force P, the deflection of the ends of the beam (point A)

 - 07 (+) (2) and its midpoint (point B),

W, Pl g (+ 9GU2-64U -

16U)

(3)

where is constructive

dimensional parameter.

You can write

without a beat

Q

50

Q

five

five

0

five

0

five

W, f. (U) and W, ffJU), where the dimensionless functions ft (U) and fi (U) characterize the influence of the coordinates of the support points of the beam on its deflection and the transverse thickness variation of the bar.

In the case of P-const

fi (U) 4.15-10-2 (U-6U2-heif + u); ft (U) 0.26-10-2 (5--40U-f 96U2-641 / - -IW) (4)

The graphs of the functions f (U) 102 are shown in Fig. 5, curves b and b characterize the lines corresponding to fi (U) and f (U).

It is seen that as the supports approach, the deflection W increases, then decreases, becomes equal to zero (with U = 0.215), changes sign and increases (to f / (U) 0.78-10-2 with support in the center of the beam). The deflection W also decreases with, and 25 also changes sign. Optimum, from the point of view of reducing the thickness difference between the edges and the center of the beam, the case takes place at Uo 0.23, then fi (U) f2. (U). In this case, the deflections in the center and along the edges are equal, the maximum thickness difference does not take place between the center of the sheet and its edges, but between the center and thickness in the intermediate sections, and the difference itself is very small. Deflection, 5xlO at U, 23, it is less than when supporting the barrel rolls 2 and 3 along the edges, 51 times and less than when supporting the work roll in its center, 31 times. The transition to controlling the sheet thickness by moving the pivot points to the side of the work roll in their optimal range results in a reduction in the transverse thickness variation (30-50 times). In the known method, with the usual stand construction, the support rolls can be shaped in such a way that the work rolls are supported on them in sections located 0.5 (1-Uo) 0.385 from the center of the barrel, i.e. to have optimal conditions for the interaction of the rolls, but they are broken during the transition to rolling a sheet of a different width, since changing the points of support without machining the support rolls (or using complex bending systems) is impossible. In the proposed method, by rolling the support rolls over the workers, it is easy to maintain optimal conditions at various values of the sheet width. In fact, the pressure distribution across the width of the roll barrel may not be uniform and can be evaluated as deviations from such an idealized scheme that may affect the efficiency of the proposed method. Let us accept (Fig. 3) the pressure distribution according to the linear law P (x) with the maximum value of the RGP in the center of the barrel.

In this case, as a result of the calculation of the deflections,

f, (U) 0.52-10 -2 (-5U + 24U2-24U - -4f-U); (5)

f (U) 1.67-10-2 (1-L-U + 15U2 -20).

The graphs of the functions fi (U) and {a (U) are shown in FIG. 6, from which it is clear that the zero difference between the deflections of the sections x 0 and X 0.51 takes place at U Up «0.31. The linear law is applied with a maximum pressure of RT at the edge of the roll barrel and decreasing it to zero in the center, i.e.

Р (х) Ргг, (1--) Р 0,5Р,

receive the distribution of the deflections, according to the functions

U (U) 3.14-102 (-U + 8U2-8U - | -U4

-f

iC

15

s)

f (U) 0.94-10-2 (1 -lOU-f-5-U2 - i 5- and j

. + U-)

The fi (U), f2, (U) plots for this case are shown in FIG. 7 and according to them (and) U (U) with and Up 0.17.

For all cases, refined calculations were performed taking into account the effect of shear forces. In this case, the deflections increase by

I 1 1 Ft /

gle j elastic modulus of the second kind;

F is the section area. This value is for steels of the order (1-f

. "

-f 0.17) and, for example, with a roll diameter

600 mm and a length of 1200 mm is equal to the factor. It follows from the calculations that, 17-0.31, there are almost no cases when the pressure is zero in the center of the sheet or on its edges. Extreme cases of loading are considered to determine the parameter Uo, which can be taken within 0.20-0.28, and the distance of support points of the work rolls from the middle of the sheet (and barrel) will be (0.22-0.30) . This justifies the choice of parameters

thickness control sheet. If, using the values of pressure in the center of the sheet P and along its edges Pg, enter a dimensionless parameter equal to the ratio of the pressure difference - 5 SRI to its average value

A, then Up 0.24 + 0.02 A, (7)

and the distance of the pivot points from the central

The 10 axis of the sheet will be C 0.26-0.02 A. The higher the pressure in the center of the sheet, determined experimentally by rolling data in previous cells or by calculations based on measurements of temperature and residual,

however, the points of support should be moved closer to the center, according to the linear equation (7). This will provide Uo values of 0.20; C 0.30 with P 0, A -2.0 and u = 0.28; C 0.22 at P. 0 and A 2.0.

Only symmetric deformation was considered, but a case is possible when, due to uneven heating of the sheet or its thickness variation, the forces on the two support rolls 5 are not equal. Because of this, the deformations of these rolls and beds are different. If these

25, the forces are equal to Е and Е., That are registered by months and 8, then the displacement of points M and N (Fig. 1)

and, 1- and U, J-,

30 where., Co-rigidity of the system, including rolls, pliers, pressure devices and beds.

In order to eliminate the misalignment of the work roll 3, which would reduce the dimensional accuracy of sheet 1, the point M with the support roll 5 is moved vertically (at 1 E) by

di

Uo

(eight)

which compensates and eliminates the negative effect of pressure asymmetry on roll 3 from the side of rolled sheet 1.

Example. A 2000x2600x250 mm steel sheet is rolled in a stand of 3600. The first broach is performed with a reduction from 250 to 200 mm and an elongation

up to 3250 mm. The width of the sheet is 2000 mm and, according to the readings of the temperature sensors and the thickness, the pressures in the center of the sheet and along its edges are equal. Since Pi P2, then A 0; C 0.26 (according to

equation (7)) and the distance from the center of the barrel (and the sheet with its precise centering) to the points of contact with the rolls 5 is 520 mm, and the distance between points M and N is 1040 mm. After that, the sheet is rotated 90 ° and rolled along a length of 2000 mm with

with a width of 2,600 mm, and with a reduction from 200 to 40 mm and an elongation of up to 10,000 mm. The distance of the contact points of the work rolls with the supporting ones from the center of the barrel is maintained at 675. mm, for which they are turned to an angle of 0.026 (1 ° 30) with the radius of the sphere by rotating the support roll cushions. In this case, in the first pass, massdose 8 shows the difference in the forces on the supports, equal to J, -1 8.MN with the rigidity of the Co 10 system, therefore the roll 5, on which the force is higher, is moved in the direction of decreasing the thickness of the sheet by and 0.8 mm When rolling a sheet in the roughing group of stands in them, the support rolls are held with a distance of contact points from the axis of the sheet equal to 675 mm. In the last two cages, the temperature sensors show edge cutting at 80 ° C relative to the center of the sheet, which increases the pressure on them by 1.2 times. At the same time P 1,2 Rt and A - 0.18; From 0.2636, and the distance from the center of the barrel to the support points of the work roll in these cages increases from 675 to 685 mm, i.e. 10 mm by turning the pad at an angle of 1.65x10 (b). Rolling does not require as much force and moments as the axial rotation of the rolls, and the system will therefore be less inertial. This example does not exhaust all possible uses of the method, which can be used during cold rolling, as well as

in automatic control systems. In this case, the devices for turning and moving the support rolls are the actuating mechanism. If the sensors give information about changes in the input parameters, the computer determines the values of P, P, A and C, i.e. the optimal location of the work roll supports, and gives the executive mechanism a command to turn the support rolls (and

their movements).

Thus, the proposed method allows simple means to reduce the transverse thickness variation of the sheet.

Claims (1)

Invention Formula The method of adjusting the cross section of sheet metal, which includes the locally forceful impact on the working roll barrel from the sectional support rolls and changing the distance between the force points by axial movement of the rolls, characterized in that, in order to simplify the means of adjustment while reducing the transverse thickness difference - sheet, the distance between the points of force change as a function of only the width of the sheet, keeping it within 0.44-0.60 width of the sheet. 2 J {u) -10 P const 0.4 a / 0,2 az FIG. five ( L m s FIG. 3 Fy 0.4 0.5 and -ten / 0.1 0.2 FIG. 6  fjuHO P-Pm (1 0.3 QM 0.5 and