SU1404127A1 - Working stand - Google Patents

Abstract

The invention relates to metallurgy, more specifically to rolling production, and can be used to improve the design of hot and cold rolling mills. The purpose of the invention is to improve the quality of the rolled strip by reducing torsional vibrations. In the drive line of a known stand, under the action of disturbances from the working and support rolls, torsional resonance oscillations occur, consisting of two frequencies: the frequencies of rotation of the workers and the frequencies of rotation of the support rolls. With the onset of resonant oscillations, the amplitude of the moment of elastic force increases significantly to 50–70% of the established moment, which negatively affects the rolling process and the quality of the rolled strip. In the proposed stand, the diameters of the rolls of the drive shafts of the drive line are chosen in accordance with a certain ratio. 3 il. in cl

Description

The invention relates to metallurgy, more specifically to rolling production, and can be used to improve the design of hot and cold rolling mills.

The purpose of the invention is to improve the quality of the rolled strip by reducing torsional vibrations.

FIG. 1 shows the rolling mill line, general view} FIG. 2 - oscillogram of the moment of elastic forces in the drive line of the base stand during rolling at a working speed of 7.5 m / s, on. FIG. 3 - calculated oscillogram of the moment of elastic forces in the drive line of the proposed stand.

The rolling stand contains frame 1 (pressure devices not shown), work 2 and 3, and support 4 and 5 rolls with pillows and individual drive lines 6 and 7 of the upper 2 and bottom 3 work rolls. The drive lines include electric motors 8 and 9. Intermediate shafts 10, reducer top lines with gears 11 and 12, reducer bottom lines with gears 13 and 14, spindles 15 and 16, and connecting elements. In the rolling stand, the dimensions of the rolls 10, spindles 15 and 16, and the diameters of the working and support rolls are made in accordance with the proposed ratio.

Offer crate works as follows.

The motor 8 of the drive line of the upper rolls 2 and 4 is connected to the latter by means of an intermediate shaft 10, the drive 11 and the driven gear 12, the shaft 10 of the driven gear 12 and spindle 15, the electric motor 9 drives the lower rolls 3 and 5 connected to the latter by the drive gear shaft 10 13, gears 13, which are engaged with the driven gear 14, and spindle 1. Through these elements, rotational movement and torque from the coil engine 8 and 9 are separately transmitted to the work rolls 2 and 3, respectively.

Dynamically, the rolling stand with an individual drive of M07KNO rolls should be represented as a series of three-mass equivalent calculation system: the first engine is the rolls. The upper and lower workers and the supporting ones are the second engine. The system has two natural frequencies

These are determined by perverted formulas.

If the system is affected by disturbances, the frequencies ji, and jij or multiples of them, then a resonant mode appears in it, characterized by a significant increase in the amplitudes of the oscillations.

In the rolling mill, such disturbances are the beats of the working and backing rolls, due to the quality of their manufacture (eccentricity, ovality, etc.).

The beat frequencies of the reference COf and the work rolls are proportional to the rolling speed V and are determined by the formulas

2 / o „:

2V / Dp

(12)

where Dg and Dp are the diameters of the support and work rolls, respectively.

The condition for the occurrence of resonant oscillations, when at a certain speed occurs the simultaneous coincidence of the beat frequency of the support roll of CO2 with the first natural frequency of the drive line b and the beat frequency of the work roll Up with the second natural frequency b of the drive line, is written as

About p- J WP,%.

(3) (4)

The obtained expressions are combined into one, and taking into account (1) and (2), we obtain the condition for the occurrence of resonant oscillations

45 Uo / Dp,

(five)

0

five

When conditions (5) are performed in the stand, resonant modes appear at several rolling speeds. The physical meaning of this is that each harmonic of the beats of a roller system at its speed can cause an increase in the amplitude of oscillations, i.e. resonance. For example, the eccentricity of the barrel rolls occurs when the main rolling speed is proportional to the reverse frequency of the rolls, the second harmonic of the support rolls and the ovality of the work rolls about 1404127

are at a rotation rate of two times less than the main one, etc.

Therefore, to avoid resonant oscillations, it is necessary that a different ratio be satisfied.

K, .D, / Dp-p, / p, K2., (6)

where the coefficients K and K characterize the degree of distance from the resonance. When carrying out the dimensions of the shafts of the drive line and the diameters of the work rolls and the support rolls, in which relation (6) is observed, the torsional vibrations are almost completely eliminated.

and thereby the quality of the rolled strip is improved.

Using the known formulas for calculating the natural frequencies of a three-mass system, formula (6) in the transformed form is written as follows:

8., - the moment of inertia of the roll system of the working stand (two workers and two bearing wells).

Further transformations (9) take into account that identical electric motors are used, i.e. Q 9 9, therefore receive

WITH,

m

(1 + m)

AiLlAl.

(1 + 9)

(ten)

where m e ,,,

  9g / 9. .

Compliance e and ej according to known formulas are expressed through the geometrical dimensions of the shafts and spindles in the engine-gearbox and gearbox-rolls of the rolling stand

25

where a is a known quantity depending on the parameters of the three-mass system,

and make up the ratio (t. PI

R,

1 + 41 - 4С,

 - l | 1 - s;

(eight)

The expression for the value of C, has

view:

(9)

reduced to the work rolls, the compliance of the drive line of the upper rolls;

reduced to the work rolls, the compliance of the drive line of the lower rolls; reduced to the working rolls the moment of inertia of the engine drive lines of the upper rolls;

reduced to the working rolls the moment of inertia of the engine drive line lower rolls;

thirty

35

40

45

m m

50

55

where D, is the diameter of the shaft between the motor of the drive line of the upper rolls and the drive gear of the gearbox,

Dj - diameter of the spindle drive line of the upper rolls;

DJ - shaft diameter between the engine and the drive gear of the gearbox drive line of the lower rolls

D. - spindle diameter of the drive line of the lower rolls J

L, is the distance between the motor of the drive line of the upper rolls and the drive gear of the gearbox;

L is the distance between the driven gear of the reducer of the drive lines of the upper rolls and the rolls of the rolling stand

L is the distance between the motor of the drive line of the lower rolls and the drive gear of the gearbox,

L4 is the distance between the driven gear of the gearbox of the lower drive shaft line and the rolls of the rolling stand i is the gear ratio of the gearbox, the same for the upper and lower drive lines. In the absence of gear i 1 i

5I40A1

% some coefficient used in the calculation of compliance.

As a result of conversions for, the ratio m -. get the expression

m

L4

(eleven)

Thus, a final ratio is obtained.

To p / p -11, - o „/ BP -g

 -.

K.DjDp,

(12)

where the value of C depends on the sizes of the shafts and spindles and is calculated from dependence (10) using dependence (11). At the same time About With. 0.25.

.Example. A fifth rolling stand of the continuous cold mill 1400 of a cold rolling strip, on which a steel strip with a width of 1050 mm and a thickness of 0.35 mm with a recess of 0.12 mm at a speed of 7.5 m / s, is taken. Natural frequencies of the drive line of this stand J5i 25 1 / s, / 3 60 1 / s. The diameters of the rolls DQ 1400 mm and Dp 600 mm.

Shaft lengths and diameters L, 10,800 mm L - 5,500 mm, L, 2,500 mm, L 6,900 mm, D, Dj 300 mm, D .. D 260. mm, i 0,685, Q 2.9, 9 4.9, At By rolling at the working speed on both spindles, substantial torsional vibrations occur (Fig. 2) with an amplitude of 20-50% of the average torque value with two frequencies of 26 1 / s and 62 1 / s. In the known stand, the doubled frequencies of rotation of the support and work rolls coincide with the first i, and the second Z., with the natural frequencies of the drive line, i.e. done

condition (5) PI // 3 | 2.24 -D./D 2 - C, 0.134.

DO / DP 2.33. At the same time m 0,536,

In the proposed stand, the shaft diameters are L,, L and Lj, 1.4. and the rolls are made as follows: D (Dj 360 mm 250 mm, DO 1500 mm, D 500 mm. At that, m 0.749, C, 0.144, fi, / | 3, 2.1, De / D 3, K.

,

0

five

0

five

Q

d.

0

276

 0.8 and the right part of condition (12) is fulfilled: 2.1 0.8i3 2.4.

When simulating the rolling process in the proposed stand together with the torsion system of the drive line on computer, the torsional oscillations practically do not occur with the indicated reductions (Fig. 3),

The ranges of variation of the coefficients K and K are selected taking into account the following factors. With K, 0.8 and K 1.2, the forced frequencies ODo P and the natural frequencies p, and differ by at least 20%. As the research results show, in this case the dynamic component of the torsional oscillations decreases significantly (by a factor of 3-5). The possible range of variation in the ratio of the diameters of the rolls of the stand due to their regrinding during operation is 15%. The error in the calculation of natural frequencies by known methods can lead to the determination of the ratio of Pr by an error of up to 15%. Therefore, the smallest value of K | and the highest value of Kj is: K, O, B - 0.85 0.6 Kj 1.2 - l 1.15-1.15 1.6.

In practical cases, when designing new mills, as well as when the work and support rolls are made with the ratio Dg / Dp 2, it is preferable to observe equality in the left part of the relation (6) and the coefficient K, to take equal to 1.6. In this case, the maximum eigenfrequency separation is achieved, and ft, which is most beneficial in terms of improving the dynamic properties of the stand.

If Du / Dp 2, it is recommended to observe the equality on the right side of the relation (6), and the K coefficient to be equal to 0.6.

The drive line of a known stand is a variable component of torsional vibrations (moment of elasticity ciin), taking into account the presence of two frequencies

five

uM (, .t + .a.,. sin, e, t

.calls an additional component of the linear speed of the rolls, equal to

uV (t) (, p, cos3, t + + V, o ra, piCosB t) / C,

a ,,; —the relative amplitudes to the vibrations are steep about the torque at frequencies B, and f5 (a, 0.3–0.7; a. 0.1–0.3);

. drive line frequencies:

M

J. - average value is cool P

The current moment is the rigidity of the drive line R, and r is the radius of the support and work rolls, respectively.

According to the calculations for the fifth stand of the cold rolling mill 1400 (R 0.7 m, g 0.3 m. Measures 50 kN m; a, 0.5; a 0.1; C 2240 kN / m) the maximum value of the roll speed deviation control DN 0.042 m / s

As a result of the occurrence of a periodic component of the speed of the roll, slippage occurs between the work roll and the support roll, which increases their wear and slippage of the work roll relative to the strip and appears on the last prints, which degrades the quality of the strip. In addition, torsional vibrations lead to periodic fluctuations in rolling force and, accordingly, to longitudinal thickness variations.

These periodical prints along the length of the strip have two periods T, and Tj, which correspond to two oscillation frequencies of the rolls p, and j, T, 2irV // b,, T, 2irV / 3j. At a rolling speed of V 8m / s, periods T, 2 m, Tj. 0.8 m

Thus, when rolling a strip in a known stand, as a result of slippage due to torsional vibrations of the rolls relative to the strip, transverse tint stripes are formed, distributed in steps of 2 m and 0.8 m, which degrade its quality and affect the processing of the strip. in the subsequent redistribution. In multi-cell mills, the observed phenomenon can occur simultaneously in several cells, in which case the deterioration of the quality of the strip surface is aggravated.

Technical and economic advantages of the Invention consist in the fact that during rolling in the proposed adhesive, where the diameters of the shafts of the drive line and the rolls are made in accordance with the relation (12),

.-

periodic torsional vibrations are eliminated, slip and rolls are absent, therefore there are no periodic transverse strips on the strip, the quality of the strip is improved, the rolling process is stabilized and the dynamic loads in the drive line gears are reduced.

Claims (1)

1. - the distance between the driven gear of the line reducer at 9.1404127 water of the upper rolls and rolls of i-kami rolling stand, - the distance between the motor Tv - the drive line of the lower rolls and the drive gear of the gearbox; - the distance between the driven gear of the reducer of the drive line of the lower rolls and the roll K of the rolling stand K ta cr eleven Lz GI " j- ijiJll FIG. Editor I. Shulla FIG 3 Compiled by I.Skoroboratsky Tehred M. KhodanychKorrektor O. Kravtsova 1 o gear ratio gearbox; the ratio of the moment of inertia of the roller system of the cage to the moment of inertia of the electric motor reduced to the work rolls 1,2-. 1.5, 0.6 - 0.8. " .- . " 0U./ m