SU1250339A1 - Prestressed working stand - Google Patents

Description

The invention relates to the main equipment of rolling mills, in particular, section and strip mills.

The purpose of the invention is to expand the technological capabilities of the stand by ensuring the rolls are diluted with preservation of its tightening forces.

FIG. 1 shows a crate in working position; in fig. 2 is a view A of FIG. 1 with a partial cut; in fig. 3 shows the node I in FIG. 2; in fig. 4 — elastic characteristic, for a package of plates in coordinates (force P — deformation X); in fig. 5 - the same for the stand.

The cage includes the upper 1 and lower 2 work rolls with cushions 3 and 4, the yoke 5 and the base 6, connecting, respectively, the upper and lower cushions, tightening bolts 7 with the hydraulic nuts 8, which provide the preliminary tightening of the cage. Gaskets 9 of coarse radial installation of rolls are placed between the pillows and coaxially with bolts 7 of the compression spring 10, tightened to a force exceeding the weight of the upper set of pillows with rollers, and a mechanism of radial mounting of rollers with eccentric sleeves 11 is built into the pillows. 3, packages of plates 12 are installed, bent in the plane of application of the load by a pre-tightening force, which are separated in the middle of their height by spacers 13, and along the loaded ends, tightened by bolts 14, are separated by spacers 15. In each upper cushion, there is a mechanism for transverse bending of plates in the form of hydraulic plungers 16, embedded in cylindrical bores 17 of pillows 3, which with one end are directed to the pressure cavity and the other to the side surface of the plates, and the axes of the plungers are perpendicular to this surface .

The prestressed stand is assembled by tightening the pillows 3 and 4, the crosspiece 5 and the base 6 by bolts 7 using the hydraulic nuts 8 when pressure is applied, which provides the tightening force Re by 1.4-1.5 times the maximum technological force at rolling - Pmax: Pz (1.4-1.5) Pmax. At THIS, the thickness h of the plates with dimensions L, B, H (Fig. 1 and 2) is determined from the condition of their longitudinal bending to the deflection boom / o (0.03-0.05) L, which corresponds to the approximation of the loaded edges of the plates by only L about "(0,002-0,006) L (Fig. 3):

| V

-Y) Rz

EVN

(one)

where .J, V is the modulus of elasticity of the material of the plates and the Punch coefficient, respectively.

The volume of V plate packs almost does not depend on the relationship between the overall dimensions of L, S and I and with sufficient accuracy can be represented as

Y -. P -

(2)

where X is the greatest longitudinal approximation of the supporting edges of the plates, equal to the working stroke when lifting the upper roll;

0 (f - the limit of elasticity of the material of the plates.

The thickness h of the gaskets 13 and 15 between the plates is determined from the condition of the free provision of the working stroke X, at which the cross sections of the plates are rotated through the greatest angle f (l / cos (p-1), (3)

Where

(p 2arcsmV2 (0.5-l / 0 5-0.5 - {+ 0, 125 (7) (4)

Expressions 3 and 4 are derived from the updated Mises equation for lateral deflection.

with 2LV2 (PH-b) Pz, g - gr;: 7

nFiT

where Рз, / н is the puffing force and the force of the end of the package operation, respectively, of the equation relating the greatest stroke

and transverse deflection of the plates.

/ V4LJt - exact buckling equation

,

with a plate height of L 60–150 mm, which can provide a working stroke X (0.10–0.12) mm, sufficient to protect modern varietal and strip mills and to open pre-stressed stands, the X value is only (0.002- 0.006), 12-0.9 mm, respectively, at / 0 (0.03-0.05) L. Such values / o are best, since at 003L it is difficult to control the straightening of the plates while weakening the cage tightening force. and, at 05L, the working stroke X of roll 1, which is necessary for opening the crate for technological reasons or and its overload.

The force P3 is two orders of magnitude greater than the maximum compressive force of the springs 10; therefore, when rolling with forces not exceeding P3, the rigidity of the stand — Co (Fig. 4) is very high and is determined only by the rigidity of the roll block with the pillows.

In the event of a possible weakening of the tightening torque of the stands during operation to the Pmax value, for example, due to relaxation of stresses, the plate 12 is straightened,

which will indicate the need for tightening the bolts 14.

If it is necessary to open the cage during operation, i.e., dilute the rolls, for example, to skip the roll without crimping, the plates 12 are bent using the plungers 16 of the transverse bending mechanism by supplying fluid to the bore cavities 17. At the same time, the springs 10 compress, straighten cushion, lift the upper roll with cushions. The rolls are automatically collapsed when the fluid is depressurized.

Due to the use of a package of plates 12 with gaskets 13 in the middle of their height L and with gaskets 15 at the ends, bolted 14, the required force of bending them to the deflection boom / corresponding to the rolls solution / 3 / is only (as the sum of the forces for the clamped ends beams loaded in the middle of the length)

RT (5)

 the total required cross-sectional area S of the bores 17 at a fluid pressure (P) is equal to

32EBHh4X (6)

In emergency situations associated, for example, with the gripping of the quenched end of the strip, a fold on it, etc., the plates 12 are longitudinally bent, the joint between the upper piece 3 and the gaskets 9 is opened, i.e. the upper roll is almost instant

five

but (the lag time does not exceed the time limit; the luperiod of the natural oscillation frequency of the prestressed stands (0.0001-0,0002 s) rises). With

Thereby, the rigidity of the cage drops by 5-6 orders of magnitude and even when the upper roll 1 is raised by the value X (0.10-0.12) L, the force in the cage cannot exceed the value PH (1.05-1.06) Ps. It should be noted that the accuracy and stability of limiting emergency loads in the stand is almost independent of the accuracy of manufacturing the plates 12 and is determined by the stability of the elastic characteristics - E h, which for elastic steels and alloys do not depend on the operation time, loading rate, temperature and other factors.

Thus, the proposed pre-stressed stand provides stable and reliable protection from emergency loads while simultaneously ensuring the rigidity of the stand, the possibility of its opening and control of the pre-tightening force, which makes it possible to choose a tightening force 1.5-2 times lower than in comparison with the known stands (i.e., reduce the dimensions of the stands) or, with a given tightening force, increase the load capacity of the stand 1.5-2 times.

The technical and economic effect of the implementation of the invention is formed by reducing accidents, downtime of rolling mills, increasing their maneuverability, as well as reducing the dimensions of the stands at a given load capacity or increasing the load capacity at given dimensions.

fpueZ

sri.Z

ABOUT

PP (0.002-0.006) L

Phie. 4Pf .Ob} P

X (0, W- 0.72U

РЗ

 GO-} S o

FIG. five

Claims (1)

A PRELIMINARY TENSIONED ROLLING CELL, comprising a base, upper and lower rolls with pillows and compression springs between them, a mechanism for radially installing rolls with eccentric bushings, a crosshead connecting the pillows of the upper roll, coupling bolts with hydraulic nuts integrated therein, characterized in that, for the purpose of expanding the technological capabilities of the stand by providing rolls with preservation of the preliminary effort of its tightening, it is equipped with packages of plates installed between the pillows of the upper roll and traverse d and curved in the plane of application of loads by the tightening force of the coupling bolts to the deflection boom equal to 3-5% of their height, and each pillow of the upper roll has a lateral plate bending mechanism made in the form of a plunger hydraulic cylinder mounted perpendicular to the side surface of the plates, between the plates the package in its middle part and at both ends interacting with the traverse and the upper “cushion”, gaskets are fixed, equal in length to the plates, with a thickness h \ ^ h (\ / cozy – 1), where h is the thickness of the plates; φ is the largest angle of rotation of the cross section during bending of the plates. SU ... 1250339 FIG