RU2504444C1 - Method of lengthwise rolling tree-roll stand roll pass boring - Google Patents

Abstract

FIELD: process engineering.

SUBSTANCE: invention relates to metal forming and can be used for making passes in stands of reduction and gaging mills. Proposed method installing and attachment of the stand body with roll at stand bed and boring the pass at rotation of rolls. Detachable support plate with opening not closing the pass is attached at stand body. Said detachable support plate has guide holes made above the butt of roll flanges with maximum distance from rolling axis to receive spacer wedges with inclination angle of 0.2-0.3 rad at one end. Straining force is applied to opposite end for boring the pass.

EFFECT: adjustment of clearance made in roll production and operation.

4 dwg

Description

The invention relates to the field of pipe production, and more specifically to a method for bore gauges of rolls of a three-roll mill stand for longitudinal rolling, and can be most effectively used in the manufacture of gauges in stands of reduction and calibration mills.

A known method of boring calibers of rolls of a three-roll stand for longitudinal rolling, see the book "Reduction mills" V.P. Anisiforov, L.S. Zeldovich et al., Metallurgy Publishing House, 1971, pp. 173-174, including the installation and fastening of the cage body with rolls on the pedestal of a special machine that provides rotation to the rolls, and cutting the caliber with a spindle and a cutter. This method has found application in almost all pipe plants.

A disadvantage of the known method for bore gauges of rolls of a three-roll mill stand for longitudinal rolling is the inaccuracy of the resulting gauge, since when it is bored, deviations from the nominal dimensions of the mill itself and additional gaps at various points of mating of the stand elements that occur during operation are not taken into account.

There is also a method of boring calibers of rolls of a three-roll stand, see RF patent 2430801, class. B21B 13/10, claimed June 16, 2009, publ. 10.10.2011, including mounting the cage body with rolls on a pedestal, installing technological half rings on the side surfaces of the rolls, shifting the rolls with a special mechanism towards each other until the technological half rings stop and cutting the caliber. The force of pressure arising from this on each roll selects the available gaps.

However, this method is applicable only in stands with the ability to move the roll units by means of a complex system of levers, as described in the aforementioned patent, or by means of pressure mechanisms installed in the stand body.

Meanwhile, all stands with an adjustable roll position have reduced stiffness due to additional mechanism elements. Therefore, to obtain high-quality rolled products, unregulated stands are used in which the roll units are mounted directly in the bores of a rigid bed.

Of the known closest in technical essence is the method of boring calibers of a three-roll stand for longitudinal rolling, described in the patent of Germany No. 3911930, class. B21B 31/00 claimed 04/12/89, publ. 10.25.90 g.

This method of boring the calibers of rolls of a three-roll stand of longitudinal rolling comprises installing and securing the stand body with rolls on a machine pedestal, cutting a circular groove (base) on the stand body, from which, after installing special reference rolls with the help of devices, reference dimensions are recorded, fixing organic inaccuracies inherent this crate. These control dimensions are taken into account each time when machining newly installed rolls in the mill stand on a machine. Then carry out the cutting of gauges during rotation of the rolls.

A disadvantage of the known method of bore calibres of rolls of a three-roll stand of longitudinal rolling is that it does not allow avoiding mistakes during boring caused by inevitable clearances, which are formed both during the initial manufacture of the stand as a whole and during the operation of the rolls due to the development of various mates, which reduces the accuracy of the bore caliber.

The objective of the present invention is to provide a method for bore gauges of rolls of a three-roll mill stand for longitudinal rolling, which allows to increase its accuracy and to ensure during the boring process a selection of gaps formed both in the manufacture of the rolls and during their operation.

The problem is achieved in that in the method of bore gauges of rolls of a three-roll stand of longitudinal rolling, including installation and fastening of the case of the stand with rolls on a pedestal of the machine and cutting the gauge during rotation of the rolls, according to the invention, a removable support plate with an opening that does not close the caliber is fixed on the stand body , in a removable base plate above the junction of the roll flanges with a maximum distance from the rolling axis, guide holes are made to accommodate the spacer rods in the form of wedges with an inclination angle equal to 0.2-0.3 radians at one end, and a force is applied to the other end of each spacer rod, providing a stress state in which the caliber is cut.

This embodiment of the method of bore gauge rolls of a three-roll stand of longitudinal rolling makes it possible to increase the accuracy of the bore of gauge rolls by selecting all the gaps that are formed both in the manufacture of the rolls and during operation due to wear of the mating elements of the stand (roll-shaft pair, pillows, bearings and etc).

This is achieved by the fact that when boring a caliber, spacer rods in the form of wedges at one end under the action of a force acting on their other free ends are inserted between the rolls of the stand and gaps are selected in all mates, while the rolls are installed in their working position during rolling. As a result, the caliber after such boring is accurate, which improves the quality of the resulting pipes.

The angle of the wedges is 0.2-0.3 radians. When the angle of inclination of the wedges is less than 0.2 radians, jamming occurs, and when the angle is more than 0.3 radians, it will be necessary to increase the force on the support rods, which will lead to wear of the wedge and rolls. In addition, the force applied to the other end of the spacer rod is determined by the ratio T> 0.1G, where G is the weight of the roll assembly. At T <0.1 G, the force will not be enough to select all the gaps in the stand.

To explain the invention, an example of the method is described below with reference to the accompanying drawings, in which:

figure 1 shows a three-roll stand of longitudinal rolling with a removable base plate fixed to it;

figure 2 is a section aa in figure 1;

figure 3 is a diagram of the distribution of forces on the flanges of the rolls;

figure 4 is a diagram of the selection of the optimal angle of inclination of the wedge.

The method of boring calibers rolls of a three-roll stand for longitudinal rolling is as follows. The housing 1 of the stand with rolls is installed and fixed on a special pedestal of the machine (not shown), while providing rotation to the rolls. On the casing 1 of the crate, a removable base plate 2, for example, of a triangular shape, is fixed with bolts 3. The removable base plate 2 has a hole "a" that does not close the caliber. In a removable base plate 2 above the junction of the roll flanges with a maximum distance from the rolling axis, that is, along the edge of the flanges, guide holes 4 are made to accommodate the spacer rods 5. The rods 5 have a wedge shape at one end with an inclination angle of 0.2-0 , 3 radians by which the rods enter the gap between the flanges of the rolls. At the other end, the rods 5 exit from the guide holes 4 of the base plate 2. On the removable base plate 2, a force means 6 is fixed, for example, in the form of an elastic element that acts with a force T on the free end of the spacer rod 5, creating a stress state in which the cutting is carried out caliber rolls, with a force of T> 0.1G, where G is the weight of the roll assembly. The cutting of the caliber is carried out during the rotation of the rolls 7 with an angular velocity ω.

To determine the optimal angle of inclination of the wedge and the force acting on the wedge, we consider figures 3, 4.

, где α - угол наклона клина.Under the action of the axial force T, the force on the roll flange without taking into account friction in the contact zone

where α is the angle of inclination of the wedge.

The force on the flange of the roll taking into account friction

where β = arctan f, α is the angle of inclination of the wedge in radians, f is the friction coefficient, with the plus sign when the rolls rotate towards the wedge, the minus sign when the rolls rotate along the wedge.

Considering the latter option as optimal, we conclude that the wedge angle cannot be less than the coefficient of friction, since this means jamming of the system, but at the same time it should not be much higher than this value. When the coefficient of friction is steel-brass or steel-steel with lubricant f = 0.15-0.18, the optimal angle is α≈0.2-0.3.

Roll lifting force

Figure 3 schematically shows the forces N acting on the flanges of the rolls. Given that the rolls in the stand are located at an angle of 120 °, the projection of the force on the direction of preload of the roll is directed at an angle of 30 °.

From formulas (1), (2) it follows that the angle α cannot be excessively large, since in order to raise the roll unit, it will be necessary to increase the force T, respectively, the force N, that is, the pressure force on the roll flange, and therefore the contact stresses, which will contribute to accelerated wear of the wedge and increase the moment of rotation of the rolls during the processing of the caliber.

The proposed method for boring the gauges of rolls of a three-roll stand of longitudinal rolling in comparison with the known ones allows to increase the accuracy of the caliber by sampling all the gaps that are formed both in the manufacture of the stand and during operation.

Claims (1)

A method for boring calibers of rolls of a three-roll stand of longitudinal rolling, including installing and securing the stand body with rolls on a machine pedestal and cutting a caliber during rotation of the rolls, characterized in that a removable base plate with an opening not closing the gauge is fixed on the stand body in a removable base plate above the junction of the roll flanges at the maximum distance from the rolling axis, guide holes are made in which spacer rods are placed, one end of which is made in the form of a wedge with an inclination angle of 0.2-0.3 ra diana, while at the other end of each spacer rod, a force is applied to ensure the stress state of the rolls at which the caliber is cut.

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