SU1614875A1 - Process tool for two-high reducing mill - Google Patents

Abstract

The invention relates to the processing of metals by pressure and can be used on two-roll reduction mills. The purpose of the invention is to increase the service life of the tool. The technological tool of the twin-roll reduction mill contains multi-zone draft, oval pre-trim and round finishing gauges, the plane of the connector of which is turned one relative to the other at an angle of 90 °. In rough gauges, each stream is made with three arcs — the central and two identical outlet arcs with a radius larger than the radius of the central arc and the centers of all the arcs located on the stream axis of symmetry. The angular length of the central arc stream in each subsequent draft caliber is 4–6 ° more than in the previous caliber. 1 dw., 2 tab.

Description

The invention relates to the processing of metals by pressure and can be used on two-roll reduction mills.

The aim of the invention is to increase the tool life.

The drawing shows the proposed tool.

The technological tool includes seventeen draft multi-zone gauges 1, one oval pre-trim 2 and two round-fine 3. The socket planes of all calibers are rotated one relative to the other at an angle of 90 °.

Each stream of rough gauges is made of three arcs — central with a radius n and an extent defined by the angle di, and two identical outlets With a radius that is larger than the radius of the central arc. The centers of the central and final arcs are located on the symmetry axis of the stream. In this example, the center of the central arc is located in the center of the caliber, and the outlet - is offset from the center by the value of ei (eccentricity). The center of the center arc relative to the center of the gauge may be shifted towards the center of the outlet arcs, and in all cases the radius of the outlet arcs must be greater than the radius of the center arc.

The main dimensions of draft gauges — Hi height and Bi width — are chosen from the provisions common in the theory and practice of tube reduction for oval gauges. The radii n, Ri and eccentricity ei are determined from the ratios

ABOUT

with

Xj

ate

 R,, fVi I rv

I b)

+ ef

ei

BF - H

4 Hrcos

di

: Central and exhaust arches intersected; in the points located at an angle di y to the axis of symmetry of the stream, forming protrusions

i on its surface.

I The angular extent of the central arc (di) in the average caliber (8th caliber, | tabl, 1) is 104 °. The angle of the central arc of all calibers j located in front of the average gauge is less by 6 ° as the order number of the gauge decreases, and for calibers located below the average size increases by 6 ° as the order number increases. caliber. The position of the average gauge is determined by the size of the pipe deformation by the outer diameter, in which I ends the first half of the total deformation.

When determining the average caliber proceed as follows.

Determine half of the pipe deformation by outer diameter

° - -100%,

t 2

Do

i where DO is the outer diameter of the pipe to

I reduction, mm;

I DK - average diameter of the last (computational) caliber, mm.

I Determine the diameter of the pipe Dn, where the first half of the formation is provided.

I Dn Do (1-).

In this case, 1 130-64

t 2

30,100 25.4%

Dn 130 (1-) 96.7.

By comparing the diameter Dn with the average diameters of the calibers (Table 1), it is determined that the first half of the deformation should end in the 8th caliber, which is the average. The angular extent of the central arc in the average caliber is chosen equal to 104 °, since this ensures the minimal graininess of the pipes. The minimum and maximum difference in the angular extent of the central arcs of adjacent draft gauges is determined on the basis of experimental data.

Pre-finishing and finishing calibers in the preliminarily provided technological tool correspond to the calibers used

in practice, in conventional gauge rolls with oval rough gauges.

Pipe rolling using the proposed technological tool 5 is carried out as follows.

Due to the rotation of the rolls, each section of the pipe is sequentially deformed in all calibers. When the pipe is deformed in the first caliber (as in the usual split caliber 0), the wall thickening around the perimeter is uneven. The pipe thickens more in places adjacent to the caliber connector, and less in places adjacent to the tops in the second caliber rotated relative to the first by 90 °, the maximum wall thickening is in the place of the minimum, reached in first caliber.

0 Presence of convex sections of calibers in

the intersection of the central t of the discharge arcs prevents the tangential flow of the metal. Because of this, the nature of the change in the pipe wall between the top and

5, the release of the gauge may be different depending on the length of the central arc. After rolling the pipes in the system turn 1x relative to each other at an angle of 90 ° of calibers with a center arc of less than 104 °, the wall thickness is uneven with four maxima and four minima oriented At a 45 ° angle to the directions of connectors or vertices of calibers. If a

5, the extension of the central arc is greater than 104 °. Four maxima and walls are oriented in the direction of connectors and gauge tops; therefore, when pipes are reduced in rough gauges that perform the first half of the deformation and have a central arc length less than 104 °, the wall thickness is uneven with four maxima and minima oriented at an angle

5 45 ° to the directions of connectors (or vertices) of calibers.

For the second half of the deformation in calibers with an extension of the central arc greater than 104 ° at the site of the wall minima

0, maxima are superimposed, and in place of maxima are minima of wall change. As a result, the final wall thickness is relatively uniform.

After rolling in (1-2) oval pre-figures and (1-2) round fine calibers, the tube acquires a round outer profile.

The minimum and maximum differences in the length of the central arcs of the streams of adjacent calibers, as well as the stability of the roll caliber, are determined by reducing without stretching the pipes with dimensions 63.5X (8-13) MM from the pipes with dimensions 130X X (5.7-9.5) mm on a twenty-two-roll reduction mill of a pipe-rolling unit 140.

For the reduction of pipes, a technological tool is used, including 17 draft calibers, one oval prefining and two round finishing. The main parameters of the gauges — the average diameter, height, and width — are taken the same as in the current roll calibration (Table 1).

Five variants of rough gauges are characterized by a different angular extent of the central arc of each stream (Table 2).

In embodiments 1-4, on average, the rough gauge is the angular extent of the central arc of 104 °. In the group of gauges located in front of the average gauge, the length of the central arc in each previous gauge is 3,4,6 and 7 ° less than in the subsequent one, and in the group of gauges located beyond the average gauge, the length of the central arc in each subsequent gauge 3,4,6 and 7 ° more than in each previous caliber. In the fifth version, the length of the central arc is the same in all draft calibers and is 104 °.

All calibers are made by boring rolls in cages on machines designed to make oval and circular gauges. The draft gauges are bored out of two final settings of the cutting tool. When first installed, the cutting edge of the cutter is set to b the central plane of the stands passing through the axes of the rolls and the center of the gauge. The diameter of the path of the cutting edge of the tool is equal to the height of the caliber. In this way, the central areas (arcs) of the streams are bored out. In the second installation, the cutting edge of the cutter is offset relative to the central plane of the stand by an amount Xi calculated from the expression

(,

)

where DHA is the ideal roll diameter of 330 mm for all stands;

Of - the diameter of the path of the cutting edge of the cutter, mm.

The diameter of the path of the cutting edge of the cutter is determined from the expression

in 1

40id

.Of I, s, -1.

 - go

- (

+ -

BI

g

4№-e,)

idchiid

With this installation of the cutting tool made the exhaust areas.

The parameters Xi and Of for option 3 (as an example) are given in table 1.

For a long time, we studied the Q character of the wear of gauges, as well as the character of changes in the size and shape of the outer contour of the finished pipes by rolling on each of the above variants of the technological tool. In addition, 15 npi, to reduce the size of 63.5X X (13) mm to assess the inner facetness, the wall thickness of the finished roughness is measured continuously around the perimeter with a tanometric device. The value of facetedness (in%) is determined as the average difference between the four maxikus and four wall minima, which is equivalent to the average wall thickness of the pipe in cross section.

25 It has been established that as pipes are reduced using a known technological tool (option 5), the protrusions on the surface of the rolls in all draft calibers at the intersections of the central and exhaust arcs do not disappear, but appear to a greater degree. Ultimately, the cavities observed on these pipes along the four generators cease to roll in frontal and 35 fine calibers and lead to a deviation of the outer diameter in these places beyond the limits of permissible deviations.

The stability of the roll calibers is thus relatively low (the average number of tubes rolled on one set of calibers is about 950 tons). The pattern of wear of rough gauges of the technological tool for the remaining variants (1-4) is almost the same as that of 45 technological tools for variant 5. But since in the rough gauge of these tool variants, the protrusions on the surface of the rolls at the intersections of the central and discharge arcs are dispersed 0 Along the perimeter of the gauges, depressions on the surface of the pipe, leading to a deviation of the outer diameter beyond the tolerances, appear after rolling more pipes than in the case of option 5. At 5 this, the more complete , the dispersion of these protrusions (i.e., the greater the difference in the angular extent of the central arcs of adjacent calibers) within the range of Adi 3-6 °, the higher the durability of the gauges of the rolls.

The average value of the internal facet of the pipes reduced on each of the variants of the technological tool (turns out to be approximately the same. I, Averaged data on the durability of the technological tool and the size of the internal facet are presented in Table 3. This information indicates an increase in the durability of gauges is achieved when the difference in the angular extent of the central arcs of roughing ||: the alibrov is 4-6 °. With a higher ||: difference of the difference, the increase in the resistance- (; .

Thus, the proposed technological tool allows to increase the service life of the gauges of the rolls of the reduction mill. This is due to the fact that the dispersion of the protrusions on the surface of the rolls at the intersections of the central and exhaust arches along the perimeter of the gauges makes it difficult to increase the distance between the protrusions of two adjacent calibers from the beginning to the end of the mill and not localize the depressions on the pipe in a narrow area. At the same time, the valleys DT of each previous caliber roll out on the extended smooth part of each subsequent caliber, and not only in the pre-finishing and finishing calibers. As a result, the proposed technological tool can allow a greater increase in protrusions on the surface of the rolls when worn gauges than the known, and hence the greater number of tubes.

Claims (1)

and 10 claims The technological tool of the two-roll reduction mill, the contents of a number of turned relative to each other on 15 is an angle of 90 ° round fair, oval pre-finishing and multi-zone roughing gauges, each stream of which is formed by a central arc and two outlet arcs with a radius greater than the radius of the central arc, and with the centers of all the arcs located on the axis of symmetry the stream differing from which, in order to increase the service life of the tool, each following along the rolling of the roughing The 25 gauge is made with an angular extension of the central arc 4-6 ° more than the previous one. Table 1 Continued table. one table 2 Lp / fp tS Predictive Caliber Table 3 Caliber 16 HIS Caliber 77 cat5r 15 Caliber 20 V4rA jA4 ffia Vgo Net ffpjft / fflbt