SU1091950A1 - Method of rolling thick sheets - Google Patents

Abstract

one . A ROLLING method of THICK SHEETS, including prrtka, width breakdown and longitudinal rolling with asymmetrical formation of the lengths of the front and rear ends of rolls in roughing gaps, characterized in that, in order to expand the field of application while simultaneously increasing the yield of suitable metal by reducing the width of the ends of the sheets, the formation of the length of the ends of the roll is made in the process of drawing, and the length of the front end is pulled out 1.2-4 times longer than the length of the back. 2. The method according to claim 1, characterized in that, when the ratio of the stretch ratio during stretching to the stretch ratio when breaking up the shea (LRins of a smaller unit, the front and rear ends form thicker than the middle of the roll, and at the indicated ratio of a larger unit, the ends sink relative to the middle.

Description

WITH

x

: l I1 The invention relates to rolling production, namely to the production of thick sheets on reversible plate rolling mills. There is a known method of rolling sheets, including alternating along the length of the compression of the side faces of the slabs in the stand with vertical rolls. At the same time, the front and rear ends of the slab are crimped to a lesser extent than the middle part. After rolling such slabs in a transverse pattern, the length of the fan-shaped sections ij is reduced. The disadvantage of this method is the limited scope of its application, since the method can be carried out on mills, which include a stand with vertical rolls, in which pressure screws are made with the ability to move the metal and the presence of metal in the deformation zone. The closest to the proposed technical essence and the achieved result is a method of rolling thick sheets, including stretching, breaking down the width and longitudinal rolling with asymmetric formation of the lengths of the front and rear ends of the rolls in the roughing passes, which allows to reduce the face cut by separate formation of the front and the rear ends of the rim 2. The disadvantage of this method lies in the limited area of the change, as it can be implemented on mills, the broadening stands of which borudovany dvuhskorostnymn or hydraulic pressure device allowing to carry out yuschimi variable compression along the longitudinal axis ba slab at its finding in the deformation zone. The aim of the invention is to expand the field of use while simultaneously increasing the yield of the metal by reducing the dissociation of the ends of the sheets. The goal is achieved by the fact that according to the method of rolling thick sheets, including stretching, breaking widths and longitudinal rolling with asymmetrical formation of the lengths of the front and rear ends of the rolls in roughing passes, the length of the ends of the roll is formed in the process of stretching, and the length of the front rolls the end is pulled out 1.2-4 times longer than the back. At the same time, when the ratio of stretching ratio during stretching to the stretching ratio when breaking down a width of less than JPnits, the front and rear ends form thicker than the middle of the roll, and at a specified ratio of more units, the ends sink relative to the center. FIG. 1 shows the form of the finished roll (the dotted line shows the finished sheet after trimming off-spec parts), top view; Fig.2format roll after the breakdown of the width (the beginning of the campaign work rolls); in FIG. 3, the same, 3 end of the work roll campaign; in fig. 4 - the form of the roll after the run. When rolling thick sheets on reversing mills in a longitudinal pattern with a breakdown of width, the form of rolls has the form of narrowed front and rear ends (Fig. 1), which leads to increased metal consumption for the front and side trimmings. At the same time, the length of the front narrowed end is 1J2-4 times the length of the rear narrowed end, and the width of the rear end relative to the front end is on average 20-40 mm. The reason for the formation of such a form of rolls is their barrel-shapedness, obtained by dividing the width (Fig. 2). Such a form of rolls when dividing the width is formed at a ratio where | 1Л (, р is the stretching ratio during stretching; | 11рц | is the stretching ratio when When} Unp / (the shape of the roll after the breakdown of width is shown in Fig. 3. Most often, when rolling, the stretching ratio during stretching and breaking down the width is less than one, therefore the shape of the roll is barrel-shaped (Fig. 1). The smaller the ratio is the same, the bigger the barrel The length of the roll is uneven: at the ends of the roll in, within the minimum length of the outer zones, the broadening is greater than the rest (Fig. 4). At the same time, the broadening is at the front (during rolling) the end is smaller than at the rear, and since the odd gaps on the two-stand plate mills are at least 2 more than the even ones, the fan-shaped broadening at the front end of the roll is always less than the back (the front end of the roll is taken which is matched the front end of the rolling passes in odd). As a result, the finished roll is asymmetrical with respect to the transverse axis (Fig. 1), which leads to a higher metal consumption, since the cutting of the sheet is determined by the minimum width of the roll. Compensation of such a heterogeneous asymmetric strip shape can be obtained by uneven thickening or thinning of the front and rear ends of the rolls in the last pass when stretching before breaking the width. If a barrel-shaped form of a roll is expected (Fig. 2) with (Upp / RR, then at the last pass stage, it is necessary to create a thickening of the ends during thinning (thinning of the middle part of the bar), and if a form of a roll is expected to be concave (Fig. 3) with Upp / jUpy thinning of the ends. Moreover, the thinned or thickened ends of the roll are made asymmetrically relative to the transverse axis, providing a length of thickening or thinning at the front end 1.2-4 times longer than at the rear end. The thickened or thinned ends of the rolls are obtained by rolling the roll with variable crimping along its length. Variable crimping along the length of the roll is created by changing the gap between the rollers using special hydraulic devices installed under the pressure screws, creating additional pressure in them to obtain thinned sections of the roll. sequences. The initial slab is fed to the roughing stand with horizontal rollers, while the longitudinal axis of the slab is parallel to the axis of the finished roll. The choice of a further rolling pattern depends on the length of the slab and the length of the barrel ratio Lg. At LC "Lg - (200 rolls 300) mm, a drawing operation is performed, consisting of one or several rolling passes along the longitudinal axis of the slab and positively influencing the shape of the finished roll, to compensate for its barrel shape. The last pass during stretching is performed with a variable crimp along the length of the roll. If, in accordance with the reduction mode jU |, p | (lip | jl, then in the last pass thickened ends are created during stretching. If jllnp / flpw ° S the thinnest ends are created during the last pass. a horizontal plane by 90 and a width breakdown is made for several passes. When breaking down the width, in the first case, the thickened ends, and in the second case, the thickened gray core lengthens more and brings the shape of the roll towards the rectangular. The length of the thickened ends, which must be obtained in the last pass during drawing, is determined by the following method. The average value of the misalignment of the tapered ends of the roll obtained on the reversible plate mills is approximated by the equation : 51.9 Mnp / f4pw The total length of these narrowed ends, according to DonNIchermet, can be determined by the formula D 500 ((U,) l, mm (2) where the extrusion ratio of the roll in the direction of its longitudinal axis. the metal to be added to the narrowed ends of the roll to make it rectangular in plan is determined from the expression bV where h is the thickness of the finished roll, mm. 5 This volume of metal is added due to the thickening of the ends of the roll in the last pass during drawing (d) an, LU B (+ where B is the width of the slab, mm; and 62 is the length of the front and rear thickening ends of the roll, during drawing, mm H is the magnitude of the thickening of the end mm, From here: L VKSR t and g KZ2, where K is the asymmetric coefficient depending on the number of odd passes and stretching at the longitudinal penetration K, and the ratio of the stretch at longitudinal rolling and breaking the widths K K. K The coefficient K is selected in accordance with the table. Koffits Number of skips when rolling in the rough grade part asi metrichty

The coefficient of asymmetry K ras-,. is read by the formula:

K2 0.057 0.972 (71)

67x1500x14

2

16.5 mm. 2x1650x4

According to the table, the coefficient K is 1.8, and in accordance with the formula (8) Ku 1, .875.

According to the formula (7) determine the coefficient of asymmetry K K

K2

 3,375.

Solving together equations (5) and (6). we will receive:

 82 mm, f, 24.5 mm.

one

Variable crimping is carried out in the second pass during stretching. 0 Analysis of the compression mode shows that on the reversible plate mills, the ratio of ppps is in the range of 4-18, therefore the coefficient K varies in the range of 1.2-2.0. and the product of the coefficients K, - D.2 i. the asymmetry factor varies in the range of 1.2-4. Example. The implementation of the proposed method on the example of rolling a strip 14x2200x36000 mm from slab 315x1650x2550 mm on a two-stand mill 3000 Zhdanov Metallurgical Plant named after Ilyich. The rolling pattern and rolling mode are as follows: In the roughing stand, 2 passes are passed, including a second pass, profiling with lUpp 1.10, breakdown of width for 3 passes with | Cree 1.42; longitudinal rolling for 4 passes. Next, the roll enters the finishing stand, where it is rolled to a final thickness of 14 mm in 5 passes and the ratio flj is. 15.83. So KaKjUnp / | Upui 0.775, i.e. less than 1, with this ratio, a barrel-shaped form of roll is expected after breaking the width. Consequently, the second pass, when drawn, is profiled with thickened ends. In accordance with formulas (1) and (2), the average width of the narrowed ends is .0 b, p 67 mm, and the total length of these narrowed ends is); 1500 mm. According to the formula (5), we determine the total length of the thickened ends, which must be performed in the profiling pass at yN 4 mm.

As a result of the implementation of the method, the asymmetry of the roll in the plan is reduced, which leads to a reduction in the consumption of metal of 2-5 kg per ton.

effect of production

2.5 million tons per year will be at least

300 thousand „rub.

R

ui, 2

--L

/

AND

//z.J

; g

needles

.

Claims (2)

1. METHOD OF ROLLING THICK SHEETS, including buckle, breakdown of width and longitudinal rolling with asymmetric formation of the lengths of the front and rear ends of the peals in rough passes, characterized in that, in order to expand the scope while increasing the yield of metal due to the reduction of the width difference the ends of the sheets, the formation of the lengths of the ends of the roll is carried out during the broaching process, and the length of the front end is pulled 1.2-4 times longer than the length of the back. 2. The method of pop, 1, characterized in that when the ratio of the drawing ratio when drawing to the drawing ratio when the width is smaller than one, the front and rear ends are thicker than the middle of the roll, and when the ratio is greater than unity, the ends are thinned relative to the middle. SU. · "1091950 fui.1>