SU1388126A1 - Working roll for finishing stand of continuous hot rolling mill - Google Patents

Abstract

The invention relates to rolling production and can be used in the shaping of work rolls of broadband hot rolling mills. The purpose of the invention is to reduce the flatness of the strips by compensating for the thermal change in the shape of the roll barrel. The caliber of the roll barrel includes a straight section located in the middle of the barrel, and curvilinear sections adjacent to it on both sides, outlined by hyperbolic curves. Each of their curvilinear sections is filled with parabolic grooves, the center of the parabola which is 0.15-0 from the end of the barrel 20 of its length. The length of the parabolic groove is 0.15-0.25 of the length of the roll barrel, and a depth of 0.2-0.4 caliber depth. When rolling a sheet, especially towards the end of the roll campaign, parabolic grooves make it possible to take into account the thermal change in the shape of the barrel, i.e. perform the role of compensators. 1 dw., 2 tab. a (L

Description

with

00 00

Yu

05

1138

The invention relates to the processing of metals by pressure, in particular to sheet-rolling production, and can be used in the profiling of work rolls of wide-strip hot rolling mills (SHSGP).

The purpose of the invention is to reduce the failure of the bands by compensating for the thermal change in the shape of the roll barrel.

The drawing shows a work roll of a finishing stand of a continuous sheet mill of hot rolling.

The roller includes a barrel, 1 and trunnions for mounting pillows with bearings on them. The forming barrel 1 is made in the form of a hyperbolic curve ab, cd. In the middle of the roll barrel, the forming is made with a curvilinear section bc of length 1 ,. At the end sections of the roll AB, cd symmetrically to the middle of its barrel, characterized by the axis 00, the grooves are made with a parabolic concave profile. The projection length of each of the parabolic grooves efg, hmk is

1, (0.15 - 0.25) 1, (1) where 1 is the length of the roll barrel, mm.

The depth of each of the parabolic grooves efg, hmk from the profile of the hyperbolic curve ab, cd is

H, (0.2 - 0.4) V, (2) where H is the maximum concavity depth of the forming drum, mm.

The maximum deflection of the parabola, defined by the points f and t, is located from the end (σ or ds) of the barrel at a distance equal to

1 ,, (0.15 - 0.20 1. (3) The distance of the beginning of the parabolic concavity efg, hmk is defined as

 J- 1, / 2.C4)

In order to build up the profiling of the proposed roll, the extension value of the rectilinear portion of be is

1, (0.05 - 0.25) 1. (5) S Then the extent of each of the hyperbolic segments (ab or -d) is determined by the ratio

l5 (l - M) / 2. (6) Forming a roll with a hyperbolic profile (ab or cd) over a section of length li can be determined by the following expression (for section ab taking into account the symmetrical mood about the axis 00) WV (W-1) 2+ (X / lpn2W-1 ), (7)

Q

5 20 25

ZO

35

45

40

five

262

where Dyp is the current roll diameter at section ab varying from D o to D, mm; D - the maximum diameter of the barrel

roll, mm; DO - the minimum diameter of the barrel,

mm;

W is a constant depending on the order of the stand in the finishing group of the mill,, 9-1.2; X is the current constant, which varies with the length of the segment 1g from at point b to at point a, mm.

Initially, D is calculated over the entire length of the section, excluding section 1 (shown by dotted lines). Forming roll barrels in areas with a parabolic concave profile (efg or hmk) can be determined by the expression for the area fg

Dxn Df-tH, (2X; / l2) S (8) where D is the current value of the diameter on the parabolic segment fg, changing from D to DO (D {and D} are the corresponding diameters at profile points f and g), mm; Н - maximum concavity depth on the parabolic section from the hyperbolic curve aepgb, mm; X is the current coordinate, which varies with the length of the parabolic profile fg from f to Xj, l7. For the fg region, the parabolic concavity profile is determined by the formula

 D;, D {+ H / 2X; / li), (9) where Dj (fl is the current roll diameter at site ef, changes us from 1 to D. to D g (D g is the roll diameter at point e), mm ; XP is the current coordinate, varying from at point to ./2 at point e.

The diameter of the roll barrel at points e, p, and g are determined by the formula (7). The variable coordinate is accordingly determined for the point e X l5-l |; points p X lj-l3; points X l5- (l, + l).

The value of the barrel diameter at point D is determined by the dependence

D {D p-2H,. The roll works as follows.

It is advisable to install the roll in the cells of the finishing group, preferably where chalk is used (cooling, i.e. in the last 3-4 cells. These work rolls are set in pairs. In the gap formed by them, the metal is subjected to deformation At the same time, water is supplied to the intercellular spaces for cooling. At the same time, the water changes the thermal profile of the work roll. However, when using this roll, the thermal shaping of its barrel does not reflect enough to distort the desired cross-section. the bands, since the unevenness in the shaping of the thermal profile is taken into account by two zones with a concave parabolic profile.

Parabolic grooves on curvilinear sections of the barrel fulfill the role of heat shrinkage compensators for the roll barrel that occurs during the rolling process, in particular, when using interstand cooling in the finishing mill group. The length of the concave parabolic region is at a lower limit up to, 15 1 is assigned when rolling relatively thick rework bands (starting from 4 mm), and a large length up to 1 fO, 25 I is assigned when rolling relatively thin strips (1.55 mm) applied in as a tackle. A further reduction of 1 0.151 does not have an effect even on thick strips, and an increase of 1 7 0.25 1 does not have an effect in reducing the side edge concavity even on thin strips, which are more sensitive to thermal roll forming than thick strips.

When setting the depth of the parabolic grooves, the following recommendations are followed. It is rational to assign a smaller value H, 1-0.211 for rolling thin strips, and H 0.4 N for rolling relatively thick strips. A decrease in H, 0.2 N does not give a sufficient effect in terms of taking into account the heat convexity of the roll barrel, even when rolling thin strips, and may lead to the formation of concavities on the rolled-up surface, fraught with a decrease in the quality of the bands due to the appearance of a near-edge waviness. .

The depth of H, 0.4 N can also lead to thick lamellar bulges, which ultimately lead to double edge of the karobatosti after the cold rolling of the bands. The location of the maximum concavity in the areas of the roll with a parabolic profile is assigned, based on the existing mill assortment, and at 90–0.95 (B is the width of the rolled strip) the value is 1–7 0.15 1, and at 60–0 , 75 13 b, 20 1.

A decrease in this value of 1 0.15 1 causes the parabolic section to shift beyond the limit of the rolled strip, i.e. does not improve the quality of the bands. An increase of Ij 0.20 1 leads to YoMy, that the compensation concavity is located too close to the middle of the strip where no concavity from thermal roll forming is observed. Therefore, compensating for concave parabolic grooves with the specified values of the roll profile parameters allows for thermal shaping rolls, especially by the end of the roll campaign, reduce a defect such as flatness, i.e. improve the quality of the strips by providing a lentil-like profile of the treadmill for cold processing.

An example of testing the proposed roll under the conditions of ShSGP 2000 of the Novolipetsk Metallurgical Plant. Roll profiling correspond to the given data (Table 1). From an analysis of the comparative results of rolling of the proposed roll compared to the known (Table 2), it follows that the proposed roll, within all limits of the proposed boundary parameters, has the superiority expressed in improving the quality of the strips by increasing the curvature of the transverse profile of the strip, which shows In smaller defects in waviness and warpiness by 3.4 and 1.3%, respectively. The volume of substandard bands reduced by 0.61%. At the boundary values of the profiling parameters of the proposed roll, the effect approaches that provided by the known roll.

Therefore, the use of the proposed roll improves the quality

strips, which reduces the defects on the flatness of strips (such as waviness and warping).

Claims (1)

Invention Formula Work roll finishing stand continuous sheet mill hot circumscribed concave curves, characterized in that, in order to reduce the flatness of the bands by compensating for the thermal change in the shape of the roll barrel, parabolic grooves are made in its curvilinear sections, the length of which is 0.15-0.25 rolling, containing a barrel with a gauge Q, and a depth of 0.2-0.4 depth with a caliber, which is formed by a straight line segment located in the middle of the barrel, and curvilinear sections adjacent to it on both sides. pa, with the center of the parabola, outlining the shape of the groove, located from the end of the barrel at a distance of 0.15-0.2 of its length. Parameters of rolls of stands of finishing group SHSGP 2000 (SHSH) (mm: - 820 NM) H, mm0,400,250,15 H ,, mm0,080,120,160,050,080,100,030,050,06 1 ,, mm100300500100300500100300500 1 mm 300400500300400500300400500 1z, mm300350400300350400300350400 Note. 1, III - with a minimum, respectively average (optimal) and maximum limiting values of the roll parameters. table 2 Comparative results of rolling strips of size 2.8x1820 mm in accordance with the known (And) and the proposed (P) rollers pa, with the center of the parabola, outlining the shape of the groove, located from the end of the barrel at a distance of 0.15-0.2 of its length. T a b l and c a. one