SU1555007A1 - Method of regulating coolant feed in rolling - Google Patents

Abstract

The invention relates to ferrous metallurgy, in particular, to sheet-rolling production and can be used in the rolling of strips, for example, in continuous broadband hot rolling mills. The purpose of the invention is to improve the quality of the strips by stabilizing the thermal profile of the work roll. When rolling strips in the finishing group of the stands of a broadband mill, including rolling an assembly batch of strips determined by one campaign of rolls, cooling the rolls begins after a period of 0.06-0.24 of the rolling time of the assembly batch of strips, and the cooling time for the roll is determined according to dependence. 2 ill., 1 tab.

Description

The invention relates to the processing of metals by pressure, in particular to sheet-rolling production, and can be used in the rolling of strips, for example, in broadband hot rolling mills (SHSGP),

The aim of the invention is to improve the quality of the strips by stabilizing the thermal profile of the rolls,

Figure 1 shows a graph of the change-- nor the time of supply of the cooler to the working surface of the rolls in the initial period of rolling strips; FIG. 2 is a graph of the change in the supply time of the cooler to the rolls from the entrance to the deformation center with an increase in the pause time between rolling strips of different heats,

The cooling of the strips begins after a period of time equal to 0.06-0.24 of the time for rolling the volume of the assembly batch of strips. The time schedule for the supply of a cooler consists of two sections: curved be (curve 1) and de (curve 2) and straight line ck and ek (figure 1). Curvilinear sections of graphs 1 and 2 are described by the proposed dependency, which characterize the period of stabilization of the thermal profile of the roll:

g

Ova

 m

(one ,

(one)

JV JV

ate

where is the supply time of the cooler

on the roll, with;

si, during rolling cycle, pause time and rolling time, s; K 1 - a;

a is a coefficient depending on the current volume of rolled strips (a Q / Og.);

O and 0 - the current and total volumes of the installation batch of lanes. These areas characterize the rolling of strips with a steady thermal profile of the work roll 8. In this case, the cooling time of the work rolls is determined by the equality

/ V. / V,

 + t / n (.)

where soha

c

coolant supply time; rolling cycle time;

Иm and c1 ,, - machine time rolling

and the time of pauses between rolling of different lanes. During the transition to rolling another strip size, emergency or other mill stops, the cooling time of the work rolls according to schedule 3 (Fig. 2) is realized.

The cooling of the rolls begins after a period equal to the rolling time of the volume of the installation batch 0 (0.06 - 0.24) 0--, and the smaller Q value is 0.06 Og. is applicable when the volume of the assembly batch is large enough (for example, Qg-4000-5000 t) or the weight of the rolls is insignificant (for example, for ShSGP 1450), However, further

the reduction of the period (Q 0.060-) may even for the above conditions create instability of the thermal profile and lead to a decrease in the quality of the bands by increasing the dispersion of the transverse strip thickness variation. The largest period from which the roll starts cooling from the strip inlet, Q 0.240Ј, is accepted for conditions when the volume of the assembly lot is small (for example, Qg - 1500-2000 t) or the weight of the work roll is significant (for example, for SHSGP 2500). Moreover, a further increase in this period to O 0.240 is impractical even for the specified extreme values, since it can lead to a premature increase in the thermal bulge of the roll barrel and an increased distortion of the transverse strip profile, t, e. to reduce the quality of hot-rolled strips.

The method is carried out as follows.

After handling work rolls

the rolling of the strips is started without the inclusion of the work roll cooling system, and the period of delay and switching on is chosen within

Og (0.06-0.24). After rolling 12 lanes, this system is turned on and the water supply is increased as the lanes are rolled according to (1). After rolling the 28th strip, the time for supplying the roll cooler is 66 seconds, and during subsequent rolling of the strip of this size it remains unchanged equal to the time of the rolling cycle.

In the event of a transition to a new size when the ratio exceeds 0.5, partial transfer of work rolls or mill emergency stops, the pause time increases. To stabilize the heat profile of the roll, the cooling system is shut off. Depending on the duration of the pause (emergency and so on), cooling begins after a period of (0.06-0.24) 0Ј of the total volume of the assembly batch of strips or immediately after the start of rolling the strips, if the pause time was short. The output at a stable rolling rate is produced when the cooling time of the rolls changes according to the same relationship (1). The subsequent rolling of the strips after a long pause, after reaching a stable thermal profile, is carried out with a constant cooling of the rolls. The implementation of the method can be carried out with the help of known devices, used, for example, at 1CSPP 1700. At the same time, the time of water supply and the time of its disconnection can be controlled centrally from the mill control station.

The table shows the results of rolling strip size 2.4x900 mm from steel 08kp on SHSGP 1700 by the known and proposed methods.

From the analysis of the data in the table, it follows that the implementation of the proposed method improves the flatness of hot rolled strips, which significantly improves the accuracy and quality of the rolled products, reduces the amount of second grade and leads to a stable thermal profile of the work roll on a smaller metal volume.

Claims (1)

Invention Formula The method of regulating the coolant supply during rolling, including the supply of coolant with a change in its quantity during deformation and during pauses in each cycle of the batch rolling time, characterized in that, in order to improve the quality of the strips by stabilizing the thermal profile of the roll, start after a period of 0.06-0.24 times the batch rolling, and the duration of the feed in each cycle is set according to (1 - Ke ), ig 555007 where b c, OHL / LM K (1 a and 0.time of supply of the cooler to the roll, s; rolling cycle time, pause time and rolling time at cycle; -); the coefficient depending on the volume of the batch of bands and characterizing the relative period of the batch (a  Q / Qir); current and total volumes batches of bands. With constant cooling of the work rolls. 4 C / ff0,2V d 0, M FAI Editor V. Petrash Compiled by V. Ziselman Tehred M. Khodanych Proofreader M. Maksimishinets Order 521 Circulation 413 VNIIPI State Committee for Inventions and Discoveries at the State Committee on Science and Technology of the USSR 113035, Moscow, Zh-35, Raushsk nab. D. 4/5 Production and Publishing Combine Patent, Uzhgorod, st. Gagarin, 101 Phage. 2 Subscription