SU1205945A1 - Method of hot rolling of plate steel - Google Patents

Description

The invention relates to the field of rolling steel sheets and can be used in the hot rolling of steel plates on continuous and semi-continuous mills.

The purpose of the invention is to increase the productivity of the mill.

The essence of the method is that from a heating furnace, the slab is transported to a vertical stand, where it is reduced in width, and then reduced in horizontal and vertical rolls of the roughing stand. Then, continuous rolling of the roll is completed in the finishing cages. After the finished strip is released from the last stand, it is transported by an adjustable roller conveyor, on which it is cooled, then wound into a roll by a winder and removed. Due to the fact that when rolling thick strips of low-alloyed steels, the total relative reduction in the last three finishing cells should be at least 40%, and the compression in each of these stands is at least 15-20%. The relative compression in each of the two head stands also exceeds 15-20%.

The thickness of the roll out of the last roughing stand is taken so that in the middle finishing cages located in front of the last three stands, the relative reduction in each stand does not exceed 10%.

I

The table shows the parameters of the rolling strip section mm from steel 17 HS. The table shows that the metal pressure on the rolls in finishing cages x 3 and 4 is less than in other finishing cages x 3 times.

Example 1. Hot rolling 25 mm thick strip of low alloy steel is produced in a seven-square finishing group of 50 mm tolgtsin from under the kata produced from the last roughing stand, and the thickness of the bar before the last three finishing stands is 40 mm.

In the nepBoii finishing stand, the absolute reduction is about 10 mm (9.8 mm), and in one of the finishing stands located between the first finishing and the last three finishing stands 0.2 mm (according to practical data, the minimum to achieve the effect of cracking the scale) . When the thickness of the roll 40-mm absolute compression of 0.2 mm corresponds to

relative reduction of 0.5%. The remaining two finishing stands, located between the first and three last finishing stands, are not used in the rolling process.

The benefits achieved (increasing the hourly productivity of the mill, etc.) and the rationale for the optimality of the proposed method are given by Bbmie.

Example 2. Hot rolling 16 mm thick strip of low alloy steel is produced in a seven-square finishing group of 40 mm thick rolled sheet manufactured

from the last roughing stand, the roll thickness before the last three stands is 27 mm. It is not possible to carry out rolling in the first stand with an absolute reduction of 13 mm, as according to the calculations made, the back end rolling force exceeds the allowable values at a number of operating mills (2500-3000 ton).

At the same time, the crimping ability of the roughing group of the stands of many wide-strip mills does not allow obtaining a rolled core of low-alloyed steel less than 40 mm.

In this example, scaling in one of the cages located between the first and the last three finishing cages is carried out with the maximum possible compression of 10% (or 3.2 mm), which eliminates air pressure being pressed into the metal surface. In the first finishing stand, rolling is carried out with an absolute reduction of 9.8 mm with allowable irokatki forces, the remaining two finishing stands located between the first and three last finishing stands are not used during rolling.

With the implementation of Example 2, practically the same advantages are achieved as with the implementation of measure 1.

Example 3. Hot rolling a strip with a thickness of 14 mm from low-alloyed steel is produced in a seven-square finishing group of 40 mm thick rolled steel, with the thickness of

31

the kata in front of the last three finishing stands is 23.3 mm.

According to the data of the table in finishing cells - over 10%.

In this example, additional cracking of airborne scale is carried out in two cages (3 and 4), which also makes it possible to achieve more optimal conditions for cooling the roll,. than with option

The results of calculating the parameters of the band of a band of another 8 nm, a center length of 1850 mm and a tackle of 30 nm, in a continuous rpynni finishing cell of 2000 mm (the proposed mode, the calculation without accounting for mechanical cooling) ..

Note: ECE 5-7-Oj4i;

 h, - original tolcium; h is the terminal holoin; i - relative compression; P - rolling force; Itsu rolling moment O - rolling speed;

till-, loss of cross section temperature, during compression; ttg is the heat transfer temperature to the rolls; Ai - decrease in temperature at natural cooling in the interval for lUtiTb.

Editor B. Papp

Compiled by M. Blatov Tehred M. Nad

Order 8592/8 Circulation. Subscription

VNIIPI USSR State Committee

for inventions and discoveries 113035, Moscow, Zh-35, Raushsk nab., 4/5

Branch ShSh Patent, Uzhgorod, st. Project, 4

205945. 4

 increase of reduction in stand 2, output of stand 3 and cracking of scale in stand 4 with a reduction rate of 0.5%.

5 The optimal rolling mode is shown in the table. The proposed method allows to increase productivity, reduce water consumption for cooling, and increase roll durability.

Corrector S.Cherni

Claims (1)

METHOD OF HOT ROLLING TOL-. TABLE STEEL, including heating the slab, rough rolling, trimming, finishing rolling, forced cooling of the roll, transportation and winding into a roll, characterized in that, in order to increase the productivity of the mill, rolling in one or more finishing stands is carried out with a reduction ratio of 0.5 -10% in each stand. о СП С © 4 * СЛ>