UA82548C2 - Method and mill for production of thin hot-rolled strip - Google Patents

Abstract

The invention relates to the production of thin hot-rolled strip on hot mills. A method includes a sequence of following process operations. At first reverse rolling of strip is performed in two-stand roughing train for three passes, in this case in the last roughing pass the strip is forcedly cooled. Then the strip is winded into winding device, after which unwinding and subsequent rolling in continuous finishing train are performed. The rolling at the last roughing pass is performed at maximum speed of the strip:where- speed of the strip at the last roughing pass;- length of the strip at the first roughing pass;- speed of the strip at the first roughing pass;A - deceleration at braking of strip;- distance from the axis of stand to the cooling device;- distance from the axis of winding devices to the cooling device;- cooling time of strip.Also, the invention discloses a rolling mill for implementation of this method. The invention makes it possible to extend manufacturing capability of mill and corresponding method for manufacture of hot-rolled strips.

Description

Description of the invention

The invention relates to methods of production of thin hot-rolled bars on hot-rolling mills, which 2 contain rough reversible and finishing continuous rolling groups of cages on which pipe steel is rolled.

A known method of production of hot-rolled bars on a semi-continuous condition (US patent Mo3803891, IPC v2181/32I.

The condition includes: - Draft reversible rolling cage; - a winding machine; - flying scissors; - net rolling group consisting of six continuous rolling cages.

The considered method of hot rolling consists of a number of technological operations.

The slabs, after heating in the furnace and removing the scale, are sent to the draft reversible rolling mill. In this 72 cage, the staff is rolled to an intermediate thickness in several passes and wound into an intermediate roll on the last pass. The rolling operation shortens the rolling fields between the rough and final rolling groups, improves the rolling temperature conditions.

The rolling of the staff in the finishing group of cages is carried out continuously with its unwinding from the intermediate roll and ends with winding on the winders behind the finishing group.

The disadvantage of the described method of production and the rolling mill is the need to place between the draft cage and the rolling machine, an intermediate-length lead (after the penultimate odd draft pass), which can be several tens of meters (40-5Ω).

This leads, firstly, to a significant increase in the dimensions of the state and, secondly, to the uncertainty of the temperature regimes of the next finishing rolling, because the staff is in the mode of transportation from the draft cage to the winding machine for a relatively long time. heh)

A rolling mill for the production of thin hot-rolled bars, which is described in the patent, was chosen as the prototype

RF Mo2254183 C2, IPC B2181/34 dated June 20, 2005.

The condition includes: - a rough reversible rolling group consisting of two cages; so - a winding device located at a distance I. behind the second draft cage; chE - flying shears; - net continuous rolling group consisting of six cages. i am

In the considered state, reversible rough rolling is carried out in three double passes, which allows to significantly reduce the distance between the second rough cage and the rolling machine, because it is equal to М со

Set de GI - the distance between the second draft cage and the collapsing device;

Mt - the length of the staff after the first draft pass; "

Mt - the speed of the staff when rolling; sh-v s a - deceleration when braking staffs. y In this rolling method, the length of the staffs I is significantly less than in semi-continuous rolling mills with "" one draft cage, which allows to reduce the dimensions of the mill and reduce the time of transportation of the staffs to the rolling device.

The disadvantage of the considered rolling method is the impossibility of obtaining some grades of steel with reduced pressing temperatures in the final group of cages. Such grades of steel include pipe steel, in particular, 08G2SFB.

For example, when rolling bars with a width of 1570 mm and a thickness of ZOmm (at the exit from the draft group of cages), its temperature must be reduced in the section from the draft cages to the coil box (coiling machine) from 10402 s to 91020-9602С

At this temperature, it can roll in the finishing group of cages to obtain the given structure of the metal. o The invention is based on the task of creating a method of rolling staffs, which ensures the expansion of the state's technological capabilities in terms of expanding the brand composition of rolling staffs.

This task is solved due to the technical result, which consists in ensuring an adjustable decrease in the temperature of the staff in the gap between the second draft cage and the winding device.

To achieve the above result in the method of production of thin hot-rolled staffs on mills (F, hot rolling), in which reverse rolling of staffs in a two-cell rough group of cages is carried out in three passes, winding of staffs on the last rough pass into a winding device, subsequent unwinding and rolling in a continuous finishing rolling group, according to the invention, the staff on the last rough 60 pass is forcibly cooled before winding on the winding device, while the maximum speed of the staff in the last rough pass is determined by the formula: 2 mo. taya vv sht I ' 65 ahp de Mut - the speed of the staff in the last draft pass;

Mt - the length of the staff in the first draft pass;

Washes - the speed of the staff in the first draft pass; a - deceleration when braking staffs;

Il - the distance from the axis of the cage to the cooling device;

Y zmp - the distance from the axis of the winding device to the cooling device;

Iohl - Staff cooldown time.

In addition, in order to achieve the above result, a rolling mill for the production of thin hot-rolled bars, including a two-cell draft reversible group of cages, a winding device located from / about the last draft cage at a distance determined by the length of the staffs in the first draft pass, flying shears, finishing continuous rolling group, according to the invention, is supplied with a device for cooling the staffs, located in the gap between the rough reversing group of cages and the winding device, in front of the finishing rolling group.

As a result of a comparative analysis of the proposed method of production of thin hot-rolled bars with a 7/5 prototype, it was established that they have the following common features: - reversible rolling of bars in a two-cell draft group of cages in three passes, - winding of bars on the last draft pass in a winding device, - subsequent unwinding and rolling in a continuous finishing rolling group, and distinguishing features: 20 - the staff on the last draft pass is forcibly cooled before winding on the winding device, - the maximum speed of the staffs in the last draft pass is determined by the formula: 2 и Шише с рт Johl' o de Muth - the speed of the staff in the last draft pass;

Mt - the length of the staff in the first draft pass;

Washes - the speed of the staff in the first draft pass; a - deceleration when braking staffs; со 30 Il - the distance from the axis of the cage to the cooling device; chi

Y zmp - the distance from the axis of the winding device to the cooling device;

Iohl - Staff cooldown time. i am

Thus, the proposed method of production of thin hot-rolled bars has a new sequence of operations and a new method of operations. 35 As a result of a comparative analysis of the proposed rolling mill for the production of thin hot-rolled bars with the prototype, it was established that they have the following general characteristics: - a two-cell rough reversible group of cages, - the winding device is located from the last blank cage at a distance determined by the length of the bars in « du the first draft pass, - - flying shears, c - finishing continuous rolling group, with and distinguishing features: - the rolling mill is supplied with a device for cooling the staff, located in the gap between the rough reversing group of cages and the winding device, in front of the final rolling group .

In this way, the proposed rolling mill has new component parts, a new layout of these parts.

Kz There is a cause and effect relationship between distinctive features and the technical result achieved.

Due to the fact that the staff on the last draft pass is forcibly cooled before winding on and the winding device, it became possible to expand the technological capabilities of the mill and, in particular, to roll tubular s" 50 steel grades (for example, О8Г2СФБ), which have a rolling temperature in the finishing group of cages 100-150 lower than the draft. co Thanks to the fact that the maximum speed of the staff in the last draft pass is determined by the formula: 2 vv it Il zp sht I ' ahp o it became possible, without increasing the dimensions of the state in comparison with the prototype, to achieve the necessary co-cooling of the staff to the specified temperature.

Thus, the use of the proposed method and condition 60 for the production of thin hot-rolled staffs provides an expansion of the technological capabilities of the condition.

Exclusion of at least one of them from the above set of distinguishing features does not provide a solution to the task - expanding the state's technological capabilities.

The claimed technical solution is not known from the prior art, therefore it is novel.

The proposed technical solution has an inventive level, because the method of production of thin hot-rolled bo staffs on hot-rolling mills and the state itself, considered above, is not obvious to a specialist from the level of technology.

The claimed technical solution is industrially suitable, because its technical and technological implementation does not cause difficulties. According to this technical solution, a sketch design of the state for the production of thin hot-rolled steel at the Novolypetsk Metallurgical Plant was completed.

Thus, the proposed technical solution can be given legal protection because it is new, has an inventive level and is industrially applicable, meeting all the criteria of an invention.

The invention is explained by the drawing, which shows:

Fig. 1 - location of the state equipment for the production of thin hot-rolled bars.

The mill for the production of thin hot-rolled bars consists of a heating furnace (not shown in the drawing 7/0), transport rollers 1, a rough reversible rolling group consisting of two cages 2 and

C, a device for cooling the staffs 4, a winding device 5, located from the last draft cage C at a distance determined by the length of the staffs in the first draft pass, flying shears 6, a finishing continuous rolling group 7, consisting of six cages.

The dimensions of the device for cooling the staffs are selected from the condition of placing it between the last draft 7/5 Cage C and the winding device 5. This distance is determined by the formula

Yipo - Yi sht "M. i- Y zmt a de ut - the length of the staff in the first draft pass;

Washes - the speed of the staff in the first draft pass; a - deceleration when braking staffs;

Il - the distance from the axis of the cage to the cooling device;

Y zmp - the distance from the axis of the winding device to the cooling device.

The proposed method of hot rolling of thin stock is carried out by performing the following technological operations. si

The slab heated to the rolling temperature (11502С, steel 08Г2СФБ) with a thickness of 23О0mm is fed to a group of rough cages, where in three passes it is rolled to an intermediate thickness of ZOmm. At the same time, in the first draft pass, the device for cooling the staff is turned off.

On the last draft pass of the staff passes through the included device for cooling the staffs for winding. At the same time, water with a temperature of 402C in a specific volume of 40mZ/1m2 hour is supplied to the headquarters. co

The speed of movement of the staff in the last rough passage is determined by the formula:

Zo de Mut - the speed of the staff in the last draft pass; co

Mt - the length of the staff in the first draft pass;

Washes - the speed of the staff in the first draft pass; a - deceleration when braking staffs; "

Il - the distance from the axis of the cage to the cooling device;

Y zmp - the distance from the axis of the winding device to the cooling device; - s Iohl - Time of cooling staffs. "" To reduce the temperature of the staff before winding from 1040 "C to 9602, the speed of passing the staff " through the cooling device is on average 2 m/s.

After winding, the staffs in the winding device unwind it, cut its ends with flying scissors 6 and

The staff is rolled in the final rolling group of cages. It can be seen from all of the above that the proposed method of production of hot-rolled thin bars in the considered condition allows to expand its technological capabilities due to the rolling of additional pipe steels. 1st"

Claims (2)

The formula of the invention») 1. The method of production of thin hot-rolled staffs on hot rolling mills, in which reverse rolling of staffs in a two-cell rough group of cages is carried out in three passes, winding of staffs on the last rough pass into a winding device, subsequent unwinding and rolling in a continuous clean rolling group, which differs by the fact that on the last draft pass of the staff, they are forced to cool before winding, while rolling in the last draft pass is carried out at the maximum speed of the staffs: 2, 60 Mt two times that pi ohl de mit speed of the staffs in the last draft pass; b5 | dd7 the length of the staff in the first draft pass; mat 7 speed of the staff in the first draft pass; a - deceleration when braking the staff; And kl - the distance from the axis of the cage to the cooling device; the distance from the axis of the winding device to the cooling device; Group ace cooling headquarters. 2. A rolling mill for the production of thin hot-rolled stock, including a two-cell draft reversible 70 group of cages, a winding device that is located from the last draft cage at a distance determined by the length of the staff in the first draft pass, flying shears and a clean continuous rolling group, which is distinguished by , that it is equipped with a device for cooling the staff, which is placed in the gap between the rough reversing group of cages and the winding device, in front of the clean rolling group. s 7 o so «h Io) s Zo so - and? about 1 of them 50 12; ko 60 b5