CN113042526A

CN113042526A - Differential thickness rolling method for medium plate

Info

Publication number: CN113042526A
Application number: CN202110246835.5A
Authority: CN
Inventors: 檀丽静; 卢锐; 乔汇龙; 张立超; 张帅; 赵裕健; 李明
Original assignee: Handan Iron and Steel Group Co Ltd; HBIS Co Ltd Handan Branch
Current assignee: Handan Iron and Steel Group Co Ltd; HBIS Co Ltd Handan Branch
Priority date: 2021-03-05
Filing date: 2021-03-05
Publication date: 2021-06-29

Abstract

The invention relates to a differential thickness rolling method for a medium plate, and belongs to the technical field of medium plate production in the metallurgical industry. The technical scheme is as follows: the number of passes of differential thickness rolling is even, the first pass of differential thickness rolling adopts a mode that the reduction rate is gradually increased, the thickness of the steel plate rolled out in the first pass of differential thickness rolling is different in the length direction, the upper surface of the steel plate has a certain gradient, one end with a smaller thickness is meshed into the second pass of differential thickness rolling, the second pass of differential thickness rolling also adopts a mode that the reduction rate is gradually increased, the steel plate with the upper surface having the certain gradient is rolled into a flat plate with the same thickness in the length direction, and the rest is done in sequence until the last pass of differential thickness rolling. The invention has the beneficial effects that: the differential thickness rolling can realize the gripping under low pressure and the steel throwing under high pressure, so the reduction of the steel plate can be greatly increased, thereby the deformation of the core part of the steel plate is increased, the deformation is promoted to go deep into the core part of a rolled piece, the performance of the steel plate is improved, the rolling passes can be reduced, and the rolling efficiency is improved.

Description

Differential thickness rolling method for medium plate

Technical Field

The invention relates to a differential thickness rolling method for a medium plate, and belongs to the technical field of medium plate production in the metallurgical industry.

Background

With the rapid development of the fields of national transportation, mechanical manufacturing and the like, the performance requirements of thick plates or high-strength and high-toughness steel plates produced from medium and thick plates are higher and higher. And the thick plate and the high-strength and high-toughness steel plate have the problems of insufficient compression ratio and uneven deformation in the conventional rolling process. The traditional rolling process is limited by motor current and biting conditions, the pass reduction cannot be too large, and the steel plate with large reduction cannot be rolled due to the existence of impact torque during steel biting, so that the steel plate with good core structure performance cannot be obtained.

Disclosure of Invention

The invention aims to provide a differential thickness rolling method for a medium plate, which can avoid the problems of insufficient compression ratio and uneven deformation of a high-strength and high-toughness steel plate in the conventional rolling process, thereby increasing the deformation of a steel plate core part, improving the performance of the high-strength and high-toughness steel plate and solving the problems in the background art.

The technical scheme of the invention is as follows:

the method for rolling the medium plate with different thicknesses comprises the steps of rolling the medium plate with different thicknesses in the length direction in an even number of passes, adopting a mode that the reduction rate is gradually increased in the first pass of the differential thickness rolling, rolling the steel plate with the constant gradient on the upper surface in a length direction different in thickness in the first pass of the differential thickness rolling, biting the end with the smaller thickness into the second pass of the differential thickness rolling, adopting a mode that the reduction rate is gradually increased in the second pass of the differential thickness rolling, rolling the steel plate with the constant gradient on the upper surface into a flat plate with the consistent thickness in the length direction, and the like in sequence until the last pass of the differential thickness rolling.

The number of passes of the differential thickness rolling is a plurality of passes in the middle of the conventional rolling, the conventional rolling means that the reduction rate of each pass is the same, and the length direction of the steel plate rolled by each pass is a flat plate with the same thickness.

The first pass of the differential thickness rolling starts from the third pass of the conventional rolling, and the last pass of the differential thickness rolling is a certain pass before the pass of the finished product of the conventional rolling.

The reduction rate of each pass in the conventional rolling is the same, the reduction rate of each pass in the differential thickness rolling is gradually changed, the odd number of passes of the differential thickness rolling are not a flat plate, the upper surface is graded, a thin area can be bitten when even number of passes are bitten, a thick area is polished to achieve low-pressure biting, and the steel is polished under high pressure, so that the deformation of the core part of the steel plate is increased, and the performance of the high-strength and high-toughness steel plate is improved.

The invention has the beneficial effects that: (1) the differential thickness rolling can realize the gripping under low pressure and the steel throwing under high pressure, so the steel plate reduction can be greatly increased, thereby increasing the deformation of the steel plate core part, promoting the deformation to go deep into the rolled piece core part and improving the performance of the steel plate. (2) Because the rolling reduction of the differential thickness rolling pass is increased, the rolling passes of the steel plate are greatly reduced, the rolling efficiency is improved, and the yield is greatly improved.

Drawings

FIG. 1 is a schematic view of a differential thickness rolling first pass rolling process;

FIG. 2 is a schematic diagram of a second pass rolling process of differential thickness rolling;

in the figure: 1. rolling pieces; 2. a rolling mill; a1, the thickness of rolled pieces before the first pass of differential thickness rolling; b1, rolling the tail part of the rolled piece after the first pass of differential thickness rolling; c1, the head thickness of the rolled piece after the first pass of differential thickness rolling; a2, the thickness of the rolled piece after the second pass of differential thickness rolling is carried out; b2, difference thickness rolling the head thickness of the rolled piece before the second rolling; c2, and differential thickness rolling the tail thickness of the rolled piece before the second rolling.

Detailed Description

The invention is further illustrated by way of example in the following with reference to the accompanying drawings.

Referring to the attached drawings 1-2, the method for rolling the medium plate with different thicknesses comprises the steps that the number of passes of differential thickness rolling is even, the first pass of the differential thickness rolling adopts a mode that the reduction rate is gradually increased, the thickness of a steel plate rolled out in the first pass of the differential thickness rolling is different in the length direction, the upper surface of the steel plate has a certain gradient, one end with the smaller thickness is meshed into the second pass of the differential thickness rolling, the second pass of the differential thickness rolling also adopts a mode that the reduction rate is gradually increased, the steel plate with the fixed gradient on the upper surface is rolled into a flat plate with the same thickness in the length direction, and the like, until the last pass of the differential thickness rolling.

In this example, the rolling mill used a single stand reversing mill, rolling steel grades: the steel plates of the grades Q550, Q690 and the like are rolled by adopting a mode of combining differential thickness rolling and conventional rolling, the total pass of the conventional rolling is twenty-five, the first pass of the differential thickness rolling starts from the third pass of the conventional rolling, the last pass of the differential thickness rolling is the eighth pass of the conventional rolling, namely the third pass of the conventional rolling is switched into the differential thickness rolling, and the steel plates of the grades Q550, Q690 and the like are switched into the conventional rolling after the six passes of the differential thickness rolling.

Referring to fig. 1, an arrow indicates a rolling direction, an operator switches from current conventional rolling to differential thickness rolling before the third rolling, and inputs thickness values of the head and the tail of the steel plate when the third rolling is completed, for example, the thickness of the head of the steel plate of the third rolling is set to 216mm, the thickness of the tail is set to 212mm, namely the thickness a1 of the rolled piece before the first rolling of the differential thickness rolling is 223, the thickness b1 of the tail of the rolled piece after the first rolling of the differential thickness rolling is 212mm, the thickness c1 of the head of the rolled piece after the first rolling of the differential thickness rolling is 212mm, the thickness value of the whole steel plate in the length direction is gradually changed, the thickness of the tail is smaller than the thickness value of the head, so as to achieve that the fourth rolling of the conventional rolling, namely the thin steel plate region when the first pass of the differential thickness rolling is bitten, and the steel is bitten under low.

Referring to the attached figure 2, after the third rolling pass, the thickness value of the steel plate at the completion of the fourth rolling pass of the conventional rolling pass is set, the head thickness of the steel plate is set to 207mm, the tail thickness of the steel plate is set to 207mm, namely the thickness a2 of the rolled piece after the second rolling pass of the differential rolling pass is 207, b2= b1, c2= c1, because the third rolling pass of the conventional rolling pass rolls the plate with gradient, and the fourth rolling pass of the conventional rolling pass rolls the steel plate flat and cannot have the gradient to be increased. The subsequent passes of the differential thickness rolling method are set by analogy, the odd pass set tail thickness is smaller than the head thickness, the even pass set head and tail thickness is consistent, the total pass number of the differential thickness rolling method is required to be even, and the finally-obtained steel plate is ensured to be flat. And finally, switching to conventional rolling before the last pass of the differential thickness rolling method, and rolling the subsequent passes according to the conventional hot rolling method to finally obtain the finished plate.

Claims

1. A differential thickness rolling method for medium plates is characterized by comprising the following steps: the number of passes of differential thickness rolling is even, the first pass of differential thickness rolling adopts a mode that the reduction rate is gradually increased, the thickness of the steel plate rolled out in the first pass of differential thickness rolling is different in the length direction, the upper surface of the steel plate has a certain gradient, one end with a smaller thickness is meshed into the second pass of differential thickness rolling, the second pass of differential thickness rolling also adopts a mode that the reduction rate is gradually increased, the steel plate with the upper surface having the certain gradient is rolled into a flat plate with the same thickness in the length direction, and the rest is done in sequence until the last pass of differential thickness rolling.

2. The differential thickness rolling method of a medium plate according to claim 1, characterized in that: the number of passes of the differential thickness rolling is a plurality of passes in the middle of the conventional rolling, the conventional rolling means that the reduction rate of each pass is the same, and the length direction of the steel plate rolled by each pass is a flat plate with the same thickness.

3. The differential thickness rolling method of a medium plate according to claim 2, characterized in that: the first pass of the differential thickness rolling starts from the third pass of the conventional rolling, and the last pass of the differential thickness rolling is a certain pass before the pass of the finished product of the conventional rolling.