Method for producing band steel with different target thicknesses along longitudinal direction using hot continuous rolling mill set

Patent metadata

Field	Value
Publication number	US-9796008-B2
Application number	US-201214439956-A
Country	US
Kind code	B2
Filing date	Nov 30, 2012
Priority date	Oct 31, 2012
Publication date	Oct 24, 2017
Grant date	Oct 24, 2017

Abstract

The present invention relates to a method for producing hot rolled strip steel, especially the producing method of hot rolled strip steel with multiple target thicknesses in the longitudinal direction. It is a method to produce the strip steel with different target thicknesses in the longitudinal direction by using a hot continuous rolling mill. In this method, the first equal-thickness section of the strip steel is controlled with the conventional thickness control strategy, while other equal-thickness sections and the transition section between equal-thickness sections are controlled with the variable-thickness control strategy. Under the variable-thickness control strategy, the length of the first section of strip steel, the variation of thickness target value, the rolling stability and the spacing between stands are combined to determine the stand participating in the variable-thickness control, and calculate the roller gap value, as well as the time and speed of the variation of roller gap, thus achieving the producing control of strip steel with different target thicknesses in the longitudinal direction. The present invention utilizes the length of the first equal-thickness section and the variation of different target thicknesses and other related factors to determine the stands participating in the control, and then distributes the load variation among the stands, thus effectively avoiding the influence on the rolling stability due to imbalance of second flow, so that the produced strip with variable thickness in different sections in the longitudinal direction meet the user's requirements.

First claim

The invention claimed is:

1. A method for producing a target strip steel with different thicknesses in a longitudinal direction by using a hot continuous rolling mill, comprising:
rolling the target strip steel by two control types, an equal-thickness control and a variable-thickness control;
applying the equal-thickness control for a first equal-thickness section of the target strip steel, wherein the equal-thickness control distributes a load which a plurality of stands bears along a moving direction of the strip steel and in a principle of diminishing load backward from a front stand to next one;
applying the variable-thickness control for other equal-thickness sections and transition sections between equal thickness sections, wherein after occluding occurs at an end stand of the hot continuous rolling mill, wherein applying the variable-thickness control comprises:
determining stands participating in the variable-thickness control, wherein the variable-thickness control is performed by a latter portion of the stands; determining a start stand participating in the variable-thickness control, based on a length of the first equal-thickness section of the strip steel, a target thickness variation amount of each equal-thickness section, and a distance between stands and a rolling stability;
determining a load of each stand participating in the variable-thickness control; distributing a load variation amount in an equal proportion, based on a variation between a load of each stand in a former equal-thickness process and a load of each stand in a later equal-thickness section; and calculating a roller gap value of each stand corresponding to a target thickness of each equal-thickness section, according to a conversion relation between a load and the roller gap;
determining an action timing sequence of each stand participating in the variable-thickness control; calculating a time during which each stand participating in the variable-thickness control changes the roller gap; making each stand performs on a same position of the target strip steel when the roller gap is in change; and
calculating a variation velocity of the roller gap of each stand participating in the variable-thickness control when controlling each transition section between equal-thickness sections; completing a production control for the target strip steel with different thicknesses in the longitudinal direction.

2. The method of claim 1 , wherein determining the stands participating in the variable-thickness control comprises:
selecting a stand satisfying Formula (1) as the start stand I participating in the variable-thickness control:

I
=

min
⁢

{

i
,

i
∈

S
×

∑

n
=
i

(

end
-
1

)

⁢

⁢

h
n

h
end

≤

L
1

}

(
1
)

wherein: h n is a thickness of the strip steel at an outlet of the i th stand;
i is a serial number of the stand;
end is the serial number of the end stand of the hot continuous rolling mill;
L 1 is the length of the first equal-thickness section;
S is a distance from the i th stand to the (i+1) th stand, and a distance between stands of the hot continuous rolling mill is a constant; and
h end is a thickness of the strip steel at the outlet of the end stand;

the stands participating in the variable-thickness control include the i th stand to the end stand; for consideration of rolling stability, the stands participating in the variable-thickness control start to operate after steel occluding occurs at the end stand.

3. The method of claim 2 , wherein the stand with a smallest serial number among all the stands satisfying Formula (1) is selected as the start stand.

4. The method of claim 1 , wherein calculating a load of each stand participating in the variable-thickness control in the k th equal-thickness section of the target strip steel satisfies Formula (2):
T ik =T i(k−1) ×r   (2)

wherein: T ik is a load of the i th stand in the k th equal-thickness section of the target strip steel;
T i(k−1) is a load of the i th stand in the (k−1) th equal-thickness section of the target strip steel;

T i1 is an initial load of the i th stand in the first equal-thickness section; and
r is a variation factor of a load transiting from the (k−1) th equal-thickness section to the k th equal-thickness section, and satisfies Formula (3):

h
endk

=

h

(

i
-
1

)

⁢
k

×

∏

n
=
I

end

⁢

Assignees

• Baoshan Iron & Steel

Inventors

• Zhang Yong
• Zhou Xingze
• Shan Xuyi
• Zhu Konglin
• Meng Wenwang
• Zhang Chuanguo
• Pang Houjun
• Gao Zhiling

Classifications

• B21B2205/02

  Tailored blanks · CPC title

• B21B37/165 Primary

  responsive mainly to the measured thickness of the product · CPC title

• B21B37/16 Primary

  Control of thickness, width, diameter or other transverse dimensions (B21B37/58 takes precedence) · CPC title

• B21B2271/02

  Roll gap, screw-down position, draft position · CPC title

• B21B1/26

  by hot-rolling {, e.g. Steckel hot mill} · CPC title