CN112547809A - Method for improving setting precision of roll gap of rolling mill - Google Patents

Abstract

The invention discloses a method for improving the setting precision of a roll gap of a rolling mill, and relates to the technical field of metal material processing. The method comprises the steps of calculating the pressure change in the roll gap zeroing process and the rolling mill stiffness coefficient of a screw-down stroke linear section, comparing the pressure change with the initial rolling mill stiffness coefficient to obtain a stiffness coefficient compensation value, calculating the roll gap compensation value generated by the stiffness coefficient compensation value, and adding the roll gap compensation value to the initial roll gap calculation when the roll gap is set. The invention eliminates the influence of the rigidity change of the rolling mill on the setting of the roll gap in daily operation by compensating the zero adjustment precision of the roll gap of the rolling mill, ensures the setting precision of the thickness of a rolled piece, improves the hit rate of the thickness of strip steel by 1.2 percent, simultaneously has the whole function controlled by an electric PLC program, does not need manual intervention and adjustment, is synchronous with the zero adjustment of the rolling mill in time, and does not influence the operation rate of the rolling mill.

Description

Method for improving setting precision of roll gap of rolling mill

Technical Field

The invention relates to the technical field of metal material processing, in particular to a method for improving the setting precision of a roll gap of a rolling mill.

Background

In the steel rolling production, the roll gap of the rolling mill needs to be zero-adjusted after roll changing every time before rolling begins, so that the actual value of the roll gap is consistent with the calculated value, and the thickness of a rolled piece is consistent with the preset thickness. The zero adjustment process is to apply a certain pressure to the rolling mill, then calculate the bounce of the rolling mill according to the stiffness coefficient of the rolling mill initially given in the computer program, and mark zero to the roll gap of the rolling mill.

The rigidity coefficient of the rolling mill is usually obtained by a rigidity test of the rolling mill and maintained in an electrical control PLC system to be used as the initial given rigidity coefficient of the rolling mill for calculating the bounce of the rolling mill. The cycle of the mill stiffness test is long, usually 1 year or more. In the period, the rigidity coefficient is adopted for zero adjustment of the roll gap after the roll change of the rolling mill each time, but after the roll change, the rigidity of the rolling mill may change due to the influence of factors such as the roll diameter, the roll system gap and the like, and if the initial rigidity coefficient is still adopted, the roll gap calculation will have deviation, so that the thickness calculation error is caused. If the rigidity test is carried out after each roll change before the zero adjustment of the roll gap, the method is not suitable for the field production reality, the screw-down force of the rigidity test is very large and needs to reach 40000KN or even more, so that the rolling mill is damaged to a certain extent, the analysis and maintenance processes of data after the rigidity test are complex and long, and the roll change time is about 20-30 minutes, so that the requirements of the rigidity test and the data maintenance cannot be met.

Disclosure of Invention

In order to solve the problems, the invention provides a method for improving the setting precision of the roll gap of a rolling mill, which comprises the steps of acquiring a pressing stroke value and a pressure change value in a linear relation interval, calculating to obtain a zero-adjustment rolling mill rigidity coefficient, comparing the zero-adjustment rigidity coefficient with an initial rolling mill rigidity coefficient, calculating to obtain a roll gap compensation value, and accumulating the roll gap compensation value to an initial roll gap set value when the roll gap of the rolling mill is set, thereby improving the setting precision of the roll gap of the rolling mill.

In order to achieve the purpose, the invention adopts the technical scheme that:

a method for improving the setting precision of the roll gap of a rolling mill comprises the steps of calculating the pressure change in the roll gap zero adjustment process and the rolling mill rigidity coefficient of a screw-down stroke linear section, comparing the pressure change with the initial rolling mill rigidity coefficient to obtain a rigidity coefficient compensation value, calculating the roll gap compensation value generated by the rigidity coefficient compensation value, adding the roll gap compensation value to the initial roll gap calculation set during roll gap setting, and improving the setting precision of the roll gap of the rolling mill.

Further, the method comprises the following specific steps:

(1) calculating a zero-adjustment stiffness coefficient: when the roll gap is zero-adjusted, respectively acquiring roll gap pressing positions at 6000KN and 9000KN by a PLC (programmable logic controller) program in the zero-adjusted pressure rising process, and dividing the difference of the roll gap positions by the pressure difference to obtain the stiffness coefficient of the rolling mill in zero adjustment;

(2) calculating a stiffness coefficient compensation value: reducing the rigidity coefficient during zero adjustment by using the initially given rigidity coefficient of the rolling mill in the PLC program;

(3) calculating a roll gap compensation value: dividing the rolling pressure set by the current pass by a stiffness coefficient compensation value of 2 times;

(4) adding the roll gap compensation value to the roll gap given calculation when the roll gap is set: the roll gap compensation value is subtracted from the initial roll gap set value.

Compared with the prior art, the invention has the beneficial effects that:

1. the inventor finds that the roll gap needs to be pressed down to zero adjustment force when the roll gap is zero adjusted, and the roll gap is usually 10000-15000 KN. According to the elastic deformation theory of the rolling mill, when the screw-down force exceeds 2000KN, the change of the screw-down force and the roll gap value is close to the linear relation, the rigidity coefficient of the rolling mill at zero adjustment can be calculated by collecting the screw-down stroke value and the pressure change value in the linear relation interval, the rigidity coefficient at zero adjustment is compared with the rigidity coefficient of the initial rolling mill, the roll gap compensation value is calculated, and when the roll gap of the rolling mill is set, the roll gap compensation value is accumulated to the initial roll gap set value, so that the roll gap setting precision of the rolling mill is improved.

2. The invention eliminates the influence caused by the rigidity change of the rolling mill in daily operation by the compensation of the zero adjustment precision of the roll gap of the rolling mill, improves the setting precision of the roll gap, ensures the setting precision of the thickness of a rolled piece and improves the rolling stability. Meanwhile, the whole function is realized by the control of an electric PLC program, manual intervention and adjustment are not needed, the time is synchronous with the zero adjustment of the rolling mill, and the operation rate of the rolling mill is not influenced. After the method is applied to an An steel 1780 hot continuous rolling unit, the hit rate of the thickness of the strip steel is improved by 1.2 percent, and the threading stability is obviously improved.

Detailed Description

The technical solutions and effects of the present invention will be further described with reference to specific examples, but the scope of the present invention is not limited thereto.

Example 1

The embodiment is applied to 1780mm hot continuous rolling unit of the company.

According to the method for improving the setting precision of the roll gap of the rolling mill, the pressure change in the roll gap zero adjustment process and the rolling mill rigidity coefficient of the screw-down stroke linear section are calculated, the rigidity coefficient compensation value is obtained by comparing the rigidity coefficient with the initial rolling mill rigidity coefficient, the roll gap compensation value generated by calculating the rigidity coefficient compensation value is calculated, the roll gap compensation value is added to the initial roll gap calculation setting when the roll gap is set, and the setting precision of the roll gap of the rolling mill is improved.

The method comprises the following specific steps:

1. calculating a zero-adjustment stiffness coefficient: when the roll gap is zero-adjusted, in the zero-adjusted pressure rising process, roll gap pressing positions at 6000KN and 9000KN are respectively collected through a PLC program, and the rigidity coefficient of the rolling mill during zero adjustment is calculated by the following calculation formula:

K= (F₂-F₁) / ( G₂-G₁)

wherein:

k is zero adjustment stiffness coefficient, KN/mm;

F₁-a pressing force of 6000 KN;

F₂-the pressing force 9000 KN;

G₁-a pressing position at a pressing force of 6000KN, mm;

G₂-depressed position at a depression force 9000KN, mm;

2. calculating the stiffness coefficient difference:

K_dev=K₀－K

wherein:

K_dev-difference in stiffness coefficient, KN/mm;

K₀-initial stiffness factor, KN/mm;

k is zero adjustment stiffness coefficient, KN/mm;

3. calculating a roll gap compensation value formed by the rigidity difference:

S₁=F/2K_dev

wherein:

S₁-roll gap compensation value formed by stiffness difference, mm;

f, setting rolling pressure and KN in the current pass;

4. adding a roll gap compensation value formed by the rigidity difference to roll gap given calculation:

S=S₀-S₁

wherein:

s is the final roll gap set value, mm;

S₀initial roll gap set value, mm

S₁-roll gap compensation value formed by stiffness difference, mm.

According to the embodiment, through the compensation of the zero adjustment precision of the roll gap of the rolling mill, the influence of the rigidity change of the rolling mill on the setting of the roll gap in daily operation is eliminated, the setting precision of the thickness of a rolled piece is ensured, the hit rate of the thickness of the strip steel is improved by 1.2%, meanwhile, the whole function is controlled by an electric PLC program, manual intervention and adjustment are not needed, the time is synchronous with the zero adjustment of the rolling mill, and the operation rate of the rolling mill is not influenced.

Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that changes, modifications, substitutions and alterations can be made in these embodiments without departing from the principles and spirit of the invention, the scope of which is defined in the appended claims and their equivalents.

Claims (2)

1. A method for improving the setting precision of the roll gap of a rolling mill is characterized in that the method is to calculate the pressure change and the roll stiffness coefficient of a linear section of a screw-down stroke in the roll gap zeroing process, compare the pressure change and the roll stiffness coefficient with the initial roll stiffness coefficient to obtain a stiffness coefficient compensation value, calculate the roll gap compensation value generated by the stiffness coefficient compensation value, add the roll gap compensation value to the initial roll gap calculation setting when the roll gap is set, and improve the setting precision of the roll gap of the rolling mill.

2. The method for improving the setting accuracy of the roll gap of the rolling mill as claimed in claim 1, characterized by comprising the following steps:

(1) calculating a zero-adjustment stiffness coefficient: when the roll gap is zero-adjusted, respectively acquiring roll gap pressing positions at 6000KN and 9000KN by a PLC (programmable logic controller) program in the zero-adjusted pressure rising process, and dividing the difference of the roll gap positions by the pressure difference to obtain the stiffness coefficient of the rolling mill in zero adjustment;

(2) calculating a stiffness coefficient compensation value: reducing the rigidity coefficient during zero adjustment by using the initially given rigidity coefficient of the rolling mill in the PLC program;

(3) calculating a roll gap compensation value: dividing the rolling pressure set by the current pass by a stiffness coefficient compensation value of 2 times;

(4) adding the roll gap compensation value to the roll gap given calculation when the roll gap is set: the roll gap compensation value is subtracted from the initial roll gap set value.