CN101683657A - Roll forming of backup roll suitable for asymmetrical curve roll shape work roll - Google Patents

Abstract

The invention relates to a rolling mill roll of a strip cold rolling mill, in particular to a roll shape of a backup roll suitable for a strip cold rolling mill whose working rolls have an asymmetric curved roll shape. A back-up roll shape suitable for asymmetric curve roll-shaped work rolls is composed of two parts of curve superposition, one part is the back-up roll shape curve expressed by an even-order polynomial function, and the other part is the roll shape curve of the work roll, The roll shape of the work roll is superimposed on the roll shape curve of the back-up roll expressed by an even degree polynomial function in a certain proportion. During production, when the work roll moves positively and negatively, the roll shape curve of the work roll and the roll shape curve of the backup roll are staggered by a certain distance; because the shifting amount of the work roll is not large, it will not cause obvious misalignment between the roll shape of the backup roll and the work roll . Therefore, after the backup roller of the present invention is worn, the shape of the roller is symmetrical and the wear is uniform, thereby avoiding or effectively reducing the impact of asymmetric wear.

Description

Back-up Roll Shapes for Asymmetrically Curved Work Rolls

technical field

The invention relates to a rolling mill roll of a strip cold rolling mill, in particular to a roll shape of a backup roll suitable for a strip cold rolling mill whose working rolls have an asymmetric curved roll shape.

Background technique

As one of the most important products of the iron and steel industry, plate and strip play a very important role in the development of the national economy. The current strip rolling practice shows that no matter how advanced the strip shape control system and control means are equipped in the rolling mill, there are still some problems that the strip shape of some varieties and specifications is difficult to control, and the roll service period is limited due to the flatness defect. After analysis, it is found that the root of this problem is the limited ability to control the shape of the rolling mill under a certain roll configuration, and the deterioration of the initial roll shape of the roll due to wear during the service period. Therefore, for the rolling mills that have been put into production, it is necessary to pay attention to and give full play to the shape regulation function of the initial roll shape of the backing roll, and to reduce or even avoid the adverse effects of roll surface wear on the roll shape and the shape control performance of the mill. Optimize and improve the flatness control performance of the rolling mill and achieve this performance throughout the service life.

A reasonable design of the roll shape curve can alleviate the uneven longitudinal force of the roll, reduce the wear during the rolling process or make it wear evenly, directly reduce the cost, reduce the rate of defective products, and improve the production hit rate of high-quality products; reasonable The design of the roll shape curve can ensure that the thickness of the final plate is uniform in the transverse direction, so that the unevenness, the difference between the same plate and the thickness tolerance can meet the national standard, the international standard and even the strict user standard; a reasonable roll shape curve can help the rolling mill to give full play to its functions Force, expand production capacity, and can successfully develop some new varieties.

When the backup roll is a flat roll and the work roll is not a flat roll (asymmetrically curved work roll, such as CVC, CVC ⁺ , SmartCrown, UPC), it will cause asymmetric wear of the backup roll, that is to say, the operation side of the backup roll ( WS side) and the driving side (DS side) wear amount is obviously different, where the diameter of the work roll is larger, the contact pressure between the rolls is greater, and the wear amount is larger. In severe cases, the diameter difference between the WS side and the DS side is about 0.8mm. Due to the influence of asymmetrical factors such as incoming material wedge shape and strip deviation, it is easy to aggravate the asymmetric wear of the backup roller.

The main problems caused by asymmetric wear are: 1) the shape of the strip is asymmetric; 2) if there is a closed-loop feedback control, the setting value of the depression inclination is unstable and fluctuates greatly; 3) the back-up roll is asymmetrically worn when it is in service. The situation is serious. The axis of the support roller is tilted, causing the taper sleeve and the bushing of the oil film bearing to tilt, changing the size and distribution of the gaps on the four throttle sides of the static pressure chamber, which may reduce the bearing capacity of the static and dynamic pressure oil film, and aggravate the difficulty of starting and Problems such as burning oil film bearings.

At present, there are many studies on the roll shape of the backup roll and the roll shape of the work roll, but there is no research on what kind of roll shape of the backup roll should be equipped with the work roll (referring to the work roll with an asymmetric curve roll shape). The relevant patents include: Chinese patent 200510024680.1 discloses "a back-up roll that matches the roll profile curve of the work roll of a continuously variable crown mill", and Chinese patent 200410008195.0 discloses "a back-up roll that cooperates with axial movement to change the roll gap crown of the work roll ". However, there are many sets of continuously variable crown mills (CVC mills) at home and abroad. Therefore, what kind of back-up roll profile should be matched with this type of work roll with asymmetric curve profile is a novel and highly demanded topic. .

Contents of the invention

The purpose of the present invention is to provide a back-up roll shape suitable for asymmetrically curved roll-shaped work rolls. On the basis of maintaining the strip shape control ability of the rolling mill, the back-up roll can be worn symmetrically during use, thereby avoiding Or effectively reduce the impact of asymmetric wear.

The present invention is achieved in this way: a back-up roll shape suitable for asymmetric curve roll-shaped work rolls is composed of two parts of curve superposition, one part is the back-up roll roll shape curve expressed by an even-order polynomial function, and the other part is The roll shape curve of the work roll, the expression of the roll shape curve of the backup roll is:

R _SWB (x)=a×R ₁ (x)+b×R ₂ (x)

In the formula, R _SWB (x) is the backup roll shape suitable for the asymmetric curve roll shape work roll;

R ₁ (x) is the backup roll profile curve expressed by an even-degree polynomial function: the expression is: R ₁ (x) = A ₂ x ² +A ₄ x ⁴ +A ₆ x ⁶ +A ₈ x ⁸ + ...;

R ₂ (x) is the polynomial of the roll shape curve of the work roll: R ₂ (x) = A ₁ x + A ₂ x ² + A ₃ x ³ +...;

x is the coordinates of the roll body, with the center of the roll surface as the zero point,

a and b are proportional coefficients, a is 0.8-1, and b is 0.3-0.7.

The roll shape of the backup roll of the present invention is to superimpose the roll shape of the work roll on the roll shape curve of the backup roll expressed by an even-order polynomial function in a certain proportion. At this time, the movement of the work roll is zero. During the movement, the roll shape curve of the work roll and the roll shape curve of the backup roll are staggered by a certain distance. Because the movement of the work rolls is not large except for the HC rolling mill in cold rolling, it will not cause obvious dislocation between the roll shape of the backup roll and the work roll, so the positive and negative movement of the work rolls will not cause obvious uneven contact pressure . Therefore, after the backup roller of the present invention is worn, the shape of the roller is symmetrical and the wear is uniform, thereby avoiding or effectively reducing the impact of asymmetric wear.

Description of drawings

Fig. 1 is a diagram of the back-up roll profile curve R ₁ (x) and the work roll profile curve R ₂ (x) expressed by an even-degree polynomial function;

Fig. 2 is that the present invention is suitable for the back-up roll (SWB back-up roll) roll shape curve diagram of asymmetric curve roll-shaped work roll;

Fig. 3 is a comparison chart of the contact pressure between the present invention and the original roll shape.

Detailed ways

The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments.

A back-up roll shape suitable for asymmetric curve roll-shaped work rolls (referred to as SWB back-up rolls), which consists of two parts of superimposed curves, one part is the back-up roll shape curve expressed by an even-order polynomial function, and the other part is the work roll That is to say, the roll shape curve of the SWB backup roll is: the roll shape of the upper roll surface of the upper work roll is multiplied by the proportional coefficient, and then superimposed on the roll shape of the lower roll surface of the upper backup roll, and the roll shape of the lower roll surface of the lower work roll is multiplied by The same proportional coefficient is then superimposed on the roll shape of the upper roll surface of the lower support roll. The roll shape of the work roll mentioned here refers to the roll shape of the work roll with an asymmetric curve form, for example, CVC roll shape (polynomial of cubic power, odd function), CVC ⁺ roll shape (polynomial of fifth power or higher power, Odd function), SmartCrown roll shape (chord function curve).

The expression of the roll shape curve of the SWB support roll is:

R _SWB (x)=a×R ₁ (x)+b×R ₂ (x)

In the formula, R _SWB (x) is the roll shape of the back-up roll suitable for the asymmetric curved roll-shaped work roll, that is, the roll shape of the SWB back-up roll;

R ₁ (x) is the backup roll profile curve expressed by an even-degree polynomial function: the expression is: R ₁ (x) = A ₂ x ² +A ₄ x ⁴ +A ₆ x ⁶ +A ₈ x ⁸ + ...;

R ₂ (x) is the polynomial of the roll shape curve of the work roll: R ₂ (x) = A ₁ x + A ₂ x ² + A ₃ x ³ +...;

x is the coordinates of the roll body, with the center of the roll surface as the zero point,

a and b are proportional coefficients, a is 0.8-1, and b is 0.3-0.7.

The value ranges of the proportional coefficients a and b, a is 0.8~1, and b is 0.3~0.7. R ₁ (x) is a special backup roll profile curve, which can improve the rolling mill roll gap transverse stiffness and roll bending force regulation effect, in order to maintain its control characteristics, the value of the coefficient a should be larger, greater than 0.8, less than or equal to 1; The value of the coefficient b directly affects the distribution of the contact pressure between the rollers, and the distribution of the contact pressure between the rollers will affect the wear of the backup rollers. The larger the value of b, the more uniform the contact pressure between the rollers, which is more conducive to reducing the asymmetry of the backup rollers. wear, but the greater the value of b, the more obvious the decline in the secondary regulation of the roll gap stiffness and bending force. From this point of view, the value of b should not be too large, so the value of b is between 0.3 and 0.7, which is beneficial to supporting the roll. Uniform wear without significantly reducing mill controllability.

The roll shape of the SWB backup roll of the present invention is that the roll shape of the work roll is superimposed on the roll shape curve of the back-up roll expressed by an even-order polynomial function in a certain proportion. At this time, the movement of the work roll is zero. During the negative movement, the roll shape curve of the work roll and the roll shape curve of the backup roll are staggered by a certain distance, which will not cause obvious uneven contact pressure. Therefore, after the backup roller of the present invention is worn, the shape of the roller is symmetrical and the wear is uniform, thereby avoiding or effectively reducing the impact of asymmetric wear.

Example

The back-up roll suitable for asymmetric curved roll-shaped work rolls of the present invention is applied to a 1420CVC continuous cold rolling mill of a certain enterprise, and is used in the first stand back-up roll. The superposition amount is 50%, a=1, b=0.5.

The coefficients for the roll shape are as follows:

(1) The polynomial of the roll shape curve of the back-up roll in the first stand of the 1420CVC tandem cold rolling mill (the lower roll surface of the upper back-up roll):

R ₁ (x)＝4.751e ^-8 x ² -7.541e ^-13 x ⁴ +3.977e ^-18 x ⁶ -675≤x≤675

(2) CVC work roll roll shape curve polynomial (upper roll surface of the upper work roll):

R ₂ (x)＝-1.468e ^-4 x-4.934e ^-8 x ² +6.990e ^-10 x ³ -755≤x≤755

(3) Roll shape curve polynomial of SWB back-up roll (lower roll surface of upper back-up roll):

R _SWB (x)＝R ₁ (x)+0.5×R ₂ (x)

＝-7.341e ^-5 x+2.284e ^-8 x ² +3.495e ^-10 x ³ -7.541e ^-13 x ⁴ +3.977e ^-18 x ⁶

-675≤x≤675

See the roll profile graph for R ₁ (x) and R ₂ (x) in Figure 1, and the SWB backup roll profile graph in Figure 3. The SWB roll shape of the lower roll is superimposed in the same proportion, and the roll shape function of the lower roll is symmetrical to that of the upper roll along the y-axis. This is because R ₁ (x) itself is left-right symmetrical and the roll shape of the upper and lower rolls is the same. The CVC curve of the roll is left-right symmetrical, so the calculated roll shape of the lower roll and the upper roll of the SWB support roll is left-right symmetrical.

The inter-roll contact pressure of the SWB back-up roll of the present invention was compared with that of the original roll shape. Because the contact pressure distribution between the rolls includes two items: the uniformity of the contact pressure distribution between the rolls and the peak value of the contact pressure between the rolls, the former affects the uneven wear of the roll axial direction, and the latter affects the peeling of the roll. Referring to Fig. 3, it can be seen from the figure that after adopting the SWB backing roll, the distribution of the contact pressure between the rolls is more uniform, and the peak value of the contact pressure between the rolls decreases; therefore, the roll shape of the SWB backing roll of the present invention is conducive to improving the service life of the roll cycle, prolong the service life of the roll and reduce the production cost.

The production practice shows that after the SWB backing roll is used, the asymmetric wear of the backing roll is reduced from 0.5mm to 0.1mm, and the service life of the backing roll is extended by 10,000 tons.

The SWB support roll of the present invention only needs to grind the corresponding roll shape in the roll workshop, which is convenient to process and low in cost, and can be applied to strip cold rolling mills with asymmetric curved roll shapes, such as CVC rolling mills, SmartCrown, etc. rolling mill.

Claims (1)

1, a kind of support roller roll forming that is suitable for asymmetrical curve roll forming working roll, it is characterized in that: described support roller roll forming is made up of the stack of two parts curve, a part is the support roller roll shape curve of being expressed by the even polynomial function, another part is the roll shape curve of working roll, and described support roller roll shape curve expression formula is:

R _SWB(x)＝a×R ₁(x)+b×R ₂(x)

In the formula, R _SWB(x) for being suitable for the support roller roll forming of asymmetrical curve roll forming working roll;

R ₁(x) the support roller roll shape curve for being expressed by the even polynomial function: its expression formula is:

R ₁(x)＝A ₂x ²+A ₄x ⁴+A ₆x ⁶+A ₈x ⁸+…；

R ₂(x) be shape of working roll curve multinomial: R ₂(x)=A ₁X+A ₂x ²+ A ₃x ³+

X is a body of roll coordinate, is zero point with the roll surface center;

A, b are proportionality coefficient, and a is 0.8～1, and b is 0.3～0.7.

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