KR101230151B1 - Method for controlling rolling oil amount of hot rolling - Google Patents

Abstract

The present invention in the hot rolling process using the rolling oil, the hot rolling process includes a rolling flow rate control method for controlling the rolling flow rate supplied between the rolling roll and the rolling material, the rolling flow rate control method, the rolling roll and the rolling material A coefficient of friction estimating step of estimating the coefficient of friction in real time; A rolling flow rate deriving step of deriving a rolling flow rate to be supplied between the rolling roll and the rolling material by the estimated friction coefficient; And a rolling oil supplying step of supplying the rolling oil between the rolling rolls and the rolling material in a variable rolling flow rate by the derived rolling flow rate. According to the present invention, it is possible to provide a hot rolling process that can reduce the defective rate by effectively controlling the rolling flow rate in real time in the hot rolling process to improve productivity, and a high chromium ferritic stainless steel produced by the hot rolling process. have.

Description

Rolling flow control method in hot rolling process {METHOD FOR CONTROLLING ROLLING OIL AMOUNT OF HOT ROLLING}

The present invention relates to a ferritic stainless steel and a method for manufacturing the same, and more particularly, rolling in a hot rolling process for producing high chromium ferritic stainless steel having excellent surface quality by controlling sticking phenomenon and plate tipping phenomenon. A flow control method and a ferritic stainless steel produced thereby.

The present invention relates to a high chromium ferritic stainless steel having excellent surface quality and a method for manufacturing the same, and to reducing the sticking phenomenon frequently occurring in the process of hot rolling the ferritic stainless steel, thereby improving the surface quality of the ferritic stainless steel It relates to a manufacturing method.

In general, in order to reduce the occurrence of sticking in the production method of ferritic stainless steel, a hot rolling process was performed by adding a predetermined material between the rolling roll of the rolling mill used in hot rolling and the surface of the rolling material.

These methods reduce the friction between the rolling roll and the material by adding a specific material to the surface of the rolling material, thereby preventing sticking. In these methods, the friction coefficient between the rolling roll and the material that changes in real time is changed. Since it is not considered, it is difficult to control the specific material added by spraying on the surface of the rolled material. Therefore, when the amount of the specific material is small, it is not sufficient to prevent the sticking phenomenon, and when the amount of the specific material is excessive, there is a disadvantage in that bonding such as slip phenomenon may occur.

Another method for preventing the sticking phenomenon of ferritic stainless steel is to add a specific material to one surface of the rolling roll or the rolled material during hot rolling or to perform the hot rolling while maintaining the heating furnace at a specific temperature. A method is mentioned. In the former case, the specific material added to the surface has an effect of reducing the occurrence of sticking phenomenon, but does not reflect the friction characteristics of the rolled roll and the rolled material changed by applicable steel grades and other rolling conditions. There is a problem. That is, when using hydraulic rolling simply without considering the friction coefficient that is changed in real time between the rolling roll and the rolling material, the sticking phenomenon can be reduced, but the slip phenomenon due to insufficient or excessively used rolling flow rate. There is a disadvantage that this may occur, thereby causing problems such as plate tilting may occur additionally, and in the latter case, the method of reducing the sticking phenomenon by controlling the temperature of the heating furnace or the rolling material, There is a disadvantage that the material of the material produced by this method can be deteriorated.

An object of the present invention devised to solve the above problems is to provide a hot rolling process that can prevent the sticking phenomenon and slip phenomenon of the rolling material during hot rolling.

In addition, another object of the present invention is to provide a rolling flow rate control method of the hot rolling process that can improve the surface quality of the rolling material.

According to a feature of the present invention for achieving the above object, the present invention relates to a rolling flow rate control method of the hot rolling process, the rolling flow rate control method, in the hot rolling process of rolling using rolling oil, rolling roll And a coefficient of friction between the rolling material and the rolled material, and controlling the rolling flow rate supplied between the rolling roll and the rolling material by the estimated friction coefficient.

In addition, the rolling flow rate control method of the hot rolling process, the friction coefficient estimation step of estimating the friction coefficient between the rolling roll and the rolling material in real time; A rolling flow rate deriving step of deriving a rolling flow rate to be supplied between the rolling roll and the rolling material by the estimated friction coefficient; And a rolling oil supplying step of supplying the rolling oil with a variable rolling flow rate between the rolling roll and the rolling material by the derived rolling flow rate.

In the friction coefficient estimating step, the friction coefficient may be estimated based on the rolling load, the rolling speed, and the rolling torque between the rolling roll and the rolling material.

The rolling flow rate deriving step may derive the rolling flow rate to be inversely proportional to the estimated friction coefficient.

In the rolling flow rate deriving step, the estimated friction coefficient is derived from the rolling flow rate so as to fall within a range of a dead band upper limit value and a dead band lower limit value, and the dead band upper limit value is a friction coefficient at which sticking occurs on the surface of the rolled material. The lower band value may be a coefficient of friction in which plate tilt occurs due to slip of the rolled material.

In the rolling flow rate derivation step, the rolling flow rate may be limited to less than or equal to the rolling flow rate limit.

In the rolling oil supplying step, the rolling oil may be supplied between the rolling roll and the rolling material so that the friction coefficient is kept constant.

The rolled material is weight%, Cr: 17-23%, C; 0.02% or less, N: 0.02% or less, Ti: 0.2-0.4%, Mn: 0.3% or less, Cu: 0.2-0.5%, Al: 0.03-0.10%, S: 0.002% or less, Si: 0.15% or less, Nb : The content of 0.06 to 0.45% and remaining components may be high chromium ferritic stainless steel made of Fe and unavoidable impurities.

In addition, the present invention is an invention in excess of the high chromium ferritic stainless steel, the high chromium ferritic stainless steel in weight%, Cr: 17-23%, C; 0.02% or less, N: 0.02% or less, Ti: 0.2-0.4%, Mn: 0.3% or less, Cu: 0.2-0.5%, Al: 0.03-0.10%, S: 0.002% or less, Si: 0.15% or less, Nb : Rolling flow rate control method in the process of hot rolling a rolled material consisting of Fe and unavoidable impurities which satisfy the content of 0.06 to 0.45%, estimates the coefficient of friction between the rolled roll and the rolled material in real time, and estimates The rolling flow rate to be supplied between the rolling roll and the rolling material is derived by the friction coefficient thus obtained, and the rolling oil is supplied as a variable rolling flow rate between the rolling roll and the rolling material by the derived rolling flow rate, and the rolling flow rate is The formula can be satisfied.

Rolling flow rate = (-4E-5) * Friction coefficient + 0.0782

At this time, the friction coefficient is derived from the rolling flow rate so as to fall within the deadband upper limit and the deadband lower limit, the deadband upper limit is 0.3 to 0.35, the deadband lower limit may be 0.15 to 0.2.

According to the present invention as described above, it is possible to provide a hot rolling process that can increase the process efficiency by preventing the sticking phenomenon and the slip phenomenon of the rolled material.

In addition, according to the present invention can provide a rolling flow rate control method of the hot rolling process that can improve the surface quality of the rolling material by providing a novel rolling flow rate control method in the hot rolling process.

1 is a schematic flowchart of a rolling flow rate control method of a hot rolling process according to the present invention;
2 is a view schematically showing the sequence of the rolling flow rate derivation step of FIG.
Figure 3 is a graph showing the coefficient of friction derived between the upper roll and the lower roll and the rolling material over time.
4 is a graph showing a coefficient of friction according to rolling conditions.
5 is a graph showing the coefficient of friction according to the rolling flow rate.

Specific details of other embodiments are included in the detailed description and the drawings.

Advantages and features of the present invention and methods for achieving them will be apparent with reference to the embodiments described below in detail with the accompanying drawings. However, the present invention is not limited to the embodiments described below, but may be embodied in various forms. In the following description, it is assumed that a part is connected to another part, But also includes a case in which other elements are electrically connected to each other in the middle thereof. In the drawings, parts not relating to the present invention are omitted for clarity of description, and like parts are denoted by the same reference numerals throughout the specification.

Usually, in order to prevent the sticking phenomenon of ferritic stainless steel, in the hot rolling process, a high-pressure water jetting device is installed at the inlet side of the rolling roll of the rough rolling end and the finishing rolling front end, and the high-pressure water is sprayed on the hot rolled plate of the stainless steel. A method of lowering the surface temperature of a hot rolled sheet of steel to about 700 ° C is disclosed. As such, after securing a predetermined high temperature strength to the hot rolled plate of the stainless steel having the surface temperature lowered, hot rolling was immediately performed to prevent the sticking phenomenon.

In addition, the apparatus and method for preventing the sticking phenomenon of the ferritic stainless steel, by spraying steam on the surface of the rolling material, raising the exit temperature of the slab in the heating furnace, and the high temperature of the hot-rolled sheet surface before rolling starts The method of preventing a sticking shape by rolling after forming a thick scale layer on the surface of a rolling board by promoting oxidation is mentioned.

The above-described methods reduce friction between the rolling roll and the material by adding a specific material to the surface of the rolling material, thereby preventing the sticking phenomenon. These methods do not take into account the coefficient of friction between the rolling roll and the material that fluctuates in real time, making it difficult to control the specific material added by spraying on the surface of the rolling material. Therefore, when the amount of the specific material is small, it is not sufficient to prevent the sticking phenomenon, and when the amount of the specific material is excessive, there is a disadvantage in that bonding such as slip phenomenon may occur.

As another method, there is disclosed a method of spraying a mixed liquid composed of scale and water having a particle size of 100 μm or less on a rolling roll in order to prevent sticking of stainless steel. Specifically, before rolling the stainless steel, it is characterized by rolling after adsorbing fine scale particles to the rolling roll. The two published patents have a disadvantage in that a difference in the component ratio between scale particles and water may occur. In particular, this method differs in that it adds a specific material to the rolling roll, while the friction coefficient between the rolling roll and the material cannot be confirmed in real time when reducing the friction coefficient between the rolling roll and the material, so that the sticking If a phenomenon occurs, there is a disadvantage that no action can be taken.

The method for preventing the sticking phenomenon of these ferritic stainless steels is a method of adding the specific material to one surface of the rolling roll or the rolling material during hot rolling or performing the hot rolling while maintaining the heating furnace at a specific temperature. Can be summarized. In the former case, the specific material added to the surface has an effect of reducing the occurrence of sticking phenomenon, but does not reflect the friction characteristics of the rolled roll and the rolled material changed by applicable steel grades and other rolling conditions. There is a problem. That is, when using hydraulic rolling simply without considering the friction coefficient that is changed in real time between the rolling roll and the rolling material, the sticking phenomenon can be reduced, but the slip phenomenon due to insufficient or excessively used rolling flow rate. There is a disadvantage that this may occur, thereby causing problems such as plate tilting may occur additionally, and in the latter case, the method of reducing the sticking phenomenon by controlling the temperature of the heating furnace or the rolling material, There is a disadvantage that the material of the material produced by this method can be deteriorated.

Hereinafter, the present invention will be described with reference to the accompanying drawings.

1 is a schematic flowchart of a rolling flow rate control method of a hot rolling process according to the present invention.

In the hot rolling process of the hot rolling process according to the preferred embodiment of the present invention, in the hot rolling process of rolling using rolling oil, the friction coefficient between the rolling roll and the rolling material is estimated, and the rolling roll and Controlling the rolling flow rate supplied between the rolling materials.

In addition, the rolled material is a weight%, Cr: 17-23%, C; 0.02% or less, N: 0.02% or less, Ti: 0.2-0.4%, Mn: 0.3% or less, Cu: 0.2-0.5%, Al: 0.03-0.10%, S: 0.002% or less, Si: 0.15% or less, Nb : The content of 0.06 to 0.45% and remaining components may be high chromium ferritic stainless steel made of Fe and unavoidable impurities.

For example, a sticking phenomenon is mentioned as one of the surface defects which frequently occur in the said rolling material in the hot rolling process of rolling materials, such as high chromium ferritic stainless steel. The main mechanism of the sticking phenomenon is as follows. In the hot rolling process of rolling using a rolling roll at a high temperature, excessive friction may occur between the rolling material and the rolling roll, and the excessive friction may cause the surface of the rolling material to fall off. The surface of the rolled material thus dropped may be transferred to a rolling roll that is in direct contact with the press, and irregularities are generated in the rolling roll to which the rolled material is transferred. Such unevenness may cause damage to the rolling roll as the rolling process proceeds, and the rolled material may be damaged in the rolling length direction by the damaged rolling roll. This phenomenon is called sticking phenomenon.

The sticking phenomenon may occur frequently in a process of hot rolling high chromium ferritic stainless steel. In order to prevent the sticking phenomenon, at least one side of the rolling roll or the rolling material is added to a rolling roll by adding a material such as rolling oil. And friction between the rolled material can be reduced.

At this time, the rolling oil needs to control the rolling flow rate in consideration of the friction characteristics between the rolling roll and the rolling material. That is, when the rolling flow rate is used in a small amount, the sticking phenomenon as described above may occur. On the other hand, when the rolling flow rate is excessively used, the friction coefficient between the rolling roll and the rolled material may be reduced to prevent sticking, but slippage of the rolled material may occur. The slip phenomenon may include, for example, plate rolling of the rolled material, and this plate drawing may allow the rolling of the rolled material to be carried out unbalanced, and may also hinder continuous rolling to reduce the process efficiency.

The present invention relates to a rolling flow rate control method for deriving a rolling flow rate in consideration of friction characteristics between a rolling roll and a rolling material, and supplying rolling oil variably between the rolling roll and the rolling material by the derived rolling flow rate. By the rolling flow rate control method, it is possible to prevent the sticking phenomenon and the slip phenomenon by maintaining the friction characteristics between the rolling roll and the rolling material to be constant and controlling the rolling flow rate supplied between the rolling roll and the rolling material to an appropriate level. Can be. Therefore, by reducing the defective rate of the process of hot rolling a rolled material using a rolling oil, the hot rolling process with which productivity was improved can be provided.

Referring to Figure 1, the rolling flow control method according to the present invention can be largely divided into two. The rolling flow rate control method is to control the rolling flow rate supplied between the rolling roll and the rolling material by first estimating the coefficient of friction between the rolling roll and the rolling material and deriving an appropriate rolling flow rate accordingly.

Rolling flow rate control method of the hot rolling process, the friction coefficient estimation step of estimating the friction coefficient between the rolling roll and the rolling material in real time (S1); A rolling flow rate derivation step (S2) of deriving a rolling flow rate to be supplied between the rolling roll and the rolling material by the estimated friction coefficient; And a rolling oil supplying step (S3) of supplying the rolling oil in a variable rolling flow rate between the rolling roll and the rolling material by the derived rolling flow rate.

The friction coefficient estimating step (S1) is a step of estimating the friction coefficient between the rolling roll and the rolling material, the friction coefficient may be estimated by the rolling load, rolling speed, and rolling torque.

In the friction coefficient estimating step (S1), the friction coefficient may be estimated as a value varying in real time by grasping the friction characteristics between the rolling roll and the rolling material in real time. The rolling roll may include an upper rolling roll in contact with the upper surface of the rolling material, and a lower rolling roll in contact with the lower surface of the rolling material. In the friction coefficient estimating step (S1), an upper friction coefficient between the upper rolling roll and the rolling material And the lower friction coefficient between the lower rolling roll and the rolled material can be estimated separately.

In order to estimate the friction coefficient, rolling load, rolling torque and rolling speed are required. Rolling load can be measured using the load cell provided in the lower part of a rolling roll. The rolling torque may be composed of an upper rolling torque and a lower rolling torque for each of the upper rolling roll and the lower rolling roll, and the upper lower rolling torque and the lower rolling torque may be measured from the current value of the rolling roll driving motor. The coefficient of friction between the rolling roll and the rolling material can be estimated by the measured rolling load and rolling torque and the rolling speed which is the speed of rolling the rolling material.

2 is a view schematically showing the sequence of the rolling flow rate derivation step of FIG.

1 and 2, the rolling flow rate derivation step S2 may be derived from the rolling flow rate so as to be inversely proportional to the estimated friction coefficient. In addition, in the rolling flow rate derivation step (S2), the estimated friction coefficient is derived from the rolling flow rate so as to fall within the deadband upper limit value and the deadband lower limit value range, and the deadband upper limit value is a friction coefficient at which sticking occurs on the surface of the rolled material. The deadband lower limit value may be a friction coefficient at which plate tilt occurs due to slip of the rolled material. In addition, the rolling flow rate may be limited to less than the rolling flow rate limit. At this time, the dead band upper limit value and the dead band lower limit value is a value that can vary depending on the rolling material, rolling process conditions, etc., which can be determined experimentally. In addition, the rolling flow rate limit is the maximum rolling flow rate that can be used in the rolling process, which may be determined by process conditions or device characteristics, etc., to ensure the safety of the rolling process.

The friction coefficient can be estimated by being divided into the upper friction coefficient and the lower friction coefficient, respectively, by the upper rolling torque and the lower rolling torque, and the estimated friction coefficients are the rolling roll 100, the rolling material 200 and the rolling flow rate ( According to the rolling process according to 300), it can be derived by being limited within the range of the dead band upper limit value and the dead band lower limit value experimentally determined. The derived rolling flow rate 300 may be supplied between the rolling roll 100 and the rolling material 200 at a rolling flow rate limit or less.

The rolling flow rate derivation step (S2) is to derive the rolling flow rate from the friction coefficient estimated in the friction coefficient estimation step (S1), and as described above, the upper rolling rolls 110 and the lower frictional coefficients are individually. A rolling flow rate to be supplied between the lower rolling roll 120 and the rolling material 200 may be derived. In addition, the rolling flow rate 300 may be inversely proportional to the coefficient of friction. Therefore, by controlling the rolling flow rate 300, the friction coefficient between the rolling roll 100 and the rolling material 200 can be kept constant, and the rolling flow rate 300 is also raised by the upper friction coefficient and the lower friction coefficient, respectively. Rolling flow rate and lower rolling flow rate can be controlled separately.

Further, the derived rolling flow rate derived to fall within the range of the friction coefficient dead band upper limit value and the dead band lower limit value may be limited to the rolling flow rate limit or less.

Specifically, the rolling flow rate derivation step (S2) is such that the rolling flow rate according to the upper friction coefficient or the lower friction coefficient is maintained within the range of the friction coefficient dead band upper limit value and the dead band lower limit value, which are experimental values. As described above, the rolling flow rate limit is a rolling flow rate that can be supplied as much as possible to ensure the safety of the rolling process, and the stability of the process can be improved by limiting the rolling flow rate back to the rolling flow rate limit or less.

In addition, the range of the friction coefficient dead band can be obtained by the experimental value of the respective rolling materials and rolling conditions, the optimum friction coefficient may be a value included in the + /-error range from the median of the dead band upper limit and the dead band lower limit. .

The rolling oil supply step (S3) may supply the rolling oil between the rolling roll and the rolling material so that the friction coefficient is kept constant. Rolling oil supply step (S3) is a value limited by the rolling flow rate limit as described above, it is possible to supply the rolling oil between the rolling roll and the rolling material. In this case, the supplied rolling oil may be supplied in real time by the friction coefficient estimated in real time, and thus, the amount of the rolling oil may be effectively controlled so that the amount of the rolling oil is not excessively supplied.

Hereinafter, examples and comparative examples of the present invention will be described. However, the following examples are only a preferred embodiment of the present invention, and the scope of the present invention is not limited by the following examples.

1. Review of upper and lower friction coefficients over time

The rolled material is weight%, Cr: 17-23%, C; 0.02% or less, N: 0.02% or less, Ti: 0.2-0.4%, Mn: 0.3% or less, Cu: 0.2-0.5%, Al: 0.03-0.10%, S: 0.002% or less, Si: 0.15% or less, Nb : Hot rolling process was performed using a high chromium ferritic stainless steel composed of Fe and unavoidable impurities with a content of 0.06 to 0.45% as a rolling material.

The high chromium ferritic stainless steel was rolled with upper and lower rolling rolls, respectively, and at this time, rolling oil was supplied to the upper and lower portions at the same rolling flow rate to derive a friction coefficient.

3 is a graph showing the coefficient of friction derived between the upper and lower rolling rolls and the rolling material over time.

In FIG. 3, a is an upper friction coefficient which is a friction coefficient between the upper rolling roll and the rolled material, and b is a lower friction coefficient that is a friction coefficient between the lower rolling roll and the rolled material.

The magnitude of the frictional force is proportional to the normal drag, and the proportional constant is the coefficient of friction. The coefficient of friction, which indicates the degree of friction, depends on the material of the object, the smoothness of the surface, and the presence and type of lubricant. Therefore, it is not a constant that can distinguish between substances. As such, the coefficient of friction can be derived from the equilibrium equation of force by the rolling roll. The force equilibrium equation refers to a state in which the effect of the force system acting on the object is zero.

In general, the rolling process using a rolling roll may correspond to a physical phenomenon in which wheels roll on the ground. At this time, the friction coefficient between the wheel and the ground can be obtained by dividing the radius of the wheel and the vertical force acting between the wheel and the ground in the torque for driving the wheel. Therefore, in order to estimate the friction coefficient between the rolling roll and the rolled material, the rolling torque acting on the rolling roll can be obtained by dividing the radius and the rolling load of the rolling roll.

On the other hand, the rolling process has a neutral point unlike the physical phenomenon in which the wheel rolls on the ground. In the rolling process, the direction of the friction force at the entry and exit sides between the rolling roll and the rolling material may be reversed from the neutral point. That is, the position of the neutral point may be a factor that greatly influences the estimation of the friction coefficient, and the neutral point may be closely associated with the advance rate. Therefore, in order to estimate the friction coefficient, the advance rate should be considered, and the advance rate may be determined by the slip rate between the rolling roll and the rolled material.

That is, in order to derive the friction coefficient, the slip ratio of the rolling mill is measured in real time, the advance rate is obtained, and the neutral contact is determined according to the advance rate, and the applied friction coefficient derived from the rolling torque and the rolling load is applied to FIGS. It can be shown together, which is the coefficient of friction for the longitudinal direction of the rolled material.

Referring to FIG. 3, even when the same rolling roll and the rolling material were used, the upper friction coefficient and the lower friction coefficient were not the same. Therefore, it can be seen that the rolling flow rate between the rolling roll and the rolling material needs to be controlled separately by separating the upper rolling roll and the lower rolling roll. In addition, it can be seen that the upper coefficient of friction and the lower coefficient of friction fluctuate with time even when the rolling roll, the rolling material and the rolling conditions are not changed. Therefore, in order to prevent a sticking phenomenon or a slip phenomenon in the rolling process, it can be seen that the rolling flow rate to be used is also changed in real time.

2. Coefficient of friction according to rolling conditions

The rolled material is weight%, Cr: 17-23%, C; 0.02% or less, N: 0.02% or less, Ti: 0.2-0.4%, Mn: 0.3% or less, Cu: 0.2-0.5%, Al: 0.03-0.10%, S: 0.002% or less, Si: 0.15% or less, Nb : Hot rolling process was performed using a high chromium ferritic stainless steel composed of Fe and unavoidable impurities with a content of 0.06 to 0.45% as a rolling material.

In order to confirm the correlation between the friction coefficient between the rolling roll and the rolling material and the sticking phenomenon occurring on the surface of the rolling material, the friction coefficient according to the rolling conditions was checked. The rolling conditions were classified into factors of rolling temperature, rolling reduction, and rolling flow rate, and the average values of the friction coefficients for each and the occurrence of the sticking phenomenon were confirmed, which are shown in Table 1.

number Rolling temperature Rolling reduction Rolling Sticking phenomenon
Occurrence One High temperature Pressure Tongyun radish 2 High temperature Pressure Kang Yun radish 3 High temperature Coercion Kang Yun radish 4 High temperature Coercion Tongyun radish 5 Low temperature Pressure Tongyun radish 6 Low temperature Coercion Tongyun U 7 Low temperature Coercion Kang Yun U 8 Low temperature Pressure Kang Yun radish

Table 1 is for examining the correlation between the friction coefficient and the sticking phenomenon, and is an average value of the friction coefficient obtained by changing the rolling conditions. At the rolling temperature, the high temperature was 1300 ± 20 ° C. and the low temperature was 1200 ± 20 ° C. to perform rolling. In the reduction ratio, the through pressure means that the reduction was performed by applying a reduction ratio of 30% to 40%, and the decrease in pressure refers to the case of rolling at a reduction ratio of 40% to 50%, which is the reduction condition. In addition, in the reduced flow rate, the lubrication means 150 l / min, and the strong lubrication means 200 l / min, which is a relatively large rolling flow rate.

4 is a graph showing the friction coefficient according to the rolling conditions.

Referring to Table 1 and Figure 4, it was confirmed that the sticking phenomenon occurs in the conditions 6 and 7. Considering conditions 6 and 7, sticking occurs at low temperature of 1200 ± 20 ° C and step-down condition of 40% to 50%, and the condition of sticking 6 and 7 is higher than other conditions. It was confirmed that the friction coefficient had a large value. In this way, the friction coefficient in the case of the sting phenomenon will be the friction coefficient dead band upper limit and the dead band lower limit value, in the case of the rolled material as in this embodiment, the friction coefficient dead band upper limit is 0.3 to 0.35, the friction coefficient dead The lower band limit is 0.15 to 0.2.

3. Friction Coefficient According to Rolling Flow

The rolled material is weight%, Cr: 17-23%, C; 0.02% or less, N: 0.02% or less, Ti: 0.2-0.4%, Mn: 0.3% or less, Cu: 0.2-0.5%, Al: 0.03-0.10%, S: 0.002% or less, Si: 0.15% or less, Nb : Hot rolling process was performed using a high chromium ferritic stainless steel composed of Fe and unavoidable impurities with a content of 0.06 to 0.45% as a rolling material.

In order to check the change of the friction coefficient according to the flow rate change of the rolling oil supplied between the rolling roll and the rolling material, the rolling flow rate supplied between the lower rolling roll and the rolling material is the same, and is supplied between the upper rolling roll and the rolling material. The rolling process was performed while varying the rolling flow rate. Table 2 is a table showing the motor power and the rolling load applied to the upper rolling roll according to the rolling flow rate according to each condition.

Rolling flow rate (l / min) Motor power (kW) Rolling load
(ton) Top bottom Top bottom 300 350 3300 4500 1450 250 350 4200 4600 1600 150 350 4850 4900 1700 unused unused 4900 4900 1710

5 is a graph showing the friction coefficient according to the rolling flow rate.

Referring to Table 2 and Figure 5, it was confirmed that the friction coefficient has a low value as the rolling flow rate supplied to the upper rolling roll increases. That is, the rolling flow rate is a value inversely proportional to the friction coefficient, and the frictional coefficient could be kept constant by controlling the rolling flow rate.

Referring to FIG. 5, it can be seen from the trend line of the graph that the change in the friction coefficient with respect to the rolling flow rate is -4E-5, which is 250 l / min (0.01 / -4E-5) in order to reduce the friction coefficient by 0.01. This means a flow rate is required. Such a slope value may be a control gain for controlling the rolling flow rate, and thus, in the rolling oil supplying step (S3), the rolling flow rate may satisfy the following equation.

Rolling flow rate = (-4E-5) * Friction coefficient + 0.0782
(Here, (-4E-5) is by exponential notation, meaning -4 * 10 ^-5 .)

It will be understood by those skilled in the art that the present invention may be embodied in other specific forms without departing from the spirit or essential characteristics thereof. It is therefore to be understood that the above-described embodiments are illustrative in all aspects and not restrictive. The scope of the present invention is defined by the appended claims rather than the foregoing detailed description, and all changes or modifications derived from the meaning and scope of the claims and the equivalents thereof are included in the scope of the present invention Should be interpreted.

100: rolling roll 110: upper rolling roll
120: lower rolling roll 200: rolling material
300: rolling flow rate

Claims (9)

In the hot rolling process using the rolling oil,
The hot rolling process includes a rolling flow rate control method for controlling the rolling flow rate supplied between the rolling roll and the rolling material, the rolling flow rate control method,
A friction coefficient estimating step of estimating a friction coefficient between the rolling roll and the rolling material in real time;
A rolling flow rate deriving step of deriving a rolling flow rate to be supplied between the rolling roll and the rolling material by the estimated friction coefficient; And
And a rolling oil supplying step of supplying the rolling oil in a variable rolling flow rate between the rolling roll and the rolling material by the derived rolling flow rate.
In the friction coefficient estimating step, the friction coefficient is estimated by the rolling load, the rolling speed, and the rolling torque between the rolling roll and the rolling material.
The rolling oil supplying step supplies the rolling oil in real time using the friction coefficient estimated in real time in the friction coefficient estimating step, and the rolling oil supplying step includes rolling oil between the rolling roll and the rolling material so that the friction coefficient is kept constant. Rolling flow rate control method of the hot rolling process, characterized in that for supplying. delete The method of claim 1,
And the rolling flow rate deriving step derives the rolling flow rate so as to be inversely proportional to the estimated friction coefficient. The method of claim 1,
In the rolling flow rate deriving step, the estimated friction coefficient is derived from the rolling flow rate so as to fall within a range of a dead band upper limit value and a dead band lower limit value, and the dead band upper limit value is a friction coefficient at which sticking occurs on the surface of the rolled material. The lower band value is a rolling coefficient control method of the hot rolling process, characterized in that the coefficient of friction occurs the plate pull due to the slip of the rolling material. The method of claim 1,
The rolling flow rate control method of the hot rolling process, characterized in that in the rolling flow rate derivation step, the rolling flow rate is limited to a rolling flow rate limit or less. delete The method of claim 1,
The rolled material is weight%, Cr: 17-23%, C; 0.02% or less, N: 0.02% or less, Ti: 0.2-0.4%, Mn: 0.3% or less, Cu: 0.2-0.5%, Al: 0.03-0.10%, S: 0.002% or less, Si: 0.15% or less, Nb : A rolling flow rate control method for a hot rolling process, wherein the remaining component is a high chromium ferritic stainless steel composed of Fe and unavoidable impurities. In weight% Cr: 17-23%, C; 0.02% or less, N: 0.02% or less, Ti: 0.2-0.4%, Mn: 0.3% or less, Cu: 0.2-0.5%, Al: 0.03-0.10%, S: 0.002% or less, Si: 0.15% or less, Nb : Rolling flow rate control method in the process of hot rolling a rolled material consisting of Fe and unavoidable impurities which satisfy the content of 0.06 to 0.45%, estimates the coefficient of friction between the rolled roll and the rolled material in real time, and estimates Deriving the rolling flow rate to be supplied between the rolling roll and the rolling material by the friction coefficient thus obtained, and supplying the rolling oil between the rolling roll and the rolling material as a variable rolling flow rate by the derived rolling flow rate,
The friction coefficient is estimated by the rolling load, rolling speed, and rolling torque between the rolling roll and the rolling material,
Rolling oil is supplied in real time by using a friction coefficient estimated in real time, the rolling flow rate is high chromium ferritic stainless steel, characterized in that the following formula.
Rolling flow rate = (-4E-5) * Friction coefficient + 0.0782 9. The method of claim 8,
The friction coefficient is derived from the rolling flow rate so as to fall within the dead band upper limit and the dead band lower limit, the dead band upper limit is 0.3 to 0.35, the dead band lower limit is 0.15 to 0.2, characterized in that the high chromium ferritic stainless steel .

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