KR19990053865A - Determination method of rolling amount for setting work roll replacement cycle of thick plate rolling mill - Google Patents

Abstract

The present invention relates to a method for determining the rolling amount of one replacement cycle of a work roll for improving plate crown and flatness in thick plate rolling, and considering the wear characteristics of the work roll of the thick plate rolling mill. It is an object of the present invention to provide a rolling amount determination method for setting a work roll replacement cycle of a thick plate rolling mill that can minimize plate crown generation by determining the rolling amount until replacement.

The present invention comprises the steps of measuring the amount of inspection and wear for the work roll drawn from the rolling mill to complete the rolling, collecting the polishing results after roll polishing, calculating the roll wear characteristic coefficient according to the roll history, roll diameter and roll wear characteristics Combining the coefficients to calculate the rolling amount determination coefficient for the work roll and determining the once-use rolling amount by the combination of the rolling amount determination coefficient and the roll diameter in order to use the polished roll for the next roll change. The method of determining the rolling amount for setting the work roll replacement cycle of the thick plate rolling mill configured to include the gist thereof.

Description

Determination method of rolling amount for setting work roll replacement cycle of thick plate rolling mill

The present invention relates to a method for determining the rolling amount (hereinafter also referred to as 'rolling amount') for setting the replacement cycle of the work roll used in the thick plate rolling mill, and more specifically in consideration of the wear characteristics of the work roll It relates to a method for determining the rolling amount for setting the replacement cycle of the work roll of the thick plate rolling mill.

The reason why the work roll is periodically changed in the thick plate rolling mill is to minimize the occurrence of plate crowns. In the plate crown, as shown in Fig. 1, before rolling, rolls such as the shapes of (1) and (3) are rolled and the surface of the roll is abraded by the contact between the roll and the rolling material after rolling, and (2) and (4) and Likewise, the diameter Dc of the center portion of the roll becomes smaller than both edge portions, and after rolling the rolled material 5 as shown in FIG. As shown in (b), the thickness Hc of the center portion of the rolled material 6 becomes thicker than the thickness He of both edge portions.

Therefore, in order to reduce the plate crown increase phenomenon due to the increase in the amount of roll wear, the amount of rolling per roll is limited to a certain amount according to the characteristics of each rolling mill.

On the other hand, even if the rolling roll is changed periodically by limiting the rolling amount to a certain amount, wear of the rolling roll caused by the contact of the rolling material and the rolling roll during rolling cannot be avoided. Since the value is gradually increased, the flatness of the rolled material has a bad effect such as wave generation.

Conventionally, as a method for reducing the influence of the roll wear phenomenon on the crown and the shape of the rolled material, as shown in (1) and (3), the diameter Dc of the center portion of the roll is larger than the diameter De of both edge portions. By giving the so-called initial roll of the crown, and after the roll replacement as shown in Fig. 3, the rolling material is initially rolled and then the narrower width is rolled from the wide plate of the rolled material to the end after the roll replacement. The method of reducing the influence of roll abrasion on a rolling material as much as possible is employ | adopted.

However, this method can improve the plate crown shape to some extent within the roll replacement cycle. However, the plate crown and flatness results are severely changed after each roll change due to the difference in roll diameter and roll history. Since there is a problem that it is very difficult to obtain a stable quality (flatness, plate crown).

The present inventors conducted research and experiments to solve the problems of the conventional method described above, and the present invention was proposed based on the results. The present invention considers the wear characteristics of the work roll of the thick plate rolling mill in the next cycle. By determining the rolling amount (rolling amount for setting work roll replacement cycle) from replacement after replacement, to provide a rolling amount determination method for setting work roll replacement cycle of thick plate rolling mill which can minimize plate crown generation. Its purpose is to.

1 is a schematic diagram showing the shape before and after the use of the work roll to be assembled and used in a thick plate rolling mill,

(a) is the shape before and after the use of the initial work roll (maximum diameter),

(b) is the shape before and after the end of the work roll (minimum diameter).

2 is a schematic diagram showing the thickness and plate shape in the width direction of the finished product rolled,

(a) is a product worked in the initial roll unit,

(b) is the product worked at the end of roll unit.

Figure 3 is a schematic diagram showing the change in the width of the plate according to the rolling operation sequence of the rolling amount of one roll replacement in the conventional method

Figure 4 is a flow chart showing a process of determining the rolling amount for setting the replacement cycle of the work roll in accordance with the present invention

Figure 5 is a schematic diagram showing the relationship between the use history and the roll wear characteristics

Figure 6 is a block diagram showing an example of a rolling amount determination device for the situation of replacement cycle of the work roll for implementing the present invention

7 is a graph showing an example of the amount of plate crowns per replacement cycle before and after use of the present invention.

Explanation of symbols on the main parts of the drawings

1, 3: work roll after polishing 2, 4: work roll after rolling (use)

5,6: rolled finished material 8: roll grinder control computer

9: roll tracking computer 10: operation management computer

11: rolling mill control computer 12: rolling mill

The present invention provides a method for rolling a thick plate using a thick plate rolling mill including upper and lower working rolls, the method comprising: inspecting and polishing a work roll drawn from a rolling mill at a replacement time; Measuring a diameter, a roll hardness, a roll polishing amount, and a roll rolling amount of the roll polished as described above; Obtaining a roll wear characteristic coefficient αi using the following equation (1);

(Relationship 1)

αi = a × Roll diameter + b × Roll hardness + c × Rolling amount + d × Polishing amount + e

Where a, b, c, d, and e are regression coefficients

Obtaining a rolling amount determination coefficient (CORFwr) by the following formula (2) using the roll wear characteristic coefficient (αi) obtained as described above;

(Relationship 2)

COEFwr =

[COEFwr: rolling coefficient determination coefficient

Dwrt: upper working roll diameter

Dwrb: lower work roll diameter

Do: Average effective diameter of work roll (= (maximum diameter + minimum diameter) / 2)

αi: Wear characteristic factor per roll (i: Roll) number]

And calculating the rolling amount (rolling amount (WRwt until the replacement of the roll after replacing the roll) by the following equation (3) using the rolling amount determination coefficient (COEFwr) obtained as described above.

(Relationship 3)

Wrwt = STwt × COEFwr

(Here, WRwt: Rolling amount for setting work roll replacement cycle)

STwt: standard rolling amount)

It relates to a rolling amount determination method for setting the work roll replacement cycle of the thick plate rolling machine comprising a.

Hereinafter, the present invention will be described in detail.

In order to determine the rolling amount for setting the replacement cycle of the work roll according to the present invention, as shown in Fig. 4, the work roll with the replacement timing is withdrawn from the rolling mill, and then the surface wear of the roll is measured, and then the amount of roll wear is measured. , The amount of polishing is determined.

After the roll is polished according to the polishing amount determined as described above, the roll diameter, roll hardness, roll polishing amount and rolling roll amount after polishing are measured.

Next, the roll wear characteristic coefficient (alpha) i is calculated | required using following formula (1).

(Relationship 1)

αi = a × Roll diameter + b × Roll hardness + c × Rolling amount + d × Polishing amount + e

Where a, b, c, d, and e are regression coefficients

The roll wear characteristic coefficient α i is obtained by the multiple regression analysis in the form of the following formula (4) using the roll diameter, roll polishing amount, roll hardness, and rolling amount. The process is as follows.

(Relationship 4)

αi = f (roll hardness, roll diameter, rolling amount, grinding amount)

The roll wear characteristic coefficient α i is obtained by a combination of a roll polishing diameter, roll hardness, polishing amount and rolling amount per roll from the starting point of the roll to the roll used up to now. The wear characteristics of the work roll to be used are as shown in Fig. 5, the larger the hardness of the roll is, the smaller the wear coefficient of the roll is. [Fig. 5 (a)], the larger the circumferential length of the roll is. The less roll wear [see Fig. 5 (b)], the more the previous rolling amount, the deeper the thermal fatigue layer of the roll, and the greater the wear coefficient [see Fig. 5 (c)]. The wear coefficient becomes small (see Fig. 5 (d)).

Therefore, the roll wear characteristic coefficient is influenced by roll hardness (hardness / standard hardness), roll diameter (roll diameter / average diameter), rolling amount (rolling amount / standard rolling amount), and polishing amount. Multiply by (Abrasive Amount / Standard Abrasive Amount) and multiply regression analysis using roll wear characteristic coefficient as dependent variable and roll hardness, roll diameter, rolling amount and grinding amount as independent variables. The derived regression equation is the same as that of Equation (1).

The roll wear characteristic coefficient α i obtained as described above may be changed when the roll maker or the roll manufacturing method is changed. Therefore, it is preferable to rewrite the regression equation. The roll abrasion and the coefficient of characteristics (αi) were 0.9-1.1 for the roll diameter of 1050mm, the roll length of 4724mm, and the rolling amount of 5500 tons. The newly rolled new rolls are set to '1' because of the previous rolling performance. .

Next, the rolling amount determination coefficient COEFwr is obtained by the following formula (2) using the roll wear characteristic coefficient α i obtained as described above.

(Relationship 2)

COEFwr =

[COEFwr: rolling coefficient determination coefficient

Dwrt: upper working roll diameter

Dwrb: lower work roll diameter

Do: Average effective diameter of work roll (= (maximum diameter + minimum diameter) / 2)

αi: Wear characteristic factor for each roll (i: Roll number)]

Next, using the rolling amount determination coefficient COEFwr obtained as described above, the rolling amount WRwt for setting the work roll replacement cycle is obtained by the following equation (3).

(Relationship 3)

WRwt = STwt × COEFwr

(Here, WRwt: rolling amount for setting work roll change interval

STwt: reference rolling amount)

In the above formula (3), the reference rolling amount (STwt) means the average rolling amount determined according to the plant-specific operating conditions.

That is, the reference rolling amount WRwt is obtained from the relationship between the rolling amount and the roll wear amount according to the operation performance. At this time, the amount of roll wear increases proportionally as the amount of rolling increases, but since the fatigue of the roll surface accumulates more than a certain amount, the amount of roll wear rapidly increases, and the amount of rolling at this time is set as the reference rolling amount.

Rolling amount (work roll) for setting the work roll replacement cycle as described above After obtaining the rolling amount (WRwt) to be used in the replacement cycle, it is replaced in the next cycle is rolled by the amount of the rolling obtained above and then replaced.

Hereinafter, a method of determining the rolling amount will be described with reference to Fig. 6 showing an example of the rolling amount determining device for setting the replacement cycle of the work roll according to the present invention.

As shown in FIG. 6, when a new roll is first received, the roll diameter, hardness, material, maker, and the like obtained from the roll maker are input through the roll receipt record input terminal 7 of the roll history management computer 9.

Thereafter, when rolling is completed in the rolling mill 12, the roll dismantled in the rolling mill is transported by a overhead crane, set in a roll polishing machine, and the roll is polished. When roll polishing is completed, the roll polishing machine computer 8 transmits the roll diameter, roll wear amount, polishing amount, hardness, etc. collected from the polishing machine to the roll history management computer 9 by data link. In the roll history management computer 9, the roll information received from the roll grinding machine control computer 8 and the roll usage information (rolling amount) collected by the rolling mill control computer 11 are transferred to the data link through the operation management computer 10. The roll wear characteristic coefficient α i is obtained by Equation (1), the rolling amount determination coefficient COEFwr is calculated by Equation (2), and this value is transmitted to the operation management computer 10. The operation management computer, which has received the COEFwr, records this value in the COEFwr item of the atmospheric roll file, and the reference rolling amount ( STwt) and the rolling amount determination coefficient (COEFwr) are determined by the above equation (3) to determine the rolling amount of one roll replacement cycle to be worked next.

After the rolling amount for the work roll to be used is determined next, in order to minimize the effect of roll wear on the rolled plate, the rolling instruction lot in order from the wider plate to the narrower plate in sequence as shown in FIG. Lot). Next, when the work of the current roll is finished and the roll to be used next is assembled, the rolling mill control computer 11 controls the rolling mill according to the rolling order, and then may be repeated in the above-described order.

Figure 7 shows the effect by the method of the present invention, the average plate crown transition for the thickness of 10 to 15mm for each roll replacement cycle before and after applying the present invention is shown. In addition, Table 1 below shows the quantitative value of the mean and the deviation for each crown before and after the present application.

Sphere separation crown Before improvement After improvement Average (mm) 0.10 0.09 Deviation (mm) 0.020 0.007

As shown in Figure 7 and Table 1, after applying the present invention it can be seen that the deviation of the plate crown for each roll replacement number is less than before application.

That is, after applying the present invention it can be seen that the deviation is reduced to 35% compared to before application.

As described above, the present invention obtains the roll wear characteristic coefficient and the roll unit influence coefficient according to the roll usage history such as the roll diameter, hardness, polishing amount, roll wear amount and rolling amount that change every roll change, By determining the amount of rolling once, even if the usage history of the rolling roll changes with every roll change, it maintains the same level of roll wear at all times to obtain stable plate crown and flatness as well as automation without manual work. And it is quick to respond to the change of diameter and contributes to the automation of the roll unit indicating lot lot.

Claims (1)

A method of rolling a thick plate using a thick plate rolling mill including upper and lower working rolls, the method comprising: performing roll inspection and polishing on a working roll drawn out from a rolling mill at a replacement time; Measuring the diameter, roll hardness, roll polishing amount and roll rolling amount of the roll polished as described above; Obtaining a roll wear characteristic coefficient αi using the following equation (1); (Relationship 1) αi = a × Roll diameter + b × Roll hardness + c × Rolling amount + d × Polishing amount + e Where a, b, c, d, and e are regression coefficients Obtaining a rolling amount determination coefficient (COEFwr) by the following equation (2) using the roll wear characteristic coefficient (αi) obtained as described above; (Relationship 2) COEFwr = [COEFwr: rolling coefficient determination coefficient Dwrt: upper working roll diameter Dwrb: lower work roll diameter Do: Average effective diameter of work roll (= (maximum diameter + minimum diameter) / 2) αi: Wear characteristic factor for each roll (i: Roll number)] And calculating the rolling amount (rolling amount (WRwt) until replacement of the roll after replacing the roll) by the following equation (3) using the rolling amount determination coefficient (COEFwr) obtained as described above. (Relationship 3) WRwt = STwt × COEFwr (Here, WRwt: rolling amount for setting work roll change interval STwt: standard rolling amount) Rolling amount determination method for setting the work roll replacement cycle of the thick plate rolling mill characterized in that comprises a