KR100711417B1 - Dynamic bender rolling method in plate finishing mill - Google Patents

Abstract

A thick plate dynamic bender rolling method is provided.

According to the present invention, in the method for performing thick plate length rolling using multi-pass rolling, the longitudinal temperature distribution and the rolling load distribution of the thick plate are measured during each pass rolling, and the temperature distribution and the rolling load for each pass are preset. A dynamic bender rolling method characterized by adjusting a predetermined reference bender force according to the longitudinal load fluctuation by comparing with

Measuring a longitudinal temperature distribution and a rolling load distribution of the thick plate during rolling for each pass, and adjusting the predetermined reference bender force according to the longitudinal load fluctuation by comparing the temperature distribution and the rolling load for each pass; Measuring a longitudinal crown distribution of the multipass rolled thick plate surface and using this to calculate a value of bender force corresponding to longitudinal stretching in subsequent rolling; And a step of adjusting a preset reference bender force by using the calculated value of the bender force as well as the difference between the thick plate longitudinal temperature distribution and the rolling load in the final pass rolling.

Dynamic Bender Rolling, Bender Force, Shape Defect

Description

Dynamic Bender Rolling Method in Plate Finishing Mill

BRIEF DESCRIPTION OF THE DRAWINGS It is a figure which shows the nonuniformity of a plate length direction shape.

2 is a diagram defining a plate crown.

3 is a diagram illustrating the principle of conventional plate crown generation and bender control.

4 is a view showing a rolling load pattern and a bender force pattern for each pass in the conventional thick plate rolling.

5 is a view showing a change in the plate longitudinal crown in accordance with the change in the plate longitudinal load.

6 is a view showing the configuration of the rolling mill inlet-side proximity thermometer and the load cell during rolling.

7 is a view illustrating a longitudinal dynamic bender application method according to the rolling load variation.

FIG. 8 is a view showing an idea of increasing the bender force corresponding to an impact value at the beginning and completion of rolling

9 is a diagram showing a dynamic bender rolling method corresponding to a rolling load impact value and a load variation.

10 is a view showing a crown meter located on the exit side of the rolling mill during rolling.

11 is a flow chart showing a rolling process according to an embodiment of the present invention.

* Explanation of symbols for main parts of drawings *

601 ....... Load cell 602 ....... Top reinforcement roll

603 ....... Top Roll 606 ....... Rolling Plate

604,605 Proximity thermometer 609

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thick plate rolling method capable of controlling the longitudinal shape of a rolled plate during thick plate length rolling. More specifically, the plate longitudinal shape is obtained by effectively operating a bender controlling the rolling shape during thick plate length rolling. The present invention relates to a thick plate bender rolling method capable of improving quality.

As shown in FIG. 1, in general, when the thick plate is rolled, the rolled plate 101 does not have a uniform thickness and shape in the plate length direction. The rolled plate used for thick plate rolling is thick, but it does not have a uniform thickness in the longitudinal direction due to temperature variations in the plate longitudinal direction and asymmetry of the upper and lower surfaces of the plate due to fluctuations in heating and rolling history. In the longitudinal direction, the plate center thickness may be thicker than the plate end thickness or the plate center thickness may be thinner than the plate end thickness. Such a distribution of widthwise plate thickness is called a plate crown, and FIG. 2 shows a plate crown of the thick plate 201.

In thick plate length rolling, a work roll bender is used to control the plate crown described above, and the principle thereof is shown in FIG. 3, in which reference numeral 310 denotes an upper reinforcement roll, 330 an upper work roll, and 350 It shows a thick plate.

Since the thick plate length rolling mill is a four-stage rolling machine having a longer roll barrel length than the roll diameter, the roll axial elastic deformation occurs based on the center of the roll during rolling, and the elastic deformation is transferred to the plate to show the plate crown. Therefore, in order to prevent such plate crowns from occurring excessively, the vendor plays a role of suppressing roll axial elastic deformation.

In the conventional thick plate rolling, a bender is used to control the crown during length rolling, and a single bender force is applied to the rolled sheet regardless of various shapes in the longitudinal direction. However, if a bender force is applied by setting a single bender force irrespective of the longitudinal shape distribution, simple plate crown control is performed only from the viewpoint of width, and thus there is a problem in that it is difficult to reduce partial thickness defects and waves in the plate longitudinal direction. . In addition, since a single bender force is applied irrespective of the shape of the longitudinal direction, the bender force is not improved in the part that needs more bender force, and the shape is large because the bender force is large in the part that needs to give less bender force. There is a problem that worsens.

Through the rolling method using the longitudinal single bender force as described above, the rolling is always performed using the single bender force, and the rolling type product quality is improved because it does not use the bender associated with the longitudinal shape characteristics. Not only is it difficult, but also increases the number of passes when the rolling shape is not good, thereby acting as a major cause of lowering the rolling productivity and the rolling pitch.

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thick plate rolling method capable of controlling the longitudinal shape of a rolled plate during thick plate length rolling. More specifically, the plate longitudinal shape is obtained by effectively operating a bender controlling the rolling shape during thick plate length rolling. The present invention relates to a thick plate bender rolling method capable of improving quality.

Therefore, the present invention has been made in order to solve the problems of the prior art described above, when the rolling plate is located at the inlet side of the rolling mill while being rolled to the exit side in consideration of the longitudinal shape characteristics of the plate longitudinal shape change using the rolling load The purpose of the present invention is to provide a dynamic bender rolling method that can improve plate longitudinal shape quality during thick plate length rolling by dynamically applying bender force linked to plate longitudinal shape variation instead of applying a single bender force. There is this.

The present invention for achieving the above object,

In the method for performing thick plate length rolling using multi-pass rolling,

It measures the longitudinal temperature distribution and rolling load distribution of the thick plate during rolling for each pass, and compares it with the preset temperature distribution and rolling load for each pass to adjust the preset reference bender force according to the longitudinal load variation. It relates to a dynamic bender rolling method.

In addition, the present invention,

In the method for performing thick plate length rolling using multi-pass rolling,

Measuring a longitudinal temperature distribution and a rolling load distribution of the thick plate during rolling for each pass, and comparing the temperature distribution and rolling load for each pass in advance to adjust a predetermined reference bending force according to the longitudinal load variation;

Measuring a longitudinal crown distribution of the multipass rolled thick plate surface and using this to calculate a value of bender force corresponding to longitudinal stretching in subsequent rolling; And

In the final pass rolling, a step of adjusting the preset reference bender force by using the calculated value of the bender force as well as the difference in the thick plate longitudinal temperature distribution and the rolling load; and a dynamic bender rolling method comprising a.

Hereinafter, the present invention will be described in detail.

4 is a view showing a rolling load pattern and a bender force pattern for each pass during thick plate rolling. As shown in Figure 4, the lengthwise rolling of a conventional thick plate performs a rolling of about 7 to 9 passes, wherein a constant uniform bender force for the rolling load is used in the entire pass. However, as shown in Fig. 1, since the plate longitudinal direction of the thick plate is not uniform, it is uneven in the plate longitudinal direction during one pass rolling.

That is, as shown in FIG. 5, the rolling load measured by the load cell is not uniform with respect to the plate length direction but shows a certain pattern, and correspondingly, the plate crown also shows a constant pattern with respect to the length direction. Therefore, if the complete rolling plate is rolled by using a single bender force, ignoring the shape characteristics of the plate longitudinal direction, the shape problem of the plate longitudinal direction is not solved, and only after the rolling is completed, rolling is performed in the form of the final target crown. Since there is a problem, it has become a major factor that hinders the quality of rolled products. In particular, as shown in Figure 5, when the leading edge of the plate is inserted into the rolling mill at the start of 1 pass rolling, and when the tail end of the plate exits the rolling mill when the rolling is completed, the peak phenomenon compared to the actual rolling load appears by a momentary impact Can be. In this case, the existing single bender rolling method maintains a single bender force at the beginning of rolling and applies a standard bender force supporting the entire upper roll group when rolling is completed to complete the rolling.

The present invention relates to a dynamic bender rolling method for multi-pass rolling during thick plate rolling. The present invention is a method for dynamically rolling a bender in response to variations in plate longitudinal shape and rolling load to complete rolling. This will be described in detail with reference to the accompanying drawings.

6 is a view showing the configuration of the rolling mill inlet-side proximity thermometer and the load cell during rolling. In the present invention, in performing thick plate length rolling using multi-pass rolling, first, as a method of recognizing a shape varying in the longitudinal direction of a thick plate, proximity thermometers 604 and 605 are installed at the entry and exit of the rolling mill in each pass rolling. The plate longitudinal temperature distribution is measured, and the heavy plate longitudinal rolling load distribution is measured using the load cell 601. In this way, the degree of agreement between the measured rolling load distribution and the temperature distribution is calculated and quantitative data on the plate longitudinal profile distribution is obtained in connection with the rolling conditions.

Next, the present invention compares the measured plate longitudinal temperature distribution and the rolling load for each pass with the preset temperature distribution and rolling load distribution for each pass. In the present invention, the preset reference bender force for each pass provided by using the correlation between the predetermined temperature load and the rolling load is incorporated in a control means (computer), not shown. These values may vary depending on the thickness, width, and composition of the steel plate, and repeated experiments may yield optimum values consistent with the rolling of the steel plate having the desired steel grade, thickness, and width.

In the present invention, by comparing the measured temperature distribution and the rolling load with the temperature distribution and the rolling load for each pass to adjust the preset reference bending force for each pass according to the longitudinal load fluctuation. A relational formula for calculating a new bender force based on this difference has also been devised through the experiments of the present inventors, which is also embedded in the control means not shown.

Therefore, if the thick plate length rolling for each pass is performed on the basis of this newly calculated bender force, it is possible to effectively reduce the problem of shape defects in the thick plate length direction, which is a problem in the conventional process.

7 is a view showing a longitudinal dynamic bender application method of the present invention according to the rolling load fluctuation during the rolling of general steel. As shown in FIG. 7, when the rolling load increases in response to the rolling load pattern in the longitudinal direction of the plate during the rolling, the bender force is applied more than the bender force setting value, and when the rolling load decreases, the bender force is higher than the bender force setting value. It shows that the bender force can be applied dynamically in a reduced form.

On the other hand, as described above, in the thick plate length rolling, there is a problem that an impact value of the rolling load is generated at each rolling start and rolling completion for each pass. Therefore, in the present invention, as shown in Figure 8, it is preferable to add or subtract the bender force for a predetermined time after the rolling start for each pass and the completion of rolling so as to correspond to the rolling load impact force. 9 is a diagram showing the dynamic bender rolling method of the present invention corresponding to the rolling load impact value and the load fluctuation.

Also in the present invention, after measuring the longitudinal crown distribution of the surface of the multi-pass rolled thick plate, it is used to calculate the bender force value corresponding to the longitudinal stretching in the subsequent rolling, and then in the final pass rolling, the thick plate In addition to the longitudinal temperature distribution and the rolling load difference, it is also possible to adjust the preset reference bender force by using the calculated value of the bender force.

That is, as the rolling progresses as shown in Figure 10, the plate lengthwise crown distribution is measured using the crown meter 609 installed at the rear end of the length rolling mill as the length of the plate increases. And according to this crown distribution, the added value of the bender force is calculated in consideration of the length increase in rolling in the subsequent final pass rolling. This calculation process is performed through the control means described above.

And in the final pass rolling, as shown in FIG. 11, the preset reference bender force can be adjusted by using not only the calculated value of the bender force but also the difference in the above-described plate longitudinal temperature distribution and the rolling load.

By adopting such a technical configuration, it is possible to more easily eliminate plate longitudinal shape defects.

For practical application of the present invention as described above, there is provided a computer in which a desired program that can be applied to a heavy plate rolling process is incorporated, and after using this computer to effectively calculate the bender control amount in each rolling step, It can be automatically received in the individual rolling process step to carry out the desired dynamic bender rolling.

As described above, the present invention recognizes the plate shape change in the longitudinal direction by using the rolling load in consideration of the longitudinal shape characteristics when the rolled plate is located at the mouth side of the rolling mill and transported to the exit side, and applies a single bender force. Instead, by dynamically applying the bender force linked to the plate longitudinal shape variation, there is a useful effect that can improve the plate longitudinal shape quality and productivity when rolling the thick plate length.

Claims (4)

In the method for performing thick plate length rolling using multi-pass rolling, It measures the longitudinal temperature distribution and the rolling load distribution of the thick plate during rolling by each pass, and compares it with the preset temperature distribution and rolling load by each pass to adjust the preset reference bending force according to the longitudinal load variation. Heavy plate dynamic bender rolling method. 2. The thick plate dynamic bender rolling method according to claim 1, wherein a bender force is added or reduced so as to correspond to the rolling load impact force before rolling commencement and completion of rolling for each pass. In the method for performing thick plate length rolling using multi-pass rolling, Measuring a longitudinal temperature distribution and a rolling load distribution of the thick plate during rolling for each pass, and comparing the temperature distribution and rolling load for each pass in advance to adjust a predetermined reference bending force according to the longitudinal load variation; Measuring a longitudinal crown distribution of the multipass rolled thick plate surface and using this to calculate a value of bender force corresponding to longitudinal stretching in subsequent rolling; And And controlling the predetermined reference vendor force by using the calculated value of the bender force as well as the difference in the thick plate longitudinal temperature distribution and the rolling load in the final pass rolling. 4. The thick plate dynamic bender rolling method according to claim 3, wherein a bender force is added or reduced so as to correspond to the rolling load impact force before rolling commencement and completion of rolling for each pass.

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