KR100293196B1 - Method for controlling overlap of edge part of the plate when hot rolling steel plate - Google Patents

Abstract

PURPOSE: A method for controlling overlap of the edge part of the plate when rolling a hot rolled steel plate is provided which obtains a fixed width of the plate by changing roll gaps of front and rear parts as much as a roll gap of an abnormal deformation part at the first pass of broadside rolling, thereby changing the shape of a slab corner part. CONSTITUTION: In a method for hot rolling a steel slab plate in which broadside rolling is performed, the method for controlling overlap of the edge part of the plate when hot rolling a steel plate comprises the steps of obtaining overhang values(ΔWp) to be generated at front and rear parts in the given rolling conditions; obtaining roll gap correction values(Δhc) in which the obtained overhang values(ΔWp) satisfies allowable overhang values(ΔWp); obtaining roll openings(St,b) of the front and rear parts which are given during the first pass of the broadside rolling using the obtained roll gap correction values(Δhc); and hot rolling the steel plate under the normal conditions from the second pass of the broadside rolling after setting roll openings of the front and rear parts correspondingly to the obtained roll opening values(St,b) and performing broadside rolling in an ordinary manner.

Description

Method of overlapping control of plate edge during hot thick plate rolling

1 is a schematic diagram showing a thick plate rolling process.

Figure 2 is a schematic diagram showing the process of overlapping plate edge portion occurrence phenomenon

3 is a schematic view of a roll opening correction pattern in accordance with the present invention;

Figure 4 is a schematic diagram of a model rolling experiment for showing the effect of the present invention

Explanation of symbols on the main parts of the drawings

1 ... slab 2 ... horizontal roll

The present invention relates to a method of controlling the overlapping of the plate edge portion during hot plate rolling, and more particularly to control the abnormal deformation portion generated at the leading end and the rear end based on the rolling direction during the deburring rolling during the thick plate rolling process. Hot rolled plate for high precision plate width by controlling the amount of overlapping edge of final blade by changing the shape of slab edge part by changing roll gap of line and rear end as much as abnormal part in first pass An edge overlap control method.

In general, as shown in FIG. 1, the thick plate rolling process includes three steps of rolling the slab 1, such as sizing, broadside rolling, and length-finishing. In other words, the slab extracted from the furnace is subjected to even rolling in 1 ~ 2 passes, rotates the slab by 90 °, and then rolls in 3 ~ 8 passes to make the target plate width, and again makes 90 ° original condition. After rotating to 6-6 passes through the length-rolling process to produce the final thick plate product.

However, as shown in FIG. 2, the top and bottom portions of the raw material during the rolling process during the thick plate rolling process have a center surface which is not in contact with the lower surface in the slab thickness direction, which is a contact portion between the roll and the raw material, respectively. Due to the difference in the metal flow of the (unsteady deformation) is present. Hereinafter, the abnormal deformation part which arises at the time of bread baking is called an overhang. The slab in which the overhang is generated is rotated 90 ° again after the completion of the rolling process, so that the slab remains on both edges of the plate width direction and overlaps with the upper and lower surfaces as the next rolling process is performed. To develop. The amount of overlap is increased as the thickness before rolling is increased and as the rolling ratio is increased. In the case of the disintegrating material, a side crop of about 20-30 mm in the width direction of the plate is usually caused. Since the shear amount is increased, there is a problem of lowering the real rate.

Accordingly, the present inventors have conducted research and experiments to solve the above problems, and based on the results, the present invention proposes the present invention. Hot rolled sheet rolling that reduces the side crop of the edge of the final blade state by changing the shape of the slab in advance by changing the roll gap in the corners of the slab based on the rolling direction as much as that in the pass. An object of the present invention is to provide a method of overlapping plate edge control.

EMBODIMENT OF THE INVENTION Hereinafter, this invention is demonstrated.

The present invention is a hot thick plate rolling method of a steel slab subjected to bake rolling,

Obtaining an overhang occurrence amount ΔW _{p to be} generated at a line and a rear end under a given rolling condition by the following equation (1);

[Wherein, Δh _p is a line, the amount of roll gap correction at the rear end, Is the width of rolling machine, H _O , W _O is the thickness and width of the width of rolling machine, and L _d is the projected contact length between roll and material.]

Obtaining by using the to the overhang amount (△ W _p) rolgaep correction amount (△ h _C) satisfying the allowable overhang amount (△ W _p) obtained as in the above formula (2);

Obtaining roll opening degrees (S _{t, b} ) of the front end and the rear end to be applied during the first pass of the blasting rolling by the following equation (3) using the slab roll gap correction amount (Δh _C ) obtained as described above; And

(Where x is the distance from the tip to an arbitrary position in the slab width direction, ΔW ₁ : roll gap correction length, Δh ₁ is the horizontal rolling reduction rate at the top of one pass, δ ₁ : Elastic recovery),

Set the roll opening degree of the front end part and the rear end to correspond to the roll opening degree S _{t, b} obtained above, and set the roll opening degree of the top part to correspond to the roll opening degree S ₁ obtained by the following formula (4) ,

After rolling one pass of the breadmaker, the second pass of the breadmaker rolling relates to a method for controlling the overlapping of the edge portion during hot-rolled sheet rolling, including the step of hot rolling under normal conditions.

EMBODIMENT OF THE INVENTION Hereinafter, this invention is demonstrated in detail.

According to the present invention, in the hot slab rolling method of steel slab subjected to the deburring rolling, the overhang occurring during deburring rolling is predicted in advance, and the roll gap is set by calculating the line and rear end roll gap variation which minimizes the roll slab. The part relates to a method of controlling the overlap of plate edges during hot thick plate rolling, which hot rolls steel slabs by a conventional roll gap setting method.

In order to control the overlapping of the plate edge portion according to the present invention, the thickness, width, width of the width of the width of the width of the width before rolling, and path schedule should be obtained using the following formula (1) to obtain the amount of overhang ΔW _p .

Δh _p is the amount of roll gap correction at the front and rear ends, Is the width of roll width and is defined as ratio of target plate width and slab width. H _O , W _O are thickness and width of width of rolling width, and L _d is the projected contact length between roll and material.

An example of the above formula (1) may be expressed as shown in the following formula (1a).

(In the formula (1a), K ₁ , K ₂ , K ₃ , K ₄ , K ₅ represents a regression coefficient.)

Next, obtained by a rolgaep correction amount (△ h _C) satisfying the overhang amount (△ W _p) is permitted overhang amount (△ W _p) obtained as described above using the following formula (2) from the formula (1) .

A more preferred allow overhang amount (△ W _p) in the present invention is not more than 10㎜.

Using the roll gap correction amount (Δh _c ) obtained as described above, the roll opening degree (S _{t, b} ) of the front end and the rear end to be applied during the first pass of the rolling _process is considered in consideration of the elastic recovery amount (δ ₁ ) of the roll. Obtained by (3).

The △ △ h _c and W ₁ schematically it is shown in FIG. 3.

And a roll of the top opening (S ₁₎ can be calculated as shown in the following formula (4).

In equations (3) and (4), Δh _c is the thickness reduction given in the first pass of the breadboard rolling, ΔW ₁ is the roll gap correction length, and the hydraulic cylinder reduction of the AGC (Automatic gauge control) facility and the cylinder It is the value automatically given by the following formula (5) from the functional relationship with speed.

Here, V _r represents the rotational speed of the roll, and V _c represents the hydraulic cylinder reduction amount of the horizontal roll, respectively.

Next, the roll opening degree obtained at the front end and the rear end at the first pass of the baking process was set to the roll opening degree value obtained in the above (3), and the roll opening degree at the top was set to the roll opening degree value obtained in the above formula (4) and rolled. After the post-exposure rolling two passes, the steel slab is hot rolled under normal conditions, thereby eliminating the overlap of the edges.

Hereinafter, the present invention will be described in more detail with reference to Examples.

EXAMPLE

When the conventional rolling method and the line and rear end roll gap correction methods of the present invention were applied, simulation tests were performed in which the size was similar to that of 1/10 of the implementation to prove the effect. The material used in this embodiment is plasticine, which is useful for simulating the deformation behavior during rolling because the deformation property at room temperature is similar to the deformation property of hot steel at high temperature. In the simulation experiment, as shown in FIG. 4, chamfers were applied to the edges of the slab front end and the rear end, respectively, and the explosive rolling was performed according to the pass schedule shown in Table 1. At this time, the chamfering amount was determined by calculating the minimum roll gap correction amount from the overhang generation amount prediction formula proposed in the present invention. In the present invention, three model rolling experiments were carried out under the conditions shown in Table 2 below.

That is, while conventionally rolled under the conditions of the following Table 1, the invention example is rolled under the conditions of the following Table 1, but when the first pass rolling, the rolling gap is modified after modifying the roll gap of the rear end as shown in Table 2 below .

As shown in Table 3 below, the average amount of the measured values of the thicknesses of the plates produced by rolling as described above was measured.

As shown in Table 3, it can be seen that the use of the present invention can significantly reduce the amount of plate overlapping when using the conventional rolling method.

As described above, the present invention has the effect of reducing the overlapping of the edge portion of the final blade state by improving the thickness plate error rate by giving a predetermined amount of roll gap variation to the front and rear ends in the first pass of the thick plate width rolling process. .

Claims (3)

In the hot thick plate rolling method of the steel slab subjected to the depoking rolling Obtaining an overhang occurrence amount ΔW _{p to be} generated at a line and a rear end under a given rolling condition by the following equation (1); (Where Δh _p is a line, the amount of roll gap correction at the rear end, Is the width of rolling machine, H _O , W _O is the thickness and width of the width of rolling machine, and L _d is the projected contact length between roll and material) Obtaining by using the to the overhang amount (△ W _p) rolgaep correction amount (△ h _C) satisfying the allowable overhang amount (△ W _p) obtained as in the above formula (2); Obtaining roll opening degrees (S _{t, b} ) of the front end and the rear end to be applied during the first pass of the beveling rolling by the following formula (3) using the slab roll gap correction amount (Δh _C ) obtained as described above; And (Where x: distance from the tip to an arbitrary position in the slab width direction, ΔW ₁ : roll gap correction length) The roll opening degrees at the front and rear ends are set to correspond to the roll opening degrees (S _{t, b} ) obtained above, and the roll opening degrees at the top are set to correspond to the roll opening degrees (S ₁ ) obtained by the following equation (4). , Method of overlapping the plate edge portion during hot thickening rolling comprising the step of hot-rolled rolling after pass of one-roller, followed by hot rolling under normal conditions The method according to claim 1, wherein formula (1) is represented by the following formula (1a), Where K ₁ , K ₂ , K ₃ , K ₄ , and K ₅ represent the regression coefficients. Control method of overlapping plate edges during hot thick plate rolling, characterized in that displayed 3. The method of controlling sheet edge portions according to claim 1 or 2, wherein the allowable overhang generation amount? W _p is 10 mm or less.