JPS61273203A - Rolling method for thick plate - Google Patents

Abstract

PURPOSE:To decrease the allowance for transverse cutting of a thick plate by subjecting the top and bottom edges on both side surfaces of a material to be rolled to chamber edging pass rolling at the different chamfering allowances for the right and left and rolling the material with the side having smaller chamfering allowance as the front end side of the material to be rolled. CONSTITUTION:The material to be rolled is subjected to chamfer edging pass rolling symmetrical with the center at the chamfering allowance (a) and chamfering angle theta. One of the caliber rolls is axially shifted and the material is again edged by the surface of the cylindrical roll in this stage and the other caliber 2. The one side of the slab is edged and rolled down by the surface of the cylindrical roll so that the chamfering margin (a) of the slab upon ending of the rolling stage for rolling is made a2, a1, respectively. Such slab is then rotated 90 deg. and is rolled with the the side of the allowance a2 as the front end of the slab in the 1st pass of the cross rolling stage and thereafter the material is subjected to finish rolling.

Description

Detailed Description of the Invention (Industrial Application Field) The technical content described in this specification regarding the rolling of thick plates including the forming rolling process, the tentering rolling process, and the finishing rolling process includes the above-mentioned steps. We have developed a thick plate rolling method that aims to prevent as much as possible the shape defects that occur in the thick plates obtained through rolling, especially the collapsing on both sides of the rolled material that tends to occur during width rolling, and to improve the yield by making the plate cross section rectangular. It's there to suggest.

Generally, in the rolling process of thick plates, a slab manufactured using continuous casting equipment or a blooming mill is first processed into a predetermined width and thickness through a forming rolling process, then a tentering rolling process, and a finishing rolling process. .

That is, the slab extracted from the heating furnace is rolled in the longitudinal direction in one pass or multiple passes in order to obtain the reference thickness for tentering calculation in the forming rolling process, and then turned 90 degrees and passed through the tentering rolling process. , the sheet is rolled in the width direction until the desired sheet width is achieved.

Thereafter, it is turned 90 degrees again and rolled into a thick plate with a predetermined thickness in a finishing hand rolling process.

By the way, the planar shape of a thick plate in plate rolling has been greatly improved by the recent reduction control rolling method (for example, Japanese Patent Publication No. 5841481) that corrects the planar shape, but it is not necessary to trim the width of the plate. It has not yet reached that point.

Although we aim to roll thick plates without leaving any width cutting allowance, a problem that arises is the collapse that tends to occur on the sides of the plate width.In other words, in horizontal rolling, the problem is that the surface layer of the slab that comes in contact with the horizontal rolls and the inside of the slab Metal 7 - In O thick plate rolling where bulging occurs at the front and rear ends of the slab due to the difference, the collapse of the front and rear ends that occurs during tentering rolling is turned 90 degrees after the end of tentering, so it remains as a collapse on the side. This is due to this.

(Prior art) In order to prevent double pulsing that occurs on the side surfaces of a strip, there have been attempts to perform etching pass rolling using a shaping rolling mill equipped with flat rolls, for example, during the finish rolling process.
If the collapse is already large at the start of finish rolling, the effect is small.Furthermore, the so-called dogbone deformation occurs during the edge leg, so the effect of suppressing collapse cannot be said to be sufficient.

On the other hand, JP-A-59-118906 discloses a thick plate rolling method in which symmetrical chamfer etching pass rolling is performed on the inner width surface of the material to be rolled during the forming rolling process, and then the rolling process is led to the tentering rolling process. However, it does not take into account the difference in deformation behavior caused by each reduction on the leading and trailing sides of the rolled material during the tentering rolling process, so it is necessary to avoid collapse evenly on both sides of the product plate. I can't.

(Problem to be Solved by the Invention) In the tentering rolling process after performing chamfer edging bus rolling in the middle of the forming rolling process, the amount of collapse of the leading and trailing ends is influenced by the rolling direction of the first pass. receive it strongly. Generally, the tip side and the rear end side of the rolled material have a large difference in slump due to the influence of the metal lid during rolling, and the amount of slump on the rear end side is larger than the tip side of the rolled material. . Therefore, it has not been possible to completely eliminate the width cutting allowance by simply performing chamfered edging pass rolling.

This invention focuses on the above-mentioned problems that occur in conventional thick plate rolling, and aims to reduce collapse according to the plate width and the difference in deformation behavior on both sides based on the metal flow difference in the 11-rolling process. Therefore, it is an object of the present invention to establish a thick plate rolling method that can reduce or eliminate the width cutting allowance of a thick plate obtained through a finish rolling process.

(Means for Solving the Problems) The present invention provides a method for rolling a thick plate through each step of forming rolling, tentering rolling, and finishing rolling, at least in one pass of forming rolling. Then, using a combination of caliber rolls and flat rolls, chamfer etching pass rolling with different left and right chamfer allowances is performed on the upper and lower edges of both sides of the rolled material, and then the rolled material is turned 90 degrees and subjected to a tentering rolling process. This is a thick plate rolling method characterized in that in the first pass, rolling is performed with the side with less chamfer allowance on the leading end side of the material to be rolled, and the material is led to a cap rolling step and then to a finish rolling step.

Here, the chamfering allowance refers to the chamfering allowance when the main part of the pair of vertical rolls l applied to at least one pass in the forming and rolling process using the horizontal wool pair of the slab is shown in No. 111. Caliber 2 has a triangular groove cut at an angle θ to a plane perpendicular to the axis of 1.
Deformation length a in the plate width direction where the rolled material 8 is etched
The cross-sectional area of a right triangle whose base is the chamfering allowance a is defined as -a''tanθ◎ Figure 2 shows the upper and lower edges of both sides of the rolled material δ according to the present invention. An example of how to perform chamfering pass rolling with different left and right chamfering allowances a on the part is shown below, and a pair of caliber rolls are
Chamfer angle 00 on both left and right sides. θ, differs as 0□<θ, so the chamfering allowance a becomes % > a. An example is shown in which the chamfering allowance a is made asymmetric using the following method. First, a symmetrical chamfering pass rolling is performed as shown in the figure, and then one caliber wool is shifted in the fine direction (Fig. 8(b)). ) After that, etching is performed again using the cylindrical P-ru surface and the other caliber 2 to satisfy the relationship of chamfering allowance aX >&S. , and the amount of inclination (δ) that occurs on the front end side and rear end side of the rolled material in the subsequent tentering rolling step, are shown for the cases where the chamfer angle θ is 60 degrees and 50 degrees.

From Fig. 4, the amount of collapse (δ) of the side surface of the rolled material in the tentering rolling process becomes smaller as the chamfer cross-sectional area < 1-aBtan9) in the chamfer etching bath rolling performed in the forming rolling process increases, and the chamfer angle θ increases. The smaller the diameter, the smaller it is, and when comparing the front end and rear end sides of the rolled material 8 in the tentering rolling process, it is found that the rear end side is larger.

Therefore, in the chamfer edging pass rolling in the forming rolling process, the amount of collapse (δ) between the front end and rear end sides of the rolled material in the first pass of the extrusion rolling process is considered, and the collapse elimination limit value shown in Fig. 4 is calculated. For the chamfering allowance a that makes the rolled material asymmetrical on the left and right sides as the chamfered cross-sectional area (1a3tana) corresponding to (δ = 5 dotted line), adjust the chamfering allowance a to satisfy a > a The first pass is
By rolling one side with the smaller chamfer allowance a on the tip side of the rolled material, the collapse that occurs on both sides of the rolled material can be reduced to 1.
The entire length of both sides can be reduced as much as possible.

(Example) Examples will be described below.

Length 20001111% Width 1fiQQss Thickness 280
The slab (2) was exported and rolled at a ratio of 2.5.

At this time, according to FIGS. 8(a) and 8(b), in the shaping rolling process, a chamfering allowance a! 1g song, chamfer angle θ = 5
0", symmetrical chamfer etching pass rolling was performed on the left and right, then one of the caliber mills was shifted in the axial direction, and etching was performed again using the cylindrical roll surface and the other caliber 8. At this time, etching by the cylindrical roll surface Then, a 4-roll reduction is applied to one side of the slab, and the chamfer of the slab at the end of the forming rolling process is
16 m, al=20 m. The first pass of the tenter rolling process is as follows:
The slab was rolled using the side with the chamfer type '1=16 am+ as the tip of the slab, and then a thick plate with a thickness of 11 g- was obtained in a finish rolling process.

When the amount of collapse (δ) of the obtained thick plate was examined, it was about 8 to 6 inches on either side. In the case where it is not carried out, and in the middle of the forming and rolling process, chamfering allowance a = l is applied symmetrically to the upper and lower edges of both sides of the slab.
A case was investigated in which chamfer etching pass rolling was performed with f3 wts and chamfer angle θ=50°.

When the mass chamfer etching bath rolling is not performed, the amount of collapse (δ) is 15~! It was 1511m.

In addition, when the chamfering allowance a+ = 18 m and the chamfering angle 0 = 60 degrees, the amount of collapse (δ) of the side surface on the tip side of the slab during the first pass of the extrusion rolling process is 8 to 6. On the other hand, the amount of collapse (δ) of the side surface on the rear end side of the slab during the first pass of the 1stB rolling process is 10 to 14111
It was 1.

Therefore, according to the thick plate rolling method according to the present invention, since the collapse caused in the tentering rolling process is very small on both the left and right sides, it is possible to perform etching bath rolling in a vertical rolling mill equipped with flat rails in the finishing rolling process. In the end, we were able to completely eliminate the amount of collapse (δ) on the side of the thick plate.

(Effects of the Invention) According to the present invention, it is possible to prevent as much as possible the shape defect 1 of the thick plate that occurs when rolling a thick plate, especially the collapse that occurs on the width side of the thick plate, and to make the cross-sectional shape of the plate rectangular. Therefore, the cutting allowance for the board width is very small, and the yield can be improved.

[Brief explanation of the drawing]

Fig. 1 is a diagram showing the main parts of the vertical roll, Fig. 2, Fig. 8 (a) and (b) are diagrams showing the rolling procedure according to the present invention, and Fig. 4 is a diagram showing the side surface of the first rolled material. It is a figure showing the relationship between the amount of collapse (δ) and the chamfered cross-sectional area.

Claims (1)

[Claims] 1. When rolling a thick plate through each process of forming rolling process, tentering rolling process, and finishing rolling process, caliber roll or caliber roll is used in at least one pass of forming rolling process. Using a combination of and flat rolls, chamfer etching pass rolling with different left and right chamfering allowances is performed on the upper and lower edges of both sides of the rolled material, and then the rolled material is turned 90 degrees, and the first pass of the tentering rolling process is a chamfering process. A thick plate rolling method characterized in that rolling is carried out with the side with smaller thickness being used as the leading end side of the material to be rolled, and the material is led to a tentering rolling process and then to a finishing rolling process.