JPH0250802B2 - - Google Patents

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.

In general, in the rolling operation of thick plates, a slab manufactured using continuous casting equipment or a blooming mill is first processed into a predetermined plate width and thickness in 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 standard thickness for tentering calculation in the forming rolling process, 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.

After that, it is turned 90 degrees again, and in the finish rolling process,
Roll it into a thick plate with a predetermined thickness.

By the way, the planar shape of a thick plate in plate rolling has been greatly improved by recent reduction control rolling methods that modify the planar shape (for example, Japanese Patent Publication No. 1983-21481), but it does not require trimming the width of the plate. We have not yet reached the point where this is the case.

When aiming to roll a thick plate without leaving a cutting allowance for the width of the plate, a problem that arises is the collapse that tends to occur on the sides of the plate width.

That is, in horizontal rolling, bulging occurs at the front and rear ends of the slab due to the difference in metal flow between the surface layer of the slab that contacts the horizontal rolls and the inside of the slab. This is due to the fact that in plate rolling, the collapse of the front and rear ends that occurs during tentering rolling is turned 90 degrees after the completion of tentering, and remains as a collapse of the side surface.

(Prior art) In order to prevent double bulging from occurring on the width side of the strip, for example, some attempts have been made to perform etching pass rolling using a vertical rolling mill equipped with flat rolls during the finish rolling process. It is less effective if the fall is large. Also,
Since deformation of the so-called dogbone occurs during etching, the effect of suppressing collapse cannot be said to be sufficient.

On the other hand, Japanese Unexamined Patent Publication No. 59-113906 discloses a thick plate rolling method in which symmetrical chamfer etching pass rolling is performed on both width sides of the material to be rolled during the forming rolling process, and the process is then led to the tentering rolling process. However, it does not take into account the difference in deformation behavior associated with each reduction on the leading and trailing ends of the rolled material in 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 etching pass rolling in the middle of the forming rolling process, the amount of collapse of the leading and trailing ends is strongly influenced by the rolling direction of the first pass. . Generally, the tip side and rear end side of the rolled material have a large difference in inclination due to the influence of metal flow during rolling, and compared to the tip side of the rolled material,
The amount of fall on the rear end side becomes larger. Therefore, it has not been possible to completely eliminate the width cutting allowance simply by performing chamfer etching 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 based on the metal flow difference in the tentering rolling process and the difference in deformation behavior on both sides. 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) This invention provides a forming rolling process, a tentering rolling process,
When rolling a thick plate through each step of the finishing rolling process, at least one pass of forming rolling is performed using a caliber roll or a combination of a caliber roll and a flat roll to roll the upper and lower edges of both sides of the material to be rolled. Chamfering pass rolling with different left and right chamfer allowances is performed, then the material to be rolled is turned 90 degrees, and in the first pass of the tentering rolling process, rolling is performed with the side with the smaller chamfering allowance on the leading edge side of the material to be rolled. This thick plate rolling method is characterized in that a tentering rolling process is followed by a finishing rolling process.

Here, the chamfer allowance is defined as the chamfer allowance when the main part of a pair of vertical rolls 1 applied to at least one pass in the forming and rolling process using a pair of horizontal rolls is shown in Fig. 1. It is expressed as the deformation length a in the width direction of the rolled material 3, which is etched by the triangular groove-shaped caliber 2 cut at an angle θ with respect to the plane perpendicular to the axis of the roll 1. Also, the chamfered cross-sectional area is defined as the cross-sectional area of a right triangle whose base is this chamfering allowance a, 1/2a ² tanθ.

FIG. 2 shows an example of how to perform chamfering pass rolling with different left and right chamfering allowances a on the upper and lower edges of both side surfaces of the rolled material 3 according to the present invention, and a pair of caliber rolls have chamfering angles θ ₁ and θ on the left and right sides, respectively. ₂ are different as θ ₁ <θ ₂ , so the chamfering allowance a is a ₁ > a ₂ .

In addition, Fig. 3a shows an example of making the chamfering allowance a asymmetric using a pair of caliber rolls 1' having the same chamfering angle θ. After this, one caliber roll is shifted in the axial direction (Fig. 3b), and the surface of the cylindrical roll and the other caliber 2 are etched again, thereby establishing the relationship of chamfering allowance a ₁ > a ₂ to satisfy.

(Function) The relationship between the size of the chamfered cross-sectional area in the forming rolling process and the amount of collapse δ that occurs on the leading and trailing ends of the rolled material in the subsequent tentering rolling process is determined when the chamfer angle θ is 60 degrees and 50 degrees. The results are shown for each case.

From Fig. 4, the amount of fall δ of the side surface of the rolled material in the tentering rolling process becomes smaller as the cross-sectional area (1/2a ² tan θ) in the chamfering pass rolling performed in the forming rolling process becomes larger, and the chamfer angle θ becomes smaller. Comparing the front end and rear end sides of the rolled material 3 in the tentering rolling process, it can be seen that the rear end side is larger.

Therefore, in the chamfer edging pass rolling in the forming rolling process, the collapse elimination limit value ( δ=5mm
Chamfered cross-sectional area (1/2a ² tanθ) corresponding to the broken line)
The chamfering allowance a that makes the left and right sides of the rolled material asymmetric is adjusted so that a ₁ > a ₂ is satisfied.

In the first pass of the tentering rolling process, by rolling the side with the smaller chamfer allowance a as the tip side of the material to be rolled, the collapse that occurs on both sides of the material to be rolled is suppressed over the entire length of both sides. It can be reduced as much as possible.

(Example) Examples will be described below.

A slab of length 2000mm, width 1600mm, thickness 280mm,
Rolling was carried out with a tenter ratio of 2.5.

At this time, according to Fig. 3 a and b, in the forming rolling process, a vertical rolling mill equipped with a pair of caliber rolls 1' having an equivalent face deviation angle θ is used, with a chamfer allowance a = 18 mm and a chamfer angle θ = 50°. Laterally symmetrical chamfer etching pass rolling was performed, then one of the caliber rolls was shifted in the axial direction, and etching was performed again using the cylindrical roll surface and the other caliber 2. At this time, by etching with the cylindrical roll surface, a reduction of 4 mm was applied to one side of the slab, and the chamfering allowance a of the slab at the end of the forming rolling process was calculated as a ₂ =
16 mm, a ₁ = 20 mm. Then, convert this slab to 90
In the first pass of the turning and tentering rolling process, the slab was rolled with the side with the chamfer allowance a ₂ =16 mm as the tip of the slab, and then in the finish rolling process, a thick plate with a thickness of 112 mm was obtained.

When the amount of inclination δ of the obtained thick plate was examined, it was about 3 to 6 mm on both sides.

Next, in order to compare with the above example, chamfer allowance a= A case was investigated in which chamfer etching pass rolling was performed with a diameter of 18 mm and a chamfer angle θ = 50°.

First, in the case where chamfer etching pass rolling was not performed, the amount of collapse δ was 15 to 25 mm. In addition, when chamfering allowance a = 18mm and chamfering angle θ = 50 degrees,
The amount of inclination δ of the side surface at the leading end of the slab during the first pass of the tentering rolling process is 3 to 6 mm, while the amount of collapse δ of the side surface at the rear end of the slab during the first pass of the tentering rolling process is 3 to 6 mm. The amount of collapse δ was 10 to 14 mm.

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, in the finishing rolling process, if the etching pass rolling is performed using a vertical rolling mill equipped with flat rolls, 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 defective shape of a 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]

Figure 1 is a diagram showing the main parts of the vertical roll, Figure 2 is a diagram showing the main parts of the vertical roll,
3a and 3b are diagrams showing the rolling procedure according to the present invention, and FIG. 4 is a diagram showing the relationship between the amount of inclination δ of the side surface of the material to be rolled and the chamfered cross-sectional area. 1...Vertical roll, 1'...Caliber roll pair,
2... Caliber, 3... Material to be rolled.

Claims (1)

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