JPS61135402A - Edging method of metallic slab - Google Patents

Abstract

PURPOSE:To reduce crop losses by subjecting a slab to rolling reduction by feeding it larger than an ordinary feed at the 1st rolling reduction and then pressing it from both sides in sequence under the fixed amount of feed and the fixed opening and closing width. CONSTITUTION:In subjecting the foremost end of a continuously cast slab 2 to rolling reduction; anvils 1 are first retreated till the distance (d) between them attains W0, and the foremost end of slab 2 is fed by the amount ST of feed larger than an ordinary one. Successively, after performing the prescribed amount of edging, the edging is continued under an amplitude 2(a), a frequency (f) and a feeding amount SM by an ordinary method. In this way, the deformation of the front end part of slab 2, such as a fish tail, is prevented and the plane shape of said part is improved. Accordingly, the cut-off percentage at the front end part is reduced, that is, the crop loss is reduced.

Description

[Detailed Description of the Invention] (Industrial Application Field) This specification describes the prevention of planar shape deterioration when the width of a metal slab as a material for hot strip mill rolling is reduced over the entire length using a press method. This paper proposes the development result of advantageously achieving press method width reduction as a preliminary processing for common use in rolling leaf materials of multiple sizes of hot strips using continuously cast slabs obtained by conventionally used materials for hot strips. Slabs used to be manufactured from steel ingots by the blooming rolling method, but in recent years, they have been manufactured by continuous casting, abbreviated as continuous casting, which has significantly improved yields and reduced energy consumption.
It is well known that the manufacturing cost of hot rolled copper strip has been significantly reduced.

Additionally, there is a trend toward synchronized operation of continuous casting and hot strip mills to promote energy and manufacturing process efficiency.

For this purpose, it is being considered to integrate the width of the continuous cast slab into a smaller number of sizes and reduce the width of the slab by a large amount in the rolling process so that it can fit the tracks of many types of product coils.

(Prior Art) The general method for reducing the width of a slab is to perform one or more rolling steps using a so-called V-H rolling method using a pair of vertical rolls. 1) Even if you go to the trouble of rolling the width, it will not work! [During subsequent horizontal rolling, a considerable amount of width reversion occurs, resulting in poor width reduction efficiency. Tensile stress acts in the rolling direction at the center, and there is a risk of damaging the internal material.

(8) The front and rear ends have a fishtail-like planar shape and the crop size increases.

(4) There were problems such as ◎ where the width was narrower at the front and rear ends than at the center, resulting in poor width accuracy. Several methods have been proposed to solve these problems. For example, a method using a caliber vertical roll was proposed for problem 11 (Japanese Patent Publication No. Sho*Y-86619). (Japanese Patent Application Laid-Open No. 155-101168).

However, such a method not only requires a large press machine in addition to a large vertical rolling mill, but also cannot satisfactorily solve the above problems.

As an alternative to the V-H rolling method, which has the problems mentioned above, a method has been proposed in which the entire length of the steel ingot is rolled down using a press method (
(Special Publication No. 5a-40987).

This example targets blooming rolling in the light area, but although it is easy to apply it to width reduction of slabs by taking measures such as preventing buckling deformation, it is possible to apply it to width reduction of slabs by taking measures such as preventing buckling deformation. Since it is rolled down several times, the rolling force is very large and productivity may be poor.

Separately, the slabs are sequentially fed into a pair of anvils that periodically open and close at predetermined intervals with a relatively small amplitude.
A width reduction method that compresses the width of the slab can be considered. Although the method of rolling down metal materials using such a continuous forging method is small-sized, it is used for steel bars and the like. For example, machines from the Austrian company George Fischer fall under this category.

The inventors applied this method to width reduction of slabs.
After extensive research, we found that the above problems (1) and (11)
It was found that the width reduction efficiency was extremely high as the width reduction was significantly improved and the reduction penetrated sufficiently to the center of the width, but as the width reduction amount increased, the tip and end became flat. It became clear that the shape changed and the number of four-piece broth increased.

C. Problems to be Solved by the Invention] It is an object of the present invention to provide a method for preventing fishtail shape deformation and improving the planar shape of the tip in a slab width reduction method using a continuous forging method.

Means for Solving Problem C) This invention provides a slab width reduction method in which a metal slab is sequentially fed between a pair of anvils that are periodically opened and closed at predetermined intervals dMIN to dMAX, and the slab width is compressed. , When rolling down the tip to mvt, the anvil width d is the entire slab width W
0, the feed amount of the slab is 8 pieces, and the feed amount of the normal section is S.
A step of setting the slab larger than M, feeding the slab, and pressing the tip part with a predetermined width in the positioned state, and then a constant feeding chamber 8) Ll constant opening/closing "dMIN ~
This is a method for width reduction of a metal slab, which is characterized by a step of rolling and compressing at dM■ combined with a step of pressing.

Now, 2nd P1! J shows the basics of the continuous forging width reduction method.

Anvil 1,1rr-11! ! The rattan slabs 2 are placed horizontally opposite each other across the width of the rattan slabs 2.

The planar shape of the anvil 1.1 consists of a spacing p parallel to the continuous casting slab 2 and a tapered portion a having an angle θ. Taper p1%
g 4:2 curve may be used.

A pair of anvils 1.1 are synchronized with an amplitude ga and a frequency f'''C.
It is driven to open and close periodically, and the minimum interval between the anvils is set to a predetermined SW,
Set to . A pair of anvils opening and closing like this 1.1
Slabs with a radius of W0 are sequentially fed into the opening to perform width reduction.

Now, when the anvil 11J'19IId is fed from the position of the tip of the slab when it is in the closed part equal to the width cut sew, to the position fIt [phase] in synchronization with the anvil retreating, the amount of feed is geometrically SM-jl a/tan
θ becomes O If width reduction is performed under these conditions, the leading edge will be
When the material is rolled down by the taper S, the material at the width end flows forward along the taper due to the influence of the taper, and the planar shape becomes a fishtail, and the width becomes smaller than the predetermined width W0.

For this reason, when the slab width-reduced in this way is hot-rolled in a hot strip mill, the tip shape of the sheet bar becomes like the fourth □□□ (mu), and the amount of cut-off increases.

In order to eliminate such a planar shape, according to the present invention, as shown in FIG.
Continuously cast slab 2 is fed by a value ST larger than the constant temperature feed amount SM as described above for the normal part other than the leading edge part, and the width reduction is performed by a predetermined amount. The width reduction is continued with the amplitude 2a, frequency @f, and feeding amount SM according to the method.

Table 1 shows the results of experiments conducted by varying the ST conditions.

[Function] Thickness 220 gtXN 180011111X Length 89
A steel slab of Kyosha got about 001u1 in width W□-
After width reduction to 1,000 mm, it was decided to roll it into a 3.2-mm hot rolled steel strip coil in a hot strip mill, and its mt ratio was the same as the planar shape of the crop cut off by the sheet parr in front of the finishing rolling mill. Shown in the table. The same table also lists the results for width reduction using the V-H rolling method for comparison.

In slab 41 to which the V-n rolling method was applied, 0.59%
There is a huge Lotsupuros. Continuous press method, normal reduction method (slab black 2) crop truncation rate is 0.4
2%, which is a little less than 9% compared to the V-H rolling method, but it is still not in a satisfactory state.

On the other hand, when ST is increased, the shape changes from a fishtail to a double tongue shape as shown in FIG. 4 rQl, or further to a tongue shape as shown in FIG. 4(B). S
It can be seen that as T increases, the crop truncation rate also decreases significantly. However, if ST is set too large, a large tongue will result, which will actually increase the crop truncation amount, so it is important to note that ST has an appropriate value. Recognize.

In the case mentioned above, condition 5 shown for slab &6
T-7126 has the lowest crop truncation rate, which can be reduced to 57% compared to the conventional continuous press method (slab A2) and 70% compared to the vn rolling method.

In addition, with the aim of further reducing crop loss, trapezoidal anvils 1' and 1' are used, as shown in Figure 8, and the width of the leading edge is slightly larger than the specified width W. By doing this, the 451st (G l, (B
We were able to reduce the droop (&l1m less) at the leading edge as shown in Figure 1 and create a more rectangular planar shape as shown in Figure 4 (Dl).Table 1 shows the conditions and cropping amount at this time. As shown in (Slab 169), the crop truncation amount could be reduced to 0.14%.

The planar shape of the slab after the press width reduction is the parallel K of the trapezoidal anvil 1.1' shown in Fig. 8 (if the full length of lBI+ is used, it will be like Fig. 5 (Al, but as shown in the above) It is not necessary to use this shape as the shape of the tip width to prevent the tip layer from sagging.
It is certain that a similar shape will have the same effect.

Effects of invention C] By consolidating continuous %-A/do sizes, it is possible to reduce to the minimum the conventionally unavoidable lotup loss associated with width reduction, which is essential when applying continuous cast slabs to hot strap rolling materials of multiple sizes. 0

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram of a continuous press width reduction method according to the present invention, FIG. 4th PA is a comparison diagram of the top planar shape of the sheet par, and FIG. 5 is an explanatory diagram of each different embodiment.

Claims (1)

[Claims] 1. Periodically at predetermined intervals from d_M_I_N to d_M_A_
In the slab width reduction method in which a metal slab is successively fed between a pair of anvils that open and close up to A stage in which the feed amount S_T is set larger than the feed amount S_M in the normal section, the slab is fed, and the tip is pressed at least once or more to a predetermined width while the slab is positioned, and then a constant feed is performed. Quantity S_M, constant opening/closing width d_M
A method for reducing the width of a metal slab, characterized by combining steps of sequentially compressing at _I_N to d_M_A_X.