JPH0117808B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for cutting steel slabs such as continuous cast slabs, and in particular, the invention relates to a method for cutting steel slabs such as continuous cast slabs, and in particular, to the occurrence of crops due to width expansion, overlapping, etc. that occur at the front and rear ends of the product when the cut steel slabs are rolled. This invention relates to a method for cutting steel slabs that is effective in reducing the amount of steel as much as possible and improving the efficiency of rolling operations.

Conventionally, in order to suppress the occurrence of cropping due to widening and overlapping of the front and rear ends of a product after rolling a steel billet such as a continuous cast slab, steel is rolled as shown in Figures 1a to c. Front and rear ends 1 of piece 1
It is known that a is preformed into a tapered shape in the thickness direction or width direction (hereinafter referred to as preforming) and then rolled.

One method that is effective for this preforming is, for example, as shown in FIG.
In order to form a, V-shaped blades 2 as shown in FIG. 2 are used, and as shown in FIG. A method is proposed in which the blades 2, 2 are cut into the steel piece 1 by the same amount or approximately the same amount. If the steel billet 1 is cut in this way, the front and rear ends 1a of the steel billet 1, which is the material to be rolled, can be preformed into a tapered shape at the same time as it is cut, so that the cutting work and the preforming work can be performed separately as in the conventional method. There is no need to carry out this process, which improves work efficiency, reduces the amount of crops generated during rolling, and prevents cutting burrs from appearing on the surface 1b of the steel billet 1, so even if this is rolled, it is possible to reduce the amount of crop generated during rolling. It is thought that the amount of crop generation can be further reduced because it is less likely to produce bald spots that extend into a mountain shape on the surface of the product.

For this reason, cutting the steel billet 1 using the V-shaped blade 2 is very effective in reducing the amount of crops generated after rolling, but in order to further reduce the amount of crops generated, It is desired that the cutting edge angle θ ₁ of the V-shaped blade 2 be further increased to increase the amount of preforming and to sharpen the shape of the cut surface 1a of the steel piece 1 after cutting.

However, if the cutting edge angle θ ₁ is increased, the required maximum cutting force of the cutting device increases, and a large-capacity cutting device becomes necessary, which is not preferable.

The present invention was made in view of such problems,
It is possible to cut a steel piece with a maximum cutting force that is almost the same as that of a conventional V-shaped blade, and at the same time preform the cut end into a tapered shape. By increasing the size and sharpening the cut surface shape, it is possible to further suppress the amount of cropping at the front and rear ends of the rolled product when it is rolled, and to improve the efficiency of the rolling operation. The present invention provides a method for cutting steel pieces that can be cut.

In order to achieve this purpose, a pair of blades has a two-stage blade part in which the angle of the blade gradually increases from the tip to the root, and the blade edge is tapered. The two blades are placed facing each other with a piece of steel in between, and both blades bite into the piece of steel to cut it.

Next, the present invention will be explained in detail with reference to embodiments shown in the drawings.

Fig. 4 shows an embodiment of the two-stage blade according to the present invention, in which the tip 3a of the first stage blade forms an angle of θ ₁ , and the second stage on the base side continues from this. The blade portion 3b is a two-stage blade 3 having an angle of θ ₂ and θ ₁ <θ ₂ and has a two-stage blade portion with a tapered cutting edge. These blades 3, 3 are placed opposite to each other with the piece of steel 1 in between, and both blades 3, 3 are movable, or one of the blades 3, 3 is made movable, and both blades 3, 3 are moved toward the piece of steel 1. The cutting is continued by the same amount or approximately the same amount, and the cutting is completed approximately at the center of the board thickness, as shown in FIG.
Note that FIG. 5 shows the state immediately before the cutting is almost completed and the vicinity of the center of the plate thickness of the steel piece 1 is broken and separated by the blade parts 3a and 3b.

Here, to explain the relationship between the cutting force and the amount of biting of the conventional V-shaped blade 2 into the steel piece 1 by the one-sided blade 2 (% ratio to the plate thickness), based on FIGS. 3 and 7, the blade edge angle When the pair of V-shaped blades 2 of θ ₁ each bite into the steel piece 1, and both cutting edges 2a reach A% of the plate thickness, respectively (the position shown by the two-dot chain line in Fig. 3, and the position shown in Fig. 7). The cutting force reaches its peak at point a on the curve 2), and when the cutting tool 2 bites further and the cutting edge 2a reaches B% of the plate thickness (the position shown by the solid line in Figure 3 and the point on curve 2 in Figure 7). point b]
At this point, the central portion of the steel piece 1 is broken and separated. Then, as shown from point a to point b of curve 2 in FIG. 7, the cutting force rapidly decreases from the time when the cutting edge 2a reaches A% of the plate thickness. This is because as both blades 2 dig into the steel slab 1, the plastic deformation region penetrates the entire thickness of the steel slab 1, and as the penetration progresses further, the steel slab 1 at the center of the thickness is cut. This is because the tensile stress acting on the parts that do not exist increases, resulting in constriction and eventually separation and cutting.

In addition, when the cutting edge angle θ ₁ of the V-shaped blade 2 was set to 70 degrees and an experiment was conducted using a steel plate test piece, A was 36% and B was 36%.
It was 46.5%.

In this way, the cutting force reaches its peak when the cutting edge of the pair of V-shaped blades reaches a certain point in the plate thickness (A% in this case), and the cutting force reaches its peak after that point (B% in this case).
The multistage blade according to the present invention was developed in consideration of the property that the cutting force decreases until then.

That is, the first stage blade part 3a of the two-stage blade ₃ in FIG. The height corresponds to A% of
A step blade portion 3b is formed, and the angle θ ₂ formed by this blade is
is made larger than the cutting edge angle θ ₁ of the first stage blade portion 3a.

A pair of two-stage blades 3 formed in this way,
3 into the steel piece 1 and cut it as shown in FIG. Then, the cutting force increases following the same change as the cutting force curve of the V-shaped blade 2 shown in FIG. 7, and as shown by the two-dot chain line in FIG. When the tip 3d of the first stage blade portion 3a of No. 3 bites in by an amount corresponding to A% of the plate thickness at that height, the maximum cutting force by the V-shaped blade 2 is approximately equivalent to the curve in FIG. The cutting force is maximum at point a.
When the blade 3 bites further, this time the first stage blade part 3
The second stage blade portion 3 has an angle θ ₂ larger than the angle θ ₁ of a.
b comes into contact with the steel piece 1 and begins to bite into it. Then, as shown by the solid line in Figure 5, the blade 3 is B% of the plate thickness.
When the steel piece 1 penetrates to a depth corresponding to , the steel piece 1 is fractured and separated approximately at its center. At this time, the cutting force curve of the two-stage blade 3 changes as shown by curve 1 in FIG. It breaks and separates at point C.
The change in cutting force of this two-stage blade 3 from point a to point c does not change suddenly like the change in cutting force from point a to point b of the V-shaped blade 2, but changes gradually. do. This is because the angle θ ₂ of the second stage blade part 3b is larger than the angle θ ₁ of the first stage blade part 3a, so resistance is generated when the second stage blade part 3b bites into the steel piece 1. . However, the first stage blade part 3a of the two-stage blade 3
From the point at which the cutting edge part 3a bites into the steel slab 1 to A% of the plate thickness at that height, the wedge action of the cutting edge 3a has a strong influence on the steel slab 1, and the force that separates the steel slab 1 from side to side is large. The cutting force will not be greater than point a. Note that the angles formed by the blades of this two-stage blade 3 are ₃₀ to 90 degrees and 2
It is desirable that the blade portion θ ₂ of the step is 50 to 130 degrees.
Of course, the angle θ ₂ of the second stage blade portion 3b must be smaller than 180 degrees.

In this way, if the pair of two-stage blades 3, 3 are cut into the steel piece 1 by cutting it, the maximum cutting force is almost the same as that of the conventional V-shaped blade 2, and the surface side of the steel piece 1 has the fifth edge. As shown in the figure and FIG. 6, since the shape of the cut end by the V-shaped blade 2 is preformed one step more on one side, the cut surface shape can be made into a smooth streamlined shape.

In addition, materials to be cut that can be applied to the present invention include:
It is not limited to steel billets such as continuously cast steel billets, but may of course be a general steel plate or the like.

As is clear from the above description, the present invention has a two-stage blade portion in which the angle of the blade gradually increases from the tip to the root of the blade, and has a tapered blade tip. The cutting capacity of the cutting device is almost the same as that of conventional V-shaped blade cutting devices, and the cutting capacity of the cutting device is almost the same as that of conventional V-shaped blade cutting devices. The amount of surface preforming can be increased, and the shape of the cut surface becomes smooth and streamlined, so the width of the cut section can be expanded after rolling.
Since overlapping and the like can be minimized and the amount of cropping can be further reduced, the yield is significantly improved. Of course, since no cutting burrs are generated on the surface of the steel piece during cutting, it is possible to reduce the number of sludge defects that occur on the front and rear ends of the material after rolling, thereby reducing the amount of cropping.

Since the cut surface can be made into a tapered shape at the same time as it is cut, it is no longer necessary to perform the cutting operation and the preforming operation to make the end tapered at separate locations and equipment, as was the case in the past. In addition, it is possible to reduce the installation area of equipment and improve work efficiency in rolling work, etc. In particular, if the method of the present invention is applied to cutting continuously cast steel pieces such as continuous slabs, the work process can be reduced as described above. Since it is possible to shorten and reduce the temperature of the continuously cast steel billet, it is possible to prevent a drop in the temperature of the continuously cast steel billet, and it becomes possible to directly roll the cut continuous cast billet without reheating it. Furthermore, since the temperature is high, the cutting force can also be reduced. In addition, according to the present invention, the cross-sectional shape of the cut end becomes a smooth streamlined shape, so it is easy to get caught in the rolling roll during rolling, and furthermore, when the cut steel piece is conveyed on a roller table, it does not catch on the roller. disappears. Furthermore, when cutting a steel slab such as a continuously cast slab in which the central part of the slab cross section is unsolidified, the two-stage blade of the present invention wraps the unsolidified part of the cut end in a solidified surface structure, which is not possible compared to conventional methods. The breakout prevention effect is improved by one level compared to the V-shaped blade. As mentioned above,
The present invention exhibits various excellent effects.

[Brief explanation of drawings]

Figures 1 a to c are perspective views illustrating an example of a method for preforming the front and rear ends of a steel billet to be rolled, and Figures 2 and 3 each illustrate a conventional V-shaped blade and a cutting method using it. The front view, FIG. 4, FIG. 5, and FIG. 6 are respectively a front view illustrating an embodiment of the two-stage blade according to the present invention, a front view illustrating a cutting method using this blade, and a front view illustrating a cutting method using this blade. FIG. 7 is a perspective view illustrating the shape of the cut end, and FIG. 7 is a graph illustrating the relationship between the cutting force and the amount of cutter penetration by the conventional V-shaped blade and the two-stage blade according to the present invention. 1...Steel piece, 2...V-shaped blade, 3...2-stage blade, _θ1 , _θ2 ...Blade angle.

Claims (1)

[Claims] 1 A pair of two-stage blades with a tapered edge and a two-stage blade section in which the angle of the blade gradually increases from the tip to the root of the blade, and the height of the first stage blade section is the height corresponding to the depth of penetration in the plate thickness direction when the cutting force is maximum, the angle of the blade is made larger in the second stage than the first stage, and the first stage is Cutting of a steel billet, characterized in that the angle is 30 to 90 degrees, and the second stage is 50 to 130 degrees, and the pair of two-stage blades sandwich the steel billet, face each other, and bite into the steel billet to cut the steel billet. Method.