JPH03204149A - Method and device for cutting continuously casting strand - Google Patents

Abstract

PURPOSE:To cut a strand with a little cutting allowance in a short time by gas-cutting a constricted part after forming the constricted part to the strand by pressurizing with a pushing edge at the time of cutting the strand produced with continuous casting method. CONSTITUTION:In the case of cutting the strand 1 produced with the continuous casting to make this into the cast slab 2 having the suitable length, at first the pushing edges 3 having triangle or trapezoid cross section of 60 - 90 deg. angle alphaof the edge part are pressurized to at least both side faces opposed of the strand 1 with a pushing means 4 to form the constricted part 11. In this case, after making cross sectional area of the remaining part 12 in the constricted part 11 in the cross section of strand 1 to 30 - 60% (desirably 40 - 50%) the cross sectional area of strand 1, the remaining part 12 in the constricted part 11 is cut with gas cutter 5 to make the cast slab 2 having the prescribed length. As the cutting allowance is little, yield of the cast slab 2 is goods, and as the melt-cutting slag at the time of gas-cutting is little, at the time of rolling the cast slab 2, removal of the melt-cutting slag is unnecessary, and the rolled stock having excellent quality is obtd.

Description

[Detailed description of the invention] [Industrial application field]

The present invention relates to improvements in strand cutting techniques in continuous casting of metals, particularly steel. This invention is particularly useful when applied to cutting vertical strands. [Conventional technology] There is an in-line rolling technique in which strands produced by continuous steel casting are rolled as they are, but in many cases, they are cut into slabs of appropriate length and used for subsequent processing. . This strand cutting is usually done using propane gas +020F.
This is done using a gas cutting method using a frame made of e-powder.
Since gas cutting takes time to cut and results in loss of cutting margin, cutting methods using shearing have been attempted [
For example, [Shinko Giho J Vol. 38 No. 4 (1988) p.
65 to 68], - parts are in practical use. However, even though it is heated, a large force is required to shear the steel strand, and the damage caused by the shearing force is significant, so the strands to which the new shearing method can be applied are small-diameter, relatively soft steel types. limited to. In addition to the above-mentioned problems, gas cutting also causes cutting slag produced by the frame to adhere to the end face of the slab, which is actually more important in practical terms. This is because cutting slag causes indentation flaws and rough skin during rolling. Although the adhesion of cutting slag is limited to a small amount when curved strands are gas cut in a horizontal position, it is serious when it comes to vertical strands. In either case, the countermeasure is to apply a scraper to remove the slab when it is moved, but since the actual wAk: cannot be completely removed, it is removed manually by grinding with a grinder. This is the current situation. On the other hand, strand cutting by shearing has the disadvantage that cracks and burrs are likely to form on the cut end surface when the target is a sticky material such as special steel, especially stainless steel. In addition, cavities and pipes that tend to form at the center of the strand are melt-sealed in the case of gas cutting, but in shearing, the inner surface is exposed and oxidized, and as a result, it is not crimped during the rolling process. The problem is that it has to be truncated over a considerable length. [Problems to be Solved by the Invention] The purpose of the present invention is to solve the above-mentioned problems in continuous casting strand cutting, and to improve the combination of the commonly used gas cutting method and the new cutting method, which has only been put into practice in limited cases. Our goal is to provide a rational strand cutting technology that combines advantages.

[Means to solve the problem]

As shown in FIG. 1, the continuous casting strand cutting method of the present invention which achieves the above object is a method in which a strand (1) formed by continuous casting is cut into slabs (2). The blade (3) is pushed in from at least two directions to form a constriction (11), and the remaining part (12) of this constriction is cut by a gas cutter (5). Reference numeral (8) is the frame of the gas cutter. The ratio of pushing and gas cutting can be selected arbitrarily, but generally the cross-sectional area of the portion (12) remaining at the constriction is 30 to 60%, particularly 40 to 50%, of the cross-sectional area of the strand.
It is recommended to implement it so that As can be understood from the description of the cutting method with reference to FIG. 1, the cutting device of the present invention is a device for cutting a strand (1) formed of a continuous slab to produce a casting (2). , two pushing blades (3) and its pushing means (4) provided at opposing positions for creating a constriction (11) in the strand, and moving both of them as the strand advances and returning them to their original positions. It is characterized by comprising a traveling means (6) for returning the strand, a gas cutter (5) for cutting the constricted part of the strand with a frame, and its traveling means (7). The blade may be pushed in from two directions using a straight blade, reducing only the thickness of the strand in the pushing direction. It is preferable to use a pushing blade having a receded shape to form a constriction around the entire circumference of the strand, as shown in FIG. 3A. If the strand has a square cross section, it is sufficient to press the strand from its opposing edges toward the center, as shown in FIG. 3B. Alternatively, as shown in Fig. 4, by providing push-in blades in four directions with straight parts to be pushed in, and sequentially pushing each pair of opposing blades from Fig. 4 to Fig. 5, the strands can be A constriction can be formed around the entire circumference. The cross-sectional shape of the pushing blade can be flat, wedge-shaped, trapezoidal, or circular. A shape in which the tip has an arcuate cross section as shown in FIG. 6B is optimal. The angle α of this cross section is preferably selected from the range of 30 to 90''. As mentioned in the introduction, the present invention is particularly useful when dealing with vertical strands, and the reason for this is as follows: In this case, the device naturally has the pushing blade upward,
A gas cutter is placed below. [Function 1] The formation of a constriction by pushing the pushing blade into the strand does not result in complete cutting, so it does not cause problems with cracking or burrs on the end surface of the slab. Even if there is a cavity or pipe in the center, unless it is sheared, it will be crimped and not exposed, and the subsequent gas cutting will melt and seal it, so only a small amount of end portions will be cut off after rolling. Since gas cutting only cuts the remaining part of the constriction due to pushing, it takes half or less time compared to conventional gas cutting on the entire surface. The portion lost as cutting margins is also reduced accordingly. Not only does the amount of slag itself decrease, but as shown in Figure 7, for example, even when slag (9) is generated, most of the slag (9) is due to the slope (13) formed by pushing the end of the slab.
It stops at that part and does not reach the circumferential surface, so it does not interfere with rolling. In a typical embodiment of the present invention, the end faces of the slab are obliquely slanted from both sides, which is convenient for rolling operations, and the cropping that is unavoidable when rolling a slab with flat end faces. virtually eliminates the occurrence of [Example] A vertical strand cutting device with a circular cross section of 350 m in diameter was manufactured. The push-in blade has the shape shown in Figure 6B (
α=75°), and the remaining part of the constriction formed is a square with − sides of 200 to 25051I. (The area ratio decreases to 42-65%.) The above indentation is approximately 20% even for relatively hard materials.
Press the blade for a few seconds with a 0 ton hydraulic press.
Therefore, it is possible. When the strand loss rate is, for example, 0.7 TrL/min, the travel distance of the pushing blade is several tens of meters. this is,
This was achieved by a mechanism that uses a separate hydraulic cylinder to reciprocate. A gas cutter with a slightly smaller capacity than the conventional one was used in an effort to minimize the cutting margin, but the time required for gas cutting was only 60% of the conventional one. As a result, the traveling distance of the gas cutter could be significantly shortened, and it was easy to install the above-mentioned push-in blade device.
The amount of slag generated was only about 1/3 that of the conventional method, and there was no need to remove it prior to rolling.

【Effect of the invention】

According to the cutting technology of the present invention, continuous casting strands can be
Cuts with less cutting margin and slag than conventional gas cutting,
The slab can be rolled as is without the need to remove adhering slag. In rolling, there is no problem of oxidation of the central cavity that can occur when shearing occurs, and the chamfered edges of the slab significantly reduce the cropping of the edges of the rolled material compared to flat edges. You can do less. In this way, according to the present invention, there is no need to remove the slag from the end of the slab, and no special equipment or work is required. The cutting margin when cutting the strand is reduced,
Combined with the ability to reduce the amount of cutoff at the ends of the rolled material, the yield of products can be increased.

[Brief explanation of drawings]

FIG. 1 is a side view for explaining continuous casting strand cutting according to the present invention. FIG. 2 is a plan view showing a preferred embodiment of the pushing blade. Figures 3A and 3B show the preferred shape of the constriction caused by pushing the blade; A shows the shape of the constriction when the blade is pushed into a strand with a circular cross section; B shows the shape of the constriction when the blade is pushed into a strand with a rectangular (square) cross section; Both are cross-sectional views of the strand. 4 and 5 are diagrams showing a cross section of a strand and a pushing blade for explaining another method of forming a constriction. FIGS. 6A and 6B are sectional views showing preferred examples of the shape of the pushing blade. FIG. 7 is a cross-sectional view showing the generation of cutting slag and its adhesion during gas cutting using a suitable push-in blade. 1... Strand 11... Constriction 12... Remaining portion 2... Slab 3... Pushing blade 4... Pushing means 5... Gas cutter 6.7... Traveling means 8. ... Fused slag No. 1111

Claims (7)

[Claims] (1) In the method of cutting strands formed by continuous casting to produce slabs, a blade is pushed into the strand from at least two directions to form a constriction, and this constriction is cut by gas cutting. Features continuous casting strand cutting method. (2) The cross-sectional area of the constriction is 30% of the cross-sectional area of the strand.
2. The cutting method according to claim 1, wherein the cutting method is carried out in such a manner that the cutting rate is .about.60%, in particular 40-50%. (3) Using a pushing blade whose center part is set back in a V-shape, if the strand has a square cross section, push from the opposite edges toward the center to create a constriction around the entire circumference of the strand. 2. The cutting method according to claim 1, wherein the cutting method is carried out by forming. (4) The cutting method according to claim 1, wherein pushing blades each having a straight portion to be pushed are provided in four directions, and each pair of opposing blades is sequentially pushed to form a constriction around the entire circumference of the strand. (5) In a device that cuts a strand formed by continuous casting into slabs, two pushing blades and a pushing means are provided at opposing positions to create a constriction in the strand, and both are used to advance the strand. Strand cutting of continuous casting characterized by comprising: a traveling means for moving the strand as the strand moves and returning it to the original position; a gas cutter for cutting the constricted part of the strand with a frame; and the traveling means. Device. (6) The cutting device according to claim 5, wherein the tip of the pushing blade has a triangular or trapezoidal cross section, and the angle thereof is in the range of 60 to 90 degrees. (7) The cutting device according to claim 5, wherein the push-in blade and the gas cutter are arranged above and cut vertically descending strands.