JPH11277225A - Method for preventing adhesion of gas cutting shear droop and device therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the adhesion of shear droop by gas cutting by spraying high- pressure water for blowing off the melt drooped from a cut end along the rear surface of the cutting point to be cut by scanning a slab with a gas torch from above the slab. SOLUTION: Preferably the pressure of the high-pressure water is specified to over 10 to 30 kgf/cm<2> , the downward spreading angle from the horizontal direction of the high-pressure water to 5 to 15 deg. and the flow rate of the high-pressure water to 3 to 15 liter/minute.m. While the slab 4 progresses in a transporting line, the gas torch 1 is moved in the transverse direction of the slab 4 and is cut. During this cutting work, the injected high-pressure water 7 is blown near to the cut end 8 on the rear surface of the slab 4 from a water injection nozzle 3 to blow off the melt flowing to the cut end 8, by which the adhesion of the shear droop is prevented. As a result, the adhesion of the shear droop to the slab 4 is eventually prevented even if a shear droop removing stage is not disposed. In addition, the need for separately disposing intricate devices, such as a coating applicator for an adhesion preventive agent and shear droop recovering device for an iron plate for adhesion prevention, is eliminated.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for preventing the attachment of gas cutting droop, and more particularly, to the so-called "cut dripping" that occurs when a steel slab is gas cut to a predetermined length in a continuous casting facility. Is a technique for preventing the slab after being cut off from adhering to the back surface of the slab and soiling the slab after cutting.

[0002]

2. Description of the Related Art In a continuous casting facility for steel slabs, solidified slabs are continuously drawn from a mold. Therefore, if the material is transported to a subsequent step (for example, hot rolling) as it is, it must be cut to a required length at the receiving end. For this reason, the slab which is still moving is usually cut at the rearmost end of the continuous casting facility to a length desired by a subsequent process. When the cast piece has a small cross section, a shearing (blade) type cutting device is sometimes used, but in most cases, a gas cutting type is used.

By the way, when a slab is cut with gas from the upper surface to the lower surface, usually, a melt generated at the time of cutting adheres to the back surface of the cut portion. These deposits are called "who". If the dirty slab to which the deposit is attached is rolled as it is, it causes a roll or a product to be scratched. Therefore, after cutting the slab, it is necessary to remove the “drain” from the back of the slab. There are a wide variety of methods for this removal, such as using a manual scarf (scratch), a rotary hammer, a fixed blade, a grinder, and the like.
The removal step is provided, and secondary adverse effects such as an increase in equipment due to an increase in the number of steps and a decrease in slab temperature are also caused. Therefore, in order to solve such a problem, several gas cutting methods have been developed so far, in which "nobody" adheres to the slab.

For example, Japanese Patent Application Laid-Open No. 53-067660 discloses a "method of cutting a slab after applying an anti-adhesion agent for a molten material to a slab in advance." Also, JP-A-53-10
No. 2251 proposes a "method of pasting an iron plate on the back surface of a cut portion of a slab in advance, attaching a" bar "to the iron plate, and removing the entire iron plate from the slab after the gas cutting is completed."
Furthermore, recently, in order to facilitate the subsequent handling of the melt flowing down, water is sprayed at a pressure of about ² to 10 kgf / cm ² from a nozzle that moves in synchronization with the gas torch, and the melt is granulated. Technology (referred to as granulation) is also used (see FIG. 1).

[0005]

However, in the technique described in Japanese Patent Application Laid-Open No. 53-067660, it is important to control the concentration of the coating agent and to maintain the stirring device and the nozzle of the coating agent. There is a problem that fluctuates greatly. In the technique described in Japanese Patent Application Laid-Open No. 53-102251, it is not only difficult to collect the iron plate to which "who" has adhered, but also it is necessary to provide a separate collection device or to periodically clean the soot. There was a problem. In addition, the above-mentioned granulation is not one in which water is directly sprayed on the back surface of the slab, but is separated from the bottom surface of the slab and sprayed on the molten material that is falling, so that the adhesion of the molten material to the back surface of the slab is Not prevented.

In view of such circumstances, the present invention provides a method for preventing dripping from adhering to the back surface of a cut point even when gas is cut from a slab by a continuous casting facility. And devices ".

[0007]

Means for Solving the Problems In order to achieve the above object, the inventor reviewed the technique of spraying the granulation water. Then, the present inventors have focused on the fact that the melt generated during gas cutting is removed before flowing down from the cut end, and made intensive efforts to realize the present invention, thereby completing the present invention. That is, in the present invention, a gas torch is scanned from above the slab in the width direction of the slab that has been extracted from the continuous casting mold and is still traveling on the conveying line, and the slab is gas-cut. At this time, a method for preventing gas cutting dripping from adhering is characterized in that high-pressure water is blown along a back surface of a cutting portion of the slab and blows away a melt coming from a cut end.

Further, the present invention provides that the pressure of the high-pressure water is set at 10
This is a method for preventing gas cutting dripping from adhering to a maximum of 30 kgf / cm ² . Further, the present invention is characterized in that the downward spread angle of the high-pressure water from the horizontal direction is 5 to 15 °, or the flow rate thereof is 3 to 15 liter / min · m. Is the way.

[0009] In addition, the present invention is an apparatus for preventing adhesion of a melt produced by gas cutting of a slab that has been extracted from a continuous casting mold and is still traveling on a conveying line to the backside of the slab. An apparatus for preventing gas cutting dripping, wherein a water jet nozzle for spraying high-pressure water is provided along the back side of the cutting section of the slab, beside the transfer line corresponding to the cutting section of the slab. .

[0010] According to the present invention, the melt produced by cutting the slab is blown off at the cut on the back surface of the slab, so that it does not adhere to the back surface of the slab. As a result, a slab to which the molten material does not adhere is obtained, and can be sent to a subsequent process without any care.

[0011]

Embodiments of the present invention will be described below with reference to the drawings. First, as shown in FIGS. 1 (a) and 1 (b), the adhesion preventing device according to the present invention is arranged beside a conveying line of a slab 4 drawn from a continuous casting mold (not shown). . It has a structure in which the slab 4 does not move in the width direction, and a water supply pipe (not shown) separate from that for the granulation, a water pressure boosting pump (not shown), Is formed with a water jet nozzle 3 (also referred to as a spray tip) whose shape becomes flat.
The water injection nozzle 3 is different from water for granulation in that the direction of water injection is opposite to the direction of travel of the slab 4. This is because water that has collided with the cutting point on the back side of the slab enters the cut 8 and does not hinder the gas cutting operation.

1 (a) and 1 (b) show a slab 4
A gas torch 1 for cutting through and a nozzle 2 for granulation are also described. The gas torch 1 and the nozzle 2 for granulation are different from the water injection nozzle 3 according to the present invention.
In the traveling direction 5 and the width direction 6. Next, a method for preventing adhesion according to the present invention using such an apparatus will be described.

The slab 4 is cut by moving the gas torch 1 in the width direction of the slab 4 while traveling on the transport line. The method for preventing adhesion according to the present invention is characterized in that, while the cutting operation is being performed, high-pressure water 7 is sprayed from the water injection nozzle 3 to the vicinity of the cut 8 on the back surface of the slab, and the melt flowing to the cut 8 By blowing away, "Who"
This is to prevent the adhesion of.

At this time, the pressure of the high-pressure water 7 is increased from more than 10 to 3
It is preferable that the pressure be 0 kgf / cm ² . 10
If the weight is not more than kgf / cm ² , the melt at the cut 8 may not be blown off over the entire width of the slab 4,
If it exceeds 30 kgf / cm ² , the temperature of the back side of the slab may be too low, and gas cutting may be abnormal or impossible.

Further, in the present invention, as shown in FIG. 2 (a), the water injection nozzle 3 to be used is kept almost horizontal with respect to the slab, and the downward divergence angle ( (Indicated by α in the figure) is preferably kept at 5 to 15 °. If the angle is less than 5 °, water may not sufficiently be applied to the back surface of the slab to prevent adhesion, and if the angle exceeds 15 °, water may enter the cut 8.

Further, in the present invention, it is preferable that the spraying water amount is controlled within a certain flow rate range in accordance with the size of the cast slab to be cut. For example, thickness 220 mm, width 1500 m
When cutting m cast pieces, the rate is 3 to 15 liters / min.m per cast piece. If the amount of water increases more than 15 liters / minute · m, the slab 4 will be cooled too much, affecting its material, or especially at the beginning of cutting,
This causes cutting failure, and if it is less than 3 liters / minute · m, the amount of water is so small that “who” cannot be blown off.

2 (a) and 2 (c) are shown in FIG.
Is a view of the injection state of the high-pressure water 7 shown in FIG.

[0018]

EXAMPLE A molten steel made of ultra-low carbon steel was continuously cast to produce a slab 4 having a thickness of 220 mm and a width of 1600 mm. At that time, an experiment was conducted in which high-pressure water was sprayed from the water injection nozzle shown in FIGS. The experimental conditions were as follows:
Two levels of 0 and 30 kgf / cm ² , flow rates of 5, 10,
20, 30 liters / min, 4 levels, the spread angle (α)
At two levels of 10 ° and 30 °. Further, the adhesion of the “who” was determined by cooling the cast slab that had been cut, observing the back surface with the naked eye, and judging the quality.

[0019]

As described above, according to the present invention, it is possible to prevent the "slump" from adhering to the slab without providing the "slump" removing step conventionally performed. Further, it is not necessary to separately provide a complicated device such as an application device of an anti-adhesion agent and a recovery device of an iron plate for preventing adhesion.

[Brief description of the drawings]

FIG. 1 is a view showing a state in which an adhesion preventing device according to the present invention is arranged on a slab transfer line, (a) is a front view,
(B) is a plan view.

FIGS. 2A and 2B show a state in which high-pressure water is injected from the adhesion preventing device according to the present invention, wherein FIG. 2A is a side view, FIG. FIG.

[Explanation of symbols]

REFERENCE SIGNS LIST 1 gas torch 2 nozzle for granulation 3 water injection nozzle 4 slab 5 slab traveling direction 6 slidable range of gas torch and nozzle for granulation 7 injected high-pressure water

Claims (5)

[Claims] 1. A gas torch is scanned from above the slab in the width direction of the slab that has been extracted from the continuous casting mold and is still traveling on the conveying line, and the slab is cut by gas. A method for preventing gas cutting dripping from adhering, wherein high pressure water is blown along a back surface of a cutting portion of the slab and blows away a melt flowing from a cut end. 2. The pressure of the high-pressure water is more than 10 to 30 kgf.
^{2. The} method for preventing adhesion of dripping gas according to claim 1, wherein the pressure is set to / cm ² . 3. The spread angle of the high-pressure water downward from the horizontal direction is 5 to 15 °.
The method for preventing gas cutting dripping described in the above. 4. The flow rate of the high-pressure water is 3 to 15 liter /
The method for preventing gas cutting dripping according to any one of claims 1 to 3, wherein the amount is set to minutes · m. 5. An apparatus for preventing adhesion of a melt produced by gas cutting of a slab that has been removed from a continuous casting mold and is still traveling on a conveying line to the back surface of the slab, A sticking prevention device for gas cutting draughters, wherein a water jet nozzle for spraying high-pressure water is provided along a back side of a cutting portion of the slab beside a conveying line corresponding to the cutting portion.