JP2002035932A - Scarfing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain excellent scarfed surface automatically by controlling scarfing velocity variation, scarfing oxygen pressure and gas pressure in order to prevent generation of unscarfed portions and deep cracks. SOLUTION: Before starting scarfing of a billet, pre-heat point (Point P) is heated. When this point is detected to that it has reached a high temperature, a scarfing torch is turned back toward an end face of the billet (Point B'), where his speed scarfing is then made to start toward advancing direction, when it has reached the point F subjected to less heat-influence by pre-heating, from this point F', low speed scarfing is conducted and after generating enough amount of scarfing slag at the point F", it is scarfed at the standard speed until point H that the proximate position of the final point of scarfing G, from where scarfing velocity is increased again to scarf final width of the billet. After finishing one way scarf, slow speed scarf toward reverse direction is conducted in order to eliminate remained scarfing slag and the like, thus perfect scarfed surface is attained.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fusing method for removing fuzz dripping adhered to an end face of a slab when the upper and lower surfaces of the slab are fused.

[0002]

2. Description of the Related Art In the process of manufacturing a slab, when the upper and lower surfaces of the slab are cut by a gas cutting machine in order to remove surface flaws and the like, as shown in FIGS. 1, 2 (a) and 2 (b). In this case, the generated slag runs down from the upper surface to the end surface 2 and extends from the lower surface to the end surface. Such cutting sagging is the result of re-solidification of the molten slab, and if rolled as it is, it may cause slab flaws and must be removed before rolling. Instead, a manual cutting method using a hand-scarf nozzle, a grinder grinding, and a cutting method using a mechanical gas cutting machine are generally used. However, according to these methods, the cutting sagging cannot be completely removed mechanically and automatically without leaving or excavating.

[0003]

SUMMARY OF THE INVENTION The present invention has been made in view of the above points, and has been developed in order to prevent the uncut portion from being left behind and the occurrence of a deep dug portion. Another object of the present invention is to automatically obtain a good cutting surface by controlling the fluctuation of the cutting speed, the cutting oxygen pressure and the gas pressure.

[0004]

In order to solve the above-mentioned problems, the present invention provides a fusing method that uses a temperature detecting device such as a temperature sensor to preheat a fusing start position before fusing is started. After monitoring the condition and confirming that sufficient heating was obtained,
Start cutting. Continue to monitor the cutting surface during cutting, perform temporary movement in the opposite direction at the start part, and control the cutting speed and / or cutting oxygen pressure and gas pressure during subsequent cutting, Once the cutting of the billet width is completed, it is immediately moved in the opposite direction, and the remaining portion is cut to obtain a completely cut surface.

[0005]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a view showing cutting edges 3 and 4 of an end face 2 of a billet 1 manufactured by continuous casting.
2 (a) and 2 (b) are a front view and a cross-sectional view taken along the line XX 'of the cutting machine 5 traveling in the direction of A (a billet width) provided opposite to the cutting machine. It is. FIG. 3 shows an implementation state of the cutting machine.

In FIG. 3, a cutting crater 5 forms a slit-shaped oxygen injection port 6 for cutting oxygen by superposing an upper unit 5 'and a lower unit 5 ". First, the upper unit 5 'and the lower unit 5 "
Gas is ejected from a gas ejection hole (not shown), and low-pressure oxygen is ejected from an oxygen
And heats a starting point P suitable for preheating. The steel slab to be heated usually has a temperature from normal temperature to about 600 ° C., and is heated to about 1200 ° C. For monitoring the temperature, a temperature sensor 8 such as a temperature sensor or an ITV camera linked to the cutting machine is used. Subsequently, in order to start fusing from point B on the end face of the slab, it moves from point P to point B 'near point B. It should be noted that the cutting from the point B 'is sufficient for the cutting from the point B on the end face. Conversely, if the cutting is performed from the point B, the cutting dripping adheres to the side E' of the slab 1 or the deep digging occurs. Problems arise.

[0007] When the cutting is started from the point B 'in the direction A (slab width) in the direction of the slab, each air on the upper and lower surfaces of the slab provided in the cutting direction is close to the cutting crater. Blasting prevents the dripping of the molten metal from rebounding to the upper and lower surfaces of the steel slab. FIG. 5 schematically shows the transition of the cutting speed in the slab width direction. In the cutting from the point B ′ to the direction A, since the vicinity of the point P is heated, the cutting is performed deep into the cut surface. since the not cause, to the vicinity of the point P of the start preheating performs scarfing raises the scarfing speed as shown in FIG. 5 to f _1. In this region, even if the cutting speed is increased, excessive combustion reaction in the high temperature steel slab due to preheating is suppressed, and the generated heat, which is the main heat source required for cutting, is easily generated due to the high temperature. Therefore, a good cut surface can be obtained.

If a cutting machine with a high cutting speed passes this point P, the influence of heat at the starting point of preheating is reduced.
The generated slag is also small, and in order to prevent the interruption of the erosion due to this, the slicing speed is reduced to f ₂ to generate sufficient slag, and the cutting is performed at a low speed for a while from the point F ′ in FIG. After accumulating slag, advance to the next F ″ point, and after this point, accelerate and increase the standard cutting speed f ₃ suitable for cutting, and continue cutting in the direction A.

When the point H, which is about 350 mm from the point G at the final cutting point, is reached, the steel cuttings 3 and 4 are prevented from wrapping around and sticking to the side E ″ surface adjacent to the cutting surface. order to suppress the combustion reaction, if the. scarfing speed to increase the scarfing speed high speed f ₄ than the standard speed to f _4, to continue the scarfing to point G of the final point at that speed,
The fusing in the direction A is completed once. Therefore, no cutting sags 3 and 4 occur.

However, in this case, as shown in FIG.
On the abraded surface near the point, the abrasion sag 3, 4 may slightly remain, or the scale S of the steel slab after the combustion reaction newly attached to the abraded surface may be seen. Therefore, in order to obtain a complete scarfing surface, while returning the scarfing crater it in the opposite direction at about one-third of the speed of scarfing speed f _4, remove the scarfing sag 3,4 and scale S remaining I do.

The above description has been made on monitoring and controlling the combustion reaction of the slab by making the cutting speed of the cutting crater faster or slower than the standard cutting speed, and performing the cutting. Apart from this, the same purpose can be achieved by keeping the cutting speed constant and changing the cutting oxygen pressure and the gas pressure. That is, from the cutting start point B ', the cutting oxygen pressure is lowered to lower the combustion reaction to reduce the combustion reaction, advance to the point F', and increase the pressure from the point F 'to the point F "where the influence of the preheating heat is small. The reaction is accelerated, and a standard cutting oxygen pressure is set from the F ″ point. Then, the pressure is lowered from the point H near the final point, and a low pressure of the cutting oxygen pressure is supplied to perform the cutting until the final point, and the reverse movement from the final point is performed at a relatively low oxygen pressure. Perform grinding. In these cases, it goes without saying that the gas pressure is increased or decreased in proportion to the cutting oxygen pressure.

Further, as one method for obtaining a better cutting surface, the same object can be achieved by simultaneously increasing and decreasing the cutting speed, the cutting oxygen pressure and the gas pressure.

In the actual cutting method of the present invention, temperature detection,
A series of movements such as cutting oxygen pressure and gas pressure, running of a cutting machine having a cutting crater, and the like are performed without any trouble via a separately provided control device (not shown). The monitoring of the cutting surface during cutting is performed by the temperature detecting device linked to the cutting machine, and this information is sent to the cutting machine to control the movement according to the condition of the cutting surface.

[0014]

As described above, according to the cutting method according to the present invention, in order to remove the cutting sagging in the cross section of the slab, deep digging and preheating by overheating to ensure the stability of the cutting. In order to eliminate the remaining of the cutting sagging due to shortage etc., perform the cutting while monitoring the cutting surface precisely and change the cutting speed or the cutting oxygen pressure independently or simultaneously to advance the cutting crater. In addition, since reverse cutting is performed to perform cutting without leaving any residue, good results can be obtained over the entire cut surface, and the effect on the industry is great.

[Brief description of the drawings]

FIG. 1 is a plan view showing a cutting edge and a cutting crater on an end face of a steel piece.

FIG. 2A is a front view, and FIG. 2B is a sectional view taken along line XX ′ of FIG. 2A.

FIG. 3 is a view for explaining the cutting sag removal operation.

FIG. 4 is a diagram when the cutting crater is moved backward from a final point.

FIG. 5 is a schematic diagram showing a transition of a fusing speed when performing fusing in a billet width direction.

FIG. 6 is a view showing a machined surface of a billet when performing the reverse movement of FIG. 4;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Slab 2 Slab end face 3, 4 Drilling 5 Drilling crater 5 'Upper unit 5 "Lower unit 6 Oxygen outlet 7 Preheating flow 8 Temperature detector S Scale

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Hiroshi Takagi 4-29-5 Taito, Taito-ku, Tokyo Japan Sping Co., Ltd. (72) Toshiaki Nakagawa 1-2-1, Marunouchi, Chiyoda-ku, Tokyo Inside Nippon Kokan Co., Ltd. (72) Inventor Ken Matsuzaki 1-2-1, Marunouchi, Chiyoda-ku, Tokyo Japan Inside Nippon Kokan Co., Ltd. (72) Inventor Shunji 1-2-1, Marunouchi, Chiyoda-ku, Tokyo Sun Honko Co., Ltd.

Claims (3)

[Claims] 1. Before the start of cutting, the preheating point (point P) at the end of the steel piece is heated, and if this is detected as a high temperature, the cutting crater is returned to the end face (point B ') once, and from there. In the traveling direction, high-speed cutting is started, and if the process proceeds to a point (point F ') where the thermal influence of the preheating is small, low-speed cutting is performed to reduce the amount of slag necessary for cutting. After sufficient generation, the process proceeds at the standard cutting speed from (F "point), and when the final cutting point (G point) approaches, the cutting speed starts again from that point (H point). And then perform the final cutting of the slab width, and if the cutting from one direction is completed, perform a slow cutting in the opposite direction to further remove the residue of the cutting slag. A cutting method characterized by obtaining a perfect cutting surface. 2. The cutting method according to claim 1, wherein when a high-speed effect is to be obtained instead of a high-speed or low-speed cutting speed with respect to a standard cutting speed, the oxygen pressure and the gas pressure are increased. A fusing method characterized by lowering the pressure and increasing the pressure when obtaining a low-speed effect, so that the fusing is performed at the same speed. 3. The cutting method according to claim 1, wherein the cutting is adjusted as a low speed or a high speed with respect to a standard cutting speed, and the oxygen pressure and the gas pressure are simultaneously changed to perform the cutting. A cutting method characterized by adjustment.