JPS5976665A - Gas cutting method of thin steel material - Google Patents

Abstract

PURPOSE:To prevent lowering of work efficiency due to adhesion of slag to the cut face in gas cutting of a thin steel material by tilting a cutting torch at a specified angle to the direction opposite to the advance direction of cutting. CONSTITUTION:When gas cutting a steel plate especially a thin steel plate of Cr-Mo steel etc. less than 15mm. in thickness, a torch 2 is inclined at an angle alpha of 70-45 deg. to the direction opposite to the direction 3 of advance of cutting of the steel plate 1 and cutting is performed by spouting gas in the direction 6. Oxidation reaction between oxygen gas for cutting and Fe of the steel plate is sufficiently effected to produce Fe2O3. Further, because of sufficient generation of heat of reaction, slag is blown off without adhering to the cut face. Thus, the removal of slag after cutting is not necessary, and high speed cutting becomes possible.

Description

[Detailed Description of the Invention] 7 (Part 11) relates to a gas cutting method for Pv steel materials that enables high-speed scrap cutting and does not deposit slag on the surface to be cut. Conventionally, ttb When cutting scraps of steel materials, keep the cutting torch perpendicular to the surface of the material to be cut, or hold the cutting torch in a state where the northern part of the cutting torch is tilted 5 to 10 degrees in the direction of cutting progress with respect to the vertical. -1 of gJJ section
- Cutting was performed at an angle of 80 to 85 degrees with the surface.

FIG. 1 and tJIJz are perspective views of essential parts for explaining these conventional methods. In the figure, l is the material to be cut, 2 is the torch, 3 is the cutting direction, 4 is a line perpendicular to the surface of the material to be cut, 5 is the surface of the cut S, and O is the tilt angle of 1. be.

The conventional gas cutting method described in
When the speed is increased above mm/min, there are problems of the first order.

l) It becomes impossible to supply enough cutting 02 to sufficiently oxidize the slag (FeO, FezOa), and the metal (Fe + C
), it melts and adheres to I+1, resulting in a slag that is difficult to peel off and requires grinding to remove. In particular, thin steel plates made of Or'-Mo steel, which has a high melting point, are difficult to peel off and require a considerable number of man-hours and processes to remove, which is a factor that hinders the efficiency of cutting operations.

2) As the cutting progresses! There was a problem in that the area around the ilJ fracture was heated, the steel plate was distorted due to the thermal stress, and this *W caused the flame to fly and the cutting to stop.

The relationship between the cutting speed and the difficulty of removing the slag in gas cutting is well known, as the faster the cutting speed, the more difficult it becomes to remove the slag, and this releasability is the biggest factor limiting the cutting speed. .

To achieve high-speed cutting, (1) Supplementary oxygen is supplied to form iron oxide slag that is easy to peel off, making it easier to peel off.

(2) Remove slag by secondary means.

(3) Separate the solo by applying or painting a slag separating agent on the back side of the steel machine.

Methods such as these are generally known.

The present invention, unlike the above methods, provides a gas cutting method that is extremely easy to implement and highly effective, without using a separate means for peeling off the slag, and in which the slag does not stick to the surface to be cut. It is.

As a result of various experiments, the present invention has shown that the angle between the cutting torch and the upper surface of the steel material is 70 by tilting the cutting torch in the opposite direction of cutting progress.
By holding the cutting torch at an angle of ~45 degrees and performing gas cutting, slag does not stick to the cut surface, eliminating the need for the slag removal work that was previously required, and allowing the same plate thickness ( This is an innovative gas cutting method that successfully doubles the cutting speed of conventional methods (15 mm or less).

FIG. 3 is a perspective view showing the method of the present invention. The cutting torch 2 is tilted to the opposite side to the cutting direction 3, and the angle between the cutting torch 2 and the material to be cut is 70 to 45 degrees.

If the angle between the cutting torch and the top surface of the material to be cut exceeds 70 degrees, the cutting length will be short and the reaction thermology that promotes the oxidation reaction between 02 and Fe will not occur, making high-speed cutting impossible. If the angle between the torch and the two surfaces to be cut is less than 45 degrees, the distance between the cutting torch and the corner of the steel material to be cut will be too large at the beginning of cutting, making it difficult to heat the steel material to the ignition temperature. Therefore, the angle between the cutting torch and the material to be cut was set in the range of 45 to 70 degrees.

In addition, 6 in FIG. 3 indicates 02 airflow.

The distance between the νJ cutting torch and the upper surface of the steel material may be in the range of 5 to 15 mm as in the case of normal gas cutting.

The appropriate wall thickness of the steel material to which the present invention is applied is 15 mm or less. When the wall thickness exceeds 15 mm, as shown in Figure 4, the distance #7 between the cutting torch and the cutting start position of the steel plate becomes long, causing the material to be cut to have an ignition temperature of 11'l,' (800 to 9
00°C) becomes difficult. However, if you install a device that lowers the y1 with the cutting 1-ch tilted, or use the f-cutting burner zero to assist in preheating, the 15
It is also possible to cut steel materials with a wall thickness exceeding mm.

The cutting speed of gas cutting can be increased if the oxidation reaction rate can follow. In the woodworks and Ming Dynasties, by tilting the p-cutting 1-chi in the direction opposite to the cutting direction,
/J widening the cross section, increasing the amount of reaction heat for the same heat capacity h, increasing the reaction rate, and increasing the gas cutting speed by h.
It was made into an I-function.

In addition, in the present invention, since the reaction enthusiasm increases, the supplied 02 effectively reacts with Fe, resulting in FeO that is easy to peel off.
This is blown away by the cutting 02 airflow, or falls onto the coagulation 011 with the slag's own hair. Moreover, even if it adheres slightly, it can be easily peeled off. Therefore, slag does not adhere to the cut surface.

As described above, the cutting method according to the present invention can significantly speed up gas cutting compared to the conventional method, eliminates the need for slag removal on the cutting surface, eliminates the need for slag removal, and eliminates the need for cutting. It has become possible to save labor and increase efficiency, and it has also become possible to prevent presser defects caused by slag in the subsequent process, improving quality and speeding up the consistent processing process.

The present invention can be applied to cutting not only steel plates but also shaped steel.

EXAMPLE Gas cutting was performed using a steel (SS 40) and a Cr-Mo steel. The results are summarized in Table tjtl1.

In Table 1, "poor flatness of the cut surface" in the column of speed limiting factor r- indicates that the unevenness of the cut surface is 1 mm or more. In the conventional state (comparative example) in which the angle of the cutting torch is vertical or slightly inclined in the direction of cutting progress, the speed limiting factors are poor slag removal and cutting interruption, and the maximum cutting speed is 450 to 500 mm.
/ min.

In the method of cutting according to the present invention in which the torch is tilted in the opposite direction of cutting progress and the angle formed with the - plane of the workpiece is 70 to 45 degrees, the factor that limits the cutting speed is the flatness 1 of the cut surface. There was no slag adhesion, and the ν1 cutting speed of 1000 mm/min, which is twice that of the conventional method, was achieved. Furthermore, if the flatness standard mentioned above can be ignored, high-speed cutting of 1000 mm/min or higher is also possible.

In addition, in the conventional method, C
Although the power of r-Mo steel was difficult to remove slag and the cutting speed was restricted, the method of the present invention was able to perform gas cutting at rotational speed in both cases.

[Brief explanation of the drawing]

Figures 1 and 2 are perspective views showing the conventional gas cutting method, and Figure 3 is a perspective view showing the conventional gas cutting method.
The figure is a perspective view explaining the present invention in detail, and Figure 4 is a board JIN.
FIG. 1 is a perspective view illustrating a thick case. l... Material to be cut 2... Cutting torch, 3... Cutting progress direction, 5... Surface to be cut, 6... 02 air flow,
7...Distance between the cutting torch and the part to be cut, θ...For incision; -Inclination angle of -chi, α...For incision I/-chi and νJ cutting 4A], and Angle patent applicant: Kawasaki Steel Corporation Patent attorney: Yoshio Kosugi Figure 1 Figure 2 Figure 3

Claims (1)

[Claims] 1. In a gas cutting method for thin steel materials having a wall thickness of 15 mIn or less, the cutting torch is tilted in the direction opposite to the cutting direction and the angle between the cutting torch and the upper surface of the steel material is maintained at 70 to 45 degrees for gas cutting. A gas gino cutting method for thin steel materials.