JPH04262897A - Method and device for high speed scarfing - Google Patents

Abstract

PURPOSE:To stably execute the searfing of bead on the case of the manufacturing line speed of the shapes, and to easily treat the slag and the plasma gas generated at the scarfing time from sticking on the high speed scarfing method and device. CONSTITUTION:On the shapes manufacturing line of the high line speed, the bead 3 is molten with the plasma arc from the plasma torch 4, also the molten metal of this molten bead is blowed away by using the blow from the assitant blow nozzle 5 set on rear step of the plasma torch in the flow direction of the manufacture line, the scarfing surface is made flat, the slag is reduced from sticking by wetting on the front surface of the above shaped steel at a preceding stage of the above plasma torch on the line flow direction for manufacturing.

Description

[Detailed description of the invention]

0001

[Field of Industrial Application] This invention relates to a high-speed cutting method and apparatus for removing corner protrusions, so-called beads, which occur during the manufacture of H-section steel, T-section steel, etc., by cutting at high speed. It is something.

0002

2. Description of the Related Art Conventionally, the following methods and equipment for removing protrusions and surface flaws generated in shaped steel, slabs, etc., are generally known.

[0003] ① Concerning the removal of beads at the corners of welded H-shaped steel, in particular, the setting conditions for melting with a plasma torch for bead melting, and the bead removal device (Japanese Patent Application Laid-Open No. 1993-1991) regarding the fixing device for this plasma torch. (Refer to Publication No.-271093).

[0004] ■ A cutting method in which cutting oxygen is sprayed behind (within 50 mm) the molten pool formed by a plasma torch to shorten the preheating time and prevent deep sinking at the start of cutting (Japanese Patent Application Laid-open No. (See Publication No. 59-163076).

[0005] As in the case of (1) above, oxygen is sprayed behind the molten pool formed by a torch, and the plasma melting method and apparatus (Japanese Patent Laid-Open No. 59-159268).

[0006] ■ Plasma gouging method (Japanese Patent Publication No. 2-4834
(See Publication No. 7).

[0007]

[Problems to be solved by this invention] However, the above-mentioned ■
However, if the speed of the shape steel production line is up to about 30 m/min, stable cutting is possible without any particular problems.
When the production line speed is at high speeds of 40 m/min or more, molten steel remains, resulting in incomplete cutting. Furthermore, due to the dry condition, plasma gas adheres to the product, making it impossible to completely remove it.

[0008] In addition, the methods ① and ③ form a molten pool with the width to be cut, so they may be suitable for cutting flat plate parts, but they are not suitable for cutting corner parts of shaped steel. becomes impossible. Furthermore, the main purpose of methods (1) and (3) is to provide supplementary energy with oxygen, and corner portions cannot be melted by using the method of using an auxiliary nozzle that sprays oxygen.

[0009] Furthermore, regarding item (2), although this is also effective for flat plates, it becomes impossible to cut corner portions as the production line speed increases, as in item (2) above.

[0010] This invention was devised in view of the above-mentioned circumstances, and its purpose is to stably perform bead cutting even when the production line speed of section steel is high, and to eliminate the problems that occur during cutting. It is an object of the present invention to provide a high-speed cutting method and apparatus that can simplify the process of adhering slag and plasma gas.

[0011]

[Means for Solving the Problems] As shown in FIG. 1, when removing the bead 3 generated at the corner portion of the H-section steel 2 during the manufacture of the H-section steel 2, plasma arc and molten steel melted by the plasma arc are used. The scattering direction is only along the bead surface, and the major difference from gouging of a flat plate is that the degree of freedom in the range of molten steel scattering is low.

In the present invention, the plasma (air and oxygen) cutting torch 5 is arranged with respect to the section steel as shown in FIG.
As shown in Figures 1 and 3, the angles of θ1, θ2, and θ3 are set to predetermined angles (the angle setting range is according to JP-A-1-2710).
The blow nozzle 5 is arranged in the same manner as in the No. 93 publication), and an auxiliary blow nozzle 5 is provided behind it.

The same effect can be obtained whether the auxiliary blow nozzle 5 has a small diameter or a large diameter. However, in the case of a small diameter, the setting of the injection direction becomes severe, and the effect may be reduced due to variations in the injection position setting. Moreover, in the case of a large diameter, it is necessary to increase the blowing pressure, which causes waste.

[0014] Also, whether the auxiliary blow nozzle 5 is installed at a close distance from the torch 4 (30 to 50 mm from the torch) or at a far distance, it will not affect the molten steel melted by the plasma. There is no particular problem if the position is such that a constant pressure can be applied by blowing. However, if this mounting position is set closer, the blowing pressure of the blower can be set to a lower pressure, which is advantageous because there is no waste. Furthermore, the mounting position of this auxiliary blow nozzle 5 is as follows.
Any position is suitable as long as the blow from the nozzle can be sprayed along the bead surface and pressure can be applied by the blow to the molten steel portion melted by the plasma.

The attachment position of the auxiliary blow nozzle 5 in the embodiment of the present invention, which will be described later, is the torch main body 4a along the plasma torch because of space considerations and to simplify the setting of the attachment position etc. mentioned above. I decided to install it on.

The auxiliary blow nozzle 5 is attached to the torch main body 4a so that the nozzle jetting direction is shifted from the torch jetting direction toward the flow direction of the section steel, as shown in FIG. This is done at a position shifted from the flow direction of the section steel. This is because if the nozzle injection direction is toward the entrance side of the shaped steel rather than the torch center line 7, the molten steel will not be blown away properly, and the molten steel will adhere to the surface of the shaped steel 2.

On the other hand, in the present invention, the surface of the shaped steel is wetted by the cooling nozzle 6 before the plasma torch 4 in the shaped steel production line. This is because if the entire shaped steel is wetted before melt cutting, the scattered molten steel will not adhere to the surface of the shaped steel, and a smooth and beautiful cut surface will be obtained.

Furthermore, by wetting the surface of the shaped steel in this manner, the fume generated by plasma during cutting, which often remains in a yellowish color on the surface of the shaped steel, can be melted into water. Therefore, fumes can be removed only by washing with water during post-processing, and the apparatus can be simplified. However, if the amount of water is too large, the cutting surface will deteriorate, so mist cooling is best.

The high-speed melt cutting method and apparatus having such a configuration can perform the following operations.

(1) Effects of high-speed cutting When the shape steel production line operates at a low speed (~30 m/min), the penetration of the shape steel is slow, so the amount of molten steel melted per unit time is low and the molten steel is blown away only by the force of the plasma. However, according to the configuration in which the auxiliary blow nozzle is attached to the torch body of the plasma torch of the present invention described above, even when the speed of the section steel production line is high (40 m/min or more), bead cutting work can be performed. can be performed stably and reliably.

That is, when the production line speed becomes high, molten steel is generated in excess of the capacity of the plasma, and is not completely blown away by the plasma and remains as it is. Since gouging with a plasma arc is performed with molten steel remaining on the top surface of the bead, the cut surface becomes uneven and slag adheres around the bead, resulting in a very poor appearance. You can eliminate things.

(2) Effect of blowing from the auxiliary blow nozzle The main purpose of the blowing from the auxiliary blow nozzle configured as described above is to blow away the molten steel melted by the plasma, but the blowing from the auxiliary blow nozzle is mainly aimed at blowing away the molten steel melted by the plasma. It is also effective in blowing away slag.

[0023] From this, if slag adhesion occurs between the material and the torch, the current flows through the slag, causing arc instability, but this can be prevented. Blow also has the effect of cooling the nozzle of the plasma torch, extending the life of the nozzle.

[0024]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The high speed cutting method and apparatus of the present invention will be explained below with reference to the illustrated embodiments.

First, a description will be given of a high-speed cutting apparatus for carrying out the high-speed cutting method of the present invention.High-speed cutting apparatus 1 (see FIGS. 1 to 4) is installed on a production line for welded H-section steel.
is attached to the main body 4a along the plasma torch 4, and is attached to the main body 4a along the plasma torch 4, which uses a plasma arc to cut the bead 3 that is generated at the corner part of the H-shaped steel 2 during manufacture. Bead 3 with torch 4
It is equipped with an auxiliary blow nozzle 5 that injects blow into the molten steel formed by cutting and blowing it away, and a cooling nozzle 6 that wets the surface of the H section steel 2 at a stage before the plasma torch 4 in the H section steel manufacturing line. There is.

The auxiliary blow nozzle 5 is attached to the torch main body 4a so that the nozzle jetting direction is deviated from the torch jetting direction toward the flow direction of the section steel.
That is, as shown in FIG. 2, the position is shifted from the torch center line 7 in the flow direction of the H-section steel 2.

The diameter of the auxiliary blow nozzle 5 is 10φ.
I'm using the one from Furthermore, this auxiliary blow nozzle 5
The blowing from the molten steel may be performed using N2, O2, air, etc. as long as it has the ability to blow away the molten steel. Note that the blowing in this embodiment uses air, which is inexpensive.

Furthermore, in order to apply pressure to blow away the molten steel by air blowing from this auxiliary blow nozzle 5,
Naturally, this pressure is also applied to the plasma arc from the plasma torch 4. At this time, in order to prevent the arc from being bent and the cutting depth becoming extremely shallow if the force of the plasma arc is weak, the pressure and flow rate of the plasma working gas must be higher than in normal cutting. be.

However, if both the pressure and the flow rate become too high, arc transfer may not occur, so in consideration of these, in this example, the pressure was increased to 5 to 10K.
g/cm2, and the flow rate is 60 to 120 l/min.
shall be.

Further, the plasma working gas from the plasma torch 5 generally has a swirling flow in order to improve its straightness. However, since the direction of the molten steel scattering changes depending on the direction of this swirling flow, the swirling direction needs to be a direction in which the molten steel is likely to be easily scattered. Note that in the arrangement shown in FIG. 2, which is this embodiment, a clockwise rotational swirl flow occurs.

By using the high-speed cutting apparatus 1 having such a configuration, when the bead 3 generated at the corner portion of the H-section steel 2 is removed by the method of the present invention, compared to the conventional method shown in the table of FIG. Good results were obtained as shown in the table of FIG. The evaluations in the tables in FIGS. 5 and 6 are as in the table shown in FIG. 7.

Note that the auxiliary blow nozzle 5 in this invention
As mentioned above, the blowing from the plasma arc has the effect of bending the plasma arc from the plasma torch 4, so when melting a flat plate, the depth of cutting by the plasma arc can be controlled by adjusting the blowing pressure. is also possible.

[0033] This makes it possible to keep the plasma output conditions constant and to control the work of dissolving and removing the beads 3 only by adjusting the blow pressure.

[0034]

Effects of the Invention By combining the plasma conditions of the plasma torch, the blow from the auxiliary blow nozzle, and the wetting of the surface of the shaped steel with the cooling nozzle, stable melt cutting at high speeds can be achieved. That is, it is possible to avoid cutting the shape steel base material during the bead melting and removal operation when the shape steel production line is running at high speed, and the yield can be improved. Furthermore, since the adhesion of slag can be reduced, the appearance can be improved, and post-treatment can be simplified since secondary treatment is no longer necessary.

[Brief explanation of the drawing]

FIG. 1 is a schematic front view showing a high-speed cutting apparatus of the present invention.

FIG. 2 is a view taken along line AA in FIG. 1;

FIG. 3 is a view taken along line BB in FIG. 1;

FIG. 4 is a view taken along line CC in FIG. 1;

FIG. 5 is a table showing conventional bead cutting conditions.

FIG. 6 is a table showing the bead cutting state of the present invention.

FIG. 7 is a table showing evaluation states in the tables of FIGS. 5 and 6;

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1...High speed cutting device, 2...H-beam, 3...Bead, 4...Plasma torch, 4a...Torch main body, 5...Auxiliary blow nozzle, 6...Cooling nozzle, 7...Torch center line.

Claims (2)

[Claims] 1. A high-speed cutting method for stably removing beads at corners of a welded steel section that occur during the production of a welded section steel when the line speed for manufacturing the welded section steel is high,
The bead is melted by a plasma arc from a plasma torch, and the molten steel resulting from the bead melting is blown away using a blow from an auxiliary blow nozzle provided after the plasma torch in the flow direction of the production line to form a machined surface. A high-speed melt cutting method characterized by smoothing the surface of the section steel and wetting the surface of the section steel at a stage upstream of the plasma torch in the flow direction of the production line. [Claim 2] A high-speed cutting device installed on a production line for welded steel sections in order to remove beads at the corners of the steel sections that occur during the production of welded steel sections, and the beads are cut using a plasma arc. It is attached to the plasma torch and the torch body along the plasma torch.
An auxiliary blow nozzle that injects blow into the molten steel after bead cutting with the plasma torch, and a cooling nozzle that wets the surface of the shaped steel at a stage before the plasma torch in the shaped steel manufacturing line. Characteristic high-speed cutting equipment.