JPH1133714A - Method of cutting steel material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method which prevents heat deformation of a steel member, and ensures the cutting quality at the starting point of gas cutting by cutting of the steel member after completion of the preheating process. Preheating is applied to a target position of the steel member after positioning the burnt gas flame for preheating in an incised hole which is formed by laser beam in the steel member. SOLUTION: A preheating process and a cutting process of the steel member 6 using a gas cutting torch is carried out after the incised hole 7 is formed with the laser cutting torch 5 in the steel member 6. In the cutting process of the incised hole, the incised hole 7 for starting gas cutting is formed in the steel member 6 by the laser beam 9 which is emitted from a laser cutting torch 5. The incised hole 7 consists of a circular hole 10 which is 10-50 millimeter in diameter and a cut groove 12. In the preheating process, the steel member 6 is preheated by positioning the burnt gas flame for the preheating in the boundary between the formed circular hole 10 of the incised hole 7 and the cut groove 12. In this case, the preheating time of the steel member 6 is shortened, because the edge formed in the boundary between the circular hole 10 and the cut groove 12 is heated intensively.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for cutting steel.

[0002]

2. Description of the Related Art Conventionally, in gas cutting of a steel material, a steel material is preheated by a preheating flame, a cut portion is formed in a preheating portion of the steel material by a gas cutting flame, and a target gas cutting is started from the formed cut portion. It is performed in order. The notch is formed
It is carried out continuously with the completion of preheating work for steel products. Further, the intended gas cutting is continuously performed upon completion of the forming operation of the cut portion.

FIG. 3 shows an example of a method for cutting the steel plate 1. When cutting the steel plate 1 by using both gas cutting and laser cutting, as shown in FIG. 3, it is general to cut the long cutting line 2 by gas and cut the short cutting line 3 by laser. In the gas cutting, a target cutting is started after forming a hole-shaped cut portion 4 at the end of the cutting line 2.

[0004]

By the way, in the case of the above-described method for cutting a steel material, (1) the piercing time required for forming a cut portion at the start of gas cutting is long, and (2) the piercing time is greatly increased due to the above (1). There has been a problem that the steel material may be thermally deformed due to excessive heat. (3) As shown in FIG. 3, if the cuts 4 are concentrated on a part of the steel sheet 1, the thermal deformation of the steel sheet 1 increases, so that the problem (2) becomes more prominent.

[0005] The present invention has been made in view of the above-mentioned problems, and (a) can form a cut hole in a short time;
(B) It is an object of the present invention to provide a method of cutting a steel material in which a cut hole is easy to form and its shape is stable, and (c) a heat input of the steel material is reduced to prevent thermal deformation and the like. It is assumed that.

[0006]

According to the first aspect of the present invention, a notch forming step of forming a notch for starting gas cutting in a steel material by a laser beam, and a preheating gas is formed in the formed notch. A steel material comprising: a preheating step of positioning a flame to preheat a target position of the steel material around the cut hole; and a cutting step of cutting the steel material by a cutting gas flame after completion of the preheating step. Is a means for solving the above-mentioned problem. In the present invention, since the steel material preheating step and the cut hole forming step are separated and the cut holes are formed by a laser beam, heat input to the steel material can be suppressed, and thermal deformation of the steel material can be reduced. Can be prevented. Further, in the formation of the cut hole by the laser beam, the cut hole having the desired shape can be easily obtained. Various shapes such as a circle, an ellipse, a rectangle, and a groove can be adopted as the cut hole formed in the cut hole forming step.

According to a second aspect of the present invention, the cut hole has a diameter of 10
When a configuration including a circular hole of about 50 mm and a kerf extending radially outward from the circular hole and narrower than the kerf of the gas cutting is adopted, from the vicinity of the boundary between the circular hole and the kerf. Initiate gas cutting or steel preheating. The cutting step is performed by a gas cutting torch, and has a diameter of 10 to 5 mm.
Since the 0 mm circular hole is larger than the diameter of the preheating flame of a general gas cutting torch (around 10 mm), the positioning accuracy of the gas cutting torch with respect to the cut hole at the start of the preheating step is reduced. In the preheating step, heat input concentrates on the steel material around the kerf, so that the preheating time is shortened. Preferably, the cut grooves are formed by a cutting laser emitted from a laser cutting torch. In this case, since the cutting width of the kerf becomes a general cutting laser diameter (1 mm or less), the steel material can be efficiently preheated by aligning the center of the preheating flame with the kerf width center in the preheating step. it can.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the steel material cutting method according to the present invention will be described below with reference to FIGS. In the present embodiment, first, as shown in FIG. 1, a notch 7 is formed in a steel material 6 (steel plate) using a laser cutting torch 5 (a notch forming step), and then gas cutting is performed as shown in FIG. The preheating step and the cutting step of the steel material 6 are performed using the torch 8.

As shown in FIG. 1, in the cut hole cutting step,
The laser beam 9 emitted from the laser cutting torch 5 forms a cut hole 7 for starting gas cutting in the steel material 6. The cut hole 7 has a circular hole 10 having a diameter of 10 to 50 mm, and extends radially outward from the circular hole 10.
1 (see FIG. 2). In FIG.
The cutting width a of 2 corresponds to the diameter of the laser beam 9 and is 1 m
m or less. The cut width a of the cut groove 12 may be 1 mm or more, but it is necessary that the cut width is not larger than the cut width of gas cutting. Also, the kerf 12
In the cutting process, the steel 6
Extends on a cutting line 13 for cutting the line. Although the kerf 12 shown in FIG. 1 is straight, it may have a curved shape.

As shown in FIG. 2, in the preheating step, the steel material 6 is preheated by positioning the preheating gas flame 11 at the boundary between the circular hole 10 and the cutting groove 12 of the cut hole 7 formed. At this time, since heat is intensively input to the edge 14 formed at the boundary between the circular hole 10 and the cut groove 12, the preheating time of the steel material 6 can be reduced. The preheating gas flame 11 is positioned at the boundary between the circular hole 10 and the kerf 12 after detecting the circular hole 10 by, for example, a sensor of a voltage detection method or the like. Gas flame 11
When the diameter is 10 mm or more, positioning of the preheating gas flame 11 with respect to the circular hole 10 is facilitated. Also,
The edge 14 can adopt various shapes such as a shape protruding inside the circular hole 10.

After a predetermined preheating time has elapsed, the gas flame from the gas cutting torch 8 is switched to the gas flame 15 for cutting, and the process immediately proceeds to the cutting process. Steel material 6 while moving gas flame 15
Disconnect. At this time, while the cutting gas flame 15 is moving on the kerf 12, the heat input of the steel material 6 near the kerf 12 is efficiently performed, so that the cutting can be started smoothly. The gas flame 15 for cutting is moved by moving the gas cutting torch 8 or the steel material 6.

According to this steel material cutting method, since the cut-out hole 7 is formed by the laser beam 9, the cutting gas flame 1 is cut.
The heat input to the steel material 6 can be suppressed as compared with the case where the steel material 6 is formed by using the steel material 5, and even when the plurality of cut holes 7 are concentrated on a part of the steel material 6, the thermal deformation of the steel material 6 can be prevented.
In addition, the formation of the cut hole 7 by the laser beam 9 is more important in gas cutting, since the cut hole 7 having the desired shape can be formed more easily than the case of forming by the cutting gas flame 15. The cutting quality at the start of cutting can be ensured, thereby improving the cutting quality of the entire steel material 6. Further, prevention of thermal deformation of the steel material 6 is also obtained by shortening the preheating time in the preheating step.

In the above-described embodiment, cutting of a steel plate is described. However, the method of cutting a steel plate according to the present invention can be applied to various types of steel such as shaped steel. 1 and 2 show an example in which the cutout hole 7 is formed at the end of the steel plate 1, the cutout hole 7 may be formed at the center of the steel plate 1.

[0014]

As described above, according to the steel material cutting method of the present invention, the steel material is formed after performing a notch hole forming step for forming a notch hole for starting gas cutting in the steel material. A preheating step of positioning a preheating gas flame in the cut hole and preheating a target position of the steel material around the cut hole;
After the completion of the preheating step, a cutting step of cutting the steel material by a cutting gas flame is performed. (A) Since the cut holes are formed by the laser beam, heat input to the steel material is small, and thermal deformation of the steel material is reduced. (B) Since the cutting holes are formed by the laser beam, the forming accuracy of the cutting holes is improved, so that the cutting quality at the time of starting the gas cutting can be surely secured. It works.

[0015] According to a second aspect of the present invention, the notch has a diameter of 10-5.
If a configuration having a circular hole of 0 mm and a kerf extending radially outward from the circular hole and smaller than the kerf of the gas cutting is adopted, in the preheating step, the steel material around the kerf is narrowed. Since concentrated heat input is obtained, (c) the preheating time can be shortened, and (d) the above (c) has an excellent effect of preventing thermal deformation of the steel material.

[Brief description of the drawings]

FIG. 1 is a view showing an embodiment of a steel material cutting method of the present invention, and is a perspective view showing a cutting hole forming step.

FIG. 2 is a view showing an embodiment of the steel material cutting method of the present invention, and is a perspective view showing a preheating step and a cutting step.

FIG. 3 is a plan view showing a conventional example of a method for cutting a steel material.

[Explanation of symbols]

6 ... steel (steel plate), 7 ... cut hole, 9 ... laser beam, 1
0: circular hole, 11: gas flame for preheating, 12: kerf, 15
... gas flame for cutting.

Claims (2)

[Claims] 1. A steel material (6) by means of a laser beam (9).
Forming a cutting hole (7) for starting gas cutting in a hole, positioning a preheating gas flame (11) in the formed cutting hole, and positioning a steel material around the cutting hole. And a gas flame for cutting (1) after completion of the preheating step.
A cutting step of cutting the steel material according to 5). 2. A circular hole (10) having a cut hole having a diameter of 10 to 50 millimeters, and a cut groove (12) extending radially outward from the circular hole and smaller than a cut width of gas cutting. The method for cutting a steel material according to claim 1, further comprising: