JP2001150170A - Method for cutting material by laser beam - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cutting method by which a think object can be cut even by a low output laser beam oscillator. SOLUTION: The cutting method comprises a first step for cutting a prescribed pitch P regarding a cutting direction by moving (1) a laser beam downward while irradiating the work 12 at an oblique angle from the oblique upside regarding the thickness direction of the work and a second step moving (2) the irradiation position of the laser beam upward after cutting the prescribed pitch P and moving (3) the laser beam in the cutting direction by the prescribed pitch P. The above first step and the above second step are repeated until the cutting is completed.

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 a material using a laser beam, and more particularly to a method for cutting a material using a laser beam suitable for cutting concrete or rock.

[0002]

2. Description of the Related Art A method of cutting a metal plate using a laser beam is well known. Conventional laser beam cutting
As shown in FIG. 6, a laser beam from a laser oscillator 31 is guided to a laser torch 32 by an optical fiber 31, and the laser torch 32 is arranged above the plate surface of the work 33,
This is performed by moving the laser beam in a direction parallel to the plate surface while irradiating the laser beam perpendicularly to the plate surface.

[0003] On the other hand, there is an increasing demand for utilizing cutting by laser light for cutting a material such as concrete. Cutting concrete with such laser light
For example, it is reported in Taisei Construction Technology Research Institute bulletin No. 20.

[0004]

According to this report, between the output of the laser oscillator and the cuttable wall thickness, in the case of reinforced concrete, at least 15 kW for cutting a 180 mm-thick one, the thickness is required. It has been confirmed that an output of 5 kW or more is required even at 110 mm.

The reason for this is that the penetration power is determined by the laser output. In the conventional cutting method, a laser oscillator having a larger output is required as the thickness of the object to be cut increases. In other words, in the conventional method, the only way to cut a thick object is to increase the laser output, and even if it is increased, there are cases where processing cannot be performed depending on the thickness of the target object, or sufficient processing speed cannot be obtained and it is not practical. Come out.

Further, when a high-power laser oscillator is introduced, the cost of the processing apparatus itself increases, which ultimately leads to an increase in cutting cost.

It is an object of the present invention to provide a cutting method which can cut a thick object even with a low-output laser oscillator in order to solve the above-mentioned problem.

[0008]

According to the present invention, there is provided a method for cutting a material by irradiating a laser beam, wherein the material to be cut is irradiated with a laser beam from an obliquely upper side or an obliquely lower side in a thickness direction thereof. A first step of cutting at a predetermined pitch in the cutting direction by moving the irradiation position downward or upward while irradiating at an oblique angle, and after the cutting at the predetermined pitch, the irradiation position of the laser beam Moving upward or downward, and moving in the cutting direction by the predetermined pitch, repeating the first step and the second step until the cutting is completed. This is a material cutting method using a laser beam as a feature.

In this cutting method, it is preferable that the oblique angle is in the range of 30 to 60 degrees with respect to the vertical direction.

In the present cutting method, the material is concrete or rock whose cutting direction is a horizontal direction and thickness direction is a vertical direction.

The first step is to irradiate a laser beam at an oblique angle from above at an oblique angle to a position forward from the upper end of the material to be cut by the predetermined pitch with respect to the cutting direction. A first partial cutting step of cutting the material to a predetermined depth by moving the laser beam to a predetermined depth, and a second step of moving the laser beam irradiation position in a direction opposite to the cutting direction following the first partial cutting step. Following the partial cutting step and the second partial cutting step, the irradiation position of the laser beam is moved slightly downward, and the first
A third partial cutting step of moving in the cutting direction to a position corresponding to the first irradiation position in the partial cutting step of the first to third partial cutting step,
It may be realized by repeating until cutting in the thickness direction is completed.

As the laser beam, a laser beam generated by a YAG laser oscillator having an output of several KW or less can be used.

According to the present invention, in a method of cutting a material by irradiating a laser beam, the material to be cut is moved in a horizontal direction while irradiating the laser beam at an oblique angle from below obliquely. A first step of performing cutting at a predetermined pitch with respect to the cutting direction in the up-down direction, and after the cutting at the predetermined pitch, moving the laser beam irradiation position to the initial position, A second step of moving only in the cutting direction,
A method for cutting a material by laser light is provided, wherein the first step and the second step are repeated until cutting is completed.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention provides a method of cutting a thick material (hereinafter, referred to as a workpiece) with low output laser light by controlling the attitude and movement of a laser torch. To this end, at the time of cutting, the laser torch is tilted with respect to the work, and the laser torch is moved downward or upward while irradiating the laser light obliquely from above or below, so that one pass (from top to bottom or from bottom to top) is performed. )
When the irradiation of the minute is completed, the laser beam is returned to the original position, and the moving operation of sending the laser torch at a predetermined pitch in the cutting direction is repeated, so that a thick work can be cut.

FIG. 1 shows a first mode of the moving operation of the laser torch. In FIG. 1, in this embodiment, a cutting direction is defined as a horizontal direction and a thickness direction is defined as a vertical direction for a work 12 made of concrete. The laser torch 11
At an initial position at the start of processing, the workpiece 12 is disposed obliquely upward with respect to the workpiece 12 and inclined so that the irradiation angle forms an acute angle θ with respect to a direction directly below. In this state, the workpiece 12 is moved downward while irradiating the laser beam at an oblique angle from above in the thickness direction with respect to the thickness direction (FIG. 1), thereby cutting the workpiece 12 at a predetermined pitch P in the cutting direction. Perform (first step). In particular, the first irradiation position is set at a position forward by the predetermined pitch P in the cutting direction from the upper end of the work 12.

After the cutting at the predetermined pitch P is completed, the irradiation position of the laser beam is moved upward by moving the laser torch 11 upward (FIG. 1), and then the laser torch 11 is moved by the predetermined pitch P. Is horizontally moved in the cutting direction (FIG. 1), whereby the irradiation position of the laser beam is moved from the first irradiation position to a forward position advanced by a predetermined pitch P in the cutting direction at the upper end of the work 12. (Second step). Thereafter, by performing the same operation as the above operation (1) as shown in (1) in FIG. 1, cutting is performed for the next pitch P in the cutting direction,
Hereinafter, this is repeated until the cutting in the cutting direction is completed.

During the movement shown in FIG. 1, the oscillation operation of the laser oscillator may or may not be stopped. Further, it is preferable that the moving speed during this time is set earlier.

According to the cutting method of this embodiment, the laser beam is focused or the beam diameter is adjusted so that the processing depth can be maximized per pass, so that even a low-power laser oscillator has a large thickness. The work (thickness T) can be cut efficiently. This can be realized by adjusting the focal length by an optical system such as a focusing lens installed in the laser torch 11, or adjusting the beam diameter. That is, as is well known, the laser torch 11 includes a light receiving unit that receives laser light from an optical fiber (this diameter is dia) and a collimating lens (this focal length) that converts the received laser light into a parallel beam so as not to diffuse. Is defined as Fc), and a focusing lens that forms an image of a laser beam from the collimator lens as a spot light having a diameter d on a predetermined distance (this focal length is defined as FL) is included.

The focal length of the laser beam used at this time is:
As shown in FIG. 2, when the laser torch 11 moves in the cutting direction, the laser torch 11 is set so as to satisfy the following expression (1) so as not to hit the surface of the work 12. Further, as the cutting progresses, as shown in FIG. 3, in section A of FIG. 2, the energy loss due to the laser light hitting the cut slit-shaped portion and being reflected (see FIG. 3A) is small. The optical system in the laser torch 11 is selected so that the beam diameter of the laser beam used for cutting is as small as possible (see FIG. 3B).

The setting of the optical system at this time may be made from the following equations (1) and (2).

FL × cos θ> T (1) (FL × dia) / Fc = d (2) In this case, the inclination angle θ of the laser torch 11 is shown in Table 1 below.
As shown in the above, it is preferable to set the angle to 30 to 60 degrees (set according to the type of the material of the work 12 and the laser output) from various experimental results.

[0022]

[Table 1]

[0023]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The following is an example in which the present cutting method is adopted and the inclination angle θ = 3.
This is an example in which a reinforced concrete having a thickness of 110 mm is cut at 0 degree.

The laser oscillator used was a YAG continuous laser oscillator having an output of 3.2 kW, an optical fiber diameter dia = 0.6 mm, and FL = 1, which sufficiently satisfied the expression (1).
000 mm was selected. The collimating lens used had a focal length Fc of 125 mm so as to have a beam diameter of 4.8 mm.

In the conventional method, a processing apparatus using a 3.2 kW laser oscillator could not cut an object having a thickness of 50 mm or more.
0 mm reinforced concrete could be cut at a processing speed of 4 cm / min.

In the conventional method, a laser oscillator having an output of 5 kW is required to cut the same concrete having a thickness of 110 mm, and the cutting speed at this time is 2.5 cm / min.
On the other hand, in the present cutting method, the cutting speed is 4 cm /
min, and the effectiveness of this cutting method has been demonstrated.

FIG. 4 shows a second mode of the moving operation of the laser torch. This embodiment is characterized in that the first step in the above-described first embodiment is executed not only by a simple up-down operation but also through a plurality of partial steps as described below. FIG. 4B shows the movement locus of the spot light.

In this embodiment, the first step in the first embodiment is executed by the following first to third partial cutting steps. That is, the first step is to irradiate the laser beam from an obliquely upward position to a position in front of the upper end of the workpiece 12 by a predetermined pitch P with respect to the cutting direction at an oblique angle θ to move the workpiece 12 downward. To a predetermined depth D
1st partial cutting step (-in FIG.
1), a second partial cutting step (-2 in FIG. 4B) following the first partial cutting step, and moving the irradiation position of the laser beam in a direction opposite to the cutting direction, and a second partial cutting step. Subsequently, the laser beam irradiation position is moved slightly downward, and the laser beam is moved in the cutting direction to a position corresponding to the first irradiation position in the first partial cutting step (-3 in FIG. 4B). And
Then, the first to third partial cutting steps are repeated until the cutting in the thickness direction is completed.

As described above, the irradiation of the laser beam is returned in the direction opposite to the cutting direction, as shown in FIG.
With the oblique laser beam irradiation, a weir-shaped portion 12-1 is likely to be formed at the edge of the work 12, and there may be a case where the molten metal in the shape of hot water accumulates inside. This molten molten metal acts to block the laser beam. In the above-described cutting by laser beam irradiation from the vertical direction, there is a limit to the thickness that can be cut even when the output is increased, which is also caused by the molten metal in the form of molten metal.

Therefore, in the present embodiment, after cutting to a predetermined depth D, the spot light is once moved in the direction opposite to the cutting direction to melt the weir-shaped portion 12, so that the molten metal in the shape of a hot water is lowered. It is easy to flow out. Thus, according to the present cutting method, a thick work such as concrete can be cut with a laser oscillator having a lower output than the conventional method.

In FIG. 1, the laser torch 11 is first moved from top to bottom. However, the laser torch 11 may be moved from bottom to top while keeping the posture of FIG. In this case, the first irradiation position of the laser beam is at the corner at the lower end of the work 12 in FIG. Alternatively, the laser torch 11 may be arranged obliquely downward on the right side of the work 12 in FIG. 1 and obliquely upward, and may be moved upward from this state.
In this case, the first irradiation position of the laser beam is a position ahead of the lower end of the work 12 in FIG. 1 by a predetermined pitch P.

FIG. 5 shows a modification in which the laser torch 11 is arranged obliquely upward. In FIG. 5, the first
In the step (2), the workpiece 12 is moved in the horizontal direction while irradiating the laser beam from an obliquely downward direction at an obliquely upward angle (FIG. 5), so that the workpiece 12 is cut at a predetermined pitch P in the vertical cutting direction. I do. In the second step, after the cutting at the predetermined pitch P is completed, the irradiation position of the laser beam is moved to the initial position (FIG. 5), and is moved in the cutting direction by the predetermined pitch P (FIG. 5).
of). Hereinafter, steps similar to the above first and second steps (see FIG. 5) are repeated until the cutting in the cutting direction is completed.

In the above description, a YAG laser oscillator is exemplified as the laser oscillator, but another laser oscillator, for example, a YLF laser oscillator or a CO ₂ laser oscillator may be used. Although concrete is illustrated as the work 12, the present invention can be applied to other materials, for example, cutting such as rocks.

[0034]

According to the present cutting method, the following effects can be obtained.

1. A thick work can be cut by a low-power laser oscillator.

2. Since the thickness range that can be cut by laser light with a laser oscillator having a certain output is larger than in the case of the conventional method, a work having various thicknesses can be cut.

3. Since the power consumption of the processing device can be saved, the cutting cost can be reduced.

[Brief description of the drawings]

FIG. 1 is a view for explaining a movement operation of a laser torch in a cutting method according to the present invention.

FIG. 2 is a diagram for explaining conditions of each unit in the movement operation shown in FIG. 1;

FIG. 3 is a diagram for explaining a relationship between a laser beam and a cutting slit of a work when a portion A shown in FIG. 2 is viewed from the right side of FIG. 2;

FIGS. 4A and 4B are diagrams for explaining a second embodiment of the present invention, wherein FIG. 4A is a diagram for explaining a pool of water in a cutting portion, and FIG. It is a figure showing movement operation of a laser torch.

FIG. 5 is a view for explaining a modification of the movement operation of the laser torch of the present invention.

FIG. 6 is a diagram for explaining a conventional cutting method.

[Explanation of symbols]

 11, 32 Laser torch 12, 33 Work 30 Laser oscillator 31 Optical fiber

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Yasuo Tanno 63-30 Yuigaoka, Hiratsuka-shi, Kanagawa F-term in Hiratsuka Works of Sumitomo Heavy Industries, Ltd. F-term (reference) 2E176 AA01 DD53 4E068 AE01 CA08 DB12

Claims (6)

[Claims] 1. A method of cutting a material by irradiating a laser beam, wherein the material to be cut is irradiated while irradiating the laser beam at an oblique angle from an obliquely upper side or an obliquely lower side with respect to a thickness direction thereof. A first step of performing cutting at a predetermined pitch in the cutting direction by moving the position downward or upward; and after the cutting at the predetermined pitch, moving the laser beam irradiation position upward or downward. A second step of moving in the cutting direction by the predetermined pitch, wherein the first step and the second step are repeated until cutting is completed, and the material is cut by laser light. Method. 2. The method according to claim 1, wherein the oblique angle is in a range of 30 to 60 degrees with respect to a vertical direction. 3. The cutting method according to claim 1, wherein the material is concrete or rock, the cutting direction being horizontal and the thickness direction being vertical. Cutting method. 4. The cutting method according to claim 1, wherein the first step is a position in front of an upper end of the material to be cut by the predetermined pitch in a cutting direction. A first partial cutting step of cutting the material to a predetermined depth by irradiating a laser beam at an oblique angle from above and moving the laser beam downward, and a laser beam following the first partial cutting step A second partial cutting step in which the irradiation position of the laser beam is moved in the direction opposite to the cutting direction; and, following the second partial cutting step, the irradiation position of the laser beam is moved slightly downward, and the first partial cutting step is performed. And a third partial cutting step of moving in the cutting direction to a position corresponding to the first irradiation position in the first to third irradiation. Materials cutting method by laser beam and repeating until Ryosuru. 5. The cutting method according to claim 1, wherein the laser light is generated by a YAG laser oscillator having an output of several KW or less. Material cutting method. 6. A method of cutting a material by irradiating a laser beam, wherein the material to be cut is horizontally moved while irradiating a laser beam at an oblique angle from below at an oblique angle to a vertical direction. A first step of performing cutting at a predetermined pitch with respect to the cutting direction, and after the cutting at the predetermined pitch, moving the laser beam irradiation position to the initial position and moving the laser beam in the cutting direction by the predetermined pitch. And a second step of repeating the first step and the second step until cutting is completed.