JP2551253B2 - Cutting method of object by laser beam - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for focusing a laser beam to irradiate an object and cutting the object,
The present invention relates to a method for cutting thick objects such as concrete walls and floors.

[0002]

2. Description of the Related Art When a thick object such as concrete is cut by a laser beam, an objective optical system for focusing a beam by a lens or a mirror is not focused on the surface of the object. For example, Japanese Patent Laid-Open No. 1-271085 (B23K26)
/ 16), the efficiency of energy utilization is higher and the cutting can be performed at a higher speed when the focus is on a predetermined depth position inside the object to be cut.
In addition, it is very important to efficiently cut concrete etc. that the concrete etc. (molten dross) melted by the beam irradiation is quickly removed from the beam irradiation position, and the unmelted part is exposed to the laser beam. To do so. Regarding this point, JP-A-63-
As disclosed in Japanese Patent No. 97392 (B23K26 / 16), a method is devised so that a plurality of laser beams are used to cut while gradually widening the cutting groove, and the molten dross is smoothly removed laterally or downwardly through the cutting groove. It has been known.

[0003]

The method of gradually expanding the cut groove by using a plurality of laser beams is certainly effective, but the energy utilization efficiency is low and the equipment cost of a laser oscillator and the like is high. It was not a practical method in terms of cost. An object of the present invention is to enable cutting work to be performed in a state where molten dross is easily removed from the beam irradiation position, and to effectively use the energy of the laser beam to efficiently cut thick objects such as concrete. Is.

[0004]

Therefore, in the present invention, as shown in FIG. 1, a laser beam 1 is focused and irradiated on an object 2 to melt the object 2, and the beam irradiation point is set in a cutting line direction Y. In the method of moving and cutting the object 2, the cross-sectional shape of the beam 1 on the surface of the object 2 is elongated in the cutting line direction Y, and the cross-sectional shape of the beam 1 is cut in the cutting line at a predetermined depth or more inside the object 2. Width direction X
It has a slender shape.

[0005]

In order to smoothly remove the molten dross from the cutting groove, it is preferable to widen the groove width in the deep portion of the cutting groove. Since the molten dross immediately flows into the deep part of the groove near the surface of the object, it is not necessary to widen the groove width near the surface, and increasing the groove width near the surface wastes energy. In the method of the present invention shown in FIG. 1, since the cross-sectional shape of the laser beam 1 on the surface portion of the object 2 is elongated in the direction Y of the cutting groove 3, the width of the groove 3 is not unnecessarily widened and the energy of the beam 1 is increased. Is effectively used to deepen the groove 3. When the depth of the cutting groove 3 becomes a predetermined value or more, the cross-sectional shape of the beam 1 at that portion becomes elongated in the width direction X of the cutting groove 3, so that the groove width is widened in the deep region of the cutting groove 3.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS As shown in FIG. 1, the cross-sectional shape of a beam 1 on the surface of an object 2 is elongated in the traveling direction Y of a cutting groove 3, and in the width direction X of the cutting groove 3 above a predetermined depth of the object 2. To form the elongated shape, for example, a focusing optical system called so-called astigmatism as shown in FIG. 2 is used.

In FIG. 2, as described above, the direction of the cutting line of the object is Y, the width direction of the cutting groove is X, and the depth direction of the cutting groove (the optical axis direction of the laser beam with which the object is irradiated) is defined. Let Z. The parallel beam having a circular cross section from the laser oscillator is reflected by the plane mirror 4, the reflection is further reflected by the spherical concave mirror 5, and the focused beam is applied to the object. When the reflected beam and the focused beam pass through a vertical plane including the Y-direction (cutting direction) line and the reflected beam is incident on the concave mirror 5 at an angle (θ), the cross section of the focused beam is from the concave mirror 5. It changes according to the distance of and becomes a dissimilar shape. This is called so-called astigmatism, and the optical axis of the reflected beam is inclined by the angle θ with respect to the vertical plane of the concave mirror 5 in the Y direction, so that the focal length in the Y direction becomes long. Therefore, the focal point Z1 in the X direction is shallower than the focal point Z2 in the Y direction. As a result, as shown in FIG. 2, the beam shape is close to the cutting line direction Y near the surface of the object.
The beam shape becomes an ellipse having a major axis in the width direction X of the cutting line when the distance in the depth direction Z exceeds a certain distance. And focus Z1 and focus Z2
The beam is most narrowed between. As shown in FIG. 1, cutting is performed by setting the position where the beam 1 is converged to be the thinnest to be approximately half the thickness of the object 2.

The beam focusing optical system for carrying out the present invention is not limited to the configuration shown in FIG. 2, and there are various methods such as using an aspherical lens.

[0009]

According to the present invention, since the cross-sectional shape of the irradiation beam is elongated in the cutting line direction near the surface of the object to be cut, the width of the cutting groove is not increased more than necessary, and the energy of the beam is not increased. Is effectively used to deepen the groove. When the groove has a predetermined depth or more, the cross-sectional shape of the irradiation beam becomes elongated in the groove width direction, and the width of the cutting groove becomes wider. If the groove width is wide in the deep portion of the cutting groove, the molten dross is easily removed, the wasteful energy absorbed by the molten dross is reduced, and the cutting efficiency is improved.

[Brief description of drawings]

FIG. 1 is an explanatory view of a method of cutting an object with a laser beam according to the present invention.

FIG. 2 is a perspective view showing an example of a beam focusing optical system for carrying out the cutting method of the present invention.

[Explanation of symbols]

 1 Laser beam 2 Object 3 Cutting groove X Width direction of cutting line Y Cutting line direction Z Depth direction

Claims (1)

(57) [Claims] 1. A method of focusing a laser beam and irradiating the object to melt the object, and moving the beam irradiation point in the direction of the cutting line to cut the object, the cross section of the beam on the surface of the object. A method of cutting an object with a laser beam, wherein the shape is elongated in the cutting line direction and is elongated in the width direction of the cutting line at a predetermined depth or more inside the object.