JP2000210785A - Laser beam machine with plural beams - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make a laser beam machine having high functions such as the cutting and the welding of a thick plate, etc., by providing a variable focus lens making a part of laser beam a focus position different from other parts along an optical axis so that the variable focus lens is adjustable to put in and out to the optical axis in the inside of an optical system. SOLUTION: An optical system has an optical fiber 10, a collimator lens 11 making an outgoing light beam from the optical fiber 10 a parallel light beam, and a variable focus lens (semicircular notched lens) 12 for making a part of a beam from the collimator lens 11, for instance a half S, a short focus along an optical axis and making the remainder half L a long focus. The beam which has passed through the collimator lens 11, is deformed slenderly along the laser beam machining direction by a cylinder lens 13 whose cross-section is a semicylinderical type, and is allowed to surely reach inside a melting hole which is a weld portion on a work. A variable power lens 14 is movably arranged along the optical axis in the poststage of the cylinder lens 13, and the focus position of a laser beam is allowed to change by the movement of the variable power lens 14. By image-forming the beam which has passed through the variable power lens 14 by an image-formation lens 15, the beam waists of two focuses are formed in the optical axis direction.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multi-beam laser processing apparatus with improved laser processing capability.

[0002]

2. Description of the Related Art For example, in a laser processing apparatus for performing cutting or welding by laser, the thickness of a work to be processed is diversified. Cutting of the plank is also performed.

In this case, a long focal length lens having a large depth of focus in processing is used in order to improve the cutting ability or the welding ability. However, the beam waist size and the light condensing are considered from the Helmholtz-Lagrange invariant. Since the product of energy is constant, as the focal length increases, the focused beam diameter increases, the focused energy density decreases, and the activation of the workpiece for cutting or welding is extremely delayed or impossible. In some cases, there is a limit to long focus. That is, there is a limit to the ability of processing a thick plate.

The inventors of the present invention have focused on the dual focus focusing on such a problem. As shown in FIGS. 5 and 6, there is a similar technique for the dual focus. In FIG. 5, a wedge prism 02 is inserted into the optical path of the laser beam 01 from the fiber F to separate the light flux into two points on the same plane and condense the light beam, and the upper end of the outer wall and the upper end of the inner wall of the tube 03 Are melted at the same time, which brings about effects such as a short welding time.

In FIG. 6, the refractive index of the lens 05 is partially changed so that a short focal length lens 05 having a high refractive index is provided at the center.
There is disclosed a structure in which S and a long-focal length lens 05L having a low refractive index are integrally provided therearound and the laser beam 01 is double-focused.

[0006]

However, even in the above-mentioned prior art, the light condensing at different positions in the same plane used for melting the upper surface of the tube 03 shown in FIG. 5 and the fixed refractive index shown in FIG. Even if the double focusing in the optical axis direction by the method has an effect itself, it does not reach the high performance of the laser processing apparatus aimed at by the present inventors. Further, even with the structures shown in FIGS. 5 and 6, for example, the above-described thick plate cutting and welding cannot be conveniently performed.

SUMMARY OF THE INVENTION In view of the above problems, it is an object of the present invention to provide a multi-beam laser processing apparatus having high functionality, for example, for cutting or welding a thick plate.

[0008]

The present invention that achieves the above object has the following matters specifying the invention. According to a first aspect of the present invention, in a laser processing apparatus for irradiating a workpiece with laser light via an optical system, a part of a light beam of the laser light is changed along the optical axis to a different focal position from other parts of the laser light. A focus lens is arranged in the optical system so as to be adjustable in and out of the optical axis.

According to a second aspect of the present invention, in the first aspect, a cylindrical lens for forming a thin laser beam along a processing direction of the laser beam is arranged in at least an optical system on a long focal position side of the laser beam. And

According to a third aspect of the present invention, in the first aspect, a variable power lens for changing a focal position is arranged movably in an optical axis direction in an optical system of at least a part of the light beam of the laser light. I do.

According to a fourth aspect of the present invention, in the first aspect, the rate at which the variable focal length lens transmits the light beam is changed according to the focused energy densities of a portion of the light beam of the laser beam and the other portion. I do.

A fifth invention is characterized in that, in the fourth invention, a plurality of variable focal length lenses are provided so as to divide the light beam of the laser beam into a plurality of pieces in the circumferential direction.

According to a sixth aspect, in the fifth aspect, a plurality of variable power lenses are provided in accordance with the plurality of variable focal length lenses.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Here, an example of an embodiment of the present invention will be described with reference to FIGS. FIG. 1 shows an outline of the entire optical system. As an optical system, an optical fiber 10, a collimator lens 11 that collimates light emitted from the optical fiber 10, and a part S of a light beam from the collimator lens 11 are structurally used. Has a variable focal length lens (notch lens) 12 for making the focal point short along the optical axis. In this case, in the example of FIG. 1, half S of the light beam has a short focus and the other half L has a long focus. Therefore, the variable focal length lens 12 is constituted by a semicircular cutout lens.

A cylinder lens 13 having a semi-cylindrical cross section is disposed downstream of the variable focal length lens 12 along the optical axis of the optical system. The cylinder lens 13 deforms the light beam that has passed through the collimator lens 11 into an elongated shape along the processing direction of the workpiece by the laser light. The light beam is deformed. This is a very useful means for condensing the laser beam in the hole particularly in processing such as cutting a thick plate.

In the optical system, a variable power lens 14 is disposed at a stage subsequent to the cylinder lens 13 so as to be movable along the optical axis. The variable power lens 14 has a function of changing the focal position of the laser beam by moving on the optical axis. For example, as shown in FIG. 2A, the variable power lens 14 is brought closer to the variable power lens 12 side. In this case, the entire laser beam has a short focus, and when the laser beam is close to the imaging lens 15 as shown in FIG. 2B, the entire laser beam has a long focus. In addition,
The light flux S that has passed through the variable-focal-length lens 12 and the light flux L that has not passed through have a different focal point for image formation. The distance between the focal points is also expanded or contracted by the movement of the variable power lens 14. .

The light beam having passed through the variable power lens 14 is imaged by the image forming lens 15, and a bifocal beam waist is formed in the optical axis direction.

The outline of the embodiment of the present invention is as described above. However, in welding or cutting a work, it is often necessary to further consider it. That is, for example, as shown in FIG. 3, the laser light emitted from the laser irradiation device 20 and formed into an image has two types, a short focus and a long focus in this example, and each has its own role. For example, when cutting SUS material,
A material 2 that requires less laser energy for processing with different thermal properties under the thin plate material 21TN as shown in FIG.
In the case of having the number 2, the beam intensity of the preceding short focal point laser beam S along the cutting direction is increased and the beam intensity of the subsequent long focal point laser beam L reaching the material 22 is relatively reduced. Suitable cutting suitable for the plate thickness becomes possible.

Further, as shown in FIG.
When cutting a thick plate, the beam intensity of the preceding short focal point laser beam S is reduced and the beam intensity of the subsequent long focal point laser beam L is relatively increased, so that the thick plate can be suitably cut and the generation of residue is suppressed. It is effective for

The above-described example of FIG. 3 shows one example, but the beam intensity of the short-focus laser beam S and the beam intensity of the long-focus laser beam L are adjusted according to the material such as the thickness and thermal properties of the work. The beam intensity can be adjusted. By this adjustment method, a combination of beam strengths suitable for the thickness and the material of the work can be performed, and an optimum processing strength state for cutting or welding can be obtained. In other words, any work material can be dealt with because the focal position and beam intensity can be variously changed by the bifocal beam.

In the above description, the variable focal length lens 12, which is a notch lens, is formed in a semicircular shape, but a plurality of lenses, for example, four at 90 ° or three at 120 ° in the circumferential direction of the light beam. By arranging the lenses with different curvatures, a lens having four focal points can be obtained. Alternatively, the variable focal length lens 12 is not a semicircle (180 °) but a 3/4 circle (2
70.degree.) And the rest without a lens.

The cylinder lens 14 is provided to elongate the laser light along the processing direction of the workpiece. However, in the case of a short focus, it is not necessary to stop down the laser light. In some cases, it is better not to provide a cylinder lens on the side.

Further, by dividing the variable power lens 14 into a plurality of parts, the focal position of the laser beam can be changed to a plurality of points. Therefore, as a result, depending on the shape and number of the variable focal length lens 12 and the variable magnification lens 14 or depending on the presence or absence thereof, the number and position of the focal point of the laser beam, the mutual distance of the focal point,
Furthermore, various changes such as the beam intensity can be made.

FIG. 4 shows an example of the separation of a thick plate by a YAG laser using carbon steel as a workpiece. The horizontal axis represents the cutting speed, and the vertical axis represents the plate thickness. The cutting by one beam and the upper part show the cutting characteristics by two beams in this example.

[0025]

According to the present invention as described above, the following effects can be obtained. In a laser processing apparatus for irradiating a workpiece with laser light via an optical system, a variable focal length lens having a part of a light beam of the laser light having a different focal position along an optical axis from another part of the laser light is provided in the optical system. The laser processing capability can be improved by arranging the optical axis in and out so as to be adjustable.

In addition, by disposing a cylindrical lens for forming a thin laser beam along the processing direction by the laser light in the optical system at least on the long focal position side of the laser light, an elongated beam shape can be formed in accordance with the processing of the workpiece. By doing so, it is possible to deal with fine processing.

The focal position can be changed by disposing the variable power lens which changes the focal position in the optical system of at least a part of the light beam of the laser beam along the optical axis direction.

By changing the rate at which the variable focal length lens transmits the light beam according to the focused energy density of a part of the light beam of the laser beam and the other portions, it is possible to perform appropriate processing in accordance with the material and thickness of the work. can do.

By providing a plurality of variable-focal-length lenses and variable-power lenses, it is possible to cope with various types of processing.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of an example of an embodiment of the present invention.

FIG. 2 is a state diagram when a zoom lens is moved.

FIG. 3 is a view showing a state of a laser beam corresponding to a material and a thickness.

FIG. 4 is a characteristic diagram of a thick plate separation and cutting example.

FIG. 5 is a configuration diagram of an example of a prior art in the case of a dual focus.

FIG. 6 is a configuration diagram of a conventional example of a dual focus.

[Explanation of symbols]

 12 Variable focus lens 13 Cylinder lens 14 Variable power lens

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Hoso Nakura 2-1-1 Shinama, Arai-machi, Takasago City, Hyogo Prefecture Inside the Takasago Research Laboratory, Mitsubishi Heavy Industries, Ltd. (72) Yoshio Hashimoto 2-1-1 Shinama, Arai-machi, Takasago City, Hyogo Prefecture No. 1 Inside the Mitsubishi Heavy Industries, Ltd. Takasago Research Laboratory (72) Inventor Koji Okimura 1-1-1, Wadazakicho, Hyogo-ku, Kobe-shi, Hyogo F-term in Mitsubishi Heavy Industries, Ltd. Kobe Shipyard 2H087 KA26 RA07 SA00 SA86 4E068 CA11 CD04 CD14 CE07 5F072 AB01 KK30 MM03 YY06

Claims (6)

[Claims] 1. A laser processing apparatus for irradiating a work with laser light via an optical system, wherein a focal point of a part of a light beam of the laser light is set to a different focal position along an optical axis from another part of the laser light. A multi-beam laser processing apparatus, wherein a lens is disposed in the optical system so as to be adjustable with respect to the optical axis. 2. The multi-beam laser according to claim 1, wherein a cylindrical lens for forming a thin laser beam along a processing direction of the laser beam is arranged in at least an optical system on a long focal position side of the laser beam. Processing equipment. 3. A multi-beam laser processing method according to claim 1, wherein a variable power lens for changing a focal position is disposed in an optical system of at least a part of the light beam of the laser light so as to be movable along an optical axis direction. apparatus. 4. The multi-beam laser processing method according to claim 1, wherein a ratio of the variable focal length lens passing the light beam is changed in accordance with a focused energy density of each of a part of the light beam of the laser beam and another portion. apparatus. 5. The multi-beam laser processing apparatus according to claim 4, further comprising a plurality of variable focal-length lenses so as to divide a laser beam into a plurality of beams in a circumferential direction. 6. The multi-beam laser processing apparatus according to claim 5, further comprising a plurality of variable power lenses corresponding to the plurality of variable focal lenses.