JPH0919785A - Laser processing optical system and processing method using the same - Google Patents

Abstract

(57) Abstract: An optical system for laser processing applied to welding and cutting of metal products and a laser processing method using the same are provided. SOLUTION: In an optical system in which light from a laser oscillator is used as a laser beam for laser processing, a lens system 3
And a wedge prism 7 are inserted between the optical fiber 2 which is a light source or between the lens system 3 and the processing surface 8 to simultaneously produce a plurality of condensing and defocusing beams having different sizes, shapes and power densities.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical system for laser processing applied to welding and cutting of metal products and a laser processing method using the same.

[0002]

2. Description of the Related Art FIG. 7 shows an example of the configuration of an optical system used in conventional YAG laser welding. In FIG. 7, reference numeral 1 is a YAG laser oscillator, 2 is an optical fiber, 3 is a focusing optical system, 4 is a laser beam, 5 is a molten pool, and 6 is a welding bead. Here, the laser beam 4 from the YAG laser oscillator 1 is transmitted by the optical fiber 2, condensed by the welding condensing optical system 3, and used for welding.

[0003]

By the way, in the welding of aluminum alloys, in the method shown in FIG. 7, the reflectance of the laser beam 4 is high and the pulse laser is usually used in the YAG laser. However, due to the high cooling rate, cracks may occur in the weld.

For this reason, recently, as shown in FIG.
A method of welding while preheating with the G laser oscillator 1 has been proposed.

The method shown in the figure uses two YAG laser oscillators 1 shown in FIG. 7 to prevent welding cracks.
Welding is carried out while preheating by the condensing optical system of the book.

In the method shown in FIG. 8, since all of the two types of equipment are used, the processing equipment becomes expensive, and the welding head portion becomes large, so that the application to narrow spaces and the approach to the application target can be made flexible. There is a problem that it will damage.

Further, since two welding condensing optical systems 3 are also used, it is difficult to make the optical axes of the two laser beams 4 the same, and the irradiation of the laser beam 4 on the material becomes oblique and the beam energy is increased. In addition to the decrease in density, the energy density setting depends on the inclination of the optical axis of the welding condensing optical system 3, so that there is a problem that the adjustment is not easy.

In view of the above problems, it is an object of the present invention to provide a laser processing optical system capable of performing sound processing without cracks and the like, and a processing method using the same.

[0009]

The structure according to the present invention for achieving the above object is an optical system for forming a laser beam for processing used in a laser processing apparatus for performing laser processing using light from a laser oscillator, A wedge prism is inserted in the optical axis direction of the laser beam between the lens system and the light source, or between the lens system and the processing surface, to simultaneously generate multiple focusing and defocusing beams with different sizes, shapes, and power densities. Is characterized by.

In the above laser processing optical system, by adjusting the insertion amount of the wedge-shaped prism by a predetermined amount,
A feature is that the ratio of laser output to a plurality of laser beams is appropriately adjusted.

On the other hand, the laser processing method is characterized in that laser processing is performed by using a processing apparatus equipped with the above laser processing optical system.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION The contents of the embodiments for carrying out the present invention will be described in detail below.

As shown in FIG. 1 (a), the processing optical system of the present invention is an integrated welding condensing optical system 3, which is provided between the light source (optical fiber 2) and the condensing optical system 3. A wedge prism 7 is inserted in the optical axis direction on the optical system 3 and the processed surface 8, that is, on the image side to divide the laser beam 4. Further, the division ratio of the laser beam 4 is determined by the size of the inserted wedge prism 7 in the optical axis direction.

The structure of the processing optical system of the present invention is shown in FIG.
As shown in FIG. 3, most of the laser beam 4 emitted from the optical fiber 2 is reflected by the condensing optical system 3 at a point P on the processing surface 8.
Is collected. FIG. 1B shows a state of the split laser beams 9 and 10 on the S plane of FIG. FIG.
1C shows a state of the split laser beams 9 and 10 on the W plane of FIG. As shown in FIG. 1B, a part of the laser beam 4 is bent by the inserted wedge prism 7, and defocus occurs due to the thickness of the wedge prism 7. Therefore, apart from the point P, the laser beam 4 is separated from the optical axis by d. It is also focused on the point Q.

Therefore, as shown in FIG. 1C, the spot 10s of the laser beam 10 focused on a very small area on the processed surface 8 and the laser beam having a certain spread at a position slightly distant from the spot 10s. 9 spots 9s can be formed at the same time. Therefore, if the processed surface 8 is scanned while the optical fiber 2 and the condensing optical system 3 are integrated, the processed surface 8 is heated by the spot 9s of the laser beam 9 having a certain extent of spread and then condensed on a minute area. The focused spot 10s of the laser beam 10 is welded.

In FIG. 1A, only the laser beam 4 emitted from one point of the optical fiber 2 is shown, but in reality, the image of the core of the optical fiber 2 is spread around the points P and Q. Have, but omit. Also, the spot 9 with the above spread
The size of s is determined by the defocus amount at the point Q, that is, the thickness of the wedge prism 7. The distance between the spot 9s having the spread and the focused spot 10s is determined by the shift amount of the point Q, that is, the wedge angle of the wedge prism 7.
Further, the laser output balance between the laser beam 9 having a spread and the laser beam 10 condensed on the optical axis is determined by the size of the wedge prism 7 and the insertion amount thereof.
The shape of the laser beam 9 having a spread is almost equal to the shape of the wedge prism 7 on the surface S.

Here, the defocus amount δ at the point Q and the point Q
The magnitude of the shift amount d is: ε: wedge angle of wedge prism 7, t: average thickness of wedge prism 7, n: refractive index of wedge prism 7, f: lens focal length,

## EQU1 ## .delta. = T.multidot. (N-1) /n.apprxeq.t/3. Also, the deflection angle of the optical axis after passing through the wedge prism 7 is

## EQU2 ## .epsilon. '=. Epsilon. (N-1) .apprxeq..epsilon. / 2. Therefore, the shift amount of the point Q (distance from the optical axis) is

## EQU00003 ## d = .epsilon. '. F.apprxeq.f.epsilon./2.

The wedge prism 7 may be arranged between the condensing optical system 3 and the processed surface 8. However, since the imaging magnification is generally 1 or less, the numerical aperture (NA: Numerical Aperture) is larger on the exit side than on the entrance side of the lens,
A large spherical aberration is likely to occur due to the insertion of the wedge prism 7, so that the focused spot is blurred.

Next, a preferred embodiment of the twin beam laser processing optical system of the present invention will be described with reference to FIGS. 2 to 5, but the present invention is not limited to this.

FIG. 2 shows a lens configuration according to the present embodiment, FIG. 2 (A) is a front view of an optical system for twin-beam laser processing, and FIG. 2 (B) is a plan view thereof. The optical system of this embodiment is the condensing optical system 3 of the laser processing apparatus shown in FIG.
The wedge prism 7 according to the present embodiment is configured to be inserted between the light source, that is, the optical fiber 2 and the condensing optical system 3. Further, the actual focusing optical system 3 is composed of five combined lenses for aberration correction, and a protective glass 12 is installed on the processed surface 8 side for use in welding.

The following "Table 1" shows the characteristics of the two kinds of wedge prisms 7 to be inserted into the condensing optical system 3 in the present embodiment. Here, in the wedge prism 7 No. 1, the focused spot 10 s on the optical axis is a spot having a spread with respect to 0.23 mmφ (herein referred to as “heating spot”) 9 s of the wedge prism 7 No. 1. 0.62 x (0 to 0.
70) mm. Similarly, in the wedge prism No. 2, the heating spot 9s is 0.48 × (0 to 0.56) mm.

[0022]

[Table 1]

FIG. 3 shows an inserting mechanism of the manufactured wedge prism 7. As shown in FIGS. 3 (A) and 3 (B), the cylindrical member 21 communicating with the condensing optical system 3 is provided with a moving means 22 via a frame 22, and a rotating lever 23 of the moving means 22 is provided. By rotating, the wedge prism 7 fixed to the moving member 24 is inserted or pulled out by a predetermined amount in the optical axis direction. The position where the tip of the wedge prism 7 is aligned with the optical axis L of the optical system is the origin (zero), the direction in which the wedge prism 7 is inserted is "+", and the direction in which it is pulled out is "-". did.

4A to 4G, when the insertion position of the wedge prism 7 is variously changed, the black acrylic is irradiated with the laser beams 9 and 10 condensed by the optical system of the present invention. The result of evaporating is shown schematically. As shown in FIGS. 4A to 4G, it was confirmed that the laser beams 9 and 10 were divided in any case. It was also confirmed that the splitting ratio of the focused laser beams 9 and 10 can be freely changed by changing the insertion position of the wedge prism 7 (left: heating pattern,
Right: Shows the welding pattern). The wedge prism 7 used here is the one shown in No. 1 of "Table 1".

[0025]

[Example] An "Example" in which an aluminum alloy (A5052) having a plate thickness of 1 mm is welded under the following "conditions" using the optical system of the present invention will be described. FIG. 5 shows a schematic drawing of the result of welding an aluminum alloy.

<Conditions> (1) Twin beam condition Beam spacing: 0.5 mm Energy distribution ratio Leading: Trailing = 4: 6 (2) Welding condition average output: 510w peak output: 5.3kw pulse frequency: 10pps Duty: 10% Speed: 0.3m / min Plate thickness: 1mmt

As shown in FIGS. 5A and 5B, the plate thickness 1
It was confirmed that even if welding of an aluminum alloy of mm was performed, the twin beam processing method using the optical system of the present example did not cause cracking. This is due to the preheating effect of the preceding laser beam 9.

However, in the conventional single beam processing method, as shown in FIGS. 6 (A) and 6 (B), despite welding under the same conditions for all other conditions,
A crack 31 was formed that penetrated the entire thickness of the front and back of the aluminum alloy having a plate thickness of 1 mm.

[0029]

As described above, in the optical system of the present invention, a wedge prism is inserted between the lens system and the light source, or between the lens system and the processing surface, and a plurality of collections having different sizes, shapes and power densities are provided. Since a variety of twin beams can be obtained with a simple device that simultaneously produces a light beam and a defocused beam, it is possible to perform sound processing without cracks in laser processing such as welding and cutting.

Further, by adjusting the insertion amount of the wedge prism by a predetermined amount, it is possible to realize desired laser processing in which the ratio of laser output to a plurality of laser beams can be adjusted appropriately.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of an optical system according to an embodiment of the present invention.

FIG. 2 is a configuration diagram of an optical system according to an embodiment of the present invention.

FIG. 3 is a schematic view of a wedge prism insertion mechanism according to the embodiment of the present invention.

FIG. 4 is a situation diagram of an acrylic burn pattern according to an embodiment of the present invention.

FIG. 5 is a schematic diagram showing a welding result according to an example of the present invention.

FIG. 6 is a schematic diagram showing a welding result according to a conventional example.

FIG. 7 is a device configuration diagram during conventional YAG laser welding.

FIG. 8 is a device configuration diagram at the time of YAG laser welding using two conventional devices.

[Explanation of symbols]

 1 YAG Laser Oscillator 2 Optical Fiber 3 Condensing Optical System 4 Laser Beam 5 Weld Pool 6 Weld Bead 7 Wedge Prism 8 Worked Surface 9 Laser Beam Passing Through Wedge Prism 10 Laser Beam Through Only Lens 11 Luminous Flux 12 Protective Glass 9s Spot 10s spot

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Shoichi Hamada 1-1-1, Wadasaki-cho, Hyogo-ku, Kobe-shi, Hyogo Mitsubishi Heavy Industries, Ltd. Kobe Shipyard (72) Inventor Takashi Akabane, Hyogo-ku, Kobe-shi, Hyogo 1-1-1 Tasakicho Mitsubishi Heavy Industries, Ltd. Inside Kobe Shipyard (72) Inventor Katsura Otaki 3 2-3 Marunouchi Marunouchi, Chiyoda-ku, Tokyo Inside Nikon Corporation

Claims (3)

[Claims] 1. An optical system for forming a laser beam for processing, which is used in a laser processing apparatus for performing laser processing using light from a laser oscillator, wherein a wedge between a lens system and a light source or between a lens system and a processing surface. An optical system for laser processing, characterized in that a prism is inserted in the optical axis direction of the laser beam to simultaneously produce a plurality of focusing and defocusing beams having different sizes, shapes, and power densities. 2. The laser processing optical system according to claim 1, wherein the insertion amount of the wedge-shaped prism is adjusted by a predetermined amount to appropriately adjust the ratio of laser output to a plurality of laser beams. Optical system for laser processing. 3. A laser processing method, wherein laser processing is performed by using a processing apparatus including the laser processing optical system according to claim 1.