WO2016059951A1

WO2016059951A1 - Direct diode laser processing device and sheet metal processing method using same

Info

Publication number: WO2016059951A1
Application number: PCT/JP2015/076929
Authority: WO
Inventors: 小林　哲也; 伊藤　亮平
Original assignee: 株式会社アマダホールディングス
Priority date: 2014-10-14
Filing date: 2015-09-24
Publication date: 2016-04-21
Also published as: JP6035303B2; JP2016078046A

Abstract

A direct diode laser processing device is equipped with: a laser oscillator (11) that oscillates multi-wavelength laser light; a transmission fiber (12) that transmits the multi-wavelength laser light oscillated by the laser oscillator (11); a collimator lens (15) that converts the multi-wavelength laser light transmitted by the transmission fiber (12) into parallel light; and a condensing lens (18) that condenses the multi-wavelength laser light that has been converted to parallel light by the collimator lens (15), thereby irradiating a material to be processed (W). A material having a greater wavelength dispersion than that of quartz is used for the collimator lens (15) and/or the condensing lens (18), thereby forming multiple light concentration points at different positions on the light axis, and spreading out the intervals between the multiple light concentration points.

Description

Direct diode laser processing apparatus and sheet metal processing method using the same

The present invention relates to a direct diode laser processing apparatus and a sheet metal processing method using the same.

2. Description of the Related Art Conventionally, as a laser processing apparatus for processing a sheet metal, an apparatus using a carbon dioxide gas (CO ₂ ) laser oscillator, a YAG laser oscillator, or a fiber laser oscillator as a laser light source is known. The fiber laser oscillator has advantages such as better light quality and extremely high oscillation efficiency than the YAG laser oscillator. For this reason, a fiber laser processing apparatus using a fiber laser oscillator is used for industrial purposes, particularly for sheet metal processing (cutting or welding).

In recent years, a DDL processing apparatus using a direct diode laser (DDL: Direct Diode Laser) oscillator as a laser light source has been developed. The DDL processing apparatus superimposes multiple-wavelength laser light using a plurality of laser diodes (LD) and transmits the laser light to the processing head using a transmission fiber. Then, the laser light emitted from the end face of the transmission fiber is condensed and irradiated on the workpiece by a collimator lens and a condenser lens.

By the way, in a laser processing apparatus for sheet metal processing, it is required that a thick plate can be cut at a higher speed. For this reason, in Japanese Patent Application Laid-Open No. 2008-44000 (Patent Document 1), multi-wavelength laser light is condensed by a condensing lens that does not have an achromatic function, and is on the same optical axis due to the influence of chromatic aberration. By focusing on different positions and irradiating the workpiece, and repeatedly turning on the laser light in the order of shorter wavelengths, high-performance processing is possible even for thick materials.

However, in Patent Document 1, chromatic aberration generated when a synthetic quartz condenser lens having no achromatic function is used, but the interval between multiple focal points due to chromatic aberration is not positively increased.

The present invention has been made in view of the above problems, and according to the present invention, it is possible to positively increase the interval between multiple focal points caused by chromatic aberration when condensing multi-wavelength laser light. It is possible to provide a direct diode laser processing apparatus capable of forming a beam suitable for plate cutting and a metal plate processing method using the same.

According to one aspect of the present invention, a laser oscillator that oscillates multi-wavelength laser light, a transmission fiber that transmits multi-wavelength laser light oscillated by the laser oscillator, and a multi-wavelength laser light transmitted by the transmission fiber A collimator lens for converting the parallel light into a parallel light, and a condensing lens for condensing the multi-wavelength laser light converted into the parallel light by the collimator lens and irradiating the workpiece with at least one of the collimator lens and the condensing lens. Direct diode laser processing apparatus that forms a plurality of condensing points at different positions on the optical axis and disperses the intervals between the plurality of condensing points by using a material having a wavelength dispersion larger than quartz for any one of them. And the processing method of a metal plate using the same is provided.

It is a perspective view showing an example of a DDL processing device concerning one embodiment of the present invention. FIG. 2A is a front view showing an example of a laser oscillator according to an embodiment of the present invention. FIG. 2B is a side view showing an example of the laser oscillator according to the embodiment of the present invention. It is a schematic diagram showing an example of a laser oscillator concerning one embodiment of the present invention. It is a graph showing an example of the oscillation wavelength of the laser oscillator which concerns on one Embodiment of this invention. It is a schematic diagram showing an example of a collimator lens and a condensing lens concerning one embodiment of the present invention. It is a graph showing the peak intensity with respect to d2 of each wavelength. It is a simulation result showing the change of the focal position for every material of a lens. It is a simulation result showing the change of the focal position for every combination of the material of a lens.

Embodiments of the present invention will be described with reference to the drawings. In the following description of the drawings, the same or similar parts are denoted by the same or similar reference numerals.

Referring to FIG. 1, the overall configuration of a direct diode laser (hereinafter referred to as “DDL”) processing apparatus according to the present embodiment will be described. As shown in FIG. 1, a DDL processing apparatus according to an embodiment of the present invention includes a laser oscillator 11 that oscillates multi-wavelength laser light LB, and a transmission fiber (process) that transmits the laser light LB oscillated by the laser oscillator 11. Fiber) 12 and a laser beam machine 13 for condensing the laser beam LB transmitted by the transmission fiber 12 to a high energy density and irradiating the workpiece (workpiece) W.

The laser processing machine 13 includes a collimator unit 14 that converts the laser light LB emitted from the transmission fiber 12 into substantially parallel light by the collimator lens 15, and the laser light LB converted to substantially parallel light in the X-axis and Y-axis directions. A bending mirror 16 that reflects downward in the Z-axis direction perpendicular to the laser beam, and a processing head 17 that condenses the laser beam LB reflected by the bending mirror 16 with a condenser lens 18. Although not shown in FIG. 1, a lens driving unit that drives the collimator lens 15 in a direction parallel to the optical axis (X-axis direction) is installed in the collimator unit 14. The DDL processing apparatus further includes a control unit that controls the lens driving unit.

The laser processing machine 13 further includes a processing table 21 on which the workpiece W is placed, a portal X-axis carriage 22 that moves in the X-axis direction on the processing table 21, and an X-axis direction on the X-axis carriage 22. And a Y-axis carriage 23 that moves in the Y-axis direction perpendicular to the axis. The collimator lens 15 in the collimator unit 14, the bend mirror 16, and the condensing lens 18 in the processing head 17 are fixed to the Y-axis carriage 23 in a state where the optical axis has been adjusted in advance. Move in the axial direction. It is also possible to provide a Z-axis carriage that can move in the vertical direction with respect to the Y-axis carriage 23 and to provide the condenser lens 18 on the Z-axis carriage.

The DDL processing apparatus according to the present embodiment irradiates the workpiece W with the laser beam LB having the smallest condensing diameter (minimum condensing diameter) condensed by the condensing lens 18 and coaxially assisting gas. The X-axis carriage 22 and the Y-axis carriage 23 are moved while spraying and removing the melt. Thereby, the DDL processing apparatus can cut the workpiece W. Examples of the workpiece W include various materials such as stainless steel, mild steel, and aluminum. The plate thickness of the workpiece W is, for example, about 0.1 mm to 50 mm.

The laser oscillator 11 will be described with reference to FIGS. 2A and 2B, the laser oscillator 11 includes a housing 60, the DDL module 10 housed in the housing 60 and connected to the transmission fiber 12, and the housing 60. A power supply unit 61 that is housed in the DDL module 10 and supplies power to the DDL module 10, a control module 62 that is housed in the housing 60 and controls the output of the DDL module 10, and the like are provided. An air conditioner 63 that adjusts the temperature and humidity in the housing 60 is installed outside the housing 60.

As shown in FIG. 3, the DDL module 10 superimposes laser light having multiple wavelengths (λ ₁ , λ ₂ , λ ₃ ,..., Λ _n (hereinafter referred to as {λ _i }). And output. The DDL module 10 includes a plurality of laser diodes (hereinafter referred to as “LD”) 3 ₁ , 3 ₂ , 3 ₃ ,... 3 _n (n is an integer of 4 or more), LD 3 ₁ , 3 ₂ , 3 ₃ , · · · _{3 n} to the fiber ₄ _1, 4 2, _{4 3,} is connected via a · · · _{4 n,} the spectrum of performing spectral beam combining (spectral beam combining) the laser beam of multiple wavelengths {lambda _i} A beam combining unit 50 and a condensing lens 54 that condenses the laser light from the spectral beam combining unit 50 and enters the transmission fiber 12 are provided.

Various semiconductor lasers can be used for the plurality of LD3 ₁ , 3 ₂ , 3 ₃ ,... 3 _n (hereinafter referred to as a plurality of LD3). The combination of the type and number of the plurality of LDs 3 is not particularly limited, and can be appropriately selected according to the purpose of sheet metal processing. The wavelengths λ ₁ , λ ₂ , λ ₃ ,..., Λ _n of the plurality of LDs 3 are selected to be, for example, less than 1000 nm, selected from a range of 800 nm to 1000 nm, or selected from a range of 910 nm to 950 nm. be able to.

The laser light of multiple wavelengths {λ _i } is controlled by group (block) management for each wavelength band, for example. The output can be variably adjusted individually for each wavelength band. In addition, the output of the entire wavelength band can be adjusted so that the absorptance is constant.

In the cutting process, a plurality of LDs 3 are simultaneously operated, and an appropriate assist gas such as oxygen or nitrogen is blown near the focal position. As a result, the laser beams of the respective wavelengths from the LD 3 ₁ , 3 ₂ , 3 ₃ ,... 3 _n cooperate with each other and also with the assist gas such as oxygen to melt the workpiece at a high speed. Further, the molten work material is blown off by the assist gas, and the work is cut at a high speed.

The spectral beam combining unit 50 includes a fixing unit 51 that bundles and fixes the emission ends of the fibers 4 ₁ , 4 ₂ , 4 ₃ ,... 4 _n to form a fiber array 4, and fibers 4 ₁ , 4 ₂ , 4 _3. ,... 4 _n Collimator lens 52 that collimates laser light from _n, diffraction grating 53 that diffracts multi-wavelength {λ _i } laser light and matches the optical axis, and a plurality of LDs 3 A partial reflection coupler 55 constituting a resonator is provided with a reflection surface provided at the end. Note that the position of the partial reflection coupler 55 shown in FIG. 3 is an example, and is not particularly limited thereto.

As shown in FIG. 4, the laser oscillator 11 oscillates laser light having multiple wavelengths (five wavelengths λ ₁ to λ _{5 in} FIG. 4). For this reason, when the laser beam from the laser oscillator 11 is condensed by the lens, chromatic aberration occurs. Therefore, in the present embodiment, in order to positively use chromatic aberration, at least one of the materials of the collimator lens 15 and the condenser lens 18 has a wavelength dispersion larger than that of quartz (in other words, multifocusing). Use materials that are highly effective. As a material having a larger wavelength dispersion than quartz, zinc sulfide (ZnS), zinc selenide (ZnSe), or the like can be used. As a material of at least one of the collimator lens 15 and the condenser lens 18, a material having a larger wavelength dispersion than quartz is used, so that the influence of chromatic aberration becomes more conspicuous and the interval between multiple focal points on the optical axis is further increased. Multiple focal points can be distributed.

Note that the materials of the collimator lens 15 and the condenser lens 18 may be the same material or different materials. If one of the collimator lens and the condensing lens 18 is ZnS or ZnSe, multiple focusing is possible compared to the case where both the collimator lens and the condensing lens 18 are quartz.

Here, as shown in FIG. 5, the distance between the exit end of the transmission fiber 12 and the collimator lens 15 is d0, the distance between the collimator lens 15 and the condensing lens 18 is d1, the condensing lens 18 and the processing point (condensing point). Point) The distance from P is d2. For example, it is assumed that light having five wavelengths of 800 nm, 810 nm, 820 nm, 830 nm, and 840 nm is output and combined in a wavelength range of 800 nm to 840 nm, and d0 = 97.8 mm and d1 = 1500 mm. In this case, d2 at wavelengths of 800 nm, 810 nm, 820 nm, 830 nm, and 840 nm are 134.2 mm, 135.2 mm, 136.1 mm, 137.0 mm, and 137.8 mm, respectively. Multiple focal spots with an interval of 9 mm are formed.

Also, for example, assume that light of five wavelengths of 960 nm, 970 nm, 980 nm, 990 nm, and 1000 nm is output and coupled in a wavelength range of 960 nm to 1000 nm, and d0 = 100.9 mm and d1 = 1500 mm. In this case, d2 at wavelengths of 960 nm, 970 nm, 980 nm, 990 nm, and 1000 nm are 130.4 mm, 131.4 mm, 132.3 mm, 133.2 mm, and 134.0 mm, respectively. Multiple focal spots with an interval of 9 mm are formed.

<Example>
An example of the DDL processing apparatus according to the present embodiment will be described. It is assumed that a plano-convex lens made of ZnSe with a curvature R = 147.808 mm is used as the collimator lens 15 and a plano-convex lens made of ZnSe with a curvature R = 221.711 mm is used as the condenser lens 18. In the laser oscillator 11, light of five wavelengths of 910 nm, 920 nm, 930 nm, 940 nm, and 950 nm is output and coupled in a wavelength range of 910 nm to 950 nm. Note that a continuous wave can be used as the laser light.

For example, when d0 = 100 mm and d1 = 1500 mm, as shown in FIG. 6, d2 of wavelengths 910 nm, 920 nm, 930 nm, 940 nm, and 950 nm are 131.9 mm, 132.9 mm, 133.8 mm, 134.7 mm, and 135, respectively. 0.5 mm, and multiple focal points with an interval of about 0.9 mm are formed within the range of 3.6 mm. Therefore, it is suitable for cutting a workpiece W having a thickness of about 0.9 mm to 3.6 mm, for example.

In FIG. 6, the horizontal axis indicates d2, and the vertical axis indicates the peak intensity of the laser light of each wavelength. The light output of each wavelength emitted from the transmission fiber and the BPP are the same. From this, it can be seen that the peak intensity of each wavelength is shifted in the d2 direction (processing depth direction). This indicates that it is superior to thick plate cutting.

In the above, the substantial Rayleigh length of the laser light with multiple wavelengths (the Rayleigh area of the laser light with the shortest focal length (the area covered by the Rayleigh length above and below the beam waist in the laser light) The distance to the lowest end of the Rayleigh region of the laser beam having a long focal length is preferably substantially equal to the thickness of the workpiece.

FIG. 7 shows the simulation results for the focal length of the lens (design wavelength: 1080 nm) and the change in the focal position depending on the wavelength of each material under the same conditions. In the simulation, the distance d0 to the collimator lens 15: 100 mm, the focal length of the collimator lens 15: 100 mm (a plano-convex lens with a design wavelength of 1080 nm), the distance d1: 1500 mm between the collimator lens 15 and the condenser lens 18, Focal length: 150 mm (plano-convex lens with a design wavelength of 1080 nm). The vertical axis shows the change of the focal position with a wavelength of 1 nm. “C” on the horizontal axis indicates the collimator lens 15, and “F” indicates the condenser lens 18. From FIG. 7, it can be seen that ZnS and ZnSe form a multifocal with a wider focal interval than quartz.

FIG. 8 shows a simulation result of a change in focal position due to a combination of materials under the same conditions as in FIG. The vertical axis shows the change of the focal position with a wavelength of 1 nm. “C” on the horizontal axis indicates the collimator lens 15, and “F” indicates the condenser lens 18. From FIG. 8, it can be seen that if ZnS or ZnSe is used for either the collimator lens 15 or the condensing lens 18, a multiple focus having a wider focal distance than quartz is formed.

As described above, according to the present invention, by using a material having a wavelength dispersion larger than that of quartz for at least one of the collimator lens 15 and the condenser lens 18, the curvature of the lens as in the related art is specially made. A plurality of condensing points can be formed at different positions on the optical axis without using a changed multifocal lens, and the intervals between the plurality of condensing points can be further dispersed. Therefore, a beam suitable for the thick plate can be formed, and the cutting process can be speeded up also for the thick plate.

Further, by changing the combination of the materials of the collimator lens 15 and the condensing lens 18 according to the type of the thick plate, the interval between the plurality of condensing points can be varied, and the beam is suitable for the thick plate to be processed. Can be formed.

Further, by simultaneously operating a plurality of LDs 3 and blowing an appropriate assist gas such as oxygen or nitrogen to the vicinity of the focal position, high-speed cutting can be performed.

Although the present invention has been described according to the embodiment, it should not be understood that the description and drawings constituting a part of this disclosure limit the present invention. From this disclosure, various alternative embodiments, examples and operational techniques will be apparent to those skilled in the art. It goes without saying that the present invention includes various embodiments not described herein. Therefore, the technical scope of the present invention is defined only by the invention specifying matters according to the scope of claims reasonable from the above description.

According to the present invention, it is possible to positively increase the interval between multiple focal points caused by chromatic aberration when condensing multi-wavelength laser light, and to form a beam suitable for cutting a thick plate. A diode laser processing apparatus and a metal plate processing method using the same can be provided.

(US designation)
This international patent application is related to the designation of the United States, and the benefit of the priority right under US Patent Act 119 (a) for Japanese Patent Application No. 2014-209896, filed on October 14, 2014, is disclosed. Cite the contents.

Claims

A laser oscillator that oscillates multi-wavelength laser light;
A transmission fiber for transmitting multi-wavelength laser light oscillated by the laser oscillator;
A collimator lens that converts multi-wavelength laser light transmitted by the transmission fiber into parallel light;
A condensing lens that condenses the multi-wavelength laser light converted into parallel light by the collimator lens and irradiates the workpiece;
At least one of the collimator lens and the condensing lens is made of a material having a wavelength dispersion larger than that of quartz, and a plurality of condensing points are formed at different positions on the optical axis. A direct diode laser processing apparatus, characterized in that it is configured to disperse.
The direct diode laser processing apparatus according to claim 1, wherein at least one of the collimator lens and the condenser lens is made of zinc sulfide or zinc selenide.
3. The direct diode laser processing apparatus according to claim 1, wherein a wavelength of the multi-wavelength laser light is in a range of 800 nm to 1000 nm.
The direct diode laser processing apparatus according to any one of claims 1 to 3, wherein a thickness of the workpiece is 0.9 mm to 3.6 mm.
5. The direct diode laser processing apparatus according to claim 1, wherein a substantial Rayleigh length of the multi-wavelength laser light is substantially equal to a plate thickness of the workpiece.
A method of processing a metal plate having a plate thickness of 0.9 mm to 3.6 mm using the direct diode laser processing apparatus according to any one of claims 1 to 4,
Simultaneously irradiating a predetermined processing position of the metal plate with multi-wavelength laser light having different focal positions in the thickness direction of the metal plate;
Spraying an assist gas to the processing position. A method for processing a metal plate.
The method for processing a metal plate according to claim 6, wherein the processing is cutting of a sheet metal.