Patent Publication Number: US-2016221120-A1

Title: Laser processing apparatus

Description:
FIELD 
     The present invention relates to a laser processing apparatus for processing a workpiece by irradiating the workpiece with laser. 
     BACKGROUND 
     Attempts have been made in recent years to use high output semiconductor lasers as laser processing apparatuses. However, because semiconductor laser beams include laser beams of plural wavelength bands, focal distances of the respective wavelengths become different from one another when the semiconductor laser beams are condensed. 
     Conventionally, superposing laser beams of different wavelength bands, though not semiconductor laser beams, to condense the laser beams onto the same optical axis has been disclosed, for example, in Patent Literature 1 and Patent Literature 2. 
     CITATION LIST 
     Patent Literature 
     Patent Literature 1: Japanese Patent Application Laid-open No. 2001-196665 
     Patent Literature 2: Japanese Patent Application Laid-open No. 2006-263771 
     SUMMARY 
     Technical Problem 
     A laser processing apparatus described in the above cited Patent Literature 1 is supposed to be able to irradiate the same part of a workpiece with output beams of two lasers, but focal distances of laser beams having different wavelength bands are difficult to be made the same by a condenser lens, and even if crown glass and flint glass are used, for example, focal distances of laser beams having different wavelength bands are difficult to be made the same. Therefore, like a laser processing apparatus described in Patent Literature 2, focal positions of superposed laser beams having different wavelength bands may be deliberately made different from one another with respect to a thickness direction of a workpiece, to obtain effects of the respective wavelength bands. However, in order to improve processing accuracy, power density is desirably increased by condensing laser beams to a smaller spot. 
     The present invention solves the above described problems, and an object thereof is to provide a laser processing apparatus that enables focal positions of laser beams having different wavelength bands to coincide with one another. 
     Solution to Problem 
     In order to achieve the object above, according to an embodiment of the present invention, there is provided a laser processing apparatus, comprising: a laser output device that oscillates laser beams having plural wavelength bands; a spectrometer that respectively disperses the laser beams of the respective wavelength bands; and a condenser that condenses each of the laser beams dispersed by the spectrometer independently and matches focal points of the laser beams to the same position. 
     In this laser processing apparatus, since each of the laser beams dispersed by the spectrometer is independently condensed by the condenser to match their focal points to the same position, focal positions of the laser beams having different wavelength bands are able to be made to coincide with one another. As a result, by the laser beams having different wavelength bands being condensed to a smaller spot and power density being increased, processing accuracy is able to be improved. 
     According to another embodiment of the present invention, the spectrometer is formed of a prism, and the condenser is formed of a group of lenses. 
     In this laser processing apparatus, by application of the dispersion by the prism and the condensing by the group of lenses, laser energy loss between the incidence from the laser output device and the irradiation of the workpiece with the laser is able to be suppressed. 
     According to another embodiment of the present invention, the spectrometer is formed as a collection of prisms that respectively disperse the laser beams of the respective wavelength bands and make the laser beams into plural annular light beams having different diameters centering around the same optical axis, and the condenser is formed as a collection of lenses that condense the respective annular light beams with the same optical axis at the center. 
     In this laser processing apparatus, by dispersing the laser beams of the respective wavelength bands into the plural annular light beams centering around the same optical axis and condensing these annular light beams with the same optical axis at the center, the apparatus is able to be downsized. 
     According to another embodiment of the present invention, the laser processing apparatus comprises an irradiation head that has the spectrometer and the condenser, and emits the laser beams of the respective wavelength bands; a moving mechanism that relatively moves a supporting table that supports the workpiece and the irradiation head; and a control device that adjusts the relative movement between the supporting table and the irradiation head by the moving mechanism, and various conditions of the laser beams output from the laser output device. 
     In this laser processing apparatus, by adjusting the relative movement between the supporting table and the irradiation head by the moving mechanism and the various conditions of the laser output from the laser output device, focal positions of the leaser beams having different wavelength bands are made to coincide with one another, the laser beams having different wavelength bands are condensed to a smaller spot to increase power density, and processing of the workpiece with laser is able to be conducted while improvement in the processing accuracy is achieved. 
     Advantageous Effects of Invention 
     According to the present invention, focal positions of laser beams having different wavelength bands are able to be made to coincide with one another. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is a schematic configuration diagram schematically illustrating a laser processing apparatus according to an embodiment of the present invention. 
         FIG. 2  is a schematic configuration diagram schematically illustrating an irradiation head of a laser processing apparatus according to a first embodiment of the present invention. 
         FIG. 3  is a schematic configuration diagram schematically illustrating an irradiation head of a laser processing apparatus according to a second embodiment of the present invention. 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     Hereinafter, an embodiment of a laser processing apparatus according to the present invention will be described in detail, based on the drawings. This invention is not limited by this embodiment. For example, in this embodiment, a case, where a plate shaped workpiece is processed, will be described, but the shape of the workpiece is not particularly limited. The shape of the workpiece may be any of various shapes. Further, in this embodiment, a case where a hole is formed in a workpiece, a case where a workpiece is cut along a straight line, or a case where a workpiece is welded, will be described; but by adjusting a position to be processed on the workpiece, that is, a position to be irradiated with laser, a shape other than a hole or a straight line, for example, a shape having a bending point or a curved shape, may be applied. Furthermore, in this embodiment, a laser and a workpiece are relatively moved by the workpiece being moved, but the laser may be moved, or both the laser and the workpiece may be moved. 
       FIG. 1  is a schematic configuration diagram schematically illustrating the laser processing apparatus according to this embodiment. A laser processing apparatus  10  has, as illustrated in  FIG. 1 , a laser output device  12 , a guiding optical system  14 , an irradiation head  16 , a moving mechanism  18 , a supporting table  20 , and a control device  22 . By irradiating a workpiece  8  arranged on the supporting table  20  with laser L, the laser processing apparatus  10  processes the workpiece  8 . In this embodiment, with respect to the laser processing apparatus  10 , a surface of the workpiece  8  will be referred to as “XY plane”, and a direction orthogonal to the surface of the workpiece  8  will be referred to as “Z direction”. 
     The workpiece  8  of this embodiment is a plate shaped member. As the workpiece  8 , a member made of any of various materials, such as, for example: Inconel; Hastelloy; stainless steel; ceramic; steel; carbon steel; ceramics; silicon; titanium; tungsten; resin; plastics; and glass, may be used. Moreover, as the workpiece  8 , a member made of any of: fiber reinforced plastics, such as carbon fiber reinforced plastics (CFRP), glass fiber reinforced plastics (GFRP), and glass mat thermoplastics (GMT); various metals, such as ferroalloys other than steel plates or aluminum alloys; other composite materials; and the like may also be used. In addition, if welding is performed, a mechanism for supplying a filler material, powder, and the like may be included. 
     The laser output device  12  is a device that outputs laser. The laser output device  12  oscillates laser beams having plural wavelength bands. This laser output device  12  is, for example, a semiconductor laser oscillator. 
     The guiding optical system  14  is an optical system that guides the laser output from the laser output device  12  to the irradiation head  16 . The guiding optical system  14  of this embodiment is an optical fiber. One end portion of the guiding optical system  14  is connected to a laser output port of the laser output device  12  and the other end portion thereof is connected to the irradiation head  16 . The guiding optical system  14  outputs the laser output from the laser output device  12  towards an input port of the irradiation head  16 . The configuration of the guiding optical system  14  is not limited to this example. The laser processing apparatus  10  may guide the laser to the irradiation head  16  through reflection, condensing, and the like of the laser by use of a combination of any of mirrors and lenses serving as the guiding optical system  14 . Or, the laser may be directly guided from the laser output device  12  to the irradiation head  16 . 
     The irradiation head  16  irradiates the workpiece  8  with the laser L output from the guiding optical system  14 . Details of the irradiation head  16  will be described later. 
     The moving mechanism  18  has an arm  30 , and a driving source  32  that moves the arm  30 . A distal end of the arm  30  supports the irradiation head  16 . The driving source  32  is able to move the arm  30  in three XYZ axial directions. By the moving mechanism  18 , it is able to irradiate various positions on the workpiece  8  with the laser L from the irradiation head  16 , by causing the arm  30  to be moved in the XYZ directions by the driving source  32 . Further, the moving mechanism  18  has a position detector  34  that detects positions of the irradiation head  16  in the XYZ directions. In this embodiment, the moving mechanism  18  is a mechanism that causes the irradiation head  16  to be moved by the arm  30  and the driving source  32 , but a mechanism that causes the irradiation head  16  to be moved by an XY stage, an XYZ stage, or the like may also be used. 
     The supporting table  20  supports the workpiece  8  at a predetermined position. In the laser processing apparatus  10 , the supporting table  20  may be formed as the XY stage that moves the workpiece  8  in the XY directions. 
     The control device  22  controls operation of each unit. The control device  22  adjusts various conditions of the laser output from the laser output device  12 , and adjusts a position of the irradiation head  16  relative to the workpiece  8  by causing the irradiation head  16  to be moved by the moving mechanism  18 . 
     This laser processing apparatus  10  causes laser to be output from the laser output device  12 . In the laser processing apparatus  10 , the guiding optical system  14  guides the output laser L to the irradiation head  16 . In the laser processing apparatus  10 , the moving mechanism  18  moves the irradiation head  16 , while the position detector  34  detects the positions of the irradiation head  16  in the XYZ directions. Thereby, the laser processing apparatus  10  is able to process the workpiece  8 . 
     First Embodiment 
       FIG. 2  is a schematic configuration diagram schematically illustrating an irradiation head of a laser processing apparatus according to this embodiment. As illustrated in  FIG. 2 , the irradiation head  16  has, inside a casing  16 A supported by the above described moving mechanism  18 , a spectrometer  16 B and condensers  16 C, provided therein. The spectrometer  16 B respectively disperses the laser beams of the respective wavelength bands incident from the guiding optical system  14 . In  FIG. 2 , a mode, in which laser beams of two wavelength bands are respectively dispersed, is illustrated. The condensers  16 C respectively condense the laser beams dispersed by the spectrometer  16 B independently and match focal points thereof to the same position. 
     The spectrometer  16 B is formed of a prism, and by the laser beams incident on the spectrometer  16 B from the guiding optical system  14  passing therethrough, the laser beams of the respective wavelength bands are dispersed into different directions due to a difference in refractive index. 
     The condensers  16 C are respectively provided correspondingly to the laser beams of the respective wavelength bands dispersed by the spectrometer  16 B. Each of the condensers  16 C is formed as a group of lenses having: a parallel optical system  16 Ca that makes the laser incident from the spectrometer  16 B into parallel light; and a condensing optical system  16 Cb that condenses the laser made into the parallel light by the parallel optical system  16 Ca. The parallel optical system  16 Ca and the condensing optical system  16 Cb in  FIG. 2  are schematically illustrated, and their lens configuration is not limited. 
     In this irradiation head  16 , the workpiece  8  is irradiated with the laser L that has been condensed. In this embodiment, the laser output device  12  oscillates laser beams having plural (two in  FIG. 2 ) wavelength bands. After being respectively dispersed by the spectrometer  16 B into the respective wavelength bands, these laser beams are made into parallel light beams by the parallel optical systems  16 Ca in the condensers  16 C respectively, and laser beams L 1  and L 2  of the respective wavelength bands are independently emitted with their focal points matched to the same position (a position (surface) to be processed on the workpiece  8 ). 
     As described above, the laser processing apparatus  10  of this embodiment includes: the laser output device  12  that oscillates laser beams having plural wavelength bands; the spectrometer  16 B that respectively disperses the laser beams of the respective wavelength bands; and the condensers  16 C and  16 C that respectively condense the laser beams dispersed by the spectrometer  16 B independently and match their focal points to the same position. 
     By this laser processing apparatus  10 , since the laser beams dispersed by the spectrometer  16 B are respectively condensed by the condensers  16 C and  16 C independently and their focal points are matched to the same position, focal positions of the laser beams L 1  and L 2  having different wavelength bands are able to be made to coincide with each other. As a result, by the laser beams L 1  and L 2  having different wavelength bands being condensed to a smaller spot and power density being increased, processing accuracy is able to be improved. 
     Moreover, preferably, in this laser processing apparatus  10  of this embodiment, the spectrometer  16 B is formed of the prism and the condenser  16 C is formed of the group of lenses. 
     In this laser processing apparatus  10 , by application of the dispersion by the prism and the condensing by the group of lenses, laser energy loss between the incidence from the laser output device  12  and the irradiation of the workpiece  8  with the laser L is able to be suppressed. 
     Second Embodiment 
       FIG. 3  is a schematic configuration diagram schematically illustrating an irradiation head of a laser processing apparatus according to this embodiment. As illustrated in  FIG. 3 , the irradiation head  16  has, inside a casing  16 D supported by the above described moving mechanism  18 , a collimator  16 E, a spectrometer  16 F, and a condenser  16 G provided therein. The collimator  16 E makes laser beams incident from the guiding optical system  14  into parallel light beams. The spectrometer  16 F respectively disperses the laser beams of the respective wavelength bands incident from the collimator  16 E. In  FIG. 3 , a mode, in which laser beams of three wavelength bands are respectively dispersed, is illustrated. The condenser  16 G condenses each of the laser beams dispersed by the spectrometer  16 F independently and matches focal points thereof to the same position. 
     The spectrometer  16 F is a collection of prisms continuously arranged and formed in a disk shape, and is called a cone lens. By the laser beams incident from the collimator  16 E passing therethrough, this spectrometer  16 F respectively disperses the laser beams of the respective wavelength bands according to differences in refractive index, and makes the laser beams into plural annular light beams R 1 , R 2 , and R 3  having different diameters and centering around the same optical axis S. 
     The condenser  16 G is formed as a collection of plural (three, in this embodiment) lenses  16 Ga,  16 Gb, and  16 Gc continuously arranged outward from the center and formed in a disk shape, so as to condense each of the annular light beams R 1 , R 2 , and R 3 , with the same optical axis S being at the center. 
     In this irradiation head  16 , the workpiece  8  is irradiated with the laser L that has been condensed. In this embodiment, the laser output device  12  oscillates laser beams having plural (three, in  FIG. 3 ) wavelength bands. After being respectively dispersed into the respective wavelength bands and made into the annular light beams R 1 , R 2 , and R 3  by the spectrometer  16 F, these laser beams are respectively condensed by the condenser  16 G, and the laser beams L 1 , L 2 , and L 3  of the respective wavelength bands are emitted with their focal points independently matched to the same position (a position (surface) to be processed on the workpiece  8 ). 
     As described above, the laser processing apparatus  10  of this embodiment includes: the laser output device  12  that oscillates laser beams having plural wavelength bands; the spectrometer  16 F that respectively disperses the laser beams of the respective wavelength bands; and the condenser  16 G that condenses each of the laser beams dispersed by the spectrometer  16 F independently and matches their focal points to the same position. 
     By this laser processing apparatus  10 , since the laser beams dispersed by the spectrometer  16 F are respectively condensed by the lenses  16 Ga,  16 Gb, and  16 Gc of the condenser  16 G independently and their focal points are matched to the same position, focal positions of the laser beams L 1 , L 2 , and L 3  having different wavelength bands are able to be made to coincide with one another. As a result, by the laser beams L 1 , L 2 , and L 3  having different wavelength bands being condensed to a smaller spot and power density being increased, processing accuracy is able to be improved. 
     In addition, preferably, in the laser processing apparatus  10  of this embodiment, the spectrometer  16 F is formed as the collection of prisms that respectively disperse the laser beams of the respective wavelength bands and make the laser beams into the plural annular light beams R 1 , R 2 , and R 3  having different diameters centering around the same optical axis S, and the condenser  16 G is formed as the collection of the lenses  16 Ga,  16 Gb, and  16 Gc that condense the respective annular light beams R 1 , R 2 , and R 3 , with the same optical axis S at the center. 
     By this laser processing apparatus  10 , since the laser beams of the respective wavelength bands are dispersed into the plural annular light beams R 1 , R 2 , and R 3  centering around the same optical axis S and these annular light beams R 1 , R 2 , and R 3  are condensed with the same optical axis S at the center, focal positions of the laser beams L 1 , L 2 , and L 3  having different wavelength bands are able to be made to coincide with one another. As a result, by the laser beams L 1 , L 2 , and L 3  having different wavelength bands being condensed to a smaller spot and power density being increased, processing accuracy is able to be improved. In particular, in this laser processing apparatus  10 , by dispersing the laser beams of the respective wavelength bands into the plural annular light beams R 1 , R 2 , and R 3  centering around the same optical axis S and condensing these annular light beams R 1 , R 2 , and R 3  with the same optical axis S at the center, the apparatus is able to be downsized as compared with the above described first embodiment. 
     Reference Signs List 
     
         
           8  WORKPIECE 
           10  LASER PROCESSING APPARATUS 
           12  LASER OUTPUT DEVICE 
           16  IRRADIATION HEAD 
           16 A CASING 
           16 B SPECTROMETER 
           16 C CONDENSER 
           16 D CASING 
           16 E COLLIMATOR 
           16 F SPECTROMETER 
           16 G CONDENSER 
           16 Ga,  16 Gb,  16 Gc LENS 
         S OPTICAL AXIS