Abstract:
This laser processing machine, which processes a work piece mounted on a table by irradiating the work piece with a laser light, is provided with: an optical head having a nozzle that sprays a liquid to form a columnar liquid flow and introducing a laser light into the nozzle and shining said light; and an alignment adjustment device having a reflector that is disposed so as to face the optical head and reflects the laser light, and a light-shielding portion around the portion of the reflector that reflects the laser light, and adjusting the position or orientation of introduction of the laser light into the columnar liquid flow.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    This application is a U.S. National Stage patent application of International Patent Application No. PCT/JP2015/052755, filed Jan. 30, 2015, which is hereby incorporated by reference in the present disclosure in its entirety. 
     
    
     FIELD OF THE INVENTION 
       [0002]    The invention relates to a laser beam machine and an alignment adjusting method therefor, the laser beam machine being configured to machine a workpiece by directing the laser beam through a liquid flow in the form of a pillar formed by a liquid discharged through a nozzle, wherein the laser beam machine has an alignment adjusting function for aligning the optical axis of the laser beam and the axis of the liquid flow. 
       BACKGROUND OF THE INVENTION 
       [0003]    In a laser beam machine configured to machine a workpiece by directing the laser beam through the pillar-like liquid flow formed by a liquid discharged through a nozzle, the optical axis of the laser beam and the axis of the pillar-like liquid flow must be aligned with each other. Patent Literature 1 discloses a laser beam machine provided with such an alignment adjusting device. 
         [0004]    The alignment adjusting device of Patent Literature 1 is configured to move a jet nozzle and an optical fiber relative to each other so as to align the center of an image of the laser beam with the center of an entrance opening of the jet nozzle, based on the images of the entrance opening of the jet nozzle, for discharging a liquid to form a liquid pillar, and the laser beam. 
       PATENT PUBLICATIONS 
       [0005]    Patent Literature 1: JP-A-2011-235347 
       BRIEF SUMMARY OF THE INVENTION 
       [0006]    The laser beam used in laser beam machines is classified in Class 4 of security standard of JIS (Japanese Industrial Standards) C6802 and IEC (International Electrotechnical Commission) 60825-1. In the alignment adjusting device of Patent Literature 1, such laser beam of Class 4 is exposed, and therefore, the laser beam machine must be in an environment in compliant with a safety regulation defined by Class 4, in order to adjust the alignment safely, resulting in a larger factory. 
         [0007]    The invention is directed to solve the problem of the prior art, and the objective of the invention is to provide a laser beam machine and alignment adjusting method, which enable to adjust the alignment between the pillar-like liquid flow and the laser beam safely and easily. 
         [0008]    In order to achieve the above described object, according to the invention, a laser beam machine for machining a workpiece by irradiating a laser beam to the workpiece mounted to a table, comprising an optical head having a nozzle configure to discharge liquid to form a pillar-like liquid flow, the optical head a laser beam into the nozzle to irradiate, and an alignment adjusting device, having a reflecting plate, disposed to face the optical head, for reflecting the laser beam, and a shielding part disposed around a portion of the reflecting plate, the portion being adapted to reflect the laser, the alignment adjusting device being configure to adjust the incident position and the angle of the laser beam relative to the pillar-like liquid flow is provided. 
         [0009]    Further, according to the invention, a method of adjusting the alignment of a laser beam in a laser beam machine for machining a workpiece by irradiating a laser beam to the workpiece mounted to a table from an optical head having a nozzle configure to discharge liquid to form a pillar-like liquid flow, the optical head introducing a laser beam to irradiate, comprising the steps of disposing a reflecting plate so as to face the nozzle of the optical head, enclosing the space between the nozzle and the reflecting plate by a shielding member configured to prevent a leakage of the laser beam, irradiating the laser beam toward the reflecting plate, and moving the position of the focal position of the laser beam so as align the optical axis of the laser beam reflected by the reflecting plate with the center of the nozzle is provided. 
         [0010]    According to the invention, the reflecting plate, configured to reflect the laser beam, is disposed to face the optical head, and the shield member is disposed around the portion, adapted to reflect the laser beam, of the reflecting plate, and therefore when adjusting the alignment, the laser beam leakage is prevented. Thus, in the laser beam machine of the invention, the alignment adjustment can be carried out in an equipment environment according to less dangerous Class 1, while in the prior art, the alignment adjustment must be carried out in compliance with Class 4 of JIS C6802 or IEC 60825-1. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0011]      FIG. 1  is a schematic section of an optical head and an alignment unit according to a preferred embodiment of the invention, wherein optical head is positioned at an alignment adjustment position, and the laser beam is irradiated. 
           [0012]      FIG. 2  is a schematic section of the optical head and the alignment unit, similar to  FIG. 1 , wherein the optical head is apart upwardly from the alignment unit, and the laser beam is not irradiated. 
           [0013]      FIG. 3  is a perspective view of the alignment unit. 
           [0014]      FIG. 4  is a plan view of the alignment unit, showing a reflecting plate positioned at a rotational position for alignment adjustment. 
           [0015]      FIG. 5  is a plan view of the alignment unit, similar to  FIG. 4 , showing the reflecting plate positioned at a rotational position for measuring the output power of the laser beam. 
           [0016]      FIG. 6  is a plan view of the reflecting plate. 
           [0017]      FIG. 7  is a perspective view of an example of a laser beam machine to which the invention is applied. 
           [0018]      FIG. 8  is a schematic illustration showing an example of a window displayed on a display of the laser beam machine. 
           [0019]      FIG. 9  is a schematic illustration, similar to  FIG. 8 , showing an example of a window for teaching an operator a step of adjusting the focus of camera. 
           [0020]      FIG. 10  is a schematic illustration, similar to  FIG. 8 , showing an example of a window for teaching an operator a step of aligning a target circle and a nozzle with each other. 
           [0021]      FIG. 11  is a schematic illustration, similar to  FIG. 8 , showing an example of a window wherein the target circle and the nozzle are aligned with each other. 
           [0022]      FIG. 12  is a schematic illustration, similar to  FIG. 8 , showing an example of a window for teaching an operator a step of adjusting the focus of laser spot. 
           [0023]      FIG. 13  is a schematic illustration, similar to  FIG. 8 , showing an example of a window for teaching an operator a step of adjusting the X-axis position of the laser spot. 
           [0024]      FIG. 14  is a schematic illustration, similar to  FIG. 8 , showing an example of a window for teaching an operator a step of adjusting the Y-axis position of the laser spot. 
           [0025]      FIG. 15  is a schematic illustration, similar to  FIG. 8 , showing an example of a window when the alignment adjustment is completed. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0026]    With reference to the attached drawings, a preferred embodiment of the invention will be described below. 
         [0027]    With reference to  FIG. 7 , showing an example of a laser beam machine to which the invention is applied, a laser beam machine  100  comprises a table  108  to which a workpiece is attached, an optical head  10  configured to move linearly relative to the table  108  in three orthogonal X-, Y- and Z-aces directions. The optical head  10  and the table  108  are enclosed by a cover  102 . The cover  102  has a safety door  106 , slidable in the right-left direction (X-axis direction). Opening the safety door  106  allows an operator to access the optical head  10  and the table  108  through an opening  104 . The safety door  106  is provided with an open-close sensor  106   a  for detecting the safety door  106  closed. The table  108  is provided with an alignment unit  40  and an intimate-contact detecting device  50  (refer to  FIG. 1 ). 
         [0028]    An operating panel  110  for the laser beam machine  100  is mounted to a front side wall of the cover  102 . The operating panel  110  has a display  112 , adapted to display parameters, indicating the condition and operation of the laser beam machine  100 , icons for teaching an operator the operation procedures and so on, and a various operating buttons  114 . The display  112  may be a touch panel, adapted to allow an operator to carry out a various operation to the laser beam machine  100  by touching an icon with his (her) finger. Further, the operating panel  110  is incorporated with a controller for controlling the laser beam machine  100  in accordance with the operator&#39;s input and a program contained in the controller. 
         [0029]    The laser head  10 , shown in  FIGS. 1 and 2  as an example, comprises a laser irradiation head  16  which is enclosed in a housing  12  and configured to receive the laser beam from a laser oscillator  14  via an optical conduit  14  such as an optical fiber, and to irradiate the laser beam toward a collimation lens  18 . The laser beam from the laser irradiation head  16  is parallelized by the collimation lens  18 , reflected to a second mirror  22  by a first mirror  20 , and reflected toward a focus lens  24  by the second mirror  22 . The laser beam is irradiated outside the housing  12  through a nozzle head  26 , after being condensed by the focus lens  24 . At that time, the optical axis of the laser beam irradiated from the optical head  10  is substantially parallel to the Z-axis. 
         [0030]    The first and second mirrors  20  and  22  have planner reflecting surface, and motors  20   a  and  20   b  as a mirror orientation adjusting means for adjusting the orientations of the reflecting surfaces (the directions perpendicular to the reflecting surfaces), whereby adjusting the direction of the laser beam irradiated from the optical head  10 . The first and second mirrors  20  and  22 , in particular the second mirror  22 , adapted to reflect the laser beam toward the focus lens  24 , include(s) a dielectric multilayer suitable for the wave length of the laser beam irradiated from the laser oscillator  14  to reflect the laser beam and to transmit lights having wave lengths other than the wave length of the laser beam. In particular, it is formed by depositing a dielectric multilayer on a glass plate. Forming the second mirror  22  by such a dielectric multilayer enables the positions of the nozzle  26   b  and the laser beam irradiated through the nozzle  26  to be monitored by a camera  32 . 
         [0031]    The nozzle head  26  comprises a tubular member configured to receive water supply from a water source  30  via a conduit  28 . Provided in a bottom wall of the nozzle head  26 , facing the table  108 , is a nozzle  26   b  for discharging a water jet. Opposite to the bottom wall, a top wall, facing the focus lens  24 , is provided with a window  26   a  formed of a transparent member such as glass. The nozzle  26   b  is fluidly communicated with the outside of the housing  12  of the optical head  10  via orifice  12   b  formed in the bottom wall of the housing  12 . 
         [0032]    The alignment unit  40  is positioned at a position on the table  108  so as to be faced to the optical head  10  by moving the optical head  10  and the table  108  relatively to each other by the three orthogonal X-, Y- and Z-aces feed devices of the laser beam machine  100 . The alignment unit  40  comprises a base member  48  configured to be secured to the table  108 , an annular lower holding member  46  secured to a top face of the base member  48 , an annular upper holding member  44  detachably attached to the lower holding member  46 , a reflecting plate  42  held between the upper and lower holding members  44  and  46 , and an annular light shielding member  34  fixed to a top face of the upper holding member  44 . 
         [0033]    The light shielding member  34  is made of a light-impermeable material regarding the laser beam irradiated from the optical head  10 . The shielding member may be formed of a material, for example a synthetic resin sponge or a foamed rubber, which can intimately contact with the bottom face  12   a  of the housing  12  of the optical head  10  so as not to form a gap, allowing a light leakage, between the shielding member  34  and the optical head  10 . 
         [0034]    The reflecting plate  42  may be formed of for example stainless steel, and is circumferentially rotatably held between the upper and lower holding members  44  and  46 . As shown in  FIGS. 3-6 , when held between the upper and lower holding members  44  and  46 , the reflecting plate  42  is positioned so that a portion  42   a  thereof projects out of the upper and lower holding member  44  and  46 , facilitating an operator to rotate the reflecting member  42 . At that time, a portion  42   b , diametrically opposite to the part  42   a,  is positioned on the optical axis of the optical head  10 . Further, the reflecting plate  42  includes a radially extending cutout part  42   c,  disposed on the outer periphery, and a flat part  42   d,  which is disposed diametrically opposite to the cutout part  42   c,  and is formed by flatting a portion of the outer periphery perpendicularly relative to the radial direction. 
         [0035]    Further, embedded in the table  108  of the laser beam machine  100  is a output power meter  80  having a sensor part which is disposed on the optical axis of the laser beam irradiated by the optical head  10 , which is positioned at an alignment adjustment position, whereby measuring the power of the laser beam irradiated from the optical head  10 . As shown in  FIG. 5 , rotating the reflecting plate  42  to position the cutout part  42   c  of the reflecting plate  42  on the optical axis of the laser beam allows the output power of the laser beam to be measured. At that time, an operator can position the cutout part  42   c  based on the position of the flat part  42   d  disposed diametrically opposite to the cutout part  42   c.    
         [0036]    The intimate-contact detecting device  50  is a device for detecting that the bottom face of the housing  12  of the optical head  10  intimately sufficiently contacts as shown in  FIG. 1 , and comprises an interlock switch  54  attached to the bottom face of the housing  12 , a switch cover  52  enclosing the interlock switch  54 , a pin  56  disposed to enter the switch cover  52  through an opening  52   a  formed in a bottom face of the switch cover  52 . The pin  56  is oriented in the Z-axis direction in this embodiment, and accommodated within a pin cover  58  secured to the table  108 . Incidentally, the power meter  80  may be embedded in the base member  48  of the alignment unit  40 , instead of the table  108 . 
         [0037]    The pin cover  58  comprises a boxlike member having an opening in a side wall  58   b,  allowing an operator to access the inside of the pin cover  58  from the outside. Formed in a top wall of the pin cover  58  is an opening  58   a  through which the pin  56  extends toward the interlock switch  54 . The pin  56  has a radially extending flange part  56   a  provided at a lower end opposite to the interlock switch. In this embodiment, the flange part  56   a  includes a magnet (not shown), while the pin cover  58  is made of a magnetic material such as iron, etc., so that the flange part  56   a  can be magnetically attached to the inner surface of the top wall of the pin cover  58 . 
         [0038]    The operation of the embodiment will be described below. 
         [0039]    When the water is supplied to the nozzle head  26  from the water source  30  via conduit  28 , the water is discharged through the nozzle  26   b,  whereby a pillar-like liquid flow (water pillar)  60 , extending in the Z-axis direction, is formed. The laser beam from the laser oscillator  14  is transmitted via the optical conduit  14   a , the laser irradiate head  16 , collimation lens  18  and first and second mirrors  20  and  22  to focus lens  24  concentrating the laser beam, then is irradiated toward the table  108  after passing through the window  26   a  of the nozzle head  26 , the water in the nozzle head  26  and the pillar-like liquid flow  60 . In order to bring the laser beam into the pillar-like liquid flow, after concentrated by the focus lens  24 , an alignment adjusting operation is carried out to align the laser beam and the pillar-like liquid flow  60  with each other. 
         [0040]    When an operator selects alignment adjusting function on the operating panel  110  and presses a start button on the operating panel  110 , the optical head  10  starts to be moved to an alignment adjustment position by the X-, Y- and Z-axes feed devices of the laser beam machine  100 . The optical head  10  is moved above the alignment unit  40  then lowered along the Z-axis until the bottom face  12   a  of the housing  12  of the optical head  10  intimately contacts the shield member  34  of the alignment unit  40 . Then, the pin  56  of the intimate-contact detecting device  50  abuts the interlock switch  54  to close the interlock switch  54 , whereby the controller of the laser beam machine  100  judges that the optical head  10  has reached the alignment adjustment position and stops the Z-axis feed. In this connection, the optical head  10  may be moved to the alignment adjustment position by defining the movement to the alignment adjustment position in a program read by the controller, or by previously teaching the alignment adjustment position to the controller by an operator through a teaching operation. 
         [0041]    When the safety door  106  is opened for the alignment adjustment, if the pin  56  does not abut the interlock switch  54 , then the controller of the laser beam machine  100  judges that the optical head  10  is not at the alignment position, whereby inhibiting the irradiation of the laser beam, and displaying a warning on the display  110  and/or generating a warning sound. Further, when the optical head  10  is moved to the alignment position, if the optical head  10  is excessively lowered in the Z-axis direction, the pin  56  can be automatically detached from the pin cover  58 , since the pin  56  is attached to the pin cover  58  by the magnet of the flange part  56   a.  Furthermore, if the optical head is located at a position deviated from the alignment position in the X- or Y-axis direction, pin  56  cannot enter the opening  52   a  of the switch cover  52 , whereby being detached from the pin cover  58 . 
         [0042]    Further, the controller of the laser beam machine  100  stores the alignment position, which is previously taught by an operator, as the coordinates of the respective feed axes of the laser beam machine. Therefore, when the alignment adjustment is carried out with the safety door  106  opened, if the coordinates of the respective feed devices of the laser beam machine are different from the stored alignment adjustment position, the controller of the laser beam machine  100  judges that the optical head  10  is not at the alignment position, whereby inhibiting the irradiation of the laser beam, and displaying a warning on the display  110  and/or generating a warning sound. 
         [0043]    After the operator presses a start button on the operating panel  110  to move the optical head  10  toward the alignment adjustment position by the X-, Y- and Z-axes feed devices of the laser beam machine  100 , a window  200  is displayed, as shown in  FIG. 8 , on the display  112  of the operating panel  110 . The window  200  includes target circle  208 , including a cross lines  206   a  and  206   b,  which is generated in the window  200  by the laser beam machine, a text displaying region  201  for displaying a text message for teaching an operator the respective steps of the alignment adjusting method, and a continue icon  210  for allowing an operator to successively proceed with the alignment adjusting operation. The continue icon  210  can be selected after the movement to the alignment adjustment position is completed. Incidentally, the target circle  208  has a diameter larger than that of the nozzle  202 . 
         [0044]    After the optical head  10  is moved to the alignment adjustment position, the laser beam is irradiated from the optical head  10  with an alignment output power lower than that for machining. At that time, the laser beam is not aligned with the position of the nozzle, and therefore when irradiated, the laser beam is irregularly reflected in the nozzle head  26 . A portion of the irregularly reflected laser beam is reflected by the reflecting plate  42  so as to come to the camera  32  through nozzle  26   b.  Therefore, the contour of the nozzle  26   b  is displayed on the display  112  as nozzle  202  with the inside bright and the outside dark. In  FIG. 9 , the optical axis of the laser beam is not aligned with the center of the nozzle  202 , and the reflection of the laser beam on the inner wall of the nozzle head  26  is shown as a laser spot  204 . Then, when an operator taps the continue icon  210 , a text message, “Please Adjust Camera Focus”, for instructing the operator to adjust the focus of the camera is displayed in the text displaying region  201  of the window  200 , as shown in  FIG. 9 . In this connection, it should be noted that an operator must access the optical head  10  in order to adjust the focus of the camera  32 , and therefore, if the shield member  34  is not provided, then the operator may be exposed to the laser beam. 
         [0045]    When the operator taps the continue icon  210 , a text message, “Please Move Circle To Nozzle” for instructing the operator to align the target circle  208  and the nozzle  202  is displayed in the text displaying region  201  of the window  200 , as shown in  FIG. 10 . When the operator taps moving icons  214 ,  216 ,  218  and  220 , the target circle  208  moves, along with the cross lines  206   a  and  206   b,  in the direction indicated by each of the moving icons  214 - 220 . 
         [0046]    After the target circle  208  is move to a position substantially concentric with the nozzle  202 , as shown in  FIG. 11 , when the operator taps the continue icon  210 , a text message, “Please Adjust Laser Spot Focus” for instructing the operator to adjust the focus of the laser beam is displayed in the text displaying region  201  of the window  200 , as shown in  FIG. 12 . The focus of the adjustment of the laser spot is carried out by moving the focus lens  24  in the direction of the optical axis. In order to carry out the operation for moving the focus lens  24 , in the prior art, a risk that an operator must access the optical head  10 , and therefore in the prior art, the operator may be exposed to the laser beam. 
         [0047]    After the operator adjusts the focus of the laser spot, when the operator taps the continue icon  210 , the laser focus icon is disappeared, a text message, “Please Align X-Axis Positions of Laser Spot and Circle” for instructing the operator to position the laser spot  204  in the X-axis direction is displayed in the text displaying region  201  of the window  200 , and two vertical auxiliary lines  224   a  and  224   b  are displayed at either sides of the vertical (in the Y-axis direction) cross line  206   a,  as shown in  FIG. 13 . When the operator taps moving icons  214 ,  216 ,  218  and  220 , the laser spot moves in the direction indicated by each of the moving icons  214 - 220 . The laser spot is moved by driving the motors  20   a  and  22   a  of the first and second mirrors  20  and  22  so as to change the orientation of the first and second mirrors  20  and  22 . Accordingly, the incident position or angle of the laser beam is adjusted. The operator can easily position the laser spot  204  in the X-axis direction by locating the laser spot  204  between the auxiliary lines  224   a  and  224   b,  indicated by broken lines, as shown in  FIG. 13 . 
         [0048]    After the laser spot  204  is positioned in the X-axis direction, as shown in  FIG. 13 , when the operator taps the continue icon  210 , the vertical auxiliary lines  224   a  and  224   b  are disappeared, a text message, “Please Align Y-Axis Positions of Laser Spot and Circle”, for instructing the operator to position the laser spot  204  in the Y-axis direction is displayed in the text displaying region  201  of the window  200 , and two horizontal auxiliary lines  226   a  and  226   b  are displayed at either sides of the horizontal (in the X-axis direction) cross line  206   b,  as shown in  FIG. 14 . When the operator taps moving icons  214 ,  216 ,  218  and  220 , the laser spot moves in the direction indicated by each of the moving icons  214 - 220 . The operator can easily position the laser spot  204  in the Y-axis direction by locating the laser spot  204  between the auxiliary lines  226   a  and  226   b , indicated by broken lines, as shown in  FIG. 14 . Accordingly, the laser spot  204  is positioned substantially concentrically with the nozzle  202 . 
         [0049]    Then, when the operator taps the continue icon  210 , the horizontal auxiliary lines  226   a  and  226   b  are disappeared, and the optical head  10  moves back to the previous position when the above-described alignment adjusting operation was started. 
         [0050]    According to the embodiment, the optical head  10  can be surely moved to the alignment adjustment position by controlling with the controller. Further, the respective steps of the alignment adjusting operation procedure, for aligning the axis of the pillar-like liquid flow  60  and the optical axis of the laser beam, are successively displayed on the display  112  of the operating panel  110 , whereby preventing an operator from mistaking the operation procedure, and the laser beam being irradiated under unshielded condition, whereby allowing an operator to carry out the operation easily and safely. 
         [0051]    Further, according to the embodiment, when the optical head  10  is positioned at the alignment adjustment position, the bottom face of the housing  12  of the optical head  10  contacts intimately with the shielding member  34  to prevent the laser beam being leaked during the alignment adjusting operation. Thus, in the prior art, an alignment adjusting operation must be carried out in compliance with a regulation such as Class 4 of JIS C6802 or IEC 60825-1. In the laser beam machine  100  according to the embodiment, the alignment adjusting operation can be carried out in compliance with class 1, and therefore an operator can be carried out the alignment adjusting operation with the safety door  106  opened. 
       REFERENCE SIGNS LIST 
       [0052]      10  Optical Head 
         [0053]      12  Housing 
         [0054]      14  Laser Oscillator 
         [0055]      16  Laser Irradiation Head 
         [0056]      18  Collimation Lens 
         [0057]      20  First Mirror 
         [0058]      22  Second Mirror 
         [0059]      24  Focus Lens 
         [0060]      26  Nozzle Head 
         [0061]      26   a  Nozzle 
         [0062]      30  Water Source 
         [0063]      32  Camera 
         [0064]      34  Shielding Member 
         [0065]      40  Alignment Unit 
         [0066]      42  Reflecting Plate 
         [0067]      42   c  Cutout Part 
         [0068]      42   d  Flat Part 
         [0069]      44  Upper Holding Member 
         [0070]      46  Lower Holding Member 
         [0071]      48  Base Member 
         [0072]      50  Intimate-Contact Detecting Device 
         [0073]      60  Pillar-like Liquid Flow 
         [0074]      100  Laser Beam Machine 
         [0075]      108  table 
         [0076]      110  Operating Panel 
         [0077]      201  Nozzle 
         [0078]      204  Laser Spot 
         [0079]      208  Target Circle