Abstract:
Moving enclosures for laser equipment are provided. A machine tool installation is disclosed, including (a) a laser cutting head configured to be movable in three dimensions; (b) a workpiece support configured to support a workpiece in operative relationship with the laser cutting head; (c) a skirt configured to surround the laser cutting head on three sides and intercept light that passes from the head and is reflected off of the workpiece or workpiece support; and (d) a protective cover positioned to intercept light that is reflected off of the workpiece or workpiece support and is not intercepted by the skirt. The skirt and protective cover are configured to move laterally with the laser cutting head.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of U.S. Ser. No. 12/446,857, filed Nov. 23, 2009, which is a 371 of International PCT Application No. PCT/US2006/060188 filed Oct. 24, 2006. The contents of both of these priority applications are hereby incorporated by reference in their entirety. 
    
    
     TECHNICAL FIELD 
     This invention relates to moving enclosures for laser equipment, to protect operators from uncontrolled beam reflection during laser operation. 
     BACKGROUND 
     It is important to protect operators working around laser equipment, e.g., equipment for laser cutting of workpieces, from uncontrolled beam reflection during laser operation. Such reflection, which can occur for example while a part that is being cut by a laser is tipped, could injure the operator if it contacts the operator&#39;s body. It is also important, however, that the operator have easy access to parts of the equipment that need to be changed or maintained, for example the cutting head, when the laser is not operating. 
     In some cases, for example as disclosed in U.S. Pat. No. 6,987,241, the equipment may be enclosed in a stationary cabin-like enclosure that is accessed through sliding doors. 
     SUMMARY 
     The disclosure features enclosures for laser equipment that are movable and that allow easy access to a cutting head of the laser equipment while providing effective safety protection when the laser is in operation. 
     In one aspect, the present disclosure features a machine tool installation comprising: (a) a laser cutting head configured to be movable in at least two dimensions; (b) a workpiece support configured to support a workpiece in operative relationship with the laser cutting head; (c) a skirt configured to surround the laser cutting head on three sides and intercept light that passes from the head and is reflected off of the workpiece or workpiece support; and (d) a protective cover positioned to intercept light that is reflected off of the workpiece or workpiece support and is not intercepted by the skirt; the skirt and protective cover being configured to move laterally with the laser cutting head. 
     Some implementations may include one or more of the following features. The skirt may be configured to move vertically with the cutting head, or, alternatively, the skirt may be configured to move vertically independently of the cutting head. In the latter case, the machine tool installation may include a skirt drive motor and a cam arrangement configured to raise and lower the skirt in response to input from the skirt drive motor. The machine tool installation may also include a controller configured to control the vertical height of the skirt, and a height regulation device comprising a sensor configured to detect the vertical position of the workpiece and transmit a signal to the controller. 
     The skirt may be configured to move horizontally, in a second direction orthogonal to the lateral movement, with the laser cutting head. The skirt may be configured to move within the protective cover, which in some implementations is not configured for movement in the second direction. The skirt may include an array of pins mounted on a substantially U-shaped bracket. The pins may be arranged in a labyrinth, with their long axes extending generally parallel to the direction of light emitted by the laser cutting head. 
     The protective cover may include a door, and may define open side and back regions. The machine tool installation may also include a motion device configured to move the protective cover and laser cutting head laterally. In some cases, the machine tool installation also includes a support structure from which the protective cover and laser cutting head are cantilevered and along which the protective cover and laser cutting head move laterally. Alternatively, the machine tool installation may include a pair of opposed rails between which the motion device is mounted and along which the motion device, protective cover and laser cutting head move laterally. In the latter case, the protective cover may in some cases be mounted directly on the laser cutting head. 
     In another aspect, the disclosure features a moving enclosure for a machine tool installation including a laser cutting head configured to be movable in at least two dimensions, the enclosure comprising: (a) a skirt configured to surround the laser cutting head on three sides; (b) a z-axis motion control unit, on which the skirt is mounted, configured to position the skirt vertically relative to a workpiece to be machined; and (c) a protective cover positioned to intercept reflected light from the laser cutting head that is not intercepted by the skirt; the skirt and protective cover being configured to move laterally with the laser cutting head. 
     The disclosure also features methods of protecting operators of machine tool installations from laser light using the moving enclosures disclosed herein.The details of one or more implementations are set forth in the accompanying drawings and the description below. Other features and advantages of the enclosures disclosed herein will be apparent from the description and drawings, and from the claims. 
    
    
     
       DESCRIPTION OF DRAWINGS 
         FIG. 1  is a perspective view of a laser machine tool installation including a moving enclosure according to one implementation. 
         FIG. 2  is a front view of the moving enclosure shown in  FIG. 1   
         FIGS. 3 and 4  are front and bottom views, respectively, of a skirt portion of the moving enclosure shown in  FIG. 1 . 
         FIG. 5  is a view of the moving enclosure shown in  FIG. 1  taken from below. 
         FIG. 6  is a side cross-sectional view of the moving enclosure shown in  FIG. 1 . 
         FIG. 7  is a side view of a spring mounted pin used in the skirt portion shown in  FIGS. 3 and 4 . 
         FIG. 8  is a front view of the skirt portion of a moving enclosure according to an alternative embodiment. 
         FIG. 9  is a top view of a moving enclosure according to an alternative implementation. 
     
    
    
     DETAILED DESCRIPTION 
     Referring to  FIG. 1 , a laser machine tool installation  10  includes a moving enclosure  11  that surrounds a laser cutting head  8  ( FIG. 2 ), a workpiece bed  2  including a plurality of workpiece supports  3  and sub-supports  4  disposed orthogonal to the supports  3 . The workpiece supports  3  are configured to support a workpiece (not shown), e.g., a sheet of metal, beneath the laser cutting head during a cutting operation. The moving enclosure  11  protects the operator from laser light reflected off of the workpiece supports, sub-supports or workpiece, as will be discussed in detail below. The installation  10  also includes material transfer units  5 ,  6 , configured to place the workpiece on the workpiece bed prior to processing and remove it from the bed after processing. 
     The moving enclosure  11  includes a protective cover  14  having a protective door  12 , e.g., a bifold door. In the implementation shown in  FIG. 1 , the laser cutting head  8  and the protective cover  14  are cantilevered out from a rear support surface  100  of the installation  10 , and are mounted on a motion unit  13 . The motion unit  13  includes a motor (not shown) that moves the laser cutting head horizontally in the x direction. The cutting head moves in the y direction along y-direction guides (not shown), and in the z direction on z-direction guides installed on a z-axis plate  120  ( FIG. 3 ). The laser cutting head moves relative to the protective cover  14  in the y direction (towards and away from the protective door  12 ), and the z direction (up and down within the protective cover), and with the protective cover in the x direction (laterally). In the x direction, the protective cover and laser cutting head travel along the support surface  100 . Motion of the head and cover in the x direction allows the laser cutting head and protective cover to move out of the way during placement and removal of a workpiece by the material transfer units, and allows the cutting head to make cuts in the x direction when it is in operation. Motion of the head in the y direction within the protective cover allows the cutting head to make cuts in the y direction, while motion of the head in the z direction allows the distance between the cutting head and the workpiece to be adjusted, e.g., to compensate for different workpiece thicknesses and/or to utilize different processing techniques. 
     During cutting, it is important that the operator of the machine tool installation  10  be protected from stray laser light that may reflect off of the workpiece, the workpiece supports  3 , or the sub-supports  4 . The protective door  12  protects the operator from stray laser beams that are directed towards the front (door side) of the cover  14 , while allowing the operator to access the laser cutting head within the enclosure  11 , e.g., to change the head. 
     In order to minimize the weight of the protective cover  14  and allow it to be easily moved in the x direction, and avoid collisions with cut parts, the protective cover  14  is open in regions  20 ,  22  along its sides and also is open at the back. Thus, a secondary device is needed to protect the operator from reflected laser beams in these areas. To provide this protection, the moving enclosure  11  further includes a skirt  28  ( FIGS. 3-4 ) that surrounds the laser cutting head on three sides  30 ,  32  and  34 , corresponding to the open side and back regions of the protective cover. The skirt  28  is open at the front (front opening  7 ,  FIG. 5 ), allowing the operator to easily access the laser cutting head  8  when the protective door  12  is open. Referring to  FIG. 5 , which shows the laser cutting head  8  from the bottom, the skirt  28  is designed so that when the laser cutting head  8  is in its position furthest from the protective door  12  in the y direction, reflected laser light could escape from the open front  7  of the skirt at any point within angle A. The width W of door  12  is preferably selected to cover the entire area into which the reflected laser light exiting from the front of the skirt could escape when the laser cutting head is in the position shown in  FIG. 5 . For example, if angle A is approximately 30 degrees, and the maximum distance D between the door  12  and the laser cutting head  8  is about 1.5 meters, the width W of the door is preferably about 830 mm. Advantageously, since angle A is relatively small (e.g., less than 60 degrees and preferably less than 40 degrees), and the maximum distance between the laser head and the door is relatively short (e.g., less than 3 meters), the door  12  can be relatively small. For example, the width W of door  12  may be less than 3 meters, preferably less than 2 meters. 
     Preferably, the skirt  28  is small relative to the size of the protective cover  14  within which it moves, and closely surrounds the laser cutting head  8 . Referring now to  FIGS. 3 and 4 , the skirt  28  is preferably formed of an array of pins  25  that extends downwardly from side legs  26  of a U-shaped bracket  24 . In this implementation, the bases  29  of the pins, which define the bottom of the skirt, are substantially level with the tip of the nozzle  9  of laser cutting head  8 . As a result, as shown in  FIG. 6 , when the nozzle  9  is positioned close to the workpiece  23  during cutting, the bottom of the skirt will also be close to the workpiece. For example, distance D between the bottom of the pins and the upper surface of the workpiece may be less than 5 mm, preferably about 1 to 2 mm. 
     The pins  25  are arranged to form a labyrinth, i.e., by staggering the rows of pins. This labyrinth arrangement prevents a reflected laser beam (which cannot turn a corner) from passing through the skirt  28 . The skirt is positioned relative to the laser nozzle so that the side arms  30 ,  32  of the skirt protect the operator in side regions  20 ,  22  ( FIG. 1 ) and the back  34  of the skirt protects the operator at the back of the laser machine tool installation. As discussed above, the operator is protected at the front of the installation by the protective door  12 . 
     The pins, which may be made, for example, of brass, are mounted so that they can pivot freely with respect to the side legs  26 . The pins may be of any desired length which will provide adequate light capture, for example about 2 to 4 cm long. In some implementations, the pins are spring-mounted on the side legs  26 , e.g., the pins  25  may include a pin body  33  and a coil spring  35  disposed around an upper portion of the pin body, as shown in  FIG. 7 . The freedom of movement of the pins prevents the skirt from being damaged by movements of the workpiece; if the workpiece tips during processing, the pins can deflect out of the way without damage. 
     The height of the base of the pins relative to the workpiece should generally be readily adjustable. When the laser is in operation, to protect the operator the bases of the pins should generally be very close to the workpiece, e.g., a vertical distance of less than 5 mm, preferably 1 mm or less. To accomplish this, the array of pins is preferably capable of being adjusted upward to accommodate workpieces having different thicknesses or non-uniform thickness. In some implementations, this adjustment is provided by mounting the skirt of pins to travel vertically with the laser head. Thus, in the implementation shown in  FIGS. 3 and 4 , the U-shaped bracket  24  carrying the pins is mounted on a Z-axis plate  21  of the motion unit  13 , so that the skirt of pins will move vertically with the laser cutting head  8 . 
     However, in some processes the laser nozzle may be turned on when it is a significant vertical distance from the workpiece, in which case the operator could be exposed to reflected laser light if the bases of the pins were elevated at the level of the laser nozzle. Thus, in some implementations the skirt of pins is mounted so as to move vertically (in the z direction) independently of the laser cutting head. The skirt of pins still travels with the laser cutting head in the x-y plane. 
     An example of an implementation in which the pins are mounted to move vertically independently of the laser cutting head is shown in  FIG. 8 . In this implementation, the pin bracket  45 , carrying pins  46 , is raised and lowered by a motor  44 , e.g., a motor with a Profibus controller. The motor raises and lowers the pin bracket  45  through transmission belt  50  which rotates cam  52 , which is connected to the pin bracket  45  via roller  54 , brace  56  and guides  58 . The cutting head  8 , with nozzle  9 , is mounted on a separate z-axis plate  2  which is movable independently of the pin bracket  45  by a z-axis drive (not shown). 
     When the bracket  45  and pins  46  are in an upper, reference position (e.g., 50 mm about the workpiece (z=0)), a reference switch  62  (in its ON position) indicates that the pin bracket  45  is in this upper position. Initially, the nozzle  9  is also in a raised position, e.g., at z=105 mm. The distance between the vertical positions (in the z direction) of the nozzle  9  and the pin bracket  45  is stored by the controller as a reference distance (RD). 
     When the cutting head is moved downward by the Z-axis plate  2 , a switch  60  turns to the ON position. Switch  62  first turns OFF (cam  66  moves away.) The distance RD and the actual position of the Z-axis plate  2  are then used to calculate the distance that the pin bracket  45  must move in order to be sufficiently close to the workpiece  47 . After this calculation has been made, the motor  44  lowers the pin bracket  45  until the bases  64  of pins  46  are very close to the workpiece  47 , e.g., 1 to 2 mm from the workpiece. Switch  62  turns ON, activated by cam  65 , and switch  60  turns ON, activated by cam  13 . Two signals from switches  60  and  62  in a down position are needed for safety. Generally, in this position the bases  64  of the pins will also be about 1 mm above the bottom of nozzle  9  (unless the nozzle  9  is positioned unusually high above the workpiece during this first lowering step). 
     At this stage, in some implementations a height regulation feature is turned on. The height regulation feature includes one or more sensor(s) (not shown) that sense the z position of the top surface of workpiece  47 , and send a signal to the z-axis drive causing the z-axis plate  2  to move as needed to maintain an appropriate distance between the cutting head and the workpiece during operation. 
     The height regulation feature may also be used to regulate the height of the pins, e.g., to accommodate differences in thickness of the workpiece, or tipping of the workpiece during cutting. This is accomplished by the sensors sending the same signal, indicating the position of the top surface of the workpiece, to the controller of the motor  44 . 
     During the cutting operation, the nozzle  9  may be raised above the workpiece  47 , for example up to 50 mm, for special cutting operations or for other reasons. Because the pin bracket  45  is controlled independently by motor  44 , the pin bracket will stay in place immediately above the workpiece  47  to protect the operator. When the cutting operation is over, the motor  44  will return the pin bracket  45  to its raised, reference position, allowing the workpiece  47  to be easily removed. 
     Referring now to  FIG. 9 , in some implementations the laser cutting head is mounted on a double supported motion unit (often referred to as a gantry mount), rather than being cantilevered out from a supporting surface  100  as shown in  FIG. 1 . When a gantry mount is used, a motion unit  70  is mounted on a pair of rails  72 ,  74 , that define a machine frame  76 . A brace  78  is positioned at the front of the machine frame  76 , connecting rails  72 ,  74 . In this case, the skirt  28  is mounted on the motion unit  70 , and a protective front panel  80  is mounted directly to the laser cutting head  8  to protect the operator in the open front area of the skirt  28 . The protective front panel includes a door  82 , similar to door  12  discussed above with reference to  FIG. 1 . As discussed above, the skirt  28  may be mounted to move in the z direction with the cutting head  8 , or may be controlled by a separate drive to move independently of the cutting head. 
     Other embodiments are within the scope of the following claims. 
     For example, if the skirt is extended so that its arms extend the full length of travel of the laser cutting head, the skirt need not travel with the laser cutting head in that direction (i.e., towards and away from the protective door.)