Abstract:
An apparatus for trimming at least one overhanging layer from a workpiece, the apparatus comprising a laser configured to produce a cutting beam capable of cutting the overhanging layer, a cutting head comprising an upper element and a lower element, wherein the cutting head is configured to receive the cutting beam and split the cutting beam into a first portion and a second portion, wherein the first portion exits the cutting head through a upper element and the second portion exits the cutting head through a lower element, and a sensor configured to detect and control movement of the cutting head relative to the workpiece.

Description:
FIELD OF THE INVENTION 
     The present invention relates, in general, to a new and improved device and method for removing the edge of a laminated board which has a laminate veneer extending out from the top and/or bottom of the board. It more particularly relates to a device which automatically senses and cuts, with a laser, the edge of a laminated board which has a laminate veneer extended out from at least one surface of the board. 
     BACKGROUND OF THE INVENTION 
     Recent environmental regulations and the depletion of old-growth forests have made it increasingly difficult and expensive to obtain high-quality lumber for use in wood products. One way to address the difficulty and expense of obtaining high-quality lumber is to use a veneer laminate. Veneered parts are created by affixing a higher-quality veneer, such as high-grade or clear wood or melamine, over a lower-quality core, such as medium density fiberboard (MDF), particleboard, plywood, laminated veneer lumber (LVL), or finger-jointed stock. Veneered laminates more efficiently utilize high-quality wood, reducing wood requirements and associated costs. 
     Manufacturing this veneered material requires several steps. After applying a laminate layer to the surface of a core, the edge of a laminated board may extend outward from the perimeter of one or both surfaces of the core. The overhanging laminate layer is undesirable, and is typically removed by striking the overhanging layer until it breaks closer to the edge of the core. This process often causes chipping of the veneer&#39;s edges, which may cause injury to the production personnel and end user as they handle the sharp edges of the material. Installers typically do not use the full sheet of material if it has cracks in the veneer around the perimeter. Therefore, end users often view the edge of the material as a waste product. p Therefore, there is a need for a process of removing overhang material which is highly accurate in production implementation, and which may be efficiently integrated into material manufacture to lower costs and improve results. 
     SUMMARY OF THE INVENTION 
     The present invention provides a simple and inexpensive device to automatically sense and trim the edge of a laminated board which has a laminate veneer extended outward from the top and/or bottom of the board. The cutting device maintains a preset distance from the edge of the board and trims the overhanging veneer. This invention is especially useful when trimming an overhanging layer from any type of regular or irregular shaped board. The present invention has a further advantage of providing sufficient positioning accuracy and repeatability to create smooth edges over a variety of surfaces including circles, arcs, polygons, etc. 
     According to a preferred embodiment of the invention, the single and/or dual surface trimmer and automatic edge sensing device is carried out by the use of a laser that is controlled and guided so as to remove overhanging laminate material by directing laser beam energy at the junction of the board and the laminate. A laminated board that needs trimming is placed in the laser cutting area and centered for cutting. The laser trimmer is then activated and a cutting beam begins moving along the perimeter of the board while trimming the overhanging laminate. 
     A sensor provides a feedback signal allowing relative positioning of the workpiece with respect to the laser beam. In an alternative embodiment, the sensor may provide a feedback signal allowing relative positioning of the laser beam with respect to the workpiece. The sensor is capable of sensing the edge of any type of regular or irregular shaped board, (circle, arc, polygon, etc.). The sensor detects the edge of the board and adjusts itself to cut at the junction of the board and the veneer laminate layer. 
     The laser proceeds around the perimeter of the board, cutting the excess melamine laminate layer from the top and/or bottom edges of the board at the same time. If there are any curves in the perimeter of the board or if the board is not straight in the cutting area, the automatic edge sensor will move the cutting head closer or farther from the board to keep the proper preset distance from the perimeter of the board while creating a smooth cutting edge. 
     The workpiece may be fastened to a standard production table or, alternatively, the workpiece may be mounted for relative movement in a two-axis positioner table. A robotic arm can also be used to guide the laser beam source in the required pattern extending in two or three dimensions. 
     Many other features, advantages, and objects of the invention will become apparent to those versed in the art upon reference to the accompanying drawings and detailed description, in which preferred embodiments incorporating the principles of the invention are disclosed as illustrative examples. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The invention may be more completely understood by considering the detailed description of various embodiments of the invention that follows in connection with the accompanying drawings. 
     FIG. 1 is an isometric view of the automatic edge sensing laser cutter of the present invention in an exemplary production environment with workpiece shown. 
     FIG. 2 is an partial isometric view of the automatic edge sensing laser cutter of the present invention with workpiece shown. 
     FIG. 3 is an isometric view of the automatic edge sensing laser cutter of the present invention. 
     FIG. 4 is a cross-sectional side view showing the general internal structure of the automatic edge sensing laser cutter of the present invention. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     In the following detailed description, certain specific terminology will be employed for the sake of clarity, but it is to be understood that the same is not intended to be limiting and should not be so construed inasmuch as the invention is capable of taking many forms and variations within the scope of the appended claims. 
     A device employing the automatic edge sensing laser cutter of the present invention is illustrated in FIG. 1. A cutting head  2  is configured to facilitate the removal of overhanging portions of upper laminate  4  and lower laminate  6  from workpiece  8 . Cutting head  2  is rotatably fastened to arm  10 . Arm  10  can comprise a robot arm manipulator, and enables cutting head  2  to move about workpiece  8 , while upper laminate  4  and lower laminate  6  are removed. As head  2  approaches a comer of workpiece  8 , head  2  swivels to align head  2  with the next edge of the workpiece. In a preferred embodiment, head  2  is capable of delivering a laser beam  20  shown in FIG&#39;S.  3  and  4  while rotating 360 degrees as it trims the perimeter of workpiece  8 . 
     In an exemplary production environment, workpiece  8  is loaded onto feed rollers  12  and contacts sheet stop  16 . Clamps  14  operate to position and square workpiece  8 . Clamps  14  can preferably operate by pneumatic or electronic means, although such operation is not critical to the claimed invention. 
     Workpiece  8  may also be fastened to a multi-axis positioning system. Such systems are commercially available and may be driven by a multiplicity of electric motors controlled by a small computerized controller, or alternatively, by electromechanical actuation of a multiplicity of cams and mechanical devices which move workpiece  8  in a proper pattern about laser beam  20  at appropriately controlled rates. 
     With reference to FIG. 2, sensor  18  is disposed on head  2 . Sensor  18  generates signals corresponding to the distance of head  2  from the edge  30  of workpiece  8 . The signals are interpreted by a microprocessor, Programmable Logic Controller (PLC), relays, or similar devices, and are used to control the motion of head  2 . The device controlling the motion of head  2  can be adjusted to vary the degree of sensitivity. In many production settings for example, small chips or nicks in the edge  30  of workpiece  8  may be insignificant. In these situations, the cutting motion of head  2  would generally be unaffected. Sensor  18  may be connected to a microprocessor or similar device through connector  46 , shown in FIGS. 2 and 3. 
     Sensor  18  can comprise a variety of forms and may be disposed at a variety of locations while remaining within the scope of the invention. However, the sensor  18  is preferably located in a position that allows sensor  18  to supply sufficient information to trim laminate  4  and laminate  6  from workpiece  8 . In a preferred embodiment, sensor  18  is an ultrasonic sensor that precedes cutting beam  20  as the beam  20  moves along its cutting path. Such ultrasonic sensors capable of gauging features such as distance are commercially available, and hence the details are not given. 
     FIG. 3 shows the path of laser beam  20  into cutting head  2 . Beam  20  can be produced by several types of commercially available lasers. However, a carbon dioxide laser is likely to be the least expensive in both initial cost and cost over the required lifetime. Beam  20  can exit head  2  at either or both of the upper element  32  and lower element  34 . The beam exiting lower element  34  terminates in vertex  54 . The beam exiting upper element  32  terminates in vertex  56 . When beam  20  exits lower element  34  and upper element  32  simultaneously, it is desirable to focus vertex  54  and vertex  56  to improve trimming performance. 
     In a preferred embodiment, head  2  is adjustable for trimming workpieces with a variety of thicknesses. Head  2  can be adjusted by moving top focus  44  relative to lower element  34 . Upper element  32  moves in the same direction as top focus  44  and in proportion to top focus  44 . Workpiece thicknesses of 0.125″ to 1″ are common dimensions, although workpieces with other thicknesses can also be trimmed using the present invention. 
     FIG. 4 illustrates a cross-sectional view showing the internal operation of a preferred cutting head  2  as it trims laminate  4  and laminate  6  from workpiece  8 . The portion of laminate  4  and  6  extending past edge  30  can be discarded as waste  48  and  50 . Sensor  18 , shown in FIGS. 1-3 detects the location of edge  30  of workpiece  8  relative to head  2 . The position of head  2  is automatically adjusted based on information provided by sensor  18  shown in FIGS. 2 and 3. 
     Beam  20  enters head  2  near the area that head  2  is attached to arm  10 . Beam  20  travels through beam splitter  22  which divides a portion of beam  20  into beam  36  and a portion of beam  20  into beam  38 . In a preferred embodiment, head  2  is rotatably fastened to arm  10 . Due to the rotational nature of head  2  relative to arm  10 , it is desirable for the beam splitter to operate in all directions. Accordingly, beam splitter  22  is preferably an omni-directional beam splitter configured to evenly divide energy from beam  20  as head  2  rotates. 
     Beam  36  travels through focusing optic  52  and upper element  32 , where it trims laminate  4  at the junction  40  of the workpiece  8  and laminate  4 . In contrast, beam  38 . contacts mirror  24 , mirror  26 , and mirror  28 , and travels through focusing optic  72  and lower element  34 . Beam  38  then trims laminate  6  at the junction  42  of workpiece  8  and laminate  6 . Mirrors  24 ,  26 , and  28  are preferably zero phase shift mirrors, which are commercially available and known in the art. 
     With reference to FIG. 1, an exemplary pattern of operation of the present invention will now be discussed. FIG. 1 shows a generally rectangular workpiece  8 , although the present invention also performs well with irregular shaped workpieces, (circles, arcs, polygons, etc.). 
     After loading workpiece  8  onto rollers  12 , workpiece  8  is secured by stop  16  and clamp  14 . Next, cutting head  2 , is oriented to workpiece  8  at corner  58  so that sensor  18  detects an edge of workpiece  8 . It may be necessary to adjust head  2  for the thickness of workpiece  8 . Head  2  can be adjusted using top focus  44 , shown in FIGS. 2-4. The laser is then activated to produce beam  20 , shown in FIGS. 3 and 4. Head  2  is positioned so vertex  54  and vertex  56  will be aligned at the junction of the laminated material and the edge of workpiece  8 . Head  2  begins traveling along side  60  (the cutting axis shown in FIG. 1) at a relatively constant velocity toward comer  62 . If the sensor detects a workpiece with a curved perimeter, arm  10  adjusts to move either forward or backward in a direction perpendicular to the cutting axis. As bead  2  travels, overhanging laminate  4  and  6  are removed from side  60 . 
     When head  2  reaches corner  62 , sensor  18  no longer detects the edge of workpiece  8  and the laser is deactivated. Next, head  2  rotates approximately 90 degrees until sensor  18  detects the edge of workpiece  8  along side  64 , Side  64  becomes the new cutting axis and the laser is again activated to produce beam  20 . Head  2  begins traveling at a generally constant velocity toward corner  66 . Arm  10  may also adjust to the profile of side  64  by moving head  2  in a direction perpendicular to the cutting axis. 
     When head  2  reaches the corner  66 , sensor  18  no longer detects the edge of workpiece  8  and the laser is deactivated. Next, head  2  rotates approximately 90 degrees until sensor  18  detects the edge of workpiece  8  along side  66 . Side  66  becomes the new cutting axis and the laser is again activated to produce beam  20 . Head  2  begins traveling at a generally constant velocity toward comer  68 . Arm  10  may also adjust to the perimeter profile of side  66  by moving head  2  in a direction perpendicular to the cutting axis. 
     When head  2  reaches the comer  68 , sensor  18  no longer detects the edge of workpiece  8  and the laser is again deactivated. Next, head  2  rotates approximately 90 degrees until sensor  18  detects the edge of workpiece  8  along side  70 . Side  70  becomes the new cutting axis and the laser is again activated to produce beam  20 . Head  2  begins traveling at a generally constant velocity toward comer  58 . Arm  10  may also adjust to the profile of side  70  by moving head  2  in a direction perpendicular to the cutting axis. 
     When head  2  reaches corner  58 , sensor  18  no longer detects the edge of workpiece  8  and the laser is again deactivated. Head  2  then rotates 270 degrees to the start position. Workpiece  8  can be removed and a new workpiece can be loaded onto rollers  12 . 
     With regard to the foregoing description, it is to be understood that changes may be made in detail, especially in matters of the construction materials employed and the shape, size and arrangement of the parts without departing from the scope of the present invention. For example, it will be appreciated that the head  2  may work in conjunction with one laser or multiple lasers. Similarly, multiple cutting heads could be utilized, with each cutting head trimming a unique laminate. It is intended that the specification and depicted aspects be considered exemplary only, with a true scope and spirit of the invention being indicated by the broad meaning of the following claims.