Patent Publication Number: US-2005140071-A1

Title: Table for use in cutting and including an automatically moving collection system

Description:
CROSS REFERENCE TO RELATED APPLICATION  
      The present application claims the benefit of Provisional Patent Application No. 60/532,848, which was filed on Dec. 24, 2003, and is entirely incorporated herein by reference. 
    
    
     BACKGROUND OF THE INVENTION  
      The present invention pertains to tables for supporting workpieces that are being cut and, more particularly, to such tables with moving down-draft and/or slag collection systems.  
      U.S. Pat. No. 4,058,299 discloses a cutting table with a suction unit that is positioned below the material being cut and is movable with the cutters, which are positioned above the material being cut. U.S. Pat. No. 6,165,410 discloses a cutting torch positioned above an elongated table and movable along the length of the table to cut material positioned on the table. An elongated exhaust duct is positioned beneath the table and runs parallel to the length of the table. The exhaust duct has a plurality of horizontally spaced-apart exhaust openings formed therein which are each closed by a respective movable damper. Successive dampers are opened as a slag collection bucket moves along the length of the table below the cutting torch.  
      Although tables for use in cutting and including moving collection systems are known, there is always a need for improved systems.  
     BRIEF SUMMARY OF SOME ASPECTS OF THE INVENTION  
      One aspect of the present invention relates to a table that is for supporting a workpiece while the workpiece is being cut in a manner that produces residue such as fumes and/or slag. The table includes a pervious partition having an upper surface for supporting the workpiece while the workpiece is being cut. The pervious partition has a length extending in a longitudinal direction and a width extending in a lateral direction which is perpendicular to the longitudinal direction. The table further includes a receptacle positioned below the pervious partition for collecting at least some of the residue which passes through the previous partition. The receptacle is mounted for back and forth movement in the longitudinal direction relative to the pervious partition, so that the receptacle can be moved into optimal positions beneath the pervious partition for collecting residue which passes through the previous partition. At least one actuator is mounted for causing the back and forth movement of the receptacle.  
      In accordance with one aspect of the present invention, a gantry is mounted for back and forth movement in the longitudinal direction above the pervious partition, a carriage is mounted to the gantry for back and forth movement in the lateral direction, and a cutting head is carried by and movable with the carriage. The cutting head is for cutting the workpiece while the workpiece is supported by the pervious partition. In accordance with this aspect, the receptacle defines a width which extends in the longitudinal direction and is substantially less than the length of the pervious partition, and a controller is operative for causing the actuator to operate in an advantageous manner. More specifically, and in one mode of operation, the system operates so that the receptacle moves back and forth in the longitudinal direction so as to remain substantially vertically aligned with the cutting head while the cutting head moves back and forth in the longitudinal direction.  
      In accordance with one aspect of the present invention, the receptacle is part of a down-draft system (e.g., a down-draft blower system) that is at least for drawing fumes downward through the pervious partition. In accordance with this aspect, the down-draft system further includes a duct that extends in the longitudinal direction. The duct can be positioned below the receptacle so that the receptacle extends at least partially across an upper surface of the duct. The duct is in fluid communication with the receptacle so that at least some of the fumes can be drawn along a fume-drawing flow path which extends through the pervious partition and then into the duct by way of the receptacle. In one example, the receptacle preferably extends completely across an upper surface of the duct in the lateral direction. This arrangement can be advantageous because, for example, it is space-efficient and allows the length of the receptacle to be substantially matched to the width of the pervious partition, which optimizes the collecting of residue (e.g., fumes and slag) in the receptacle.  
      In accordance with one aspect of the present invention, the table includes a frame having a plurality of beams that extend in the longitudinal direction and carry the pervious partition, and it is preferred for the beams to also carry the receptacle. In accordance with one example of this aspect, each of the beams includes an integral flange which protrudes in the lateral direction and extends in the longitudinal direction, and the receptacle is carried by the flanges for facilitating the back and forth movement of the receptacle. More specifically, and in one example, the receptacle includes a plurality of upper rolling mechanisms which respectively travel along upper surfaces of the flanges, and a plurality of lower rolling mechanisms which respectively travel along lower surfaces of the flanges, and at least one of these rolling mechanisms is connected to and driven by the actuator. Preferably the frame includes structures which are respectively mounted below the beams and support the beams so that the beams are elevated above the floor which supports the frame. At least partially as a result, the receptacle is likewise preferably elevated above the floor.  
      In accordance with one aspect of the present invention, the receptacle includes both a container defining an upper opening, and an upwardly open trough for collecting any slag passing through the pervious partition. In accordance with one embodiment of the present invention, the trough is removably mounted to the container so that the trough can be lifted out of the container to facilitate removal of slag and any other residue which has accumulated in the trough. In accordance with one embodiment of the present invention, the table does not include the down-draft system, but it does include the automatically moving receptacle/trough for collecting slag and any other residue which passes through the pervious partition. In accordance with another embodiment in which the receptacle/trough is part of the down-draft system, the trough is removably mounted to the container so that: the trough at least partially covers the upper opening of the container, and a portion of the trough and a portion of the container are in opposing face-to-face relation so that a chamber is at least partially defined therebetween. Further in accordance with this embodiment, the trough defines inlet opening(s) through which the fume-drawing flow path enters the chamber, and the container defines an outlet opening through which the fume-drawing flow path exits the chamber.  
      In accordance with one aspect of the present invention, the down-draft system further includes a passageway by way of which the duct is in the fluid communication with the receptacle. That is, the fume-drawing flowpath extends through the passageway, with the receptacle being upstream from the passageway and the duct being downstream from the passageway. In accordance with one example of this aspect, the passageway is mounted to the receptacle so that the passageway extends downwardly from a bottom surface of the receptacle and moves with the receptacle during the back and forth movement of the receptacle. The outlet end of the passageway penetrates the duct by sliding beneath and opening a portion of a longitudinally extending flap of the duct. Preferably a length of the duct that is penetrated by the mouth, and most preferably the entire length of the duct that is penetrated by the mouth, is lying on, and fastened to, the floor which supports the frame of the table. The outlet end of the passageway can be equipped with an elongate protrusion which preferably seals against, or is at least in close proximity to, a seating surface of the duct. A margin of the flap engages the seating surface while the flap (e.g., a portion of the flap) is closed. The seating surface can extend obliquely, and the outlet end of the passageway can have obliquely angled leading edges for lifting the flap away from the seating surface of the duct. In addition, the outlet end of the passageway can define multiple oppositely oriented curves for advantageously enhancing the opening and closing of the flap.  
      In accordance with one aspect of the present invention, the back and forth movement of the receptacle is controlled by a controller to provide at least two modes of operation. In an automatic mode of operation, the receptacle preferably moves so as to remain in the same vertical plane with the cutter of the gantry-style cutting system associated with the table. In a manual mode of operation, the position of the receptacle can be changed independently of the gantry-style cutting system. The controller for the receptacle can be the same controller that is used for controlling the gantry-style cutting system, or it can be a portion of that controller, or some how in communication with that controller. On the other hand, the controller for the receptacle can be a controller that is separate from the controller for the gantry-style cutting system, such as by being a separate programmable logic controller that communicates with a sensor mounted for determining the position of the gantry-style cutting system.  
      In accordance with one aspect of the present invention, a switch is positioned for detecting when the gantry-style cutting system travels beyond an end of the table, such as for being serviced. When the switch is initially triggered by one of the uprights of the gantry-style cutting system as it moves past a point proximate an end of the table, the controller responds to the triggering by ceasing the automatic movement of the receptacle. In accordance with this example, the automatic movement of the receptacle is reinitiated when the switch is triggered as a result of the gantry-style cutting system traveling from a position that is distant from the table, back to a position in which the gantry-style cutting system is vertically aligned with the table.  
      Each of, and combinations of, the foregoing and other aspects of the present invention provide advantages. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
      Having thus described the invention in general terms, reference will now be made to the accompanying drawings, which are not necessarily drawn to scale, and wherein:  
       FIG. 1  is a partially cut-away, partially schematic, pictorial view which illustrates a workpiece that is positioned on a table so that the workpiece can be cut by an associated gantry-style cutting system, in accordance with an exemplary embodiment of the present invention;  
       FIG. 1   a  is an isolated, cross-sectional view of portions of a representative carrying mechanism that is for facilitating back and forth movement of a receptacle of a down-draft system of the table of  FIG. 1 , with the cross-section taken along line  1   a - 1   a  of  FIG. 1 ;  
       FIG. 2  is an isolated, exploded pictorial view of the receptacle;  
       FIG. 3  is an isolated, cross-sectional view of the receptacle in an assembled configuration, with the cross-section taken substantially along line  3 - 3  of  FIG. 2 ;  
       FIG. 4  is an isolated pictorial view of a passageway carried by the receptacle, in accordance with the exemplary embodiment of the present invention;  
       FIG. 5  is an isolated, partially exploded view of a representative section of a duct of the down-draft system of  FIG. 1 ;  
       FIG. 6  is an isolated, pictorial view of the passageway mated to the duct, with a portion of the duct cut away, in accordance with the exemplary embodiment of the present invention;  
       FIG. 7  is a partially schematic, cross-sectional view taken along line  7 - 7  of  FIG. 6 , with an additional portion of a flap cut away to clarify the view, and further illustrating the duct laying upon and fastened to a floor which supports the table and cutting system, in accordance with the exemplary embodiment of the present invention;  
       FIG. 8  is an isolated, pictorial view of a representative portion of a channel of a duct of a down-draft system, in accordance with a second embodiment of the present invention; and  
       FIG. 9  is an isolated, cross-sectional view of the duct of the down-draft system of the second embodiment of the present invention, with the flap of the duct fully closed, and further illustrating the duct laying upon and fastened to a floor which supports the table and cutting system of the second embodiment of the present invention. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION  
      The present invention now will be described more fully hereinafter with reference to the accompanying drawings, in which some, but not all embodiments of the invention are shown. Indeed, the invention may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will satisfy applicable legal requirements. Like numbers refer to like elements throughout.  
      As illustrated in  FIG. 1 , a workpiece  10  is positioned on a table  12  having a down-draft system, so that the workpiece can be cut by a cutting system  14  in a manner which produces residue such as fumes. The workpiece  10  is preferably a piece of metal, although other workpieces are also within the scope of the present invention. Although a wide variety of cutting systems are within the scope of the present invention, the cutting system  14  of  FIG. 1  includes: a conventional gantry  16  that is positioned above the table  12  and can travel back and forth in a longitudinal direction along tracks  18 , a conventional carriage  20  mounted to the gantry for back and forth movement in a lateral direction which is perpendicular to the longitudinal direction, and a conventional cutting head  22  that is for cutting the workpiece  10 . The cutting head  22  is carried by and movable with the carriage  20 . Although only one cutting head  22  and one carriage  20  are shown in  FIG. 1 , there can be multiple carriages and accompanying cutting heads carried by the same gantry  16 . In accordance with the exemplary embodiment of the present invention, the cutting head  22  is for plasma arc cutting, but alternatively it could be for cutting with a burning fuel such as acetylene, cutting with a laser cutting head, or performing any other type of cutting which creates fumes or other types of residue which can be collected using one or more features of the table  14 .  
      In accordance with the exemplary embodiment of the present invention, the table includes a pervious partition  24  having an upper surface for supporting the workpiece  10  while the workpiece is being cut. The pervious partition  24  can be metal grating, a series of metal slats, or any other structure or structures suitable for supporting the workpiece  10  while it is being cut using the cutting system  14 . The pervious partition  24  is supported by a frame which is preferably constructed of steel and includes longitudinally extending beams  26  that are spaced apart from one another in the lateral direction. The pervious partition  24  preferably extends uniformly for substantially the entire length and width of the frame, is replaceable, and can be removed from the frame in sections. A large portion of the pervious partition  24  has been cut away in  FIG. 1  to clarify the view. In accordance with the exemplary embodiment of the present invention, the beams  26  are I-beams which are respectively mounted atop pedestals  28 . The pedestals  28  support the beams  26  above the floor  30  which supports the table  12 . Other shapes of beams  26  are also within the scope of the present invention.  
      The down-draft system of the exemplary embodiment is for drawing downward and collecting at least some of the fumes resulting from operation of the cutting system  14 . The down-draft system includes a conventional air mover  32  which is preferably equipped with a conventional filter or filtering system. The air mover  32  is in fluid communication with a duct  34  and a receptacle  36  for creating a fume-drawing flow path which extends into the receptacle, through the duct, and to the air mover, while the air mover is operating. That is, fumes resulting from operation of the cutting system  14  are drawn into the receptacle  36 , through the duct  34 , and to the air mover  32 , while the air mover is operating and the receptacle is at least about vertically aligned with the gantry  16 .  
      In one mode of operation of the exemplary embodiment of the present invention, the receptacle  36  automatically moves back and forth in the longitudinal direction with the gantry  16 , so that the receptacle remains optimally positioned for enabling the down-draft system to collect at least some of the fumes and any other residue resulting from operation of the cutting system  14 . In accordance with the exemplary embodiment of the present invention, the receptacle  36  extends at least partially across an upper surface of the duct  34 , and preferably the receptacle extends completely across an upper surface of the duct in the lateral direction. This arrangement is advantageous because, for example, it is space-efficient and allows the length of the receptacle  36  to be substantially matched to the width of the pervious partition  24 , which optimizes the drawing down of fumes and other residue into the receptacle. This also helps to maximize the amount of non-gaseous residue, such as slag, that is collected in the receptacle  36 . Other arrangements are also within the scope of the present invention.  
      As partially illustrated in  FIGS. 1 and 1  a, the back and forth movement of the receptacle  36  is preferably facilitated, in part, by four carriage mechanisms  38  which carry the receptacle  36  along the beams  26 . As partially illustrated in  FIG. 2 , the carriage mechanisms  38  are preferably respectively located proximate the four corners of the receptacle  36 . More specifically, the receptacle  36  includes opposite ends which are spaced apart from each other in the lateral direction, and there are preferably two of the carriage mechanisms  38  at each of the opposite ends. The receptacle  36  includes opposite sides which are spaced apart from each other in the longitudinal direction, and at each end of the receptacle, the carriage mechanisms  38  are preferably proximate the opposite sides.  
      As best understood with reference to  FIG. 1   a , and in accordance with the exemplary embodiment of the present invention, each of the carriage mechanisms  38  includes upper and lower rolling mechanisms  40 ,  42 . A representative one of the carriage mechanisms  38  will now be described. The upper rolling mechanism  40  is connected to the receptacle  36  by a shaft and rolls along the upper surface of a lower, inwardly-oriented flange  44  of the respective I-beam  26 . The lower rolling mechanism  42  is connected to the receptacle  36  by a shaft and rolls along the lower surface of the respective flange  44 . In accordance with the exemplary embodiment of the present invention, gear racks  46  are respectively mounted to the lower surfaces of the inwardly-oriented flanges  44  of the beams  26 , and the lower rolling mechanisms  42  are gears which are respectively meshed with the gear racks.  
      Referring to  FIGS. 1 and 2 , at least one of the gears  42  is driven by an actuator  48  which is preferably in the form of an electric motor. In some situations another of the gears  42  may also be driven by another actuator  48  which is in the form of an electric motor, or the like. As illustrated in  FIG. 2 , the two driven gears  42  are proximate one side of the receptacle  36 . As best understood with reference to  FIG. 3 , the two gears  42  proximate the other side of the receptacle  36  are not driven, but they are both mounted to the same axle  50 .  
      In accordance with the exemplary embodiment of the present invention, for each beam  26 , its flange  44 , which cooperates with (e.g. carries) two of the carriage mechanisms  38 , is an integral part of the beam as a result of the beam being originally formed (e.g., such as by extrusion and/or forging and/or stamping and/or bending) to include the flange. This advantageously enhances the strength of the table  12  and provides for efficient assembly of the table and down-draft system.  
      As best understood with reference to  FIG. 2 , the receptacle  36  preferably includes a container  52  fitted with a trough  54  and passageway  56 . The container  52  defines an upper opening  58 , and the trough  54  is removably mounted to the container so that the trough at least partially covers the upper opening. The trough  54  is upwardly open for collecting any heavy residue, such as slag, that falls through the pervious partition  24  ( FIG. 1 ) as a result of operation of the cutting system  14  ( FIG. 1 ). The container  52  preferably includes deflectors  60  which extend obliquely for deflecting any slag falling thereupon into the trough  54 . As best understood with reference to  FIG. 1 , the deflectors  60  advantageously function in a manner which seeks to prevent non-gaseous residue from accumulating upon the flanges  44  that the carriage mechanisms  38  travel upon.  
      Referring to  FIGS. 2 and 3 , the trough  54  fits into and closes the upper opening  58  of the container  52 . In this closed configuration which is illustrated in  FIG. 3 , a portion of the trough  54  and a portion of the container  52  are in opposing face-to-face relation, so that a chamber  62  is defined therebetween. The trough  54  includes two laterally extending series of inlet openings  64  that are open to the chamber  62 . Each of the inlet openings  64  is preferably covered by deflector  66 . Each of the inlet openings  64  of one of the series is hidden from view behind their respective deflectors  66  in  FIGS. 1 and 2 . The deflectors  66  advantageously function in a manner which seeks to prevent non-gaseous residue from passing into the chamber  62  within the receptacle  36 . In accordance with another embodiment of the present invention, a separate deflector  66  is not used for each inlet opening  64 . Rather, for each series of inlet openings  64 , a single, continuous deflector strip covers the inlet openings of the series.  
      As best understood with reference to  FIGS. 2 and 3 , the fume-drawing flow path extends through the inlet openings  64  of the trough  54 , into the chamber  62 , and then out of the chamber via an outlet opening  68  ( FIG. 2 ) in the bottom of the container. As illustrated in  FIG. 2 , the outlet opening  68  is preferably located at a position that is between and distant from the opposite ends of the container  52 . In accordance with the exemplary embodiment of the present invention, this advantageously seeks to substantially equalize the flow into each of the inlet openings  64 . Other arrangements of the outlet opening  68  are also within the scope of the present invention.  
      In accordance with the exemplary embodiment of the present invention, and as best understood with reference to  FIGS. 1, 6  and  7 , the receptacle  36  is in the fluid communication with the duct  34  by way of the passageway  56 , which extends downwardly from the container  52 . The passageway  56  is preferably mounted to the container  52  for traveling back and forth as part of the receptacle  36 . On the other hand, the passageway  56  can be characterized as being a component which is not a part of the receptacle but which is mounted to and travels with the receptacle. As best understood with reference to  FIGS. 2-4 , an upstream portion of the passageway  56  is preferably in the form of a rectangular box  72  which is mounted to a bottom surface of the container  52 . The box  72  preferably has an upper inlet opening  74  ( FIG. 2 ) which is in direct communication with the chamber  62  ( FIG. 3 ) within the receptacle  36 . The outlet end of the passageway  56  is preferably in the form of a wide mouth  76  which is mounted to a sidewall of the box  72 . The mouth  76  communicates with the interior of the box  72  through an outlet opening  78  ( FIG. 3 ) of the box which is defined through the sidewall of the box and surrounded by the mouth.  
      In accordance with the exemplary embodiment of the present invention, and as best understood with reference to  FIGS. 3 and 4 , the mouth  76  includes a planar bottom surface  80  and a curved top surface  82 , each of which extend between opposite sides of the mouth. The opposite sides of the mouth  76  are preferably mirror images of one another. The curved top surface  82  is shaped so that each of the sides of the mouth  76  tapers so as to become narrower at increasing distance from the other side. Each of the sides of the mouth  76  preferably terminates at a protrusion  84 . As best understood with reference to  FIG. 3 , proximate each of the sides of the mouth  76 , the curved top surface  82  preferably defines two curves respectively having centers of curvature C 1  and C 2  which are positioned on opposite sides of the bottom surface  80  of the mouth. The curves of the top surface  82  advantageously enable the mouth  76  to interact with the duct  34  ( FIGS. 1 and 5 - 7 ) in an at least generally leak-free manner, as will be discussed in greater detail below. Differently shaped mouths are also within the scope of the present invention.  
      Referring to  FIG. 5 , the duct  34  of the exemplary embodiment of the present invention includes a longitudinally extending channel  86  that is open (i.e., defines a channel opening  88 ) along one side. The channel  86  can be reinforced by internal upright supports  90 . In accordance with the exemplary embodiment of the present invention, the duct  34  extends for, and is substantially uniform along, the entire length of the table  12 , and likewise the channel opening  88  extends along, and is substantially uniform along, the entire length of the table. That is, and in accordance with the exemplary embodiment of the present invention, the channel  86  includes only one channel opening  88 , which extends for substantially the entire length of the table  12 .  
      Preferably the channel  86  and the other components of the table  12  and down-draft system of the present invention which have been discussed above in this Detailed Description section of this discloser are constructed of metal, except as would be understood by those of ordinary skill in the art. For example, any conventional filter associated with the conventional air mover  32  ( FIG. 1 ) may include fiberglass or paper filtering mediums, or any other type of conventional filter medium.  
      As illustrated in  FIG. 5 , the open side of the channel  86  has an upper, obliquely angled mounting surface  92 , and a lower, obliquely angled seating surface  94 . An upper margin of an elongate flexible flap  96  is mounted to the mounting surface  92 . The flexible flap  96  preferably is a single piece which is substantially uniform along its length and extends for substantially the entire length of the table  12 , for covering and closing the channel opening  88 . The flap  96  can be reinforced with a series of reinforcing supports  98  and secured to (i.e., sealed against) the mounting surface  92  by fasteners and a reinforcing strip  100 . The flexible flap  96  is preferably a polymeric material, and is most preferably natural gum rubber, or the like. The reinforcing supports  98  are preferably constructed of metal.  
      The lower margin  102  of the flap  96  preferably seats securely against the seating surface  94  of the channel  86 . In accordance with the exemplary embodiment of the present invention, the resilience of the flap  96 , gravity, and the partial vacuum within the duct  34  (which occurs while the air mover  32  is operating) bias the flap toward the configuration in which the lower margin  102  of the flap seats against and is sealed against the seating surface  94 . Similarly, opposite ends of the flap  96  seal against other seating surfaces (not shown) of the channel  86  or are otherwise sealed against the channel so that the flap is for substantially closing and sealing the only inlet opening (i.e., the channel opening  88 ) to the channel. It is preferred for the air mover  32  ( FIG. 1 ) to create a sufficient partial vacuum so that the lower margin  102  of the flexible flap  96  remains securely sealed against the seating surface  94 , except where the mouth  76  ( FIGS. 2-4 ,  6  and  7 ) is currently separating the lower margin of the flap  96  from the seating surface  94 .  
      Referring primarily to  FIG. 6 , during operation of the down-draft system, it is preferred for the entirety of the lower margin  102  of the flap  96  to remain in a closed configuration (e.g., seated/sealed against the seating surface  94  of the channel  86 ), except where the mouth  76  causes the flap to be in an opened configuration (e.g., the mouth is positioned between the lower margin of the flap and the seating surface of the channel). More specifically, the mouth  76  moves with the receptacle  36  ( FIGS. 1-3 ) in the longitudinal direction relative to the duct  34  so that the mouth sequentially engages portions of the flap  96  and thereby temporarily moves the respective portion of the flap from the closed configuration to the open configuration, so the interior of the mouth is open to the interior of the duct. That is, the fume-drawing flow path extends through the mouth  76  and travels with the mouth.  
      As illustrated in  FIG. 6 , one side of the mouth  76  separates the lower margin  102  of the flap  96  from the seating surface  94  ( FIG. 5 ) of the channel  86  as the receptacle  36  ( FIGS. 1-3 ) and the mouth move toward one end of the table  12  ( FIG. 1 ). Likewise the other side of the mouth  76  separates the lower margin  102  of the flap  96  from the seating surface  94  of the channel  86  as the receptacle  36  and the mouth move toward the other end of the table. As best understood with reference to  FIG. 7 , for each of the sides of the mouth  76 , it is preferred for an obliquely angled leading edge  104  of the protrusion  84  to be in opposing face-to-face relation with, and in contact with or only slightly separated from, the obliquely angled seating surface  94 , so that the leading edge lifts the lower margin  102  ( FIGS. 5 and 6 ) of the flap  96  from the seating surface. The protrusions  84  and their leading edges  104  advantageously seek to prevent the sides of the mouth  76  from becoming jammed against the flap  96 . However, other measures can be taken to prevent such jamming.  
      Referring to  FIGS. 3 and 7 , a protrusion  106  extends downwardly from the bottom surface  80  of the mouth  76 , in accordance with the exemplary embodiment of the present invention. The protrusion extends  106  in the longitudinal direction from proximate one of the sides of the mouth  76  to the other of the sides of the mouth, and a lower edge of the protrusion  106  is at least proximate the seating surface  94  of the duct  34  to restrict bypass flow. The protrusion  106  is preferably a strip of polymeric material, and most preferably a strip of natural gum rubber, or the like, which is attached to the bottom surface of the mouth  76  with a piece of angle iron, or the like.  
      As best understood with reference to  FIGS. 5 and 7 , a length of the duct  34  that is penetrated by the mouth  76 , and most preferably the entire length of the duct that is penetrated by the mouth, is lying on the floor  30  which supports the frame of the table  12  ( FIG. 1 ), in accordance with the exemplary embodiment. It is preferred for the portion of the duct  34  that is lying upon the floor  30  to be fastened to the floor by fasteners  108 , such as bolts or screws, which extend through the lower surface of the channel  86  and into the floor. Alternatively, the fasteners  108  can extend through brackets connected to the channel  86 , as illustrated in  FIG. 9 . If the floor  30  is not sufficiently level, shims can be used between the channel  86  and the floor and/or between the frame&#39;s pedestals  28  ( FIG. 1 ) and the floor to bring the mouth  76  and the opening  88  of the channel  86  into good alignment with one another.  
      Aspects of operation of the table  12  and its down-draft system will now be described, in accordance with the exemplary embodiment of the present invention. The back and forth movement of the receptacle  36  is preferably controlled by a controller to provide at least two modes of operation. In an automatic mode of operation, the receptacle  36  moves simultaneously with the gantry  16  so that the center line of the receptacle substantially remains in the same vertical plane with the cutter  22  carried by the gantry. In a manual mode of operation, the position of the receptacle  36  can be changed independently of the gantry-style cutting system  14 . The manual mode may be used to park the receptacle  36  at a position distant from the gantry  16 , such as at an end of the table  12 . With the receptacle  36  parked in this manner, the portion of the pervious partition  24  above the receptacle can be removed so that nongaseous residue collected in the trough  54  can be removed from the trough. This can be facilitated, in part and for example, by lifting the trough  54  out of and away from the container  52 .  
      The controller  110  ( FIG. 1 ) for the receptacle  36  can be the same controller that is used for controlling the gantry-style cutting system  14 , or it can be a portion of that controller, or some how in communication with that controller. On the other hand, the controller for the receptacle  36  can be a controller that is separate from the controller  110  for the gantry-style cutting system  14 , such as by being a programmable logic controller that communicates with a sensor mounted for determining the position of the gantry  16 .  
      In accordance with one version of the exemplary embodiment of the present invention, a switch  112  ( FIG. 1 ) is positioned for detecting when the gantry  16  travels beyond an end of the table  12 , such as for being serviced. When the switch  112  is initially triggered by one of the uprights carrying the gantry  16  as it moves past a point proximate an end of the table  12 , the controller  110  responds to the triggering of the switch by ceasing automatic movement of the receptacle  36 . In accordance with this example, the automatic movement of the receptacle  36  is reinitiated when the switch  112  is triggered as a result of the gantry  16  traveling from a position that is distant from the table  12 , back to a position in which the gantry is vertically aligned with the table.  
      In accordance with the exemplary embodiment of the present invention, the longitudinally extending side beams  26  and laterally extending end beams of the table  12  are preferably respectively releasably fastened to one another with nuts and bolts, or the like, while the table is fully assembled. Thus, the table  12  and associated equipment can be conveniently shipped in a disassembled configuration in which the beams (e.g., beams  26 ) are unbolted from one another. The receptacle  36  can be conveniently shipped in its fully assembled configuration, with its associated components mounted thereto, such as the carriages  20  and the passageway  56 . Thereafter, the table can be conveniently assembled.  
      An alternative embodiment of the present invention is like the exemplary embodiment, except that this alternative embodiment further includes engagement mechanisms (not shown) for aiding in closing the flap  96  of the duct  34 . The engagement mechanisms are mounted for traveling with the receptacle  36  in the longitudinal direction relative to the flap  96 . The engagement mechanisms sequentially engage the portions of the flap  96  that are adjacent the ends of the mouth  76  to urge the flap to the closed configuration. It is preferred for one of the engagement mechanisms to be proximate each of the sides of the mouth  76 . The flap  96  extends under the first engagement mechanism and then over the first side of the mouth  76 , and the flap extends over the second side of the mouth and then under the second engagement mechanism. The engagement mechanisms can each be in the form of a roller.  
      Another alternative embodiment of the present invention resembles the exemplary embodiment, except that this alternative embodiment further includes doors (not shown) at the ends of the receptacle  36  so that the slag can be removed from the receptacle via the doors. In this embodiment, a bottom surface of the receptacle  36  can be inclined downwardly in the lateral direction so that slag which falls into the receptacle will have a tendency to travel toward the doors, or will at least be easier to urge toward the doors.  
      In accordance with another alternative embodiment of the present invention, the table includes three longitudinally extending I-like beams, with pervious partitions thereabove. The three beams preferably extend parallel to one another in the longitudinal direction and are spaced apart from one another in the lateral direction. A first down-draft system is associated with an outer one of the beams (i.e., first beam) and a middle one of the beams (i.e., middle beam), and a second down-draft system is associated with the other outer beam (i.e., second beam) and the middle beam. Preferably the carriage mechanisms of the receptacle of the first down-draft system respectively travel upon: the lower flange on the side of the first beam which faces the middle beam, and the lower flange on the side of the middle beam which faces the first beam. Preferably the carriage mechanisms of the receptacle of the second down-draft system respectively travel upon: the lower flange on the side of the second beam which faces the middle beam, and the lower flange on the side of the middle beam which faces the second beam. Each of the down-draft systems of this alternative embodiment can be identical to the down-draft system of the exemplary embodiment, although it may be preferred for the ducts of the down-drafts systems of this alternative embodiment to be in fluid communication with a common header that is connected to a single air mover.  
      A second embodiment of the present invention is identical to the exemplary embodiment of the present invention, except for variations noted herein and variations that will be apparent to those of ordinary skill in the art in view of this disclosure. As best understood with reference to  FIG. 8 , rather than using separate reinforcing supports  98  ( FIG. 5 ) as in the exemplary embodiment, the reinforcing supports  98 ′ are integral with the channel  86 ′ of the duct  34 ′ ( FIG. 9 ) of the down-draft system, in accordance with the second embodiment of the present invention. More specifically in accordance with the second embodiment, the reinforcing supports  98 ′ are part of a grid  114  that is cut into the material of the channel  86 ′ and is integral with the channel. As best understood with reference to  FIG. 9 , the reinforcing supports  98 ′ of the grid  114  preferably extend obliquely, as extensions of the mounting surface  92  ( FIG. 8 ). In addition, optional lower portions of the grid  114  extend vertically and contact the floor of the channel  86 ′ in a manner that provides support to the reinforcing supports  98 ′.  
      Many modifications and other embodiments of the inventions set forth herein will come to mind to one skilled in the art to which these inventions pertain having the benefit of the teachings presented in the foregoing descriptions and the associated drawings. Therefore, it is to be understood that the inventions are not to be limited to the specific embodiments disclosed and that modifications and other embodiments are intended to be included within the scope of the appended claims. Although specific terms are employed herein, they are used in a generic and descriptive sense only and not for purposes of limitation.