Abstract:
A downdraft exhaust cutting and shuttle table mechanism includes a cutting area and a loading area, which includes first and second elongated, horizontally disposed cutting tables which are shuttled into and out of a cutting area which includes a material cutting assembly positioned therein, the shuttle table mechanism including horizontal and vertical table movement devices which are operative to move the first and second cutting tables forwards and backwards between the cutting area and a loading area generally adjacent thereto and a vertical table movement device operative to move the first and second cutting tables upwards and downwards, the vertical and horizontal table movement devices cooperating to move each of the first and second cutting tables from a loading position generally horizontally forwards into the cutting area for cutting of material mounted thereon then generally horizontally backwards into the loading area to a position generally underneath the other of the cutting tables which has been lifted into the elevated loading position, thereby cycling the first and second cutting tables to alternate use of each.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    Not Applicable. 
       STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
       [0002]    Not applicable. 
       BACKGROUND OF THE INVENTION 
       [0003]    1. Field of the Invention 
         [0004]    The present invention relates generally to cutting tables and, more particularly, to a downdraft exhaust cutting and shuttle table mechanism which includes first and second elongated, horizontally disposed cutting tables which are shuttled into and out of a cutting area which includes a material cutting assembly positioned therein, the shuttle table mechanism including horizontal and vertical table movement devices which are operative to move the first and second cutting tables forwards and backwards between the cutting area and a loading area generally adjacent thereto and a vertical table movement device operative to move the first and second cutting tables upwards and downwards, the overall device further including an exhaust duct positioned in the cutting area beneath the first and second cutting tables and a slag collector also positioned beneath the cutting table for collecting slag falling downwards from the first and second cutting tables, the vertical and horizontal table movement devices cooperating to move each of the first and second cutting tables from a loading position while in the loading area then generally horizontally forwards into the cutting area for cutting of material mounted thereon then generally horizontally backwards into the loading area to a position generally underneath the other of the first and second cutting tables which has been lifted into the elevated loading position, thereby cycling the first and second cutting tables to alternate use of each of the cutting tables. 
         [0005]    2. Description of related Art 
         [0006]    Cutting tables for cutting a work piece such as a metal plate typically include a table surface for supporting the work piece. A cutting torch assembly, which may include a plasma cutting torch, a laser cutting torch, an oxy-fuel cutting torch, or the like, may be suspended above the cutting table for cutting the metal plate. In the majority of instances, the cutting torch is computer-controlled to follow a programmed pattern or template, thus cutting the metal plate in an automated sequence, one which is easily repeatable for cutting of numerous identical pieces from a series of metal plates. 
         [0007]    Several different types of cutting table assemblies have been proposed in the prior art, including those shown in U.S. Pat. Nos. 6,039,915, 6,165,410 and 5,435,525, all of which provide various devices for removing undesirable fumes and slag from the vicinity of the cutting table by utilizing one or more exhaust ducts for evacuating the fumes and which further include a slag removal system for removing slag. However, it has been found that due to advances in the cutting systems being currently used in the industry, heavier and thicker pieces of steel may be cut using these new systems, and this results in more smoke, more waste, more light, and more noise being produced than has been produced previously, and the downdraft cutting table assemblies found in the prior art do not provide adequate solutions to the problems encountered during use of these new improved cutting systems. 
         [0008]    It has been found that the most significant impediment to use of these improved cutting systems is that the loading and unloading of the heavier and thicker plates and parts has become an ever more difficult and daunting procedure. There is, therefore, a need for an improved downdraft exhaust cutting mechanism which will speed the loading and unloading process, yet which will also allow for the use of the exhaust ducting and slag collection devices which are known and used in the industry in order to provide a safe and efficient yet significantly improved cutting table mechanism. 
         [0009]    However, one of the significant problems encountered in the prior art is that the vast majority of shuttle tables currently in use do not provide accommodation for the use of partitioned downdraft exhaust systems or for slag collection devices since the movement of the shuttle cutting tables takes precedence in the design and functional considerations of operation of the device. It has been found that these features are of critical importance in improving the operational efficiency of cutting tables, and therefore it is of critical importance to include these features in a shuttle table. 
         [0010]    Therefore, an object of the present invention is to provide an improved downdraft exhaust cutting and shuttle table mechanism which significantly improves the speed and efficiency of cutting table processes. 
         [0011]    Another object of the present invention is to provide an improved downdraft exhaust cutting and shuttle table mechanism which includes first and second elongated, horizontally disposed cutting tables which are horizontally and vertically moveable to move the first and second cutting tables from a loading position upwards or downwards while in the loading area, then generally horizontally forwards into a cutting area for cutting of material mounted thereon then generally horizontally backwards into the loading area to a position generally underneath the other of the first and second cutting tables which has been lifted into the elevated loading position. 
         [0012]    Yet another object of the present invention is to provide an improved downdraft exhaust cutting and shuttle table mechanism which will effectively double the efficiency of cutting table processes by permitting preparation and loading of one of the cutting tables while the other of the cutting tables is supporting material being cut thereon in the cutting area of the present invention. 
         [0013]    Still another object of the present invention is to provide a downdraft exhaust cutting and shuttle table mechanism which continually rotates the cutting tables such that the cutting table having material recently cut thereon is positioned beneath the cutting table having material to be cut mounted thereon in order to prevent material and debris from falling from the cut plate onto the uncut plate thus mandating removal thereof prior to cutting of the uncut material, thus greatly increasing the efficiency of operation of the present invention. 
         [0014]    Another object of the present invention is to provide an improved downdraft exhaust cutting and shuttle table mechanism which provides a protective enclosure surrounding the cutting area of the invention to protect the external surroundings from light, heat and debris produced during the cutting process, thus rendering the surrounding facility far safer and more conducive to improved worker health. 
         [0015]    Finally, an object of the present invention is to provide a downdraft exhaust cutting and shuttle table mechanism which is relatively straightforward and functional in design and construction and which is safe, effective and efficient in use. 
       BRIEF SUMMARY OF THE INVENTION 
       [0016]    The present invention provides a downdraft exhaust cutting and shuttle table mechanism including a shuttle table mechanism having first and second elongated, horizontally disposed cutting tables having opposite ends and opposite sides, a horizontal table movement device operative to alternatively move each of the first and second cutting tables forwards and backwards in a generally horizontal plane between a cutting area and a loading area generally adjacent to the cutting area and a vertical table movement device in the loading area, the vertical table movement device operative to move the first and second cutting tables upwards and downwards in a generally vertical plane. A material cutting assembly is positioned in the cutting area over the first and second cutting tables, the material cutting assembly being moveable along the length thereof to cut material positioned on the first and second cutting tables upon one of the first and second cutting tables being moved into the cutting area. An exhaust duct is positioned in the cutting area beneath the first and second cutting tables when the cutting tables are positioned in the cutting area, the exhaust duct including an exhausting device for exhausting air from within the exhaust duct. A slag collector is positioned in the cutting area beneath the first and second cutting tables when those cutting tables are positioned in the cutting area for collecting slag which is created by the material being cut which falls downwardly from the first and second cutting tables, the slag collector being selectively moveable along the length of the first and second cutting tables. Finally, the vertical and horizontal table movement devices cooperate to move the first and second cutting tables from a loading position upwards or downwards while in the loading area then generally horizontally forwards into the cutting area for cutting material mounted thereon then generally horizontally backwards into the loading area to a position generally underneath the other of the first and second cutting tables which has been lifted into the elevated loading position such that the first and second cutting tables are cycled to alternatively use each of the cutting tables for cutting of material placed thereon. 
         [0017]    The present invention as thus described provides a substantial improvement over those devices found in the prior art. For example, because the present invention includes two cutting tables which cycle with one another to move into and out of the cutting area, the efficiency of the present invention is effectively doubled over those devices and methods found in the prior art. Furthermore, because the first and second cutting tables are cycled in such a manner as to keep the recently cut material positioned underneath the new material to be cut, transfer of waste and debris from the previously cut material to the ready to be cut material is generally prevented, thus ensuring that cutting of the new material will not be degraded through the undesirable presence of debris on the material to be cut. Finally, because the present invention not only includes the shuttle table mechanism which increases the efficiency of operation of the present invention but also includes the exhaust duct and slag collector for removing harmful fumes and collecting waste and debris from underneath the cutting area, the combination of all three elements greatly improves the operating efficiency of the present invention over those devices found in the prior art, and therefore represents a significant improvement over those devices found in the prior art. It is therefore seen that the present invention provides numerous advantages over those devices and methods found in the prior art which are apparent from the present disclosure. 
         [0018]    It is to be further understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not necessarily restrictive of the invention as claimed. The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate at least one embodiment of the invention and together with the general description, serve to explain the principles of the invention. 
         [0019]    Additional aspects of the invention, together with the advantages and novel features appurtenant thereto, will be set forth in part in the description which follows, and in part will become apparent to those skilled in the art upon examination of the following, or may be learned from the practice of the invention. The objects and advantages of the invention may be realized and attained by means of the instrumentalities and combinations particularly pointed out in the appended claims. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0020]      FIG. 1  is a front perspective view of downdraft exhaust cutting and shuttle table mechanism of the present invention; 
           [0021]      FIG. 2  is a rear perspective view of downdraft exhaust cutting and shuttle table mechanism of the present invention; 
           [0022]      FIG. 3  is a detailed side elevational view of the cutting area of the present invention; 
           [0023]      FIG. 4  is a detailed front elevational view of the cutting area of the present invention; 
           [0024]      FIGS. 5 ,  6  and  7  are detailed perspective views of one of the vertical table movement devices of the present invention; 
           [0025]      FIGS. 8 and 9  are, respectively, a side elevational view and a detailed side elevational view of the cutting area of the present invention showing the exhaust duct, dampers, partitions and the slag removal device; and 
           [0026]      FIGS. 10 ,  11 ,  12 ,  13  and  14  are side elevational views of the present invention showing the cycling process which cycles the first and second cutting tables between the loading and cutting areas of the present invention. 
       
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
       [0027]    The downdraft exhaust cutting and shuttle table mechanism  10  of the present invention is shown best in  FIGS. 1-4  as including two main sections, the first being a cutting area  12  wherein metal material is cut and the second being a loading area  70  which is external of the cutting area yet generally adjacent thereto. In the preferred embodiment, the cutting area  12  would be generally similar to the cutting units described with particularity in connection with U.S. Pat. Nos. 6,039,915 and 6,165,410, the cutting area  12  including a cutting area enclosure  14  having sidewalls  16   a  and  16   b,  a front wall  18 , rear wall  20  and a plurality of viewing windows  22  formed in each of the sidewalls  16   a  and  16   b,  front wall  18  and rear wall  20 . Housed within the cutting area enclosure  14  is the material cutting assembly  24  which, in the preferred embodiment, would be of conventional variety such as a plasma cutter, laser cutter or oxy-fuel cutting torch, the material cutting assembly  24  being mounted on rails  26   a  and  26   b  to permit the material cutting assembly  24  to be moved over the entire metal piece  180  which is to be cut. It is further preferred that the material cutting assembly  24  also be transversely moveably mounted on a material cutting assembly support frame  28 , as shown best in  FIG. 4 , the material cutting assembly support frame  28  being moveably mounted on the rails  26   a  and  26   b  such that the material cutting assembly  24  may be moved into any preferred position above the metal piece  180  to be cut, thus facilitating the cutting of that metal piece  180 . 
         [0028]    A cutting table support frame  30  is housed within the cutting area enclosure  14 , the cutting table support frame  30  including an upper cutting table support section  32  which includes a pair of spaced-apart generally horizontal rails  34   a  and  34   b  which run the length of the cutting table support frame  30 , the horizontal rails  34   a  and  34   b  being generally L-shaped in cross-sectional shape, although the particular size and shape of the horizontal rails  34   a  and  34   b  is not particularly critical to the present invention so long as the horizontal rails  34   a  and  34   b  provide a sturdy and stable support structure for the first and second cutting tables  80   a  and  80   b  as will described later in this disclosure. The lower section  36  of the cutting table support frame  30  is shown best in  FIGS. 3 and 9  as including two main elements which have been used in connection with previous downdraft exhaust cutting tables, the first being the exhaust duct system  40  and the second being the slag removal device  50 . In the preferred embodiment, exhaust duct  40  would be provided with a plurality of spaced-apart openings  42  formed in the sidewalls thereof, with each of the spaced-apart openings  42  being selectively closed by a normally closed damper  44 . In operation, the dampers  44  would be opened to permit smoke and fume-laden air to pass into the interior of the duct  40  through the spaced-apart openings  42 , and the dampers  44  may be opened by any convenient means such as by cams, cylinders, etc., which only peripherally form a part of this invention and disclosure. The smoke and fume-laden air then would pass through the exhaust duct  40 , being drawn therethrough via a blower/filter unit  46  or the like, and then being directed out of the cutting are enclosure  14  as has been taught in prior disclosures. 
         [0029]    The present invention also includes a plurality of pivotably mounted partition gates  250  which extend outwardly from the sides of the exhaust duct  40  in a spaced-apart relationship. The upper ends of the partition gates  250  are pivotally secured by any convenient means to the upper cutting table support section  32 . The partition gates  250  normally hang generally vertically, as illustrated in  FIG. 9 , but may be pivotally moved to the deflected or open position illustrated in the right portion of  FIG. 9 . Each of the partition gates  250  extends generally adjacent the floor surface, thus providing a series of partitions which essentially form a series of ventilation zones so that smoke and fume-laden air pulled through the cutting tables may be drawn downwardly between the partition gates  250  and into one of the openings  42 . Appropriate means is provided for opening the dampers  44  in response to the position of the cutting torch and the slag removal device. The novel downdraft exhaust cutting table thus creates ventilation zones which are successively opened when the cutting torch assembly is positioned thereabove to ensure that polluted air created by the cutting torch assembly is exhausted downwardly into the exhaust duct  40 . 
         [0030]    The slag removal device  50  is positioned underneath the cutting table support frame  30  and would preferably include a moveably mounted frame  52  which is driven forward and backward underneath the cutting table support frame  30  via a drive motor  54  which drives a shaft  56  having a gear  58  mounted on its outer end which intermeshes with a gear rack  60  positioned on cutting table support frame  30  and running the length thereof. Mounted on the forward part of frame  52  is a slag collection blade  62  which, when driven via drive motor  54 , collects and pushes slag falling underneath the cutting table support frame  30  into a slag collection trough  64  positioned at the forward end of cutting area enclosure  14 , as shown best in  FIG. 1 . Alternatively, the slag collection blade  62  may be replaced by a slag collection bucket (not shown) which would be positioned underneath the material cutting assembly  24  at the location where the metal piece  180  is being cut in order to “catch” much of the slag falling downwards through the cutting table support frame  30 . In either case, however, it is important to note that the slag removal device  50  functions to quickly and efficiently collect and remove slag from underneath the cutting table support frame  30  which is produced during the cutting process. It should also be noted that the slag removal device  50  is designed to pass under and through the partition gates  250  as shown in  FIG. 6 , and the operation of the slag removal device  50  in traveling underneath the first and second cutting tables  80   a  and  80   b  when they are positioned in the cutting area  12  and pushing the partition gates  250  out of the way when passing therethrough is clearly shown in  FIG. 6 . 
         [0031]    The important functional features of the present invention, however, will now be described as being focused generally in the loading area  70  of the present invention. Specifically, the loading area includes a shuttle table mechanism  72  which includes a shuttle cutting table support frame  74  having a pair of shuttle cutting table support rails  76   a  and  76   b  which run the length of the shuttle cutting table support frame  74  and are generally colinearly aligned with the horizontal rails  34   a  and  34   b  on cutting table support frame  30 , thereby creating a pair of generally continuous rails on which the cutting tables may travel. Moveably mounted on the shuttle cutting table support rail  76   a  and  76   b  are first and second cutting tables  80   a  and  80   b,  each of which are generally identically to one another and would include an external generally rectangular frame  82  and the plurality of cross-brace support struts  84  which extend between opposite sides of the external frame  82  and provide support for metal pieces  180  to be supported thereon. Many different sizes, shapes and styles of cutting tables are currently used in the metal cutting industry, and therefore it is to be understood that numerous modifications to the particular size, shape and configuration of the cutting tables  80   a  and  80   b  are to be incorporated in this invention. However, it is to be noted that each of the cross-brace support struts  84  would preferably be configured to present a minimal top surface area, in the preferred embodiment, the cross-brace support struts  84  would be upright, generally parallel plates as shown in  FIG. 9 , and the metal piece  180  to be cut would be supported on the top edges of the cross-brace support struts  84 . This allows the first and second cutting tables  80   a  and  80   b  to not only support the metal to be cut, but due to the spacing of the cross-brace support struts  84  and the air gaps therebetween, the downdraft function of the present invention is enabled as air may be drawn through the first and second cutting tables  80   a  and  80   b  when they are in the cutting area  12 , down into the exhaust duct  40 , and out through the exhaust duct  40 . It is to be further noted that because each of the first and second cutting tables  80   a  and  80   b  are generally identical to one another, the following description of the elements of the first cutting table  80   a  should be understood to apply equally to the second cutting table  80   b.    
         [0032]    Mounted on and extending outwards from external frame  82  are a plurality of wheeled frame supports  86   a,    86   b,    86   c,  and  86   d  each of which would preferably include a pair of rollably mounted wheels  88   a  and  88   b  which engage the shuttle cutting table support rails  76   a  and  76   b,  and it is via the wheeled frame supports  86   a - d  that the first and second cutting table  80   a  and  80   b  are able to roll on the shuttle cutting table support rails  76   a  and  76   b  and in turn, the horizontal rails  34   a  and  34   b  on cutting table support frame  30  in the cutting area  12 . 
         [0033]    For lifting and lowering the first and second cutting tables  80   a  and  80   b,  four synchronized independent lift stations  100   a,    100   b,    100   c  and  100   d  are positioned generally adjacent to the four corners of the shuttle cutting table support frame  74 , as shown best in  FIGS. 2 ,  5 - 7  and  6 - 8 . In the preferred embodiment, each of the independent lift stations  100   a - d  would be generally identical to one another, and therefore the description of independent lift station  100   a  should be understood to apply equally to the remaining independent lift stations  100   b,    100   c  and  100   d.  Independent lift station  100   a  preferably would be constructed as a pneumatic, hydraulic or mechanical lifting station which includes a central lift pillar  102  which is vertically moveably mounted within lift station frame  104 . The central lift pillar  102  is moved up and down via the aforementioned pneumatic, hydraulic or mechanical lifting mechanism  106 , control of which would generally be performed by a computerized control system  110  which independently controls each of the independent lift stations  100   a - d  yet which also synchronizes the lifting of those central lift pillars  102  of each of the independent lift stations  100   a - d  to lift and support each of the first and second cutting tables  80   a  and  80   b.    
         [0034]    Mounted on the inner wall of the central lift pillar  102  are two wheeled frame support engagement rails  108   a  and  108   b  which are vertically spaced from one another along the inner side of central lift pillar  102  and which have a cross-sectional shape generally similar to the cross-sectional shape of shuttle cutting table support rails  76   a  and  76   b.  In fact, the wheeled frame support engagement rails  108   a  and  108   b  on the central lift pillar  102  are aligned with the adjacent shuttle cutting table support rail  76   a  when the central lift pillar  102  is in certain extended lift positions such that the wheeled frame support engagement rails  108   a  and  108   b  are aligned with and complete the shuttle cutting table support rail  76   a  such that the wheeled frame support engagement rails  108   a  and  108   b  align with and complete the shuttle cutting table support rail  76   a  so that the first and second cutting tables  80   a  and  80   b  may roll along the shuttle cutting table support rails  76   a  and  76   b  in a generally continuous manner. The true intended function of the wheeled frame support engagement rails  108   a  and  108   b  is best shown in  FIGS. 10-14 , however, in that the first and second cutting tables  80   a  and  80   b,  when positioned in the loading area  70  on shuttle table mechanism  72 , have their attached wheeled frame supports  86   a - d  supported on the wheeled frame support engagement rails  108   a  or  108   b,  depending on the height at which the central lift pillar  102  of independent lift station  100   a  is positioned. This permits the sequence shown in  FIGS. 6-8  to be accomplished, specifically that when the first cutting table  80   a  is ready for use with a metal piece  180  to be cut being placed thereon, the independent lift stations  100   a - d  are positioned such that the supporting wheeled frame support engagement rail  100   a  is aligned with the shuttle cutting table support rail  76   a  and  76   b.  This permits the first cutting table  80   a  to be rolled forwards into the cutting area  12  of the downdraft exhaust cutting and shuttle table mechanism  10  via the horizontal table movement device  120 , which, in the preferred embodiment, would be a motor connected to one of the wheels  88   a  and  88   b  on wheeled frame support  86   a  or another such appropriate horizontal table movement device which shuttles the first and second cutting tables  80   a  and  80   b  between the loading area  70  and cutting area  12 . 
         [0035]    Once the first cutting table  80   a  is positioned in the cutting area  12 , a retractable locking arm  110  mounted on the cutting table support frame  30  is moved into contact with the first cutting table  80   a  to fulfill two main purposes, one, to releasably lock the first cutting table  80   a  on the cutting table support frame  30  to prevent movement thereof during the cutting process, and two, to ground the first cutting table  80   a  so that proper cutting via the material cutting assembly  24  may be performed. The retractable locking arm  110  maintains a highly accurate horizontal placement of the table in respect to the cutting apparatus and may eliminate the requirement for “homing” or separate positioning steps by the cutting device. 
         [0036]    The cutting process then can begin, with the accompanying use of exhaust duct. 40  and slag removal device  50  as has been disclosed previously.  FIGS. 10-14  best illustrate the transfer sequence of the first and second cutting tables  80   a  and  80   b  in that simultaneous with the cutting of the metal piece  180  on first cutting table  80   a,  second cutting table  80   b,  supported on another of the wheeled frame support engagement rails  108   b,  is positioned via independent lift stations  100   a - d  to have another metal piece  182  placed thereon for a new cutting sequence to begin and then is raised upwards via independent lift stations  100   a - d  until the wheeled frame support engagement rail  108   b  is aligned with the shuttle cutting table support rail  76   a  and  76   b.  The first cutting table  80   a  is then moved back from the cutting area  12  to the loading area  70 , as shown in  FIG. 10 , the first cutting table  80   a  being moved into the loading area  70  over the shuttle cutting table support rail  76   a  and  76   b  until the wheeled frame support  86   a - d  rests on the wheeled frame support engagement rails  108   b  of independent lift stations  100   a - d.  At this point, the first cutting table  80   a,  having the metal piece  180  which was cut still mounted thereon, is positioned beneath the second cutting table  80   b  thus preventing debris from falling off of the first cutting table  80   a  onto the second cutting table  80   b  since it is positioned above the first cutting table  80   a.  The independent lifting stations  100   a - d  would then be lowered to align the wheeled frame support engagement rails  108   a  on which second cutting table  80   b  is resting with the shuttle cutting table support rail  76   a  and  76   b,  as shown in  FIG. 11 , and at this point second cutting table  80   b  may be moved from the loading area  70  to cutting area  12  via horizontal table movement device  120 . 
         [0037]    As shown in  FIG. 12 , the independent lifting stations  100   a - d  would then be raised to align the wheeled frame support engagement rails  108   b  on which first cutting table  80   a  is resting with the shuttle cutting table support rail  76   a  and  76   b,  and the first cutting table  80   a  is rolled forwards or rearwards as shown in  FIG. 13  to move the first cutting table  80   a  off of the wheeled frame support engagement rails  108   b.  The independent lifting stations  100   a - d  would then be lowered to align the wheeled frame support engagement rails  108   a  with the shuttle cutting table support rails  76   a  and  76   b.  The first cutting table  80   a  would then be moved back onto the wheeled frame support engagement rails  108   a,  as shown in  FIG. 14 , and the first cutting table  80   a  may then be lifted above the returning second cutting table  80   b,  and the entire process then continues with the first and second cutting tables  80   a  and  80   b  being cycled to keep the clean cutting surface above the already dirty cutting surface at all times. 
         [0038]    Of course, it is to be noted that numerous additions, modifications and substitutions may be made to the downdraft exhaust cutting and shuttle table mechanism  10  of the present invention which fall within the intended broad scope of the appended claims. For example, the precise size, shape and construction materials used in connection with the present invention may be modified or changed so long as the intended functional features of the invention are neither significantly degraded nor destroyed. Furthermore, the precise nature of the independent lift stations  100   a - d  may be modified or changed so long as the intended function of lifting, supporting and cycling the first and second cutting tables  80   a  and  80   b  is generally maintained. Also, it should be noted that although the present invention has been described as being used in connection with two cutting tables, it is a relatively simple matter to provide three or even four cutting tables for use with the system of the present invention, with the only significant modification being to increase the number of wheeled frame support engagement rails  108   a  and  108   b  mounted on the inner wall of central lift pillar  102  of independent lift stations  100   a - d.  Also, the present invention further contemplates that the shuttle cutting table support rail  76   a  and  76   b  of the device can be extended to facilitate the transfer of the cutting tables to another production process and/or material handling step, which may be deemed beneficial in some situations. Finally, it should be noted that although the present invention has been described as including various features which were disclosed in previously issued patents, it is believed that the use of those features in connection with the shuttle table mechanism  72  of the present invention will greatly enhance and improve efficiency of the present invention. 
         [0039]    There has, therefore, been shown and described a downdraft exhaust cutting and shuttle table mechanism  10  which accomplishes at least all of its intended objectives.