Abstract:
A workstation having an adjustable support structure is disclosed. The workstation includes a beam, a position locking apparatus, and a workpiece-supporting device slideable along the beam to a position where it is locked by the locking apparatus. The locking apparatus is configured to exert a constraining force proportional to a load force. Also disclosed is a workstation including a means for supporting a workpiece, a means for supporting a means for supporting the workpiece at a selected distance above a floor, and a means for frictionally securing the means for supporting the workpiece to the means for supporting the means for supporting the workpiece. Also disclosed is a workstation including a vertically disposed support member and at least one tooling plate assembly including a position securing apparatus for securing the tooling plate assembly in a selected vertical position and including wedging surfaces cooperating in frictionally securing the tooling plate assembly to the support member, wherein the securing force corresponds to the loading force.

Description:
[0001]    This application claims priority of U.S. application Ser. No. 60/200,788, filed Apr. 28, 2000. 
     
    
     
         [0002]    FIELD OF THE INVENTION  
           [0003]    The present invention generally relates to the field of workstations, and more particularly to heavy duty workstations for modular assembly cells having work surfaces of which the height above a supporting floor is adjustable  
         BACKGROUND OF THE INVENTION  
         [0004]    Workstations, also known as manufacturing cells, are often used in manufacturing facilities for operations on workpieces and for assembling parts to form assemblies or subassemblies. Workstations may be configured in a manner similar to that of conventional workbenches, typically having a generally flat work surface or platform for holding a workpiece while performing manufacturing operations such as fabricating, drilling, assembling, etc. Workstations may also be configured to include manufacturing tooling (e.g., an air cylinder, a power drill, screwdriver, or nut runner, riveting or spot-welding apparatus, etc.), instrumentation and/or control apparatus (e.g., for monitoring and controlling a manufacturing process or characteristic of the workpiece), parts and product bins, trays, conveyors, etc.  
           [0005]    In the past, workstations were typically designed and built for a particular manufacturing application or procedure. In most cases, the height of the work platform is fixed. The workstation or cell is normally constructed by mounting a support structure to a table. The table may be constructed from welded steel, or assembled from aluminum extrusion or steel tubing. The workstation tooling is typically mounted to the support structure in a fixed location above the work platform at an average height normally required for the assembly operation. Since each workstation is normally associated with a particular manufacturing function and a unique workpiece, the height of the support structure necessarily varies for nearly every workstation. The type of the tooling also varies from workstation to workstation. Hence, numerous different designs for the workstation support structure are often required to accommodate a single manufacturing line.  
           [0006]    Furthermore, different workstation operators may be assigned at different times to work at a particular workstation, and all operators are obviously not the same height. Since a particular workstation may be used for assembling different products having different heights at different times, it is therefore desirable for the height of the working surface to be adjustable above the floor. Preferably, the height would be infinitesimally adjustable, or at least adjustable in small increments to accommodate all operators. Most fixed-height workstation constructions are not easily re-configurable to make them adjustable in height. The fixed working height of most known workstations creates a less than ideal ergonomic situation for the operators.  
           [0007]    Some commercially available workstations are designed to have work surfaces adjustable in height. However, such workstations have numerous disadvantages. First, adjustable-height workstations have generally been of relatively small capacities in terms of weight and force that the adjustable work surface can support, e.g., often having a support capacity of less than 1000 pounds. Second, those few heavy-duty workstations that are height-adjustable are usually only adjustable in large increments. Third, such heavy-duty workstations have been relatively expensive. Fourth, those workstations that are infinitesimally adjustable in height are usually not heavy duty, and therefore tend to slip under increased loads. Fifth, known workstations often require a difficult or involved procedure to adjust the height to a different operator or workpiece. Sixth, workstations that are provided with tooling for manufacturing a particular product generally had the tooling affixed in a manner that makes it difficult to remove and replace with different tooling for another product. These disadvantages present significant difficulties in implementation of flexible manufacturing cell concepts and practices.  
           [0008]    need, therefore, exists for an infinitesimally adjustable-height work surface for a workstation that is very rugged in construction to accommodate relatively heavy workpieces and large forces, that can be adjusted quickly and easily to accommodate flexible manufacturing cell environments, and that is relatively inexpensive and easy to manufacture.  
         OBJECTS AND SUMMARY OF THE INVENTION  
         [0009]    It is an object of the present invention to provide a workstation having a work surface that is infinitesimally adjustable in height with respect to a supporting floor.  
           [0010]    It is another object of the present invention to provide an adjustable-height workstation that is ruggedly constructed and has a workpiece weight capacity and manufacturing force capacity exceeding 1000 pounds.  
           [0011]    It is a further object of the present invention to provide a workstation in which an increase in a load force causes a corresponding increase in a work surface securing force to prevent slippage.  
           [0012]    It is still another object of the present invention to provide a rugged, adjustable-height workstation that is relatively inexpensive to manufacture.  
           [0013]    It is yet another object of the present invention to provide a workstation that facilitates the use of manufacturing tooling that can be easily removed and replaced to enable manufacturing of different products at the same workstation.  
           [0014]    Accordingly, the present invention provides a workstation that is designed to be both height-adjustable for different operators and re-configurable for different products. In the preferred embodiment, the base structure of the workstation is constructed from a relatively inexpensive weldment and a vertical column composed of a standard structural steel I-beam. Only minimal machining of this I-beam is required to manufacture the workstation. A steel tooling plate is vertically disposed and mounted to the vertical column using channels such that it is able to slide vertically. A horizontal platform, along with the necessary support structure, is mounted to the vertical tooling plate to provide the work surface for the workpiece. Alternatively, a horizontal platform can be used that supports a conveyor when a part transport system is required. A locking wedge mechanism is located between the vertical column and the vertically disposed tooling plate to frictionally engage the surface of the column. This locking wedge allows the tooling plate to be positioned anywhere within a range along the vertical column and then locked. The vertical adjustment can be made using a hydraulic jack permanently attached to the workstation, or using a crane or forklift. The locking wedge mechanism allows for extremely heavy tooling or workpieces to be securely affixed to the vertical tooling plate, while maintaining its ability to be readily adjusted along the vertical column.  
           [0015]    Another embodiment of the present invention provides a support structure for a work surface, the support structure including a beam having a length and a surface, a position securing apparatus, and a workpiece-supporting device. The workpiece-supporting device is configured to be slidably restrained to the beam and to be secured to the beam in selected positions along the length of the beam by the position securing apparatus. The position securing apparatus is configured to constrain the workpiece-supporting device in the selected position notwithstanding the presence of a load force having a line of action parallel to the longitudinal axis of the beam. The position securing apparatus is further configured to exert a constraining force that is proportional to the load force.  
           [0016]    Still another embodiment of the present invention relates to a workstation including a means for supporting a workpiece, and a means for supporting the means for supporting the workpiece at a selected distance above a floor. The workstation also includes a means for frictionally securing the means for supporting the workpiece to the means for supporting the means for supporting the workpiece at the selected distance. The means for frictionally securing includes a first surface frictionally bearing upon a second surface.  
           [0017]    Yet another embodiment of the present invention relates to a workstation including a vertically disposed support member and at least one generally vertically disposed tooling plate assembly. The tooling plate assembly includes a tooling plate and a position securing apparatus for securing the tooling plate in a selected vertical position with respect to and upon the support member. The position securing apparatus includes first and second wedging surfaces configured to cooperate in frictionally securing the tooling plate to the support member. The first and second wedging surfaces are disposed to be engaged in a downward direction of movement of one of the first and second wedging surfaces. An increase in downward force upon the tooling plate increases engagement of the first wedging surface with the second wedging surface and increases frictional securing force, the securing force thereby corresponding to the loading force. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0018]    The features of the present invention which are believed to be novel are set forth with particularity in the appended claims. The invention itself, however, together with further objects and advantages thereof, may best be understood by reference to the following description when taken in conjunction with the accompanying drawings in which:  
         [0019]    [0019]FIG. 1 is a perspective view of an exemplary embodiment of the invention showing a workstation having a work surface adjustable in height above a supporting floor, and having parts bins disposed for rear loading and unloading;  
         [0020]    [0020]FIG. 2 is a perspective view of the embodiment of the workstation shown in FIG. 1, except having the parts bins replaced by a transversely disposed conveyor;  
         [0021]    [0021]FIG. 3 is a front elevational view of the adjustable height workstation shown in FIG. 1;  
         [0022]    [0022]FIG. 4 is a side elevational view of the workstation shown in FIG. 1;  
         [0023]    [0023]FIG. 5 is a top plan view of the workstation shown in FIG. 2;  
         [0024]    [0024]FIG. 6 is a partial, cross-sectional view of the tooling plate and wedge assembly taken across line  6 - 6  of FIG. 3;  
         [0025]    [0025]FIG. 7 is a partial, front elevational view of the tooling plate and wedge assembly illustrated in FIG. 6; and  
         [0026]    [0026]FIG. 8 is an exploded, partial perspective view of the wedge assembly illustrated in FIGS. 6 and 7. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0027]    Referring now to the drawings, FIGS. 1 through 5 show a workstation  10  including a fixed support structure  12  and a movable support structure  14 . Fixed support structure  12  comprises a base  16  and a support member  18 . Since the preferred method of performing assembly operations is in the vertical direction, the support member  18  in the preferred embodiment is comprised of a beam or column that is configured to extend vertically up from the base  16 . Movable support structure  14  functions as a backbone assembly and comprises a tooling plate  20 , and typically includes either a worktable  22  or tooling  24 , or both, affixed thereto. As known in the art, tooling  24  is used to perform machining or assembly operations upon a workpiece  26  mounted or resting upon worktable  22 . Tooling  24  could be attached to or associated with either fixed support structure  12  or movable support structure  14 , depending upon the particular workstation application. In the preferred embodiment, tooling plate  20  is oriented vertically instead of horizontally, since it is typically much easier to mount tooling  24  to a vertically oriented tooling plate in most workstation applications. However, as will be discussed below, the present invention is not limited to those workstations having a vertical tooling plate configuration.  
         [0028]    Optional accessories may be attached to either fixed support structure  12  or movable support structure  14 . In FIGS.  1 - 5 , a safety guard structure  28 , constructed from aluminum extrusion, is affixed to tooling plate  20  such that it moves vertically with the tooling plate. A process control and display unit (CDU)  30  may be attached to the guard structure  28 . In another embodiment, the guard structure  28  is attached to the fixed support structure  12 , either by mounting it to base  16  or to I-beam support member  18 . In this embodiment, the guard structure  28  would be lifted away from the workstation  10  in order to change the tooling for a different application.  
         [0029]    Other accessories can also be attached to either fixed support structure  12  or movable support structure  14 , such as parts and product containers. The narrow width of I-beam support member  18  allows for parts to be fed on either side of the tooling plate  20 . The configuration of FIG. 1 is also useful for modular assembly cells that have the required parts brought to the operator in bins  32 . These bins are loaded into the workstation from the rear so that the assembly operation is not interrupted. In FIG. 2, a portion of the production line apparatus, shown as a workpiece conveyor  34 , is designed to pass through the guard structure  28  for a different assembly application. Hence, as can now be appreciated, workstation  10  of the present invention is very flexible in its configuration such that it can readily be adapted for a wide variety of modular cell applications.  
         [0030]    As shown in FIG. 3, base  16  is preferably configured as a welded steel fabrication supported by leveling screws  36  positioned upon sole plates  38 . The sole plates are securely mounted to the floor in compliance with Occupational Safety and Health Administration (OSHA) regulations. Base  16  may be fabricated of low-carbon steel plate and/or structural steel sections (e.g., channels or plates).  
         [0031]    Support member  18  is comprised of an elongated structural member, such as a structural steel beam or column. In the preferred embodiment, support member  18  is a steel beam having wide flanges, such as a standard “I-beam” or “H-beam” that is typically used for columns in building construction. In an alternative embodiment (not shown), support member  18  may be constructed from any conventional wide flange beam, C-shaped or S-shaped beam stock, square or rectangular cross-section steel tube, etc. Support member  18  could also be comprised of a pair of separate parallel rails or ways, as known in the art. Support member  18  is rigidly affixed (e.g., by welding, using bolts, with brackets, etc.) to base  16 . Additional gussets (not shown) may be added, if desired, to further secure support member  18  to base  16 .  
         [0032]    Movable support structure  14  is slidably engaged upon fixed support structure  12 . As can most easily be seen in FIG. 4, tooling plate  20  in the preferred embodiment is attached to the vertical I-beam support member  18  using guiding assemblies  40  that grasp the inner edges  18   b  of the beam flanges in such a way that the tooling plate  20  can slide up and down. As will be described below, it is the combination of this guide assembly and a wedge assembly that engages with the I-beam and locks the tooling plate in a fixed position.  
         [0033]    In the preferred embodiment of the present invention, tooling plate  20  is fabricated from a steel plate. Horizontal worktable  22  is affixed to the vertically oriented tooling plate  20 , as most clearly illustrated in FIGS.  3 - 6 . Worktable  22  is also constructed of a steel plate. Worktable  22  is disposed on a pair of triangularly shaped support brackets  42  that are mounted to tooling plate  20  and worktable  22  using bolts, as shown in FIG. 4. Hence, worktable  22  will slide vertically along support member  18  with tooling plate  20 . Tooling plate  20  also includes a plurality of threaded apertures to receive standard machine screws (not shown) for attachment of tooling  24 .  
         [0034]    As shown in FIGS. 1 and 4, both the tooling  24  and the worktable  22  are mounted to tooling plate  20  such that the entire movable support structure backbone assembly 14 moves vertically along the fixed I-beam support member  18 . A major benefit of this configuration is that the workstation is easily retooled, i.e., when the modular cell system needs to be retrofitted for a new product, the new tooling is assembled on a second tooling plate and the entire backbone assembly unit is quickly exchanged for the old assembly unit. This is accomplished by removing the guard structure  28 , lifting off the old backbone assembly  14 , and installing the new backbone assembly.  
         [0035]    In FIG. 2, tooling  24  is affixed to tooling plate  20 , but no worktable  22  is used in this embodiment. Conversely, in FIG. 3, worktable  22  is affixed to tooling plate  20  but no tooling  24  is used. Hence, it can be seen that either or both the tooling  24  and/or worktable  22  can be mounted to the same tooling plate  20 , or that two individual tooling plates could be used. Furthermore, depending upon the particular workstation application, the orientation of the tooling plate  20  may be changed. In the preferred embodiment, the tooling plate  20  is oriented vertically instead of horizontally, since it is typically much easier to mount tooling to a vertical tooling plate. However, the present invention is not limited to having a vertically oriented tooling plate configuration. For example, a horizontally mounted tooling plate configuration, where the longitudinal axis of the I-beam support member  18  is horizontal, would be preferable for horizontally disposed tooling such as a horizontal milling machine.  
         [0036]    [0036]FIGS. 6 and 7 illustrate how the tooling plate  20  is mounted to I-beam support member  18 . Backbone assembly  14  includes tooling plate  20  and at least two guiding assemblies  40 , one on each side of the beam. In the preferred embodiment, four guiding assemblies  40  are used, each separated from the others on the tooling plate  20  as shown in FIG. 3. Each pair of guiding assemblies  40  is positioned on tooling plate  20  to engage the corresponding edges of the flanges of I-beam member  18 . Four large guide pins  44 , each comprised of a dowel pin pressed into an aperture in the tooling plate  20  in an interference fit, serve to slide along the edges of the I-beam flange as the tooling plate  20  is raised and lowered. One guide pin  44  is positioned near each corner of the tooling plate  20 , as shown in FIG. 3, such that they appropriately guide the tooling plate to prevent binding and misalignment.  
         [0037]    Each guiding assembly  40  includes a clamping plate  46 , two clamping screws  48 , two pivot studs  50 , and a bearing plate  52 , as most clearly shown in FIG. 7. Each clamping plate  46  has two clearance holes  54  near its center line that are unthreaded and slightly larger in diameter than the major thread diameters of clamping screws  48  for passage of the clamping screws. Tooling plate  20  includes corresponding threaded apertures  56  for receiving threaded portions of clamping screws  48 . Pivot studs  50  are threaded into tooling plate  20  as shown, such that they are positioned near the outermost edge of the clamping plate  46 . Finally, bearing plate  52 , having two clearance holes  58  similar to those of clamping plate  46 , is positioned between the rear face of the tooling plate  20  and the clamping plate  46 . Bearing plate  52  is constructed of a material having a low coefficient of friction and a relatively high wear rate, such as an ultra-high molecular weight (UHMW) polymer. One surface of bearing plate  52  is clamped against the flange of I-beam  18  by the clamping plate  46 .  
         [0038]    Using this configuration, the tooling plate  20 , clamping plate  46 , clamping screw  48 , pivot stud  50 , and bearing plate  52  cooperate to form guiding assembly  40  which can be closed by tightening clamping screws  48 . This causes the outer side of clamping plate  46  to pivot about the outermost tip of pivot stud  50  and the inner side of the clamping plate  46  to press the bearing plate  52  against the inner side of the flange of I-beam  18  to form a channel guide. This guiding assembly, in conjunction with guide pins  44 , allows the tooling plate  20  to be movable and positioned anywhere along the center portion of I-beam  18  without an undesirably large amount of lateral play or looseness. As will be seen below, the weight of the tooling plate  20  is supported by a wedge-shaped piece of steel that is trapped between the front face  18   a  of I-beam  18  and a rear surface  20   b  of tooling plate  20 .  
         [0039]    As shown in FIGS. 6 through 8, movable support structure  14  also includes a wedge assembly  60  which, in the preferred embodiment, is housed within a lower portion of tooling plate  20 . Wedge assembly  60  includes a wedge plate  62  and a recess or pocket  64  disposed within the rear surface  20   b  of tooling plate  20 , which is facing the front surface  18   a  of I-beam  18 . The floor  64   a  of pocket  64  is generally flat but is sloped at a predetermined angle from the rear surface  20   b  of tooling plate  20 . Wedge plate  62  is housed within pocket  64 . Wedge plate  62  also has a sloping surface  62   a  having an angle complementary to that of recess floor  64   a . As will be seen below, sloped floor  64   a  functions as a first wedging surface, and the sloped surface  62   a  of wedge plate  62  functions as a second wedging surface. In the preferred embodiment, the rear face  62   b  of wedge plate  62  is serrated to ensure that the wedge plate does not slip along the front surface  18   a  of the I-beam  18 .  
         [0040]    [0040]FIG. 7 illustrates that wedge plate  62  is disposed inside pocket  64  and arranged such that the wider portion of both pocket  64  and wedge plate  62  are oriented downwards. If wedge plate  62  is moved upwardly, the corresponding wedging surfaces  62   a  and  64   a  force the tooling plate  20  to move perpendicularly away from the front face  18   a  of the beam. As this occurs, guiding assemblies  40  prevent tooling plate  20  from moving further away, and the rear surface of wedge plate  62  pressing against the front surface  18   a  of tooling plate  20  secures the backbone assembly  14  to the I-beam support member  18 . The orientation of wedge plate  62  and pocket  64  are selected so that an increase in downward force upon tooling plate  20  will also cause wedge plate  62  to bear more firmly against surface  18   a  of I-beam  18 , thereby increasing the frictional force constraining tooling plate  20 . In other words, wedge assembly  60  is constructed and arranged such that any further downward motion of tooling plate  20  (parallel to the longitudinal axis of the I-beam  18 ) applies even more force to wedge plate  62  against the beam  18 . Therefore, the more force that is applied to the tooling plate  20  substantially along the longitudinal axis of I-beam  18 , either due to the weight of the workpiece  26  or the force of the tooling  24 , then the tighter wedge plate  62  will lock against front surface  18   a  of the I-beam  18 . Wedge assembly  60  is thereby self-tightening.  
         [0041]    Wedge assembly  60  also includes a release lever  70  having its center portion clamped to the front face  20   a  of tooling plate  20 . In the preferred embodiment, release lever  70  is constructed of ⅜-inch diameter hot rolled steel bar stock. As shown in FIG. 8, the center portion of release lever  70  includes a tab or tongue  72  that engages a slot  74  in wedge plate  62 , since tooling plate  20  has a cutout  76  through which tongue  72  is projected through pocket  64  into to wedge plate  62 . In the preferred embodiment, one end of release lever  70  is offset to one side of tooling plate  20  and formed as a handle  78 .  
         [0042]    When the operator lifts handle  78  of release lever  70  upwardly, tongue  72  and wedge plate  62  are forced downwardly, thereby disengaging wedge plate surface  62   b  from beam surface  18   a  in preparation for repositioning tooling plate  20  to a new height. After the wedging action has been released, tooling plate  20  can be raised or lowered to any point along the center-working portion of the I-beam  18 . Similarly, if tooling plate  20  itself is raised, wedge plate  62  moves downwardly relative to tooling plate  20  and the wedging action is also removed.  
         [0043]    Conversely, if the operator presses downwardly on handle  78  of release lever  70 , tongue  72  and wedge plate  62  are forced upwardly, thereby engaging first wedging surface  62   a  with second wedging surface  64   a  to tightly engage wedge plate  62  against front surface  18   a  of I-beam  18 . Once wedge plate  62  is raised into place, any downward motion of tooling plate  20  will further force wedge plate surface  62   b  against beam surface  18   a  and prevent any further motion of tooling plate  20 . Hence, the force of gravity on backbone assembly  14  and/or the force applied by tooling  24  against worktable  22  (if they are not affixed to the same tooling plate  20 ) will serve to further increase the securing force directly against the surface of I-beam  18  and further decrease the ability of the backbone assembly  14  to slip.  
         [0044]    Note that the coefficient of static friction of wedge plate  62  upon I-beam  18 , and, similarly, the force securing the position of tooling plate  20 , can be increased by texturing either the rear gripping surface  62   b  of wedge plate  62  or the front surface  18   a  of I-beam  18 . In the preferred embodiment, the rear surface of wedge plate  62  includes transverse serrations or diamond knurling or some other texturing, such that no additional machining has to be done to I-beam  18 .  
         [0045]    Also note that one of the principal aspects of the present invention is the correspondence of sloping surfaces  62   a  and  62   b . Note that if corresponding sloping surfaces were not used, then any downward force on tooling plate  20  would just try to pry the bottom portion of tooling plate  20  away from beam  18 , acting unevenly against only two guiding assemblies  40 . Furthermore, the downward force of tooling plate  20  would not be translated by  90  degrees to be applied evenly as a normal force against the I-beam surface  18   a  or distributed evenly across the rear surface  62   b  of the wedge plate  62 . Although this uneven application of forces may work in some light-duty applications, it is preferable that the force provided by the wedge plate  62  be applied approximately normal to the face of the I-beam, i.e., 90 degrees to the longitudinal axis of support member  18 .  
         [0046]    One skilled in the art may further note that the use of a recess or pocket  64  in the back surface of the tooling plate  20  is not the only way to form a second sloping surface. It should be understood that an additional wedge plate may be affixed to the rear surface  20   b  of the tooling plate  20  to provide the second sloping surface. Moreover, a simple angled cut-off of the lower edge of the tooling plate  20  could alternatively be used, and perhaps be the most economical approach. In the preferred embodiment, the sloping surface is at an angle of approximately 4 degrees from the longitudinal axis of the I-beam  18 . However, it is contemplated that any angle within the range of 2 degrees to 30 degrees would also serve the function of efficiently translating the downward forces applied to the tooling plate into inward forces applied against the I-beam. In the preferred embodiment, angles of 10 degrees or less are favored.  
         [0047]    The use of recess or pocket  64 , however, provides an additional advantage in the preferred embodiment. The use of pocket  64  also serves to enclose wedge plate  62  such that it remains in the correct position and orientation between the tooling plate  20  and the I-beam  18  at all times, whether or not the tongue  72  of lever arm  70  are designed to serve this purpose. In the preferred embodiment, pocket  64  also holds wedge plate  62  during assembly of the wedge assembly  60 . However, if a pocket is not used, wedge plate  62  can be held in place with a flexible cord or spring or equivalent.  
         [0048]    Backbone assembly  14  is typically too heavy to be repositioned manually by the operator. This would most certainly be the case with worktable  22 , tooling  24 , and safety guard structure  28  installed on tooling plate  20 . Therefore, several mechanisms have been provided to raise and lower backbone assembly  14 . These mechanisms may also be used to replace the tooling plate  20  with another tooling plate for a different operation at the same workstation.  
         [0049]    In the preferred embodiment, tooling plate  20  includes one or two lifting eyes, shown in FIG. 3 and FIG. 4 as shackles  80 . These shackles would be attached to a shop crane, or block and tackle, or other overhead lifting apparatus to raise and lower the backbone assembly. Tooling plate  20  may also be provided with lifting pockets (not shown) to facilitate engagement of a lift truck to provide for raising or lowering tooling plate  20  to a new position.  
         [0050]    If the tooling or worktable height is to be adjusted more frequently, such as the situation where there is a large amount of human operator intervention required at a particular workstation, an alternative lifting apparatus can be used. As shown in FIGS. 3 and 4, a hydraulic or air cylinder assembly  82 , having a cylinder  84  and a rod  86  powered by an external hydraulic or air powered unit (not shown), is provided under tooling plate  20  for adjusting the height of the backbone assembly  14 . Alternatively, any other type of jack apparatus, even an automobile jack, could be used.  
         [0051]    Accordingly, after the height of tooling plate  20  is adjusted using cylinder assembly  82 , the operator would push handle  78  downward to engage wedge plate  62 . The operator would then release the force from cylinder assembly  82 , whereupon gravity acting on the backbone assembly  14  would cause the complementary sloping surfaces of the wedging assembly  60  to force gripping surface  62   b  of wedge plate  62  tighter against the surface  18   a  of the I-beam  18 . This action locks tooling plate  20  into the desired new position. As mentioned above, any additional downward forces, caused either by the weight of workpiece  26  resting on worktable  22 , or by the forces applied by separately mounted tooling  24  against workpiece  26 , would cause wedge plate  62  to grip tighter. Hence, even though the backbone assembly  14  is adjustable to an infinite number of positions within the I-beam adjustment range, the present invention provides a locking function that is extremely strong. In the preferred embodiment, the wedge assembly  60  can support a load of over 1000 pounds without slipping.  
         [0052]    The present invention may be used in a variety of other tooling and assembly cell configurations. In particular, I-beam support member  18  does not have to be vertical as in the preferred embodiments. It is contemplated that the same wedge assembly  60  could be used with a horizontal beam orientation for use with horizontal milling or drilling machining applications. Although the vertical force of gravity will not be assisting to increase the wedging and locking forces in a horizontal orientation, the horizontal force applied by the tooling against the workpiece would serve to do so.  
         [0053]    The dimensions of the workstation of the preferred embodiment are as follows:  
         [0054]    Base  16 : 964 mm wide by 900 mm deep by 362 mm high;  
         [0055]    I-beam support member  18 : 250 mm wide by 265 mm deep by 2000 mm high;  
         [0056]    Tooling plate  20 : 395 mm wide by 1225 mm tall by 48 mm thick;  
         [0057]    Worktable  22 : 390 mm wide by 305 deep by 25 mm thick;  
         [0058]    Safety guard structure  28 : 1000 mm wide by 1100 mm tall by 700 mm deep;  
         [0059]    Worktable support bracket  42 : 250 mm deep by 155 mm high by 25 mm thick with 45 degree angle from the far edge;  
         [0060]    Bearing plate  52 : 148 mm tall by 76 mm wide by 6.4 mm thick;  
         [0061]    Wedge plate  62 : 76 mm wide by 95 tall by 21 mm thick at bottom (thickest) tapering at 4 degrees to 14 mm thick at top (thinnest) and having a tongue slot of 36 mm wide by 17 mm high, and having 6 mm by 6 mm wide by 3 mm tall cross-hatched points on the rear surface.  
         [0062]    Lever arm  70 : 425 mm long (central part) with 200 mm arm with 65 mm handle made of 10 mm diameter rod;  
         [0063]    Lever arm tongue  72 : 46 mm long by 28 wide by 10 mm thick;  
         [0064]    Tooling plate pocket  64 : 90 mm wide by 125 mm tall by 22 mm deep at bottom of wedge (deepest) sloping at 4 degrees to top of the wedge (shallowest);  
         [0065]    Tooling plate cutout  76 : 64 mm wide by 75 mm tall;  
         [0066]    Hydraulic cylinder assembly  82 : 400 mm high when at the bottom of stroke, and add 305 mm when at the top of stroke.  
         [0067]    While specific embodiments of the present invention have been shown and described herein, further modifications and improvements may be made by those skilled in the art. In particular, it should be noted that more than one tooling plate assembly could be used on the same beam to hold both the tooling and the workpiece. Moreover, a tooling plate  20  may be placed on both the front and rear sides of a single beam. Support member  18  may also be disposed horizontally upon or above a floor, and wedge assembly  60  used to secure position against a load force not related to weight. Numerous modifications may also be made to customize the present invention for various other applications. All such modifications, which retain the basic underlying principles disclosed and claimed herein, are within the scope and spirit of the invention.