Abstract:
A screw assembly for maintaining a substantially constant gap between adjacent components includes a first screw including: an exterior surface including a first threaded surface; and an inner wall defining a bore, the bore being coaxial with a longitudinal axis of the first screw, the inner wall including a second threaded surface, wherein one of the first threaded surface or the second threaded surface is arranged with a right-hand thread, and the other one of the first threaded surface or the second threaded surface is arranged with a left-hand thread.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Field of the Invention 
         [0002]    The present invention relates generally to a screw assembly and method for controlling tolerances related to stacking components, and more particularly to a screw assembly and method which can provide for interlocking of adjacent components, while maintaining locational tolerances such as a constant spacing between the components. 
         [0003]    2. Description of Related Art 
         [0004]    Various mechanical applications involve adjacent structural components, some of which may be in contact with one another, and others which may instead be spaced apart from one another. In some situations where adjacent structural components are spaced apart, tight locational tolerances may play a significant role in performance or effectiveness of the particular application. That is, maintaining a particular spacing between components in some systems or applications may be important to the functionality of the system. 
         [0005]    In some of these applications, a particular spacing between adjacent components may be difficult to establish and maintain without slight variations, for example, minor increases or decreases in the gap or spacing size. In these cases, it may be difficult to establish a stable structural connection between components, or a desired gap or spacing may be either too large or too small to create a sturdy or effective connection using traditional methods. 
         [0006]    One such application may be in the field of phased array antennas, which have seen an increase in the range of application in recent years in fields such as the defense market, including applications in communications and radar systems, as well as in various other commercial markets. For example, a phased array antenna developed by the Raytheon company, may include a radiator having a plurality of transmit/receive integrated microwave module (TRIMM) plates or columns arranged in a column assembly, and a plurality of radiating elements extending from each of the columns in the column assembly. Polarization of such a phased array antenna depends on, for example, the orientation or the alignment of the electric field radiated by the phased array antenna. A particular array orientation generates a fixed electric field alignment across all the elements of the assembly, and as such, small variations in spacing between the columns in the column assembly may have a large impact on the effectiveness, stability, and/or optimization of certain performance characteristics of the phased array antenna. Therefore, positional precision is more important for certain portions of such column assemblies, for example, the radiating elements. 
         [0007]    In these phased array antennas, if adjacent plates or columns are stacked to contact one another, the relative positioning between radiating elements may be affected by manufacturing variations in the plates or columns, for example, variations or inconsistencies in plate thicknesses. Furthermore, in such column assemblies, as the number of columns in the column assemblies increases, any plate inconsistencies may cause additional deviations from a desired spacing between the radiating elements, as error may be compounded based on the increased number of columns, and performance degradation of the antenna as a whole may further be magnified. As such, it may be desirable to provide a certain amount of clearance between adjacent plates, in order to eliminate or reduce spacing inconsistencies between the radiating elements that may be caused by manufacturing variations of the columns. In such arrangements, the columns can therefore be aligned according to positioning of the radiating elements, and the plates may then be secured in the desired positions to eliminate or reduce such variations. 
       SUMMARY OF THE INVENTION 
       [0008]    Embodiments of the present invention provide a screw assembly and method for more effectively controlling tolerances related to stacking and interlocking components. 
         [0009]    According to aspects of an embodiment of the present invention, a screw assembly for maintaining a substantially constant gap between adjacent components includes a first screw including: an exterior surface including a first threaded surface; and an inner wall defining a bore, the bore being coaxial with a longitudinal axis of the first screw, the inner wall including a second threaded surface, wherein one of the first threaded surface or the second threaded surface is arranged with a right-hand thread, and the other one of the first threaded surface or the second threaded surface is arranged with a left-hand thread. 
         [0010]    The first screw may have a first end and a second end, and may further have a head portion positioned at the first end adjacent to the first threaded surface, wherein the bore has an opening at the first end on the head portion and extends towards the second end. The head portion may be substantially cylindrical. The opening may include a countersink. 
         [0011]    At least one of the first threaded surface or the second threaded surface may include a flange portion. 
         [0012]    The screw assembly may further include a second screw including: a shaft portion including a threaded surface; and a head portion positioned on one end of the shaft portion, wherein an outer diameter of the shaft portion corresponds to the an inner diameter of the bore of the first screw and the threaded surface of the second screw is arranged with a thread that corresponds to the thread of the second threaded surface of the first screw, and wherein an outer diameter of the head portion is greater than or equal to the outer diameter of the shaft portion. 
         [0013]    The second screw may have a first end and a second end, wherein the head portion is positioned on the first end, and wherein a friction device is arranged on the shaft portion adjacent or near the second end. 
         [0014]    The screw assembly may further include a first component and a second component, wherein the first screw is positioned in the first component and the second screw is positioned in the second component, and wherein the first screw and the second screw are configured to engage. The second screw may be configured to advance into the bore of the first screw when rotated in a first direction, and the first screw may be configured to advance out of a bore of the first component when rotated in the first direction. In an initial position the first screw may be positioned in a first bore of the first component and the second screw may be positioned in a second bore of the second component, and in a clamped position, the first screw and the second screw may be engaged such that an end of the first screw abuts the second component to prevent movement of the second component towards the first component, and the head portion of the second screw abuts the second component to prevent movement of the second component away from the first component. 
         [0015]    According to aspects of another embodiment of the present invention, a method for maintaining a substantially constant gap between a first component and a second component includes: inserting a first screw into a bore of the first component, the first screw including an exterior threaded surface having a left-hand thread corresponding to a threaded surface of the bore of the first component, and an inner wall defining a bore and including a second threaded surface having a right-hand thread; aligning the second component to be adjacent to and separated by a gap from the first component, wherein a bore of the second component is substantially aligned with the bore of the first component; inserting a second screw into the bore of the second component and towards the first component, the second screw including a threaded surface having a right-hand thread corresponding to the second threaded surface of the first screw, and a head adjacent to the threaded surface; rotating the second screw in a clockwise direction to engage with the first screw; further rotating the second screw in the clockwise direction, wherein the second screw rotates the first screw in the clockwise direction and advances the first screw towards the second component until the first screw contacts a first surface of the second component; further rotating the second screw in the clockwise direction to advance the second screw into the bore of the first screw, until the head of the second screw contacts a second surface of the second component opposite the first surface. 
         [0016]    An alignment device may align the second component with the first component and to maintain the gap. 
         [0017]    The method may further include connecting the first component and the second component with at least a third screw spaced apart from the first screw and the second screw. 
         [0018]    A third screw configured to be substantially the same shape as the first screw may be inserted into the second component, and a fourth screw configured to be substantially the same shape as the second screw may be inserted into a third component, wherein the third screw and the fourth screw engage and clamp the second component and the third component together while maintaining a substantially constant gap corresponding to the substantially constant gap between the first component and the second component. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0019]    The accompanying drawings, together with the specification, illustrate exemplary embodiments of the present invention, and, together with the description, serve to explain the principles of the present invention, of which: 
           [0020]      FIG. 1  shows an exploded perspective view of a portion of a column assembly of a phased array antenna in accordance with an embodiment of the present invention; 
           [0021]      FIG. 2  schematically illustrates a top view of a column assembly of a phased array antenna in accordance with an embodiment of the present invention; 
           [0022]      FIG. 3  shows a perspective view of a screw assembly in accordance with an embodiment of the present invention; 
           [0023]      FIGS. 4A and 4B  illustrate a side view and a cross-sectional view of a set screw from the screw assembly of  FIG. 3 ; 
           [0024]      FIG. 5  illustrates a side view of a screw from the screw assembly of  FIG. 3 ; 
           [0025]      FIGS. 6A-6D  illustrate a method of interlocking adjacent components using a screw assembly in accordance with an embodiment of the present invention; and 
           [0026]      FIG. 7  is a block diagram showing a method of interlocking adjacent components using a screw assembly in accordance with an embodiment of the present invention. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0027]    Hereinafter, certain exemplary embodiments according to the present invention will be described with reference to the accompanying drawings. Some of the elements that are not essential to the complete understanding of the present invention are omitted for clarity. In addition, similar elements that appear in different drawings may be referred to by using the same or similar reference numerals. 
         [0028]      FIG. 1  is an exploded perspective view of a portion of a column assembly of a phased array antenna in accordance with an embodiment of the present invention, and  FIG. 2  is a schematic illustration of a top view of an assembled column assembly of a phased array antenna in accordance with an embodiment of the present invention. Phased array antennas having column assemblies similar to the column assemblies  101  illustrated in  FIGS. 1 and 2  have been developed by the Raytheon company, and include a plurality of TRIMM plates or columns  111 , which may be arranged adjacent to each other and spaced apart from one another. Each of the plates or columns  111  may include a plurality of supports  113  for inserting or installing radiating elements associated with the phased array antenna. Other elements may be associated with the phased array antennas, for example, feeds for electrically connecting the plates or columns  111 , and interconnecting elements  115  for holding the plates or columns  111  together and/or spaced apart at a substantially constant distance from one another. 
         [0029]    In a phased array antenna such as the one described above, polarization of the antenna depends on the orientation and/or alignment of the electric field radiated by the elements of the phased array antenna. This, in turn, may depend on, for example, a spacing between the plates and/or their associated radiating elements, the electrical and/or mechanical intercommunication between the various elements, and/or the shape of the radiating elements. For example, in the phased array antenna of  FIGS. 1 and 2 , when the column assembly  101  is in an assembled state, gaps  201  may exist between adjacent columns  111 . Such gaps may be used, for example, to provide clearance for feeds located between the columns which electrically connect the columns and their associated radiating elements and/or other elements that are positioned between the columns, or for example, to provide an exact spacing to accomplish a desired alignment between said radiating elements. Since accurate alignment of the radiating elements, rather than of the columns, is typically desirable, the gaps  201  may also serve to reduce or eliminate variations in the spacing of the radiating elements from, for example, inconsistencies or discrepancies between the thickness of the columns  111  due to, for example, manufacturing variances. Therefore, the gaps  201  can insure a more accurate spacing of the radiating elements, independent of the actual shapes or spacing between the columns  111  themselves. Additionally, the gaps  201  may exist between adjacent columns  111 , for example, to improve electrical communication between columns across the feeds, and to discourage potential cross-talk between other portions or elements of the columns themselves. 
         [0030]    After installation of a particular phased array antenna, arrangement of the antenna elements will result in a fixed electric field alignment across all the elements of the array assembly. As such, small variations in spacing between the columns in the column assembly will affect the fixed electric field. Furthermore, as the number of plates or columns  111  in a column assembly increases, any variations exhibited between any two of the columns  111  in an assembly may be compounded and magnified across the entire column assembly, having a large and potentially debilitating impact on the effectiveness, stability, and/or optimization of certain performance characteristics of the phased array antenna. Accordingly, an accurate positioning between the radiating elements of adjacent columns becomes even more significant. 
         [0031]    Therefore, in an application such as the phased array antenna described above, it may be desirable to implement a screw assembly which can maintain a desired or predetermined gap or distance  201  between two adjacent elements (e.g., columns  111  in the above example), such that any undesired variations between such spacing can be reduced or minimized, in order to improve performance of the system or application. Furthermore, with an adjustable screw assembly, variations in the gaps  201  between the columns  111  themselves can be more readily navigated, such that the screw assembly can be adjusted to bridge a wide range of distances between adjacent columns  111 , and then effectively maintain a particular distance. While the above system serves as an example in which embodiments of the present invention can be applied, it is to be understood that the application of the embodiments of the present invention should not be limited to the above system, and that the present invention can be applied to various other applications in which it may be desirable, for example, to maintain and effectively control tolerances associated with a preferred spacing between adjacent stacked elements. 
         [0032]    Description of a screw assembly including set screw  301  and screw  311  in accordance with an embodiment of the invention will be described herein, with reference to  FIGS. 3-5 .  FIG. 3  shows a perspective view of a screw assembly in accordance with an embodiment of the present invention. Referring to  FIG. 3 , an embodiment of the screw assembly includes a set screw  301  and a screw  311 .  FIG. 4A  illustrates a side view of a set screw, for example, the set screw  301  from  FIG. 3 , while  FIG. 4B  illustrates a cross-sectional view of a set screw, for example, the set screw  301  from  FIG. 3 , in accordance with an embodiment of the present invention. Meanwhile,  FIG. 5  illustrates a side view of a screw, for example, the screw  311  from  FIG. 3 , in accordance with an embodiment of the present invention. 
         [0033]    Referring to  FIGS. 3 ,  4 A, and  4 B, set screw  301  includes a threaded shaft  303 . In some embodiments, such as in the illustrated embodiments, the set screw  301  may include a substantially cylindrical head region  305  on one end of the shaft  303 . In some embodiments, the head region  305  may have a diameter that is substantially equal to or larger than a diameter of the threaded shaft  303 . In these embodiments, the substantially cylindrical head region  305  may have a substantially smooth exterior. The set screw  301  may also include a threaded bore  307  that is arranged to be substantially coaxial with a longitudinal axis of the set screw  301 . The threaded bore  307  may extend along an entire length of the set screw  301 , including the threaded shaft portion  303 , as well as the head portion  305  in embodiments which include such a head portion. As such, the threaded bore  307  may include openings on opposite ends of the set screw  301 . In some embodiments, the threaded bore  307  may include a countersink approximate at least one of the openings (e.g., as seen near the opening on the head portion  305  in  FIGS. 3 and 4B ). The countersink may promote or facilitate alignment and mating of the screw  311  upon insertion of the screw  311  into the bore  307  of the set screw  301 . 
         [0034]    In embodiments of the present invention, the set screw  301  may be configured such that the thread on threaded shaft  303  is arranged to be threaded in a different direction than the thread on the threaded bore  307 . That is, in embodiments where the threaded shaft  303  on the outside of set screw  301  is a left-hand thread, the threaded bore  307  on the inside of set screw  301  will be arranged to have a right-hand thread. Correspondingly, in the above-described embodiment, the screw  311  is configured to have its own threaded shaft portion  313  which is threaded with a right-hand thread and sized to correspond to the threaded bore  307  of the set screw  301 . That is, the threaded shaft  303  of set screw  301  and the threaded shaft  313  of screw  311  will be arranged in opposite directions. 
         [0035]    Referring to  FIGS. 3 and 5 , in addition to the threaded shaft  313 , the screw  311  may also include a head portion  315 . The head portion  315  may also be substantially cylindrical and have a diameter that is greater than or equal to a diameter of the threaded shaft  313  of screw  311 . Generally, a maximum diameter of screw  311  will be equal to or smaller than a maximum diameter of the set screw  301 . The head portion  315  of screw  311  may include one of a number of different interfaces for rotation or advancement of the screw  311 . The interface of screw  311  illustrated in  FIG. 3  is illustrated in the form of a hexagonal socket  317 , but in other embodiments, the interface may be, for example, a flathead socket, a Philips socket, or various other types of interfaces. The structure of the screw  311  is generally solid, and screw  311  typically will not have a bore similar to the bore  307  implemented into set screw  301 . Furthermore, the screw  311  may also include a friction device  319  on threaded shaft  313 , for increasing friction with the set screw  301  upon engagement with the set screw  301 . The friction device  319  may be one of a variety of different devices which may cause friction upon contact with threaded bore  307  of set screw  301 , for example, a fastener coating such as Nylok, or for example, a change or inconsistency in the threads of the threaded shaft  313 . Various other types of friction devices  319  may also be applied to screw  311 , and as such, friction device  319  is schematically illustrated in  FIG. 5  as a block. 
         [0036]    Operation of the screw assembly will now be described, with reference to  FIGS. 6A-6D  and  7 .  FIGS. 6A-6D  illustrate steps for a method of interlocking adjacent components using a screw assembly in accordance with an embodiment of the present invention, including cross-sectional views of two adjacent housings and incorporation of a screw with a set screw of a screw assembly.  FIG. 7  is a corresponding block diagram showing a method of interlocking adjacent components using a screw assembly in accordance with an embodiment of the present invention. 
         [0037]    Referring to  FIG. 7 , in block  701 , a set screw is inserted and screwed into a threaded bore of a first housing. An example is illustrated in  FIG. 6A , where set screw  301  is inserted into a threaded bore  603  of a first housing  601 . First housing  601  may be one of two adjacent plates, for example, plates similar to plates  111  as described with reference to  FIGS. 1 and 2 , or may be any of various other types of components or housings. Bore  603  is threaded to correspond to threaded shaft  303  of set screw  301 . In some embodiments, set screw  301  may be inserted into bore  603  during manufacture of housing  601 . In other embodiments, set screw  301  may be inserted into bore  603  just prior to installation of the screw assembly to hold two adjacent housings together. In embodiments where threaded shaft  303  of set screw  301  is a left hand-thread, screwing-in of set screw  301  into housing  601  involves counter-clockwise rotation of set screw  301 . 
         [0038]    In block  703 , the first housing  601  is aligned with a second housing  611 , as also illustrated in  FIG. 6A . The first housing  601  and the second housing  611  may be aligned and held, such that a preferred gap or distance separates them, as described with reference to  FIGS. 1 and 2 . Maintaining of a constant desired distance may be achieved, for example, by an alignment jig that maintains the distance between two adjacent housings during assembly of the column assembly. In other embodiments, various other structures and methods may be used to hold adjacent plates or housings together prior to installation of the screw assemblies. Furthermore, in some embodiments, the bores  603  of housings  601  may be below or outside a visual surface of the housing  601 , such that when an adjacent housing  611  is positioned at a desired spacing from housing  601 , the set screws  301  that were inserted in housing  601  may be concealed from view. 
         [0039]    In block  705 , a screw  311  is inserted into a bore  613  of the second housing  611 , which is sized to correspond to the threaded shaft  313  of screw  311 . Referring to  FIG. 6A , insertion of screw  311  into bore  613  of housing  611  advances screw  311  towards set screw  301 . In some embodiments, bore  613  of second housing  611  may be threaded, with a right-hand thread to correspond to threaded shaft  313  of screw  311 . In other embodiments, bore  613  may not be threaded, and may be sized, for example, to be slightly larger than a largest diameter of the threaded shaft  313  of screw  311 , such that screw  311  can freely move in bore  613 . 
         [0040]    In block  707 , the screw is rotated in a first direction with, for example, a screwing-in tool corresponding to an interface or socket on the screw, to engage the screw with the set screw. In these embodiments, bore  613  of housing  611  will be substantially aligned with bore  603  of first housing  601 . Referring to previously described embodiments where the threaded shaft  311  of screw  313  is a right-hand thread, upon contact of screw  311  with set screw  301 , clockwise rotation of screw  311  will cause screw  311  to engage set screw  301  and advance a first distance into bore  307  of set screw  301 , for example, as illustrated in  FIG. 6B . In the previously described embodiments in which set screw  301  is out of view after alignment of housings  601  and  611 , engagement of screw  311  with set screw  301  may further be facilitated by a countersink at the opening of bore  307  of set screw  301  as previously described. In these embodiments of the present invention, blind access and adjustment control of the screw assembly can be achieved, such that engagement and adjustment of the screw assembly can be accomplished while the set screw  301  and the interface between set screw  301  and screw  311  are out of view. 
         [0041]    As previously discussed, in some embodiments, at least a portion of threaded shaft  313  of screw  311  and/or approximate bore  307  of set screw  301  may be coated with, for example, Nylok, or any of various other fastener coatings or compounds which may serve to increase a frictional force between the surfaces of threaded shaft  313  of screw  311  and threaded bore  307  of set screw  301 . Friction may alternatively be established, for example, by a manipulation or variation in the thread or thread spacing of either the threaded shaft  313  of screw  311  or the threaded bore  307  of set screw  301 , or by any of various other friction devices  319 . This may induce, for example, a temporary hold between screw  311  and set screw  301 , such that continued rotation of the screw  311  will also result in corresponding rotation of the set screw  301 . 
         [0042]    In block  709 , rotation of screw  311  continues in a same direction as the rotation in block  707 . That is, in previously described embodiments, since screw  311  was rotated in a clockwise direction, rotation of screw  311  continues in the clockwise direction in block  709 . Conversely, in embodiments in which screw  311  is rotated in a counter-clockwise direction in block  707 , continued rotation of screw  311  in the counter-clockwise direction would occur in block  709 . Due to the friction between screw  311  and set screw  301  caused by, for example, the friction device  319  on screw  311  or set screw  301  as described in reference to block  707 , continued rotation of screw  311  will also cause a corresponding rotation of set screw  301 . As described above with respect to  FIGS. 1 ,  2 , and  6 A, in embodiments where threaded shaft  313  of screw  311  is a right-hand thread, threaded shaft  303  of set screw  301  will conversely be a left-hand thread. Therefore, rotation of set screw  311  in a clockwise direction will cause the screw  311 /set screw  301  combination to advance away from first housing  601 , such that set screw  301  begins to rotate out of bore  603  of first housing  601  and towards a surface  615  of second housing  611  that faces first housing  601 , as seen in  FIG. 6C . Continued rotation of the screw  311 /set screw  301  combination in the clockwise direction will eventually result in substantially cylindrical head portion  305  of set screw  301  contacting or abutting against the surface  615  of the second housing  611 . Upon contact of the head portion  305  of set screw  301  against the surface  615  of the second housing  611 , advancement of the set screw  301  away from the first housing  601  stops. At this point, a substantially fixed positioning is established between the first housing  601  and the set screw  301 , such that and end of the set screw  301  nearest to the second housing  611  serves as an abutment or support for maintaining a minimum distance or gap between the first housing  601  and the second housing  611 . 
         [0043]    In block  711 , after abutment of set screw  301  against surface  615 , rotation of screw  311  is further continued in the same direction as rotation in blocks  707  and  709 . Therefore, in the embodiments previously described, rotation of set screw  311  continues on a clockwise direction. Here, a force of the second housing  611  pushing against the set screw  301  and preventing further advancement of the set screw  301  away from the first housing  601  is generally greater than a force holding the screw  311  and set screw  301  together, for example, by the friction device  319  as previously described. Furthermore, since the distance between the first housing  601  and the second housing  611  may be additionally fixed or supported by, for example, an alignment jig in some embodiments, such additional support may also deter or prevent further movement of the set screw  301  away from the first housing  601 . 
         [0044]    Accordingly, after abutment of head portion  305  of set screw  301  with surface  615  of the second housing  611 , the abutment causes release of the temporary hold between screw  311  and set screw  301  (e.g., from the friction device  319 ), such that screw  311  may thereafter freely rotate independent of set screw  301 . As described above, at this point, set screw  301  is deterred from further advancement away from the first housing  601  and maintains a minimum distance or gap between first housing  601  and second housing  611 . After release of the temporary hold between screw  311  and set screw  301 , the continued clockwise rotation of screw  311  therefore advances screw  311  further into bore  307  of set screw  301 , as seen in  FIG. 6D . Rotation of screw  311  is continued until a side of head portion  315  of screw  311  comes into contact with a second side or face  617  of the second housing  611  adjacent to the bore  613 . In other words, screw  311  may be advanced into set screw  301  until screw  311  has been tightened against side  617  of the second housing  611 . 
         [0045]    Such a tightened configuration, as illustrated in  FIG. 6D , can be viewed as a clamped position, where the distance between the first housing  601  and the second housing  611  has been substantially fixed, such that the head portion  305  of the set screw  301  substantially prevents movement of the second housing  611  any closer to the first housing  601 , while the head portion  315  of the screw  311  substantially prevents movement of the second housing any further away from the first housing  601 . As such, a desired or preferred gap between the first housing  601  and the second housing  611  can be maintained. Thereafter, in embodiments where an alignment jig or other device or mechanism was utilized to hold the housings together during application of the screw assembly, said device or mechanism can be removed. 
         [0046]    In embodiments where multiple adjacent columns or components are stacked, implementation of the screw assembly or assemblies can be sequentially performed, such that after two adjacent components have been clamped together, a third component can then be clamped to one of the two adjacent components, and a fourth component can then be clamped to the third component, etc. Such assembly can continue until the desired number of components have been stacked and clamped together, such that a constant column to column tolerance gap can be achieved and maintained. As discussed above, it is generally understood that, as the number of components or elements in a particular assembly increases, the gap variations and tolerances between each pair of adjacent components causes the total variance in the assembly to increase and get compounded. Where performance of a particular application is dependent on, for example, an exact spacing between components, such as with respect to column assemblies for phased array antennas as described above, the screw assemblies in accordance with aspects of the present invention can reduce or minimize errors or variations associated with the gaps between adjacent components, such that a significant number of additional components may be added to the stack, while maintaining the desired tolerance control, such that performance of the phased array antennas can be improved. 
         [0047]    In embodiments of the present invention, a screw assembly can be utilized to stack components and to control tolerances associated with maintaining a preferred distance or gap between adjacent components in a stack. By utilizing an adjustable screw assembly according to embodiments of the present invention, components may be held at a desired distance, independent of and irrespective of manufacturing tolerances of the components themselves. Such a screw assembly may also be beneficial, for example, where a desired gap between components may be too great to maintain and keep substantially constant when no additional structural connections are implemented. Furthermore, in certain applications, the additional structural tie between components provided by the screw assemblies according to embodiments of the present invention may improve the stability of column assemblies or other structures, and to help them meet certain performance characteristics, such as tactical vibration requirements. 
         [0048]    In some embodiments, the assemblies described above may be modified, or additional features may be added to or supplement the assemblies, without departing from the spirit or scope of the present invention. For example, in some embodiments, flanges may be used on one or more of the screw elements instead of screw threads. In other embodiments the screw assemblies may further be supplemented by regular screw elements positioned at other portions of adjacent components. In such embodiments, the screw assemblies according to an embodiment of the present invention may first be installed to maintain a particular distance or gap between adjacent components, and regular screw elements may then be installed to provide additional structural support between the adjacent components after the desired gap has been established. 
         [0049]    While the present invention has been described in connection with certain exemplary embodiments, it is to be understood that the invention is not limited to the disclosed embodiments, but is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims, and equivalents thereof.